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Selective listening of concurrent auditory stimuli: An event-related potential study

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Abstract

This study employed behavioral and electrophysiological measures to examine selective listening of concurrent auditory stimuli. Stimuli consisted of four compound sounds, each created by mixing a pure tone with filtered noise bands at a signal-to-noise ratio of +15 dB. The pure tones and filtered noise bands each contained two levels of pitch. Two separate conditions were created; the background stimuli varied randomly or were held constant. In separate blocks, participants were asked to judge the pitch of tones or the pitch of filtered noise in the compound stimuli. Behavioral data consistently showed lower sensitivity and longer response times for classification of filtered noise when compared with classification of tones. However, differential effects were observed in the peak components of auditory event-related potentials (ERPs). Relative to tone classification, the P1 and N1 amplitudes were enhanced during the more difficult noise classification task in both test conditions, but the peak latencies were shorter for P1 and longer for N1 during noise classification. Moreover, a significant interaction between condition and task was seen for the P2. The results suggest that the essential ERP components for the same compound auditory stimuli are modulated by listeners' focus on specific aspects of information in the stimuli.

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... Continuous EEG activity was recorded using the Advanced Neuro Technology EEG system and a 64 channel Waveguard Cap (ANT, Inc., Enschede, Netherlands) (Rao et al. 2010). The EEG data were band-pass filtered (0.016 to 200 Hz) and digitized using a sampling rate of 512 Hz. ...
... Post hoc repeated-measures univariate ANOVAs were performed on all significant main effects. To examine region effects (frontal, central, parietal, midline frontal, midline central, and midline parietal), the electrodes were grouped for the statistical analysis (Rao et al. 2010;Zhang et al. 2011) and electrode region was included as a between-subjects factor in the ANOVA (6 levels). The electrode groups used in the analysis were as follows: The frontal electrodes included F3, F5, F7, FC3, FC5, FT7, F4, F6, F8, FC4, FC6, and FT8. ...
... Midline parietal electrodes included P1, Pz, P2, and POz. To be consistent with our previous publications that examined hemispheric effects (Rao et al. 2010;Zhang et al. 2011), an initial ANOVA was performed on the nonmidline frontal, central, and parietal electrodes across right and left electrode sites and midline electrodes were excluded from the analysis. However, because no significant hemispheric effects or interactions were found, the hemisphere factor was excluded from our reported ANOVA model and we collapsed the nonmidline left, and right electrodes for the frontal, temporal, and parietal sites, respectively. ...
Article
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The present study used auditory event-related potential (ERP) measures to investigate how the adult brain differentially processes fricative speech sounds with and without the use of a hearing aid. Synthetic stimuli for sa, sha, as, and ash were created to control for the spectral cues in the vowel and consonant portions based on naturally recorded speech. ERP responses were recorded for each sound in an unaided and a hearing aid condition using a randomized block design. At least 160 trials per stimulus were averaged for each sound per subject. The results indicated that (1) the ERP responses in the unaided condition significantly differed from the aided condition, (2) N1 peak amplitudes and latencies to s and sh significantly differed in both unaided and aided conditions as well as in syllable-initial and syllable final positions, and (3) phonological context significantly affected N1-P2 responses. Despite some minor differences, these results are consistent with our previous ERP study using natural speech stimuli, which suggests that amplification through hearing aids alters neural coding of acoustic features in speech sounds. [This work was supported by the Graduate Research Partnership Program and Grant-in-Aid, University of Minnesota.].
... The average impedance of electrodes was below 5 kOhms. The same recording was used in previous ERP studies (Rao, Zhang, & Miller, 2010;& Miller & Zhang, 2014). ERP waveform analysis was completed offline in BESA (Version 6.0, MEGIS Software GmbH, Germany) and MATLAB (Version 8.0). ...
... The search windows for N1 and P2 were respectively at 100-200 ms and 140-300 ms for the noise condition. Averaged peak amplitudes were quantified with a 10 ms window centered at the peaks (Rao, Zhang, & Miller, 2010). ...
... Based on the grand average waveforms in the quiet and noise conditions, MMN peak latency, relative to the pre-stimulus interval, was assessed within the time window of 100 -300 ms. The MMN amplitude quantification used an integration (averaging) window of 10 ms centered at peak (Rao, Zhang, & Miller, 2010). ...
... The sounds were binaurally delivered via insert earphones (Etymotic Research ER-3A). The presentation level was at 60 dB sensation level individually calibrated based on hearing threshold (Rao, Zhang, & Miller, 2010). Each visual scene lasted 2000 ms on screen. ...
... The EEG data were collected with the Advanced Neuro Technology system with 64 channels. The same system was used in previous auditory ERP studies (Rao et al., 2010; Zhang et al., 2011). The sampling rate was 512 Hz, and the bandpass was between 0.016 and 200 Hz. ...
... A midline parietaloccipital group (MPO) included POz and Oz. Similar regional groupings for electrodes were applied in previous studies (Rao et al., 2010; Zhang et al., 2011). The ERP waveforms were analyzed using areas under the waveform for given time windows instead of peaks at the regional electrode sites. ...
Article
How linguistic expressions are contextually constrained is of vital importance to our understanding of language as a formal representational system and a vehicle of social communication. This study collected behavioral and event-related potential (ERP) data to investigate neural processing of two entity-referring spatial demonstrative expressions, this one and that one, in different contexts involving the speaker, the hearer and the referred-to object. Stimulus presentation varied distance and gaze conditions with either semantically congruent or incongruent audiovisual pairings. Behavioral responses showed that distance determined the demonstrative form only in joint gaze conditions. The ERP data for the joint gaze conditions further indicated significant congruent vs. incongruent differences in the post-stimulus window of 525–725 ms for the hearer-associated spatial context. Standardized Low Resolution Brain Electromagnetic Tomography (sLORETA) showed left temporal and bilateral parietal activations for the effect. The results provide the first neural evidence that the use of spatial demonstratives in English is obligatorily influenced by two factors: (1) shared gaze of speaker and hearer, and (2) the relative distance of the object to the speaker and hearer. These findings have important implications for cognitive-linguistic theories and studies on language development and social discourse.
... Subjects were asked to verify that they could hear the acoustic stimuli clearly at a comfortable level before proceeding to MEG recording. This stimulus presentation method based on individually calibrated audiometric sensation level has previously been applied in our hearing research studies [54,55] and other MEG studies [50,56]. ...
... To derive a composite measure of differences in MEG activity for the averaged ON and OFF responses for the ramped and damped stimuli, we analyzed the global field power (GFP) for each stimulus and each subject. Similar to the calculation of GFP for EEG signals (e.g., [54]), the GFP is the root mean square of magnetic fields across all the 61 recording sensor sites at each time sample. The GFP measure has been shown to be an objective and reliable quantification method independent of sensor selection in EEG and MEG studies [60][61][62]. ...
... One potential confounding factor in comparing auditory evoked responses for time-varying sounds is the lack of balance in selective attention to the different stimuli [54,97,98]. Previous behavioral and imaging studies have used an active listening task to demonstrate the selective attentional bias for sounds with rising intensity [15,16,99]. ...
Article
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This magnetoencephalography (MEG) study investigated evoked ON and OFF responses to ramped and damped sounds in normal-hearing human adults. Two pairs of stimuli that differed in spectral complexity were used in a passive listening task; each pair contained identical acoustical properties except for the intensity envelope. Behavioral duration judgment was conducted in separate sessions, which replicated the perceptual bias in favour of the ramped sounds and the effect of spectral complexity on perceived duration asymmetry. MEG results showed similar cortical sites for the ON and OFF responses. There was a dominant ON response with stronger phase-locking factor (PLF) in the alpha (8–14 Hz) and theta (4–8 Hz) bands for the damped sounds. In contrast, the OFF response for sounds with rising intensity was associated with stronger PLF in the gamma band (30–70 Hz). Exploratory correlation analysis showed that the OFF response in the left auditory cortex was a good predictor of the perceived temporal asymmetry for the spectrally simpler pair. The results indicate distinct asymmetry in ON and OFF responses and neural oscillation patterns associated with the dynamic intensity changes, which provides important preliminary data for future studies to examine how the auditory system develops such an asymmetry as a function of age and learning experience and whether the absence of asymmetry or abnormal ON and OFF responses can be taken as a biomarker for certain neurological conditions associated with auditory processing deficits.
... Continuous EEG activity was recorded using the Advanced Neuro Technology EEG system and a 64 channel Waveguard Cap (ANT, Inc., Enschede, Netherlands) (Rao et al. 2010). The EEG data were band-pass filtered (0.016 to 200 Hz) and digitized using a sampling rate of 512 Hz. ...
... Post hoc repeated-measures univariate ANOVAs were performed on all significant main effects. To examine region effects (frontal, central, parietal, midline frontal, midline central, and midline parietal), the electrodes were grouped for the statistical analysis (Rao et al. 2010;Zhang et al. 2011) and electrode region was included as a between-subjects factor in the ANOVA (6 levels). The electrode groups used in the analysis were as follows: The frontal electrodes included F3, F5, F7, FC3, FC5, FT7, F4, F6, F8, FC4, FC6, and FT8. ...
... Midline parietal electrodes included P1, Pz, P2, and POz. To be consistent with our previous publications that examined hemispheric effects (Rao et al. 2010;Zhang et al. 2011), an initial ANOVA was performed on the nonmidline frontal, central, and parietal electrodes across right and left electrode sites and midline electrodes were excluded from the analysis. However, because no significant hemispheric effects or interactions were found, the hemisphere factor was excluded from our reported ANOVA model and we collapsed the nonmidline left, and right electrodes for the frontal, temporal, and parietal sites, respectively. ...
Article
To determine whether auditory event-related potentials (ERPs) to a phonemic fricative contrast ("s" and "sh") show significant differences in listening conditions with or without a hearing aid and whether the aided condition significantly alters a listener's ERP responses to the fricative speech sounds. The raw EEG data were collected using a 64-channel system from 10 healthy adult subjects with normal hearing. The fricative stimuli were digitally edited versions of naturally produced syllables, /sa/ and /∫a/. The evoked responses were derived in unaided and aided conditions by using an alternating block design with a passive listening task. Peak latencies and amplitudes of the P1-N1-P2 components and the N1' and P2'' peaks of the acoustic change complex (ACC) were analyzed. The evoked N1 and N1' responses to the fricative sounds significantly differed in the unaided condition. The fricative contrast also elicited distinct N1-P2 responses in the aided condition. While the aided condition increased and delayed the N1 and ACC responses, significant differences in the P1-N1-P2 and ACC components were still observed, which would support fricative contrast perception at the cortical level. Despite significant alterations in the ERP responses by the aided condition, normal-hearing adult listeners showed distinct neural coding patterns for the voiceless fricative contrast, "s" and "sh," with or without a hearing aid.
... The stimulus presentation time was determined from pilot runs to minimize the amounts of eye movement and to maximize participants' comfort and confidence level during the experiment. Sounds were presented binaurally via inserted earphones (Etymotic Research ER-3A) at 60 dB sensation level calibrated according to an individual's hearing threshold (Rao, Zhang, & Miller, 2010). The inter-trial interval was 750 ms (Fig. 2). ...
... The electrodes were grouped into nine electrode regions. Similar regional groupings of electrodes have been used in previous ERP studies (Rao et al., 2010;Zhang et al., 2011). At the anterior scalp, a left frontal (LF) group included F4, F6, F8, FC6, C6, and TP8. ...
... As in our previous work (Stevens & Zhang, 2013), the Global Field Power (GFP) was calculated in order to consider overall differences in electric potential for all 64 electrodes at every sampling point of the epoch window (Hamburger & Burgt, 1991;Lehmann & Skrandies, 1980). Sampling points for both the congruent and incongruent conditions were translated into Z scores relative to the 100 ms baseline GFP activity (Rao et al., 2010). Significant effects were taken into account when the differences (p < 0.01) persisted for at least 40 ms. ...
Article
This electrophysiological study investigated the relationship between language and nonverbal socio-spatial context for demonstrative use in speech communication. Adult participants from an English language group and a Japanese language group were asked to make congruency judgment for simultaneous presentation of an audio demonstrative phrase in their native language and a picture that included two human figures as speaker and hearer, as well as a referent object in different spatial arrangements. The demonstratives (“this” and “that” in English, and “ko,” “so,” and “a” in Japanese) were varied for the visual scenes to produce expected and unexpected combinations to refer to an object based on its relative spatial distances to the speaker and hearer. Half of the trials included an accompanying pointing gesture in the picture, and the other half did not. Behavioral data showed robust congruency effects with longer reaction time for the incongruent trials in both subject groups irrespective of the presence or absence of the pointing gesture. Both subject groups also showed a significant N400-like congruency effect in the event-related potential responses for the gesture trials, a finding predicted from previous work (Stevens & Zhang, 2013). In the no-gesture trials, the English data alone showed a P600 congruency effect preceded by a negative deflection. These results provide evidence for shared brain mechanisms for processing demonstrative expression congruency, as well as language-specific neural sensitivity to encoding the co-expressivity of gesture and speech. [See full text at http://zhanglab.wdfiles.com/local--files/publications/Stevens_Zhang_JNL2014.pdf ]
... Hz; 512 Hz sample rate) using the Advanced Neuro Technology system and a 64 channel Waveguard Cap (Enschede, Netherlands) (Rao, Zhang, and Miller 2010). The cap used the standard 10-20 arrangement of the Ag/AgCl electrodes with additional intermediate positions. ...
... In order to examine electrode region and hemisphere effects, the electrodes were grouped for the statistical analysis (Miller and Zhang 2014b;Rao, Zhang, and Miller 2010). ...
Article
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Background: Cortical auditory event-related potentials are a potentially useful clinical tool to objectively assess speech outcomes with rehabilitative devices. Whether hearing aids reliably encode the spectrotemporal characteristics of fricative stimuli in different phonological contexts and whether these differences result in distinct neural responses with and without hearing aid amplification remain unclear. Purpose: To determine whether the neural coding of the voiceless fricatives /s/ and /ʃ/ in the syllable-final context reliably differed without hearing aid amplification and whether hearing aid amplification altered neural coding of the fricative contrast. Research Design: A repeated-measures, within subject design was used to compare the neural coding of a fricative contrast with and without hearing aid amplification. Study Sample: Ten adult listeners with normal hearing participated in the study. Data Collection and Analysis: Cortical auditory event-related potentials were elicited to an /ɑs/–/ɑʃ/ vowel-fricative contrast in unaided and aided listening conditions. Neural responses to the speech contrast were recorded at 64-electrode sites. Peak latencies and amplitudes of the cortical response waveforms to the fricatives were analyzed using repeated-measures analysis of variance. Results: The P2' component of the acoustic change complex significantly differed from the syllable-final fricative contrast with and without hearing aid amplification. Hearing aid amplification differentially altered the neural coding of the contrast across frontal, temporal, and parietal electrode regions. Conclusions: Hearing aid amplification altered the neural coding of syllable-final fricatives. However, the contrast remained acoustically distinct in the aided and unaided conditions, and cortical responses to the fricative significantly differed with and without the hearing aid.
... Selective attention is known to modulate neural responses at the cortical level (Fritz et al. 2003, Fritz et al. 2007, Rao, et al. 2010. Electrophysiological techniques are well suited to the noninvasive investigation of cortical functioning (see review in Luck 2014). ...
... This channel grouping procedure has been applied successfully in our previous hearing RAO ET AL. / EAR & HEARING, VOL. 38, NO. 1, 28-41 33 research studies (Rao et al. 2010;Zhang et al. 2011;Miller & Zhang 2014;Nie et al. 2014). A correlation analysis for change in behavioral measures and change in ERP measures across sessions was also conduced. ...
Article
The objectives of this study were to investigate the effects of hearing aid use and the effectiveness of ReadMyQuips (RMQ), an auditory training program, on speech perception performance and auditory selective attention using electrophysiological measures. RMQ is an audiovisual training program designed to improve speech perception in everyday noisy listening environments. Participants were adults with mild to moderate hearing loss who were first-time hearing aid users. After 4 weeks of hearing aid use, the experimental group completed RMQ training in 4 weeks, and the control group received listening practice on audiobooks during the same period. Cortical late event-related potentials (ERPs) and the Hearing in Noise Test (HINT) were administered at prefitting, pretraining, and post-training to assess effects of hearing aid use and RMQ training. An oddball paradigm allowed tracking of changes in P3a and P3b ERPs to distractors and targets, respectively. Behavioral measures were also obtained while ERPs were recorded from participants. After 4 weeks of hearing aid use but before auditory training, HINT results did not show a statistically significant change, but there was a significant P3a reduction. This reduction in P3a was correlated with improvement in d prime (d') in the selective attention task. Increased P3b amplitudes were also correlated with improvement in d' in the selective attention task. After training, this correlation between P3b and d' remained in the experimental group, but not in the control group. Similarly, HINT testing showed improved speech perception post training only in the experimental group. The criterion calculated in the auditory selective attention task showed a reduction only in the experimental group after training. ERP measures in the auditory selective attention task did not show any changes related to training. Hearing aid use was associated with a decrement in involuntary attention switch to distractors in the auditory selective attention task. RMQ training led to gains in speech perception in noise and improved listener confidence in the auditory selective attention task.
... Recent studies have employed neurophysiological methods to evaluate LE, specifically electroencephalography, or EEG, in adults with and without hearing loss (e.g., Benikos, Johnstone, & Roodenrys, 2013;Bernarding, Strauss, Hannemann, Seidler, & Corona-Strauss, 2013;Bertoli & Bodmer, 2014Enge, Fleischhauer, Brocke, & Strobel, 2008;Erlbeck, Kubler, Kotchoubey, & Veser, 2014;Finke, Büchner, Ruigendijk, Meyer, & Sandmann, 2016;Fournier, Wilson, & Swain, 1999;Jamison et al., 2016;Marsella et al., 2017;Miles et al., 2017;Mulert, Menzinger, Leicht, Pogarell, & Hegerl, 2005;Obleser, Wostmann, Hellbernd, Wilsch, & Maess, 2012;Obleser & Kotz, 2011;Rao, Zhang, & Miller, 2010;Strauß, Kotz, & Obleser, 2013;Weisz & Obleser, 2014;Wisniewski et al., 2015; for a recent review, see McGarrigle et al., 2014). EEG provides a noninvasive measure of changes in electrical responses from populations of neurons firing in synchrony (Nunez, 1995). ...
... These include the N100, an index of attentional engagement, and the N200, an index of attention and inhibitory control (e.g., Donchin, Ritter, & McCallum, 1978;Erlbeck et al., 2014;Patel & Azzam, 2005). Increased N100 amplitudes have been elicited by changes in input demands, such as easy versus hard discrimination tasks, as well as changes in task instruction-a no-pressure condition compared with an effortful, respondas-fast-as-possible condition (Erlbeck et al., 2014;Finke et al., 2016;Mulert et al., 2005;Obleser & Kotz, 2011;Rao et al., 2010). These changes indicate increased engagement of cognitive resources for attention when processing stimuli in more difficult listening conditions. ...
Article
Purpose Improving the ability to listen efficiently in noisy environments is a critical goal for hearing rehabilitation. However, understanding of the impact of difficult listening conditions on language processing is limited. The current study evaluated the neural processes underlying semantics in challenging listening conditions. Method Thirty adults with normal hearing completed an auditory sentence processing task in 4-talker babble. Event-related brain potentials were elicited by the final word in high- or low-context sentences, where the final word was either highly expected or not expected, followed by a 4-alternative forced-choice response with either longer (1,000 ms), middle (700 ms), or shorter (400 ms) response time deadlines (RTDs). Results Behavioral accuracy was reduced, and reactions times were faster for shorter RTDs. N400 amplitudes, reflecting ease of lexical access, were larger when elicited by target words in low-context sentences followed by shorter compared with longer RTDs. Conclusions These results reveal that more neural resources are allocated for semantic processing/lexical access when listening difficulty increases. Differences between RTDs may reflect increased attentional allocation for shorter RTDs. These findings suggest that situational listening demands can impact the demands for cognitive resources engaged in language processing, which could significantly impact listener experiences across environments.
... The pitch-synchronous-overlap-add method in Praat (Boersma & Weenink, 2015) was used to normalize word duration. Auditory stimuli were presented at 60 dB sensation level (Rao, Zhang, & Miller, 2010). There were 160 trials in each block (phonetic and prosodic). ...
... Overall, our results indicate that different brain regions are recruited for each of these conditions for both the N400 and LPR. This may reflect the underlying mechanisms of how the individuals selectively tune to one dimension of information (Rao, Zhang & Miller, 2010). For the N400 component, we observed left hemisphere lateralization in the phonetic condition but right hemisphere lateralization for the prosodic condition. ...
... The average impedance of electrodes was below 5 kOhms. The same recording setup was used in previous ERP studies (Rao et al., 2010;Miller and Zhang, 2014). ERP waveform analysis was completed offline in BESA (Version 6.0, MEGIS Software GmbH, Germany) and MATLAB (Version 8.0). ...
... The search windows for N1 and P2 were respectively at 100e200 ms and 140e300 ms for the noise condition. Averaged peak amplitudes were quantified with a 10 m s window centered at the peaks (Rao et al., 2010). ...
... The ERP epoch length was 700 ms, including a pre-stimulus 216 baseline of 100 ms. The ERP data were band-pass filtered at 0.53 – 40 Hz and re-referenced to the 217Rao et al., 2010, Zhang et al., 2011). Sustained latency intervals of at least 20 ms or longer (Rao et al., 2010, Zhang et al., 2011) were highlighted where -scores indicated the GFP was significant. ...
... The ERP data were band-pass filtered at 0.53 – 40 Hz and re-referenced to the 217Rao et al., 2010, Zhang et al., 2011). Sustained latency intervals of at least 20 ms or longer (Rao et al., 2010, Zhang et al., 2011) were highlighted where -scores indicated the GFP was significant. 258 ...
Article
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The current study measured neural responses to investigate auditory stream segregation of noise stimuli with or without clear spectral contrast. Sequences of alternating A and B noise bursts were presented to elicit stream segregation in normal-hearing listeners. The successive B bursts in each sequence maintained an equal amount of temporal separation with manipulations introduced on the last stimulus. The last B burst was either delayed for 50% of the sequences or not delayed for the other 50%. The A bursts were jittered in between every two adjacent B bursts. To study the effects of spectral separation on streaming, the A and B bursts were further manipulated by using either bandpass-filtered noises widely spaced in center frequency or broadband noises. Event-related potentials (ERPs) to the last B bursts were analyzed to compare the neural responses to the delay vs. no-delay trials in both passive and attentive listening conditions. In the passive listening condition, a trend for a possible late mismatch negativity (MMN) or late discriminative negativity (LDN) response was observed only when the A and B bursts were spectrally separate, suggesting that spectral separation in the A and B burst sequences could be conducive to stream segregation at the pre-attentive level. In the attentive condition, a P300 response was consistently elicited regardless of whether there was spectral separation between the A and B bursts, indicating the facilitative role of voluntary attention in stream segregation. The results suggest that reliable ERP measures can be used as indirect indicators for auditory stream segregation in conditions of weak spectral contrast. These findings have important implications for cochlear implant (CI) studies – as spectral information available through a CI device or simulation is substantially degraded, it may require more attention to achieve stream segregation.
... amplitude may indicate the enhanced feedforward thalamocortical connectivity ascending to the primary auditory cortex (Rao et al., 2010;Yu et al., 2018). Moreover, unlike N250 and LNR, the P1 component is thought to reflect pre-attentive arousal and sound onset detection at the acoustic processing level (Pratt et al., 2008;Rao et al., 2010). ...
... amplitude may indicate the enhanced feedforward thalamocortical connectivity ascending to the primary auditory cortex (Rao et al., 2010;Yu et al., 2018). Moreover, unlike N250 and LNR, the P1 component is thought to reflect pre-attentive arousal and sound onset detection at the acoustic processing level (Pratt et al., 2008;Rao et al., 2010). This was corroborated by a domain-general effect with a similar pattern of enhanced P1 amplitude in response to formant -exaggerated nonspeech sounds as shown in the current study (Table 2 and Figure 4b). ...
Article
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The presence of vowel exaggeration in infant‐directed speech (IDS) may adapt to the age‐appropriate demands in speech and language acquisition. Previous studies have provided behavioral evidence of atypical auditory processing towards IDS in children with autism spectrum disorders (ASD), while the underlying neurophysiological mechanisms remain unknown. This event‐related potential (ERP) study investigated the neural coding of formant‐exaggerated speech and nonspeech in 24 4‐ to 11‐year‐old children with ASD and 24 typically‐developing (TD) peers. The EEG data were recorded using an alternating block design, in which each stimulus type (exaggerated/non‐exaggerated sound) was presented with equal probability. ERP waveform analysis revealed an enhanced P1 for vowel formant exaggeration in the TD group but not in the ASD group. This speech‐specific atypical processing in ASD was not found for the nonspeech stimuli which showed similar P1 enhancement in both ASD and TD groups. Moreover, the time‐frequency analysis indicated that children with ASD showed differences in neural synchronization in the delta‐theta bands for processing acoustic formant changes embedded in nonspeech. Collectively, the results add substantiating neurophysiological evidence (i.e., a lack of neural enhancement effect of vowel exaggeration) for atypical auditory processing of IDS in children with ASD, which may exert a negative effect on phonetic encoding and language learning. Lay summary Atypical responses to motherese might act as a potential early marker of risk for children with ASD. This study investigated the neural responses to such socially relevant stimuli in the ASD brain, and the results suggested a lack of neural enhancement responding to the motherese even in individuals without intellectual disability.
... There were 160 trials per block. Auditory stimuli were presented at 60 dB sensation level (Rao, Zhang & Miller, 2010). The presentation order for the phonetic and prosodic blocks was counterbalanced across participants. ...
... Overall, our results indicate that different 38 brain regions are recruited for each of these conditions for both the N400 and late positive response. This may reflect the underlying mechanisms of how the individuals selectively tune to one dimension of information (Rao, Zhang & Miller, 2010). For the N400 component, we observed left hemisphere lateralization in the phonetic condition but right hemisphere lateralization for the prosodic condition. ...
Thesis
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The present study utilized a cross-modal priming paradigm to investigate dimensional information processing in speech. Primes were facial expressions that varied in two dimensions: affect (happy, neutral, or angry) and mouth shape (corresponding to either /a/ or /i/ vowels). Targets were CVC words that varied by prosody and vowel identity. In both the phonetic and prosodic conditions, adult participants responded to congruence or incongruence of the visual-auditory stimuli. Behavioral results showed a congruency effect in percent correct and reaction time measures. Two ERP responses, the N400 and late positive response, were identified for the effect with systematic between-condition differences. Localization and time-frequency analyses indicated different cortical networks for selective processing of phonetic and emotional information in the words. Overall, the results suggest that cortical processing of phonetic and emotional information involves distinct neural systems, which has important implications for further investigation of language processing deficits in clinical populations.
... For more information about the theory of theta-regulated attention, we refer to Haab et al. (2011). In these studies, the N1 component was taken into accout as this component reflects selective attention effects related to an endogenous modulation of the incoming information (Hillyard et al. 1973;Rao et al. 2010;Hillyard et al. 1998). Furthermore, the instantaneous phase of singletrials in the alpha/ theta range was analyzed as it provides more information on the auditory information processing as averaged responses (Brockhaus-Dumke et al. 2008;Ponjavic-Conte et al. 2012). ...
Article
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In this study, we propose a novel estimate of listening effort using electroencephalographic data. This method is a translation of our past findings, gained from the evoked electroencephalographic activity, to the oscillatory EEG activity. To test this technique, electroencephalographic data from experienced hearing aid users with moderate hearing loss were recorded, wearing hearing aids. The investigated hearing aid settings were: a directional microphone combined with a noise reduction algorithm in a medium and a strong setting, the noise reduction setting turned off, and a setting using omnidirectional microphones without any noise reduction. The results suggest that the electroencephalographic estimate of listening effort seems to be a useful tool to map the exerted effort of the participants. In addition, the results indicate that a directional processing mode can reduce the listening effort in multitalker listening situations.
... For each session, continuous EEG activity was recorded using the Advanced Neuro Technology EEG system and a 64 channel Waveguard Cap [13]. Participants wore only one implant during the recording sessions, and the electrodes on the cap located near the device were deactivated during data acquisition. ...
... The observed effect on N1 amplitudes in CI users should be therefore interpreted in relation to the different degrees of effort that participants have probably invested in processing of the two tasks. Some studies reported an enhancement of N1 amplitudes with increasing task difficulty [Mulert et al., 2007;Rao et al., 2010]. Notably, when the task performance was entered as a covariate into the analysis of the N1 amplitudes in CI users in our study, the significance disappeared. ...
... However, Rao and colleagues associated the N1 component with task difficulty and task-related cognitive effort (Rao et al. 2010). Our findings fit with their interpretation, by revealing stronger N1 activity in speech stimuli as compared to nonspeech stimuli. ...
Article
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Healthy aging is typically associated with impairment in various cognitive abilities such as memory, selective attention or executive functions. Less well observed is the fact that also language functions in general and speech processing in particular seems to be affected by age. This impairment is partly caused by pathologies of the peripheral auditory nervous system and central auditory decline and in some part also by a cognitive decay. This cross-sectional electroencephalography (EEG) study investigates temporally early electrophysiological correlates of auditory related selective attention in young (20-32 years) and older (60-74 years) healthy adults. In two independent tasks, we systematically modulate the subjects' focus of attention by presenting words and pseudowords as targets and white noise stimuli as distractors. Behavioral data showed no difference in task accuracy between the two age samples irrespective of the modulation of attention. However, our work is the first to show that the N1-and the P2 component evoked by speech and nonspeech stimuli are specifically modulated in older adults and young adults depending on the subjects' focus of attention. This finding is particularly interesting in that the age-related differences in AEPs may be reflecting levels of processing that are not mirrored by the behavioral measurements.
... Continuous EEG activity was recorded from each listener using the Advanced Neuro Technology EEG system and a 64 channel Waveguard Cap (Rao et al. 2010;Miller & Zhang 2014). The Ag/AgCl electrodes on the cap were arranged in the standard 10-20 system with additional intermediate positions, and the ground electrode was located at the AFz position. ...
Article
Objective: The present training study aimed to examine the fine-scale behavioral and neural correlates of phonetic learning in adult postlingually deafened cochlear implant (CI) listeners. The study investigated whether high variability identification training improved phonetic categorization of the /ba/-/da/ and /wa/-/ja/ speech contrasts and whether any training-related improvements in phonetic perception were correlated with neural markers associated with phonetic learning. It was hypothesized that training would sharpen phonetic boundaries for the speech contrasts and that changes in behavioral sensitivity would be associated with enhanced mismatch negativity (MMN) responses to stimuli that cross a phonetic boundary relative to MMN responses evoked using stimuli from the same phonetic category. Design: A computer-based training program was developed that featured multitalker variability and adaptive listening. The program was designed to help CI listeners attend to the important second formant transition cue that categorizes the /ba/-/da/ and /wa/-/ja/ contrasts. Nine adult CI listeners completed the training and 4 additional CI listeners that did not undergo training were included to assess effects of procedural learning. Behavioral pre-post tests consisted of identification and discrimination of the synthetic /ba/-/da/ and /wa/-/ja/ speech continua. The electrophysiologic MMN response elicited by an across phoneme category pair and a within phoneme category pair that differed by an acoustically equivalent amount was derived at pre-post test intervals for each speech contrast as well. Results: Training significantly enhanced behavioral sensitivity across the phonetic boundary and significantly altered labeling of the stimuli along the /ba/-/da/ continuum. While training only slightly altered identification and discrimination of the /wa/-/ja/ continuum, trained CI listeners categorized the /wa/-/ja/ contrast more efficiently than the /ba/-/da/ contrast across pre-post test sessions. Consistent with behavioral results, pre-post EEG measures showed the MMN amplitude to the across phoneme category pair significantly increased with training for both the /ba/-/da/ and /wa/-/ja/ contrasts, but the MMN was unchanged with training for the corresponding within phoneme category pairs. Significant brain-behavior correlations were observed between changes in the MMN amplitude evoked by across category phoneme stimuli and changes in the slope of identification functions for the trained listeners for both speech contrasts. Conclusions: The brain and behavior data of the present study provide evidence that substantial neural plasticity for phonetic learning in adult postlingually deafened CI listeners can be induced by high variability identification training. These findings have potential clinical implications related to the aural rehabilitation process following receipt of a CI device.
... Based on the grand average waveforms in the quiet and noise conditions, MMN peak latency, relative to the pre-stimulus interval, was assessed within the time window of 100e300 ms. The MMN amplitude quantification used an integration (averaging) window of 10 ms centered at peak (Rao et al., 2010). ...
... The observed effect on N1 amplitudes in CI users should be therefore interpreted in relation to the different degrees of effort that participants have probably invested in processing of the two tasks. Some studies reported an enhancement of N1 amplitudes with increasing task difficulty [Mulert et al., 2007;Rao et al., 2010]. Notably, when the task performance was entered as a covariate into the analysis of the N1 amplitudes in CI users in our study, the significance disappeared. ...
Article
In normal-hearing listeners, localization of auditory speech involves stimulus processing in the postero-dorsal pathway of the auditory system. In quiet environments, bilateral cochlear implant (CI) users show high speech recognition performance, but localization of auditory speech is poor, especially when discriminating stimuli from the same hemifield. Whether this difficulty relates to the inability of the auditory system to translate binaural electrical cues into neural signals, or to a functional reorganization of auditory cortical pathways following long periods of binaural deprivation is unknown. In this electroencephalography study, we examined the processing of auditory syllables in postlingually deaf adults with bilateral CIs and in normal-hearing adults. Participants were instructed to either recognize ("recognition" task) or localize ("localization" task) the syllables. The analysis focused on event-related potentials and oscillatory brain responses. N1 amplitudes in CI users were larger in the localization compared with recognition task, suggesting an enhanced stimulus processing effort in the localization task. Linear beamforming of oscillatory activity in CI users revealed stronger suppression of beta-band activity after 200 ms in the postero-dorsal auditory pathway for the localization compared with the recognition task. In normal-hearing adults, effects for longer latency event-related potentials were found, but no effects were observed for N1 amplitudes or beta-band responses. Our study suggests that difficulties in speech localization in bilateral CI users are not reflected in a functional reorganization of cortical auditory pathways. New signal processing strategies of cochlear devices preserving unambiguous binaural cues may improve auditory localization performance in bilateral CI users. Hum Brain Mapp, 2013. © 2013 Wiley Periodicals, Inc.
... Selective attention is known to modulate neural responses at the cortical level (Fritz et al. 2003, Fritz et al. 2007, Rao, et al. 2010. Electrophysiological techniques are well suited to the noninvasive investigation of cortical functioning (see review in Luck 2014). ...
Article
Objectives: The objectives of this study were to investigate the effects of hearing aid use and the effectiveness of ReadMyQuips (RMQ), an auditory training program, on speech perception performance and auditory selective attention using electrophysiological measures. RMQ is an audiovisual training program designed to improve speech perception in everyday noisy listening environments. Design: Participants were adults with mild to moderate hearing loss who were first-time hearing aid users. After 4 weeks of hearing aid use, the experimental group completed RMQ training in 4 weeks, and the control group received listening practice on audiobooks during the same period. Cortical late event-related potentials (ERPs) and the Hearing in Noise Test (HINT) were administered at prefitting, pretraining, and post-training to assess effects of hearing aid use and RMQ training. An oddball paradigm allowed tracking of changes in P3a and P3b ERPs to distrac-tors and targets, respectively. Behavioral measures were also obtained while ERPs were recorded from participants. Results: After 4 weeks of hearing aid use but before auditory training , HINT results did not show a statistically significant change, but there was a significant P3a reduction. This reduction in P3a was correlated with improvement in d prime (d′) in the selective attention task. Increased P3b amplitudes were also correlated with improvement in d′ in the selective attention task. After training, this correlation between P3b and d′ remained in the experimental group, but not in the control group. Similarly, HINT testing showed improved speech perception post training only in the experimental group. The criterion calculated in the auditory selective attention task showed a reduction only in the experimental group after training. ERP measures in the auditory selective attention task did not show any changes related to training. Conclusions: Hearing aid use was associated with a decrement in involuntary attention switch to distractors in the auditory selective attention task. RMQ training led to gains in speech perception in noise and improved listener confidence in the auditory selective attention task.
... While the participants attention was mainly focused on maintaining the interval between button presses of ∼3 s, active/explicit processing of the auditory stimuli was not required to accomplish the task. At the same time, there are a variety of studies showing that auditory processing can be affected by specific task properties such as cognitive load, difficulty, repetition, and active vs. passive conditions (e.g., Lang and Kotchoubey, 2002;SanMiguel et al., 2008;Karns and Knight, 2009;Rao et al., 2010;Remijn and Kojima, 2010;Ben-David et al., 2011;Kam et al., 2011). From this perspective, it might be the case that the specific differences between musicians and non-musicians with respect to processing of voiced and unvoiced auditory stimuli only become apparent during conditions in which active/explicit processing of auditory input is required. ...
Article
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Musicians and musically untrained individuals have been shown to differ in a variety of functional brain processes such as auditory analysis and sensorimotor interaction. At the same time, internally operating forward models are assumed to enable the organism to discriminate the sensory outcomes of self-initiated actions from other sensory events by deriving predictions from efference copies of motor commands about forthcoming sensory consequences. As a consequence, sensory responses to stimuli that are triggered by a self-initiated motor act are suppressed relative to the same but externally-initiated stimuli, a phenomenon referred to as motor-induced suppression (MIS) of sensory cortical feedback. Moreover, MIS in the auditory domain has been shown to be modulated by the predictability of certain properties such as frequency or stimulus onset. The present study compares auditory processing of predictable and unpredictable self-initiated zero-delay speech sounds and piano tones between musicians and musical laymen by means of an event-related potential (ERP) and topographic pattern analysis (microstate analysis or EP mapping) approach. Taken together, our findings suggest that besides the known effect of MIS, internally operating forward models also facilitate early acoustic analysis of complex tones by means of faster processing time as indicated by shorter auditory N1-like microstate durations in the first ~ 200 ms after stimulus onset. In addition, musicians seem to profit from this facilitation also during the analysis of speech sounds as indicated by comparable auditory N1-like microstate duration patterns between speech and piano conditions. In contrast, non-musicians did not show such an effect.
... First, almost all previous ERP studies of auditory attention have involved sequential rather than simultaneous presentation of attended and ignored stimuli, and the mechanism of attention reflected by the N2pc appears to operate primarily or solely under conditions of simultaneous competition (see Luck & Hillyard, 1994b). Though some studies in the last decade have started to look at complex sound scenes and even simultaneously presented sounds (Rao, Zhang, & Miller, 2010), many of these studies have done so by looking at complex harmonics or mistuned harmonics (Alain, Arnott, & Picton 2001;Johnson, Hautus, & Clapp, 2003;Dyson, Alain & He, 2005;McDonald & Alain, 2005), or concurrent steady-state responses (Bidet-Caulet & Bertrand, 2005Bidet-Caulet et al. 2007;). Most sounds in these experiments were presented to both ears and lack the spatial separation that one would need to see an auditory analog of the N2pc effect (but see Deouell, Bentin, & Giard, 1998;Bidet-Caulet & Bertrand, 2005;Bidet-Caulet et al. 2007 for exceptions) or did not involve searching for a target in an unknown location (Paavilainen, Saarinen, Tervaniemi, & Näätänen, 1995;Näätänen, Paavilainen, Tiitinen, Jiang, & Alho,1993). ...
Article
Humans must often focus attention onto relevant sensory signals in the presence of simultaneous irrelevant signals. This type of attention has been explored in vision with the N2pc component, and the present study sought to find an analogous auditory effect. In Experiment 1, two 750-ms sounds were presented simultaneously, one from each of two lateral speakers. On each trial, participants indicated whether one of the two sounds was a pre-defined target. We found that targets elicited an N2ac component: a negativity in the N2 latency range at anterior contralateral electrodes. We also observed a later and more posterior contralateral positivity. Experiment 2 replicated these effects and demonstrated that they arose from competition between attended and unattended tones rather than reflecting lateralized effects of attention for individual tones. The N2ac component may provide a useful tool for studying selective attention within auditory scenes.
... The Global Field Power (GFP) was calculated as a measure of the magnitude of the MMR 88 . Unlike the waveform peak analysis at selected electrodes, the GFP provides an objective assessment of spatial scalp distribution in terms of the standard deviation of potential values for all electrodes at any sampling point in the epoch window 89 . ...
Article
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Recent studies reveal that tonal language speakers with autism have enhanced neural sensitivity to pitch changes in nonspeech stimuli but not to lexical tone contrasts in their native language. The present ERP study investigated whether the distinct pitch processing pattern for speech and nonspeech stimuli in autism was due to a speech-specific deficit in categorical perception of lexical tones. A passive oddball paradigm was adopted to examine two groups (16 in the autism group and 15 in the control group) of Chinese children's Mismatch Responses (MMRs) to equivalent pitch deviations representing within-category and between-category differences in speech and nonspeech contexts. To further examine group-level differences in the MMRs to categorical perception of speech/nonspeech stimuli or lack thereof, neural oscillatory activities at the single trial level were further calculated with the inter-trial phase coherence (ITPC) measure for the theta and beta frequency bands. The MMR and ITPC data from the children with autism showed evidence for lack of categorical perception in the lexical tone condition. In view of the important role of lexical tones in acquiring a tonal language, the results point to the necessity of early intervention for the individuals with autism who show such a speech-specific categorical perception deficit.
... In contrast to OAs, YAs only showed topographical differences corresponding to the timewindow of the P2 component between the two listening conditions. This might be linked to the role of the P2 time-window in allocation of attention to the salient stimulus during target detection [91,92]. For instance, Getzmann et al. [92] showed P2-peak changes when participants focused their attention and when the target speaker was salient during a spatial listening task. ...
Article
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Factors affecting successful listening in older adults and the corresponding electrophysiological signatures are not well understood. The present study investigated age-related differences in attention and temporal processing, as well as differences in the neural activity related to signal degradation during a number comparison task. Participants listened to digits presented in background babble and were tested at two levels of signal clarity, clear and degraded . Behavioral and electrophysiological measures were examined in 30 older and 20 younger neurologically-healthy adults. Relationships between performance on the number comparison task, behavioral measures, and neural activity were used to determine correlates of listening deficits associated with aging. While older participants showed poorer performance overall on all behavioral measures, their scores on the number comparison task were largely predicted (based on regression analyses) by their sensitivity to temporal fine structure cues. Compared to younger participants, older participants required higher signal-to-noise ratios (SNRs) to achieve equivalent performance on the number comparison task. With increasing listening demands, age-related changes were observed in neural processing represented by the early-N1 and later-P3 time windows. Source localization analyses revealed age differences in source activity for the degraded listening condition that was located in the left prefrontal cortex. In addition, this source activity negatively correlated with task performance in the older group. Together, these results suggest that older adults exhibit reallocation of processing resources to complete a demanding listening task. However, this effect was evident only for poorer performing older adults who showed greater posterior to anterior shift in P3 response amplitudes than older adults who were good performers and younger adults. These findings might reflect less efficient recruitment of neural resources that is associated with aging during effortful listening performance.
... Moreover, processing the pitch information can be confounded by other informational dimensions in the auditory stimuli. Selectively attending to task-relevant pitch processing may enhance the cortical activation for pitch encoding (Rao et al., 2010). Particularly, listeners with linguistic/musical expertise may recruit specialized cortical networks for linguistic or musical processing (Baumann et al., 2008;Zatorre and Gandour, 2008), which may override the subcortical sensory contribution to the behavioral performance (Bidelman, 2017). ...
Article
A current topic in auditory neurophysiology is how brainstem sensory coding contributes to higher-level perceptual, linguistic and cognitive skills. This cross-language study was designed to compare frequency following responses (FFRs) for lexical tones in tonal (Mandarin Chinese) and non-tonal (English) language users and test the correlational strength between FFRs and behavior as a function of language experience. The behavioral measures were obtained in the Garner paradigm to assess how lexical tones might interfere with vowel category and duration judgement. The FFR results replicated previous findings about between-group differences, showing enhanced pitch tracking responses in the Chinese subjects. The behavioral data from the two subject groups showed that lexical tone variation in the vowel stimuli significantly interfered with vowel identification with a greater effect in the Chinese group. Moreover, the FFRs for lexical tone contours were significantly correlated with the behavioral interference only in the Chinese group. This pattern of language-specific association between speech perception and brainstem-level neural phase-locking of linguistic pitch information provides evidence for a possible native language neural commitment at the subcortical level, highlighting the role of experience-dependent brainstem tuning in influencing subsequent linguistic processing in the adult brain.
... The auditory P1 and N1 are considered exogenous and time-locked to stimulus presentation. P1 (or P50) typically reflects arousal and sound onset detection (Pratt et al., 2008;Rao et al., 2010). N1 is sensitive to acoustic saliency (Näätänen & Picton, 1987;Pereira et al., 2014), audibility (Martin et al., 1999), and characteristic features of consonant and vowel categories (Digester et al., 2009;Sharma & Dorman, 1999;Tavabi et al., 2007;Zaehle et al., 2007;Zhang et al., 2005). ...
Article
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Children with autism often show atypical brain lateralization for speech and language processing, however, it is unclear what linguistic component contributes to this phenomenon. Here we measured event-related potential (ERP) responses in 21 school-age autistic children and 25 age-matched neurotypical (NT) peers during listening to word-level prosodic stimuli. We found that both groups displayed larger late negative response (LNR) amplitude to native prosody than to nonnative prosody; however, unlike the NT group exhibiting left-lateralized LNR distinction of prosodic phonology, the autism group showed no evidence of LNR lateralization. Moreover, in both groups, the LNR effects were only present for prosodic phonology but not for phoneme-free prosodic acoustics. These results extended the findings of inadequate neural specialization for language in autism to sub-lexical prosodic structures.
... P1 reflects the early sensory processing of auditory stimuli presumably generated in the auditory cortex (Herrmann & Knight, 2001;Liégeois-Chauvel et al., 1994). Larger P1 amplitudes are specifically associated with enhanced processing of auditory stimuli (Rao, Zhang, & Miller, 2010;Tang et al., 2013). Results demonstrate increased neuronal activity in response to auditory stimuli in children when they read a book or watched a movie compared to when they played a memory card game with a human partner. ...
Preprint
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Our ability to focus on a task and to ignore task-irrelevant stimuli is critical for efficient cognitive functioning. Attention control is especially required in the auditory modality as sound has privileged access to perception and consciousness. Despite this important function, little is known about auditory attention during typical everyday activities in childhood. We investigated the impact of task irrelevant sounds on attention during three everyday activities: playing a game, reading a book, watching a movie. During these activities, environmental novel sounds were presented within a sequence of standard sounds to 7 and 8 years old children and adults. We measured ERPs reflecting early sound processing and attentional orienting and theta power evoked by standard and novel sounds during these activities. Playing a game vs. reading or watching reduced early encoding of sounds in children and affected ongoing information processing and attention allocation in both groups. In adults, theta power was reduced during playing at midcentral brain areas. Results show a pattern of immature neuronal mechanisms underlying perception and attention of task irrelevant sounds in 7 and 8 year old children. While the type of activity affected the processing of irrelevant sounds in both groups, early stimulus encoding processes were more sensitive to the type of activities in children.
... For each subject, GFP values of each condition were translated into z-scores with the pre-stimulus 200 ms as baseline. Significant differences (p < 0.05) in z-scores between conditions that persisted for at least 20 ms in either group were highlighted (Rao et al., 2010;Zhang et al., 2011). Raw data and Material are available in OSF 1 . ...
Article
Full-text available
The aim of the present study was to investigate how Chinese-Malay bilingual speakers with Chinese as heritage language process semantic congruency effects in Chinese and how their brain activities compare to those of monolingual Chinese speakers using electroencephalography (EEG) recordings. To this end, semantic congruencies were manipulated in Chinese classifier-noun phrases, resulting in four conditions: (i) a strongly constraining/high-cloze, plausible (SP) condition, (ii) a weakly constraining/low-cloze, plausible (WP) condition, (iii) a strongly constraining/implausible (SI) condition, and (iv) a weakly constraining/implausible (WI) condition. The analysis of EEG data focused on two event-related potential components, i.e., the N400, which is known for its sensitivity to semantic fit of a target word to its context, and a post-N400 late positive complex (LPC), which is linked to semantic integration after prediction violations and retrospective, evaluative processes. We found similar N400/LPC effects in response to the manipulations of semantic congruency in the mono- and bilingual groups, with a gradient N400 pattern (WI/SI > WP > SP), a larger frontal LPC in response to WP compared to SP, SI, and WI, as well as larger centro-parietal LPCs in response to WP compared to SI and WI, and a larger centro-parietal LPC for SP compared to SI. These results suggest that, in terms of event-related potential (ERP) data, Chinese-Malay early bilingual speakers predict and integrate upcoming semantic information in Chinese classifier-noun phrase to the same extent as monolingual Chinese speakers. However, the global field power (GFP) data showed significant differences between SP and WP in the N400 and LPC time windows in bilinguals, whereas no such effects were observed in monolinguals. This finding was interpreted as showing that bilinguals differ from their monolingual peers in terms of global field power intensity of the brain by processing plausible classifier-noun pairs with different congruency effects.
... P2 latency to speech stimuli varied by azimuth angle was longer in the RUD and RAUHL subjects (Figure 4A), which reflects the greater cognitive effort required for cortical processing of speech and spatial cues in right-sided unilateral deafness (Tong et al., 2009;Rao et al., 2010). The longer P2 latencies in the RUD and RAUHL groups could be related to the increased reaction time for sound localization revealed by our behavioral data. ...
Article
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Profound unilateral deafness reduces the ability to localize sounds achieved via binaural hearing. Furthermore, unilateral deafness promotes a substantial change in cortical processing to binaural stimulation, thereby leading to reorganization over the whole brain. Although distinct patterns in the hemispheric laterality depending on the side and duration of deafness have been suggested, the neurological mechanisms underlying the difference in relation to behavioral performance when detecting spatially varied cues remain unknown. To elucidate the mechanism, we compared N1/P2 auditory cortical activities and the pattern of hemispheric asymmetry of normal hearing, unilaterally deaf (UD), and simulated acute unilateral hearing loss groups while passively listening to speech sounds delivered from different locations under open free field condition. The behavioral performances of the participants concerning sound localization were measured by detecting sound sources in the azimuth plane. The results reveal a delayed reaction time in the right-sided UD (RUD) group for the sound localization task and prolonged P2 latency compared to the left-sided UD (LUD) group. Moreover, the RUD group showed adaptive cortical reorganization evidenced by increased responses in the hemisphere ipsilateral to the intact ear for individuals with better sound localization whereas left-sided unilateral deafness caused contralateral dominance in activity from the hearing ear. The brain dynamics of right-sided unilateral deafness indicate greater capability of adaptive change to compensate for impairment in spatial hearing. In addition, cortical N1 responses to spatially varied speech sounds in unilateral deaf people were inversely related to the duration of deafness in the area encompassing the right auditory cortex, indicating that early intervention would be needed to protect from maladaptation of the central auditory system following unilateral deafness.
... This shows that P2 may codify the ambiguity of the stimulus or the effort for its perception. For instance, in a study using tones, Rao et al. (2010) reported a greater P2 amplitude for the stimuli easier to classify (equivalent to our stim1 and stim5) than for the more difficult ones (stim2, stim3 and stim4). ...
Thesis
Auditory Evoked Potential (AEP) is a neuroelectric response to an auditory stimulus that reflects the activities of a set of neurons along the pathways of the auditory system. This biopotential is used to aid in the diagnosis of hearing diseases and in the study of auditory processing in the human brain. The improvement of techniques for the acquisition, processing and analysis of biopotentials, makes it possible to deepen our knowledge about the auditory processing. For this, it is interesting to work with more complex stimuli, such as speech, which have more acoustic parameters that vary in time and frequency than the clicks or tones used in traditional audiometric tests. One of the ways to analyze speech processing by the human brain is through the study of categorical perception (CP) of phonemes. The categorical perception of speech sounds consists of the mapping of continuous changes in sound characteristics in discrete perceptual units during phonemic identification. The objective of this work is to investigate the neural correlates of categorical perception of phonemes in Brazilian Portuguese by analyzing the auditory evoked late response (AELR) within the scope of the acoustic characteristics of the phonemes, amplitude and latency of the responses, cortical regions involved, degree of attention to the acoustic task (passive or active) and the physical or psychophysical characteristics of the response. An experiment was carried out with tasks that involved the active and passive categorization of phonemes belonging to two different continua: one based on variations of the voice onset time (VOT), which represents a temporal acoustic cue, and another based on variations of the formant frequencies, a spectral characteristic of the stimulus. AELRs were acquired via electroencephalography (EEG). The analysis of the AELRs was performed in time and time-frequency domains in conjunction with behavioral data obtained from the participants' psychometric curves. In the time-domain the amplitudes and latencies of the AELR components, N1 and P2, were analyzed. In the time-frequency domain, data was represented through discrete wavelet coefficients. To extract the physical and psychophysical representations of the categorical coding we proposed an original regression technique that allows to work with a small amount of observations but large dimensions (a characteristic of our data set) we called, RoLDSIS. The regression coefficients and the N1 and P2 amplitudes and latencies were analyzed through contrast analysis of mixed effects models. The results showed that the categorical perception is affected by the acoustic cue but not by the task and it is coded around the P2 wave latency by the beta-band activity, a brain oscillation related to ambiguity and strength of categorical speech perception. It was observed that participants which present behaviorally stronger CP presented a larger difference between their physical and psychophysical neural representation of the stimuli. We also show that CP occurs when there is not attention to the auditory task but only for the formant based acoustic cue. Hemispheric differences were observed in the speech processing with stronger activity at the left hemisphere. Differences also were observed between frontal and temporal cortical regions where the temporal structures would perform, mainly, a spectrotemporal processing of the stimuli while the frontal structures would perform a psychophysical processing related to the CP. This study compared different dimensions related to categorical speech perception, with stimuli from Brazilian Portuguese, and confirmed many of the results found in the literature for other languages. Acquisitions were made noninvasively using a simple and reproducible protocol allowing that the analyzes we performed can be reproduced for study or evaluation of the categorical perception of participants.
... An Advanced Neuro Technology system with a REFA-72 amplifier (500-Hz sample rate; 0.016-to 200-Hz bandpass filter) and a 64-channel waveguard cap (Enschede, Netherlands) were used to record the continuous Electroencephalography (EEG) signal. The EEG cap contained shielded wires and Ag/AgCl electrodes arranged in the standard 10-20 system with additional intermediate positions (Rao et al., 2010). The ground electrode was located at the AFz site on the cap, and the average electrode impedance was kept below 10 kΩ for the entire recording session (approximately 90 min). ...
Article
Purpose Auditory sensory gating is a neural measure of inhibition and is typically measured with a click or tonal stimulus. This electrophysiological study examined if stimulus characteristics and the use of speech stimuli affected auditory sensory gating indices. Method Auditory event-related potentials were elicited using natural speech, synthetic speech, and nonspeech stimuli in a traditional auditory gating paradigm in 15 adult listeners with normal hearing. Cortical responses were recorded at 64 electrode sites, and peak amplitudes and latencies to the different stimuli were extracted. Individual data were analyzed using repeated-measures analysis of variance. Results Significant gating of P1–N1–P2 peaks was observed for all stimulus types. N1–P2 cortical responses were affected by stimulus type, with significantly less neural inhibition of the P2 response observed for natural speech compared to nonspeech and synthetic speech. Conclusions Auditory sensory gating responses can be measured using speech and nonspeech stimuli in listeners with normal hearing. The results of the study indicate the amount of gating and neural inhibition observed is affected by the spectrotemporal characteristics of the stimuli used to evoke the neural responses.
... This suggests enhanced neuronal processing of cues which are highly predictive of the target even at the earliest stages of cortical processing. This early neuronal enhancement may reflect an allocation of selective attention to the frequency of the cue that is most behaviorally relevant in a given stimulus block ( Woldorff et al., 1993 ;Rao et al., 2010 ;Fritz et al., 2007 ) and is consistent with the 'learned predictiveness' model of attention and associative learning ( Le Pelley et al., 2016 ;Mackintosh, 1975 ), whereby attention is preferentially allocated to cues that accurately predict behaviorally significant events. However, neither the amplitude nor the latency of the N1 component elicited by the cue tones was modulated by the predictability of the target. ...
Article
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Learning to anticipate future states of the world based on statistical regularities in the environment is a key component of perception and is vital for the survival of many organisms. Such statistical learning and prediction are crucial for acquiring language and music appreciation. Importantly, learned expectations can be implicitly derived from exposure to sensory input, without requiring explicit information regarding contingencies in the environment. Whereas many previous studies of statistical learning have demonstrated larger neuronal responses to unexpected versus expected stimuli, the neuronal bases of the expectations themselves remain poorly understood. Here we examined behavioral and neuronal signatures of learned expectancy via human scalp-recorded event-related brain potentials (ERPs). Participants were instructed to listen to a series of sounds and press a response button as quickly as possible upon hearing a target noise burst, which was either reliably or unreliably preceded by one of three pure tones in low-, mid-, and high-frequency ranges. Participants were not informed about the statistical contingencies between the preceding tone 'cues' and the target. Over the course of a stimulus block, participants responded more rapidly to reliably cued targets. This behavioral index of learned expectancy was paralleled by a negative ERP deflection, designated as a neuronal contingency response (CR), which occurred immediately prior to the onset of the target. The amplitude and latency of the CR were systematically modulated by the strength of the predictive relationship between the cue and the target. Re-averaging ERPs with respect to the latency of behavioral responses revealed no consistent relationship between the CR and the motor response, suggesting that the CR represents a neuronal signature of learned expectancy or anticipatory attention. Our results demonstrate that statistical regularities in an auditory input stream can be implicitly learned and exploited to influence behavior. Furthermore, we uncover a potential 'prediction signal' that reflects this fundamental learning process.
... The selective attention effect has been observed as an endogenous modulation of the N1 component. In Rao et al. (2010); Hillyard et al. (1998Hillyard et al. ( , 1973 the amplitude of N1/P2 components were enhanced in the case of attended in comparison to unattended stimuli. In many studies the effect of neural-correlates of attention is studied as an average of amplitudes of sufficiently large numbers of ERPs. ...
... Rufener et al. (2014) also found a larger N1 amplitude for older listeners in response to both speech and non-speech stimuli in selective attention tasks. This exaggerated response might be associated with task-related cognitive effort based on a tone classification task (Rao et al. 2010), where N1and P1 are enhanced during more difficult noise classification. However, P2 (~200 ms) responses to tones and gaps in noise, interestingly, do not show increased amplitude for older listeners (Alain and Snyder 2008;Lister et al. 2011). ...
Article
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Aging is associated with an exaggerated representation of the speech envelope in auditory cortex. The relationship between this age-related exaggerated response and a listener's ability to understand speech in noise remains an open question. Here, information-theory-based analysis methods are applied to magnetoencephalography (MEG) recordings of human listeners, investigating their cortical responses to continuous speech, using the novel non-linear measure of phase-locked mutual information between the speech stimuli and cortical responses. The cortex of older listeners shows an exaggerated level of mutual information, compared to younger listeners, for both attended and unattended speakers. The mutual information peaks for several distinct latencies: early (~50 ms), middle (~100 ms) and late (~200 ms). For the late component, the neural enhancement of attended over unattended speech is affected by stimulus SNR, but the direction of this dependency is reversed by aging. Critically, in older listeners and for the same late component, greater cortical exaggeration is correlated with decreased behavioral inhibitory control. This negative correlation also carries over to speech intelligibility in noise, where greater cortical exaggeration in older listeners is correlated with worse speech intelligibility scores. Finally, an age-related lateralization difference is also seen for the ~100 ms latency peaks, where older listeners show a bilateral response compared to younger listeners' right-lateralization. Thus, this information-theory-based analysis provides new, and less coarse-grained, results regarding age-related change in auditory cortical speech processing, and its correlation with cognitive measures, compared to related linear measures.
... The electrode sites for analysis were chosen based on scalp maps that showed intense activation in these regions. Similar methods for electrode grouping were used in previous ERP studies [57][58][59][60]. The frontal electrodes included F3, F5, F7, FC3, FC5, FT7 and the corresponding electrodes on the right hemisphere. ...
Article
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This electrophysiological study investigated the role of the medial olivocochlear (MOC) efferents in listening in noise. Both ears of eleven normal-hearing adult participants were tested. The physiological tests consisted of transient-evoked otoacoustic emission (TEOAE) inhibition and the measurement of cortical event-related potentials (ERPs). The mismatch negativity (MMN) and P300 responses were obtained in passive and active listening tasks, respectively. Behavioral responses for the word recognition in noise test were also analyzed. Consistent with previous findings, the TEOAE data showed significant inhibition in the presence of contralateral acoustic stimulation. However, performance in the word recognition in noise test was comparable for the two conditions (i.e., without contralateral stimulation and with contralateral stimulation). Peak latencies and peak amplitudes of MMN and P300 did not show changes with contralateral stimulation. Behavioral performance was also maintained in the P300 task. Together, the results show that the peripheral auditory efferent effects captured via otoacoustic emission (OAE) inhibition might not necessarily be reflected in measures of central cortical processing and behavioral performance. As the MOC effects may not play a role in all listening situations in adults, the functional significance of the cochlear effects of the medial olivocochlear efferents and the optimal conditions conducive to corresponding effects in behavioral and cortical responses remain to be elucidated.
... More importantly, the authors argued that the positive signal for distractor processing is an indicator of an active inhibitory process during auditory selective attention. Similarly, some recent studies also found that the frontal P2 signal pertains to inhibitory functions when participants are processing two auditory stimuli concurrently, such as pure tone sounds masked by white noise (Rao, Zhang, & Miller, 2010) or two different monosyllabic words presented simultaneously. ...
Chapter
Listening to speech in the presence of interfering auditory stimuli is a well-studied phenomenon in second language (L2) listeners. L2 auditory processing has been associated with various individual factors, such as listeners' L2 linguistic and contextual knowledge and L2 proficiency (Cutler, 2005). How efficiently and skillfully participants manage auditory interference may also be closely related to their ability to stay attentive to the target and suppress the irrelevant auditory stimuli. This review discusses the factors that modulate L2 auditory processing in noise and describes the underlying mechanisms of auditory interference control in bilingual individuals. Furthermore, we review the potential interaction between L2 proficiency and interference control in bilinguals.
... For example, when N1 and P2 were evoked by speech sounds, the amplitudes of both responses decreased with noise [9,10]. On the other hand, an enhancements of N1 and P2 in background noise were also reported [11,12]. ...
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Objectives: Cochlear implant (CI) users typically report impaired ability to understand speech in noise. Speech understanding in CI users decreases with noise due to reduced temporal processing ability, and speech perceptual errors involve stop consonants distinguished by voice onset time (VOT). The current study examined the effects of noise on various speech perception tests while at the same time used cortical auditory evoked potentials (CAEPs) to quantify the change of neural processing of speech sounds caused by noise. We hypothesized that the noise effects on VOT processing can be reflected in N1/P2 measures, the neural changes relate to behavioral speech perception performances. Methods: Ten adult CI users and 15 normal-hearing (NH) people participated in this study. CAEPs were recorded from 64 scalp electrodes in both quiet and noise (signal-to-noise ratio +5 dB) and in passive and active (requiring consonant discrimination) listening. Speech stimulus was synthesized consonant-vowels with VOTs of 0 and 50 ms. N1-P2 amplitudes and latencies were analyzed as a function of listening condition. For the active condition, the P3b also was analyzed. Behavioral measures included a variety of speech perception tasks. Results: For good performing CI users, performance in most speech test was lower in the presence of noise masking. N1 and P2 latencies became prolonged with noise masking. The P3b amplitudes were smaller in CI groups compared to NH. The degree of P2 latency change (0 vs. 50 ms VOT) was correlated with consonant perception in noise. Conclusion: The effects of noise masking on temporal processing can be reflected in cortical responses in CI users. N1/P2 latencies were more sensitive to noise masking than amplitude measures. Additionally, P2 responses appear to have a better relationship to speech perception in CI users compared to N1.
... Este mecanismo de atenção refletida funciona primordialmente ou unicamente sob condições de competição simultânea [8]. Em contrapartida, alguns estudos na última década começaram a pesquisar a resposta cortical relacionada com sons complexos e até simultâneos [9], observando harmônicos complexos, ou respostas simultâneas em estado estacionário [10]. Recentemente, houve um interesse substancial na identificação dos mecanismos pelos quais o sistema auditivo codifica e representa objetos auditivos [11]. ...
... Continuous electroencephalography (EEG) data (band- width ¼ 0.016e200 Hz; sampling rate 500 Hz) were recorded using the Advanced Neuro Technology EEG system with a REFA-72 amplifier (TMS International, Enschede, Netherlands) and a 64 channel Waveguard Cap (Advanced Neuro Technology, Enschede, Netherlands) ( Rao et al., 2010). The cap has shielded wires for 65 sintered Ag/AgCl electrodes arranged in the standard 10e20 system with additional intermediate positions. ...
Article
Discriminating a direction of frequency change is an important ability of the human auditory system, although temporal dynamics of neural activity underlying this discrimination remains unclear. In the present study, we recorded auditory-evoked potentials when human subjects explicitly judged a direction of a relative frequency change between two successive tones. A comparison of two types of trials with ascending and descending tone pairs revealed that neural activity discriminating a direction of frequency changes appeared as early as the P1 component of auditory-evoked potentials (latency 50 ms). Those differences between the ascending and descending trials were also observed in subsequent electroencephalographic components such as the N1 (100 ms) and P2 (200 ms). Furthermore, amplitudes of the P2 were significantly modulated by behavioral responses (upward/downward judgments) of subjects in the direction discrimination task, while those of the P1 were not. Those results indicate that, while the neural responses encoding a direction of frequency changes can be observed in an early component of electroencephalographic responses (50 ms after the change), the activity associated (correlated) with behavioral judgments evolves over time, being shaped in a later time period (around 200 ms) of the auditory processing.
Article
The act of shifting from one key to another is termed tonal modulation, which has been used to articulate emotion expressions and formal structures in Western music. The present study recorded cortical activity to examine how the auditory-evoked magnetic fields are affected by harmonizing music of rapidly changing tonalities. Participants were asked to covertly sing the pitch names of well-learned modulating melodies along with the harmonized or unharmonized melodies. In our musical stimuli, three flats were added to the key signature for every four beats. Such a rapid modulation is achieved by a chromatic inflection of the submediant tone between the third and fourth beats. Tonal modulations with such chromatic progressions are termed chromatic modulations. A major finding was that the amplitude of N1m (neuromagnetic response at approximately 110 ms after the onset of a stimulus) was significantly reduced by harmonization only when a modulation occurred. We also observed that harmonization enhanced the P2m (neuromagnetic response at approximately 200 ms after the onset of a stimulus) amplitude. The results provide evidence of the impacts of harmonization on attention efforts and pitch categorization.
Article
Changes in continuous sounds elicit a preattentive component that peaks at around 100 ms (Change-N1m) on electroencephalograms or magnetoencephalograms (MEG). Change-N1m is thought to reflect brain activity relating to the automatic detection of changes, which facilitate processes for the execution of appropriate behavior in response to new environmental events. The aim of the present MEG study was to elucidate whether a component relating to auditory changes existed earlier than N1m. Change-related cortical responses were evoked by abrupt sound movement in a train of clicks at 100 Hz. Sound movement was created by inserting an interaural time delay (ITD) of 0.15, 0.25, 0.35, and 0.45 ms into the right ear. Ten out of 12 participants exhibited clear change-related cortical responses earlier than Change-N1m at around 60 ms (Change-P50m). The results of source analysis showed that Change-P50m originated from the superior temporal gyrus of both hemispheres and that its location did not differ significantly from dipoles for the response to the sound onset. The magnitude of Change-P50m increased and the peak latency shortened with an increase in the ITD, similar to those of Change-N1m. These results suggest that change-related cortical activity is present as early as its onset latency at around 50 ms.
Article
In the last years, there has been a rising interest to find an objective method to estimate listening effort. Previously, we have shown that the wavelet phase synchronization stability (WPSS), gained from the instantaneous phase of auditory late responses (ALRs), could serve as a feasible measure for listening effort related factors. In the current study, we examined if the WPSS reflects the listening effort in young as well as middle-aged subjects and in persons with a different degree of hearing loss. To evoke ALR sequences, we generated syllabic paradigms with a different level of difficulty to evoke ALR sequences. We expected, due to the varying task demand, that the subjects require a measurable difference in the amount of effort to solve the paradigms. Additionally, a possible age and/or hearing loss related effect on the neural correlates of listening effort was investigated. The results indicate, that WPSS reflects the listening effort related factors needed to solve an auditory task. A further finding was that the reaction time data and the N1 wave amplitude information hardly yield any correlate of the invested listening effort. In addition, we noticed an age as well as hearing sensitivity related effect on the listening effort.
Article
Our ability to focus on a task and ignore task‐irrelevant stimuli is critical for efficient cognitive functioning. Attention control is especially required in the auditory modality as sound has privileged access to perception and consciousness. Despite this important function, little is known about auditory attention during typical everyday activities in childhood. We investigated the impact of task‐irrelevant sounds on attention during three everyday activities ‐ playing a game, reading a book, watching a movie. During these activities, environmental novel sounds were presented within a sequence of standard sounds to 7‐8‐year‐old children and adults. We measured ERPs reflecting early sound processing and attentional orienting and theta power evoked by standard and novel sounds during these activities. Playing a game versus reading or watching reduced early encoding of sounds in children and affected ongoing information processing and attention allocation in both groups. In adults, theta power was reduced during playing at mid‐central brain areas. Results show a pattern of immature neuronal mechanisms underlying perception and attention of task‐irrelevant sounds in 7‐8‐year‐old children. While the type of activity affected the processing of irrelevant sounds in both groups, early stimulus encoding processes were more sensitive to the type of activities in children.
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This paper reviews the literature on the Nl wave of the human auditory evoked potential. It concludes that at least six different cerebral processes can contribute to (he negative wave recorded from the scalp with a peak latency between 50 and 150 ms: a component generated in the auditory-cortex on the supratemporal plane, a component generated in the association cortex on the lateral aspect of the temporal and parietal cortex, a component generated in the motor and premotor cortices, the mismatch negativity, a temporal component of the processing negativity, and a frontal component of the processing negativity, The first three, which can be considered ‘true’ N1 components, are controlled by the physical and temporal aspects of the stimulus and by the general state of the subject. The other three components are not necessarily elicited by a stimulus but depend on the conditions in which the stimulus occurs. They often last much longer than the true N1 components that they overlap.
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Event-related brain potentials (ERPs) were recorded in response to unilateral arrays of letters flashed in rapid, randomized sequences to left and right visual field locations. Subjects were required to focus attention exclusively on either left or right field stimuli, or to divide attention in different proportions between the two fields, with the aim of detecting infrequent target letters. Both d’ and percent hits for target detections increased significantly as attentional allocation to a stimulus location increased. Attention operating characteristic (AOC) curves for the target detection scoreswere highly similar in form to those for the amplitudes of the long-latency, endogenous ERP components—N350-650 and P400-800 (P300). All of these measures showed gradual, nearly rectangular tradeoff functions. In contrast, the AOC curves for the early sensoryevoked components displayed steep, nearly linear amplitude tradeoffs as attention was increasingly allocated to one visual field at the expense of the other. The early and late ERP components were considered as indices of separate but interacting levels of attentional selection having different operating principles.
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The present study used magnetoencephalography (MEG) to examine perceptual learning of American English /r/ and /l/ categories by Japanese adults who had limited English exposure. A training software program was developed based on the principles of infant phonetic learning, featuring systematic acoustic exaggeration, multi-talker variability, visible articulation, and adaptive listening. The program was designed to help Japanese listeners utilize an acoustic dimension relevant for phonemic categorization of /r-l/ in English. Although training did not produce native-like phonetic boundary along the /r-l/ synthetic continuum in the second language learners, success was seen in highly significant identification improvement over twelve training sessions and transfer of learning to novel stimuli. Consistent with behavioral results, pre-post MEG measures showed not only enhanced neural sensitivity to the /r-l/ distinction in the left-hemisphere mismatch field (MMF) response but also bilateral decreases in equivalent current dipole (ECD) cluster and duration measures for stimulus coding in the inferior parietal region. The learning-induced increases in neural sensitivity and efficiency were also found in distributed source analysis using Minimum Current Estimates (MCE). Furthermore, the pre-post changes exhibited significant brain-behavior correlations between speech discrimination scores and MMF amplitudes as well as between the behavioral scores and ECD measures of neural efficiency. Together, the data provide corroborating evidence that substantial neural plasticity for second-language learning in adulthood can be induced with adaptive and enriched linguistic exposure. Like the MMF, the ECD cluster and duration measures are sensitive neural markers of phonetic learning.
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Speech and vocal sounds are at the core of human communication. Cortical processing of these sounds critically depends on behavioral demands. However, the neurocomputational mechanisms enabling this adaptive processing remain elusive. Here we examine the task-dependent reorganization of electroencephalographic responses to natural speech sounds (vowels /a/, /i/, /u/) spoken by three speakers (two female, one male) while listeners perform a one-back task on either vowel or speaker identity. We show that dynamic changes of sound-evoked responses and phase patterns of cortical oscillations in the alpha band (8-12 Hz) closely reflect the abstraction and analysis of the sounds along the task-relevant dimension. Vowel categorization leads to a significant temporal realignment of responses to the same vowel, e.g., /a/, independent of who pronounced this vowel, whereas speaker categorization leads to a significant temporal realignment of responses to the same speaker, e.g., speaker 1, independent of which vowel she/he pronounced. This transient and goal-dependent realignment of neuronal responses to physically different external events provides a robust cortical coding mechanism for forming and processing abstract representations of auditory (speech) input.
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The literature on interference in the Stroop Color–Word Task, covering over 50 years and some 400 studies, is organized and reviewed. In so doing, a set of 18 reliable empirical findings is isolated that must be captured by any successful theory of the Stroop effect. Existing theoretical positions are summarized and evaluated in view of this critical evidence and the 2 major candidate theories—relative speed of processing and automaticity of reading—are found to be wanting. It is concluded that recent theories placing the explanatory weight on parallel processing of the irrelevant and the relevant dimensions are likely to be more successful than are earlier theories attempting to locate a single bottleneck in attention.
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Single cells were recorded from cortical area V4 of two rhesus monkeys (Macaca mulatta) trained on a visual discrimination task with two levels of difficulty. Behavioral evidence indicated that the monkeys' discriminative abilities improved when the task was made more difficult. Correspondingly, neuronal responses to stimuli became larger and more selective in the difficult task. A control experiment demonstrated that changes in general arousal could not account for the effects of task difficulty on neuronal responses. It is concluded that increasing the amount of attention directed toward a stimulus can enhance the responsiveness and selectivity of the neurons that process it.
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Auditory evoked potentials were recorded from the vertex of subjects who listened selectively to a series of tone pips in one ear and ignored concurrent tone pips in the other ear. The negative component of the evoked potential peaking at 80 to 110 milliseconds was substantially larger for the attended tones. This negative component indexed a stimulus set mode of selective attention toward the tone pips in one ear. A late positive component peaking at 250 to 400 milliseconds reflected the response set established to recognize infrequent, higher pitched tone pips in the attended series.
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Behavioral and event-related brain potential (ERP) measures were used to elucidate the neural mechanisms of involuntary engagement of attention by novelty and change in the acoustic environment. The behavioral measures consisted of the reaction time (RT) and performance accuracy (hit rate) in a forced-choice visual RT task where subjects were to discriminate between odd and even numbers. Each visual stimulus was preceded by an irrelevant auditory stimulus, which was randomly either a "standard" tone (80%), a slightly higher "deviant" tone (10%), or a natural, "novel" sound (10%). Novel sounds prolonged the RT to successive visual stimuli by 17 msec as compared with the RT to visual stimuli that followed standard tones. Deviant tones, in turn, decreased the hit rate but did not significantly affect the RT. In the ERPs to deviant tones, the mismatch negativity (MMN), peaking at 150 msec, and a second negativity, peaking at 400 msec, could be observed. Novel sounds elicited an enhanced N1, with a probable overlap by the MMN, and a large positive P3a response with two different subcomponents: an early centrally dominant P3a, peaking at 230 msec, and a late P3a, peaking at 315 msec with a right-frontal scalp maximum. The present results suggest the involvement of two different neural mechanisms in triggering involuntary attention to acoustic novelty and change: a transient-detector mechanism activated by novel sounds and reflected in the N1 and a stimulus-change detector mechanism activated by deviant tones and novel sounds and reflected in the MMN. The observed differential distracting effects by slightly deviant tones and widely deviant novel sounds support the notion of two separate mechanisms of involuntary attention.
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The purpose of this study was to evaluate central auditory system maturation based on detailed data from multi-electrode recordings of long-latency auditory evoked potentials (AEPs). AEPs were measured at 30 scalp-electrode locations from 118 subjects between 5 and 20 years of age. Analyses focused on age-related latency and amplitude changes in the P1, N1b, P2, and N2 peaks of the AEPs generated by a brief train of clicks presented to the left ear. Substantial and unexpected changes that extend well into adolescence were found for both the amplitude and latency of the AEP components. While the maturational changes in latency followed a pattern of gradual change, amplitude changes tended to be more abrupt and step-like. Age-related latency decreases were largest for the P1 and N1b peaks. In contrast, P2 latency did not change significantly and the N2 peak increased in latency as a function of age. Abrupt changes in P1, P1-N1b, and N2 peak amplitude (also RMS amplitude) were observed around age 10 at the lateral electrode locations C3 and C4, but not at the midline electrodes Cz and Fz. These changes in amplitude coincided with a sharp increase and plateau in AEP peak and RMS amplitude variability from 9 to 11 years of age. These analyses demonstrated that the observed pattern of AEP maturation depends on the scalp location at which the responses are recorded. The distinct maturational time courses observed for individual AEP peaks support a model of AEP generation in which activity originates from two or more at least partly independent central nervous system pathways. A striking parallel was observed between previously reported maturational changes in auditory cortex synaptic density and, in particular, the age-related changes in P1 amplitude. The results indicate that some areas of the brain activated by sound stimulation have a maturational time course that extends into adolescence. Maturation of certain auditory processing skills such as speech recognition in noise also has a prolonged time course. This raises the possibility that the emergence of adult-like auditory processing skills may be governed by the same maturing neural processes that affect AEP latency and amplitude.
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The ability to maintain a conversation with one person while at a noisy cocktail party has often been used to illustrate a general characteristic of auditory selective attention, namely that perceivers' attention is usually directed to a particular set of sounds and not to others. Part of the cocktail party problem involves parsing co-occurring speech sounds and simultaneously integrating these various speech tokens into meaningful units ("auditory scene analysis"). Here, we review auditory perception and selective attention studies in an attempt to determine the role of perceptual organization in selective attention. Results from several behavioral and electrophysiological studies indicate that the ability to focus attention selectively on a particular sound source depends on a preliminary analysis that partitions the auditory input into distinct perceptual objects. Most findings can be accounted for by an object-based hypothesis in which auditory attention is allocated to perceptual objects derived from the auditory scene according to perceptual grouping principles.
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We used positron emission tomography to examine the response of human auditory cortex to spectral and temporal variation. Volunteers listened to sequences derived from a standard stimulus, consisting of two pure tones separated by one octave alternating with a random duty cycle. In one series of five scans, spectral information (tone spacing) remained constant while speed of alternation was doubled at each level. In another five scans, speed was kept constant while the number of tones sampled within the octave was doubled at each level, resulting in increasingly fine frequency differences. Results indicated that (i) the core auditory cortex in both hemispheres responded to temporal variation, while the anterior superior temporal areas bilaterally responded to the spectral variation; and (ii) responses to the temporal features were weighted towards the left, while responses to the spectral features were weighted towards the right. These findings confirm the specialization of the left-hemisphere auditory cortex for rapid temporal processing, and indicate that core areas are especially involved in these processes. The results also indicate a complementary hemispheric specialization in right-hemisphere belt cortical areas for spectral processing. The data provide a unifying framework to explain hemispheric asymmetries in processing speech and tonal patterns. We propose that differences exist in the temporal and spectral resolution of corresponding fields in the two hemispheres, and that they may be related to anatomical hemispheric asymmetries in myelination and spacing of cortical columns.
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To compare the localizations of different neural sources (a) obtained from intracerebral evoked responses and (b) calculated from surface auditory evoked field responses recorded in the same subjects. Our aim was to evaluate the resolving power of a source localization method currently used in our laboratory, which is based on a recent spatio-temporal algorithm used in magneto-encephalography (MEG). Auditory evoked responses were studied in 4 patients with medically intractable epilepsy. These responses were recorded from depth electrodes implanted in the auditory cortex for pre-surgical evaluation (stereo-electro-encephalography (SEEG)), as well as from surface captors (for MEG) placed on the scalp after removal of the depth electrodes. Auditory stimuli were clicks and short tone bursts with different frequencies. All middle-latency components (from 13 to 70 ms post-stimulus onset) were recorded and localized (via SEEG) along Heschl's gyrus (HG). MEG reliably localized Pam and P1m in the same area of HG that intracerebral recordings localized them in. No significant delay between SEEG and MEG latencies was observed. Both methods suggest that N1 is generated from different sources in the intermediate and lateral parts of the HG and in the planum temporale (PT). The source of P2 (PT and/or Area 22) remains unclear and was in one case, localized in different regions according to the method used. This latter component may therefore also be generated by different sources. The results suggest that both techniques are useful and may be used together in a complementary fashion. Intracerebral recordings allow the researcher to validate and interpret surface recordings.
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Hierarchical processing suggests that spectrally and temporally complex stimuli will evoke more activation than do simple stimuli, particularly in non-primary auditory fields. This hypothesis was tested using two tones, a single frequency tone and a harmonic tone, that were either static or frequency modulated to create four stimuli. We interpret the location of differences in activation by drawing comparisons between fMRI and human cytoarchitectonic data, reported in the same brain space. Harmonic tones produced more activation than single tones in right Heschl's gyrus (HG) and bilaterally in the lateral supratemporal plane (STP). Activation was also greater to frequency-modulated tones than to static tones in these areas, plus in left HG and bilaterally in an anterolateral part of the STP and the superior temporal sulcus. An elevated response magnitude to both frequency-modulated tones was found in the lateral portion of the primary area, and putatively in three surrounding non-primary regions on the lateral STP (one anterior and two posterior to HG). A focal site on the posterolateral STP showed an especially high response to the frequency-modulated harmonic tone. Our data highlight the involvement of both primary and lateral non-primary auditory regions.
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Behavioral and event-related potential (ERP) measurements were made in an auditory selective-attention paradigm, both before and after a series of inhibition or discrimination training sessions. The presence of distractors caused poor perceptual sensitivity, weak P3 responses, conservative responding, and slow reaction times relative to baseline. Distraction prompted a frontal enhancement of ERP components occurring 100-250 ms after the onset of attended signals (N1, P2, and N2). Training ameliorated behavioral interference from distraction. Participants receiving inhibition training acquired improved inhibitory processing of distractors, an effect that peaked 200 ms after distractor onset. In a proposed model, distinct excitatory and inhibitory mechanisms work interactively to maintain sensitivity to environmental change in the face of disruption from the contextual integration of irrelevant events.
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The goal of avoiding distraction (e.g., ignoring words when naming their print colors in a Stroop task) is opposed intrinsically by the penchant to process conspicuous and correlated characteristics of the environment (e.g., noticing trial-to-trial associations between the colors and the words). To reconcile these opposing forces, the authors propose a tectonic theory of selective attention in which 2 memory-based structures--dimensional imbalance and dimensional uncertainty--drive selection by processing salient, surprising, and/or correlated information contained within and across stimulus dimensions. Each structure modulates the buildup of excitation to targets and the buildup of inhibition to distractors and to memories of previous stimuli. Tectonic theory is implemented to simulate the impact of 4 types of context on the presence, magnitude, and direction of congruity effects and task effects in the Stroop paradigm. The tectonic model is shown to surpass other formal models in explaining the range and diversity of Sroop effects.
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We investigated the hypothesis that task performance can rapidly and adaptively reshape cortical receptive field properties in accord with specific task demands and salient sensory cues. We recorded neuronal responses in the primary auditory cortex of behaving ferrets that were trained to detect a target tone of any frequency. Cortical plasticity was quantified by measuring focal changes in each cell's spectrotemporal response field (STRF) in a series of passive and active behavioral conditions. STRF measurements were made simultaneously with task performance, providing multiple snapshots of the dynamic STRF during ongoing behavior. Attending to a specific target frequency during the detection task consistently induced localized facilitative changes in STRF shape, which were swift in onset. Such modulatory changes may enhance overall cortical responsiveness to the target tone and increase the likelihood of 'capturing' the attended target during the detection task. Some receptive field changes persisted for hours after the task was over and hence may contribute to long-term sensory memory.
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Linguistic experience alters an individual's perception of speech. We here provide evidence of the effects of language experience at the neural level from two magnetoencephalography (MEG) studies that compare adult American and Japanese listeners' phonetic processing. The experimental stimuli were American English /ra/ and /la/ syllables, phonemic in English but not in Japanese. In Experiment 1, the control stimuli were /ba/ and /wa/ syllables, phonemic in both languages; in Experiment 2, they were non-speech replicas of /ra/ and /la/. The behavioral and neuromagnetic results showed that Japanese listeners were less sensitive to the phonemic /r-l/ difference than American listeners. Furthermore, processing non-native speech sounds recruited significantly greater brain resources in both hemispheres and required a significantly longer period of brain activation in two regions, the superior temporal area and the inferior parietal area. The control stimuli showed no significant differences except that the duration effect in the superior temporal cortex also applied to the non-speech replicas. We argue that early exposure to a particular language produces a "neural commitment" to the acoustic properties of that language and that this neural commitment interferes with foreign language processing, making it less efficient.
Article
Behavioral and event-related potential (ERP) measurements were made in an auditory selective-attention paradigm, both before and after a series of inhibition or discrimination training sessions. The presence of distractors caused poor perceptual sensitivity, weak P3 responses, conservative responding, and slow reaction times relative to baseline. Distraction prompted a frontal enhancement of ERP components occurring 100-250 ms after the onset of attended signals (N1, P2, and N2). Training ameliorated behavioral interference from distraction. Participants receiving inhibition training acquired improved inhibitory processing of distractors, an effect that peaked 200 ms after distractor onset, In a proposed model, distinct excitatory and inhibitory mechanisms work interactively to maintain sensitivity to environmental change in the fare of disruption from the contextual integration of irrelevant events. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Book
Detection Theory is an introduction to one of the most important tools for analysis of data where choices must be made and performance is not perfect. Originally developed for evaluation of electronic detection, detection theory was adopted by psychologists as a way to understand sensory decision making, then embraced by students of human memory. It has since been utilized in areas as diverse as animal behavior and X-ray diagnosis. This book covers the basic principles of detection theory, with separate initial chapters on measuring detection and evaluating decision criteria. Some other features include: complete tools for application, including flowcharts, tables, pointers, and software;. student-friendly language;. complete coverage of content area, including both one-dimensional and multidimensional models;. separate, systematic coverage of sensitivity and response bias measurement;. integrated treatment of threshold and nonparametric approaches;. an organized, tutorial level introduction to multidimensional detection theory;. popular discrimination paradigms presented as applications of multidimensional detection theory; and. a new chapter on ideal observers and an updated chapter on adaptive threshold measurement. This up-to-date summary of signal detection theory is both a self-contained reference work for users and a readable text for graduate students and other researchers learning the material either in courses or on their own. © 2005 by Lawrence Erlbaum Associates, Inc. All rights reserved.
Article
Measures of event-related brain potentials (ERPs) have revealed two kinds of selective-attention mechanisms that operate on attended and unattended auditory stimuli. The processing negativity of the ERP reveals a mechanism of intramodal selective attention in the auditory cortex controlled by frontal cortex. This mechanism selects attended auditory stimuli for further processing when they differ from unattended stimuli in location or tonal frequency. Studies of intermodal selective attention have compared auditory ERPs during auditory and visual attention. At least in part different brain mechanisms may be involved in the selection of auditory stimuli among other auditory stimuli (intramodal selective attention)and in the selection of auditory stimuli among visual stimuli (intermodal selective attention). This is suggested by the results showing that the earlier component of the processing negativity, which is generated in the auditory cortex during intramodal selective attention, differs in scalp distribution from the early attention-related negativity elicited during intermodal selective attention. With respect to the unattended auditory stimuli, ERP studies of selective attention suggest that physical features of these stimuli are extensively processed. This is shown by the mismatch negativity component of the ERP, which is usually elicited by infrequent physical deviations in an auditory stimulus sequence both when this sequence is attended and when it is ignored. This would be impossible if the physical stimulus features were not extensively processed, even in the absence of attention.
Article
Event-related potentials (ERPs) were recorded in subjects receiving tones (left ear 300 Hz, right ear 6000 Hz) at a rapid rate and trying to detect occasional higher-pitched stimuli in a designated ear. ERPs to attended stimuli showed enhanced negative amplitudes whose topographical distribution differed from that of the exogeneous N1 component. Moreover, the latter was considerably larger for low than high tones, whereas the attention effect had similar amplitudes for the two tones. Consequently, the attention effect, even when perfectly coinciding in time with N1, does not seem to be caused by modulation of the exogeneous N1 but rather by a separate process activated by attention. This suggests that attention does not modulate initial stimulus representations in audition.
Article
We recorded topographic mapping of auditory evoked potentials (AEPs) to homogeneous series of tones delivered in the absence of any cognitive task ("neutral condition") and compared them with responses to identical stimuli when they acted as non-targets in an oddball paradigm. With respect to the neutral condition, non-target responses showed an increase in N100 amplitude which was found to depend on two different, but partially overlapping effects. The "early effect" had similar latency and topography as exogenous N100 and may reflect changes in the overall state of alertness since its amplitude declined at the end of the test. The "late effect" affected the N100s descending slope and had features consistent with those of a processing negativity. It was frontally distributed, and topographic mapping revealed a right-sided predominance. Finally, non-target responses exhibited a central positivity (P250) which did not appear in neutral AEPs. P250 shares several features, including latency, amplitude and scalp topography, with the endogenous ERP component commonly labelled "P3a". Non-target P250 could be the result of an attentional shift towards the stimuli, and reflect some aspects of the classification process. We suggest that non-target responses in simple oddball paradigms should be routinely studied along with target responses in order to improve the diagnostic capabilities of cognitive ERPs. Notably, non-target responses may help to decide whether an abnormal target-P300 is related or not to a deficit in the mobilization of attentional resources.
Article
Research in the field of selective visual attention has recently seen substantial progress in several areas. Neuroimaging and electrical recording results have indicated that selective attention amplifies neural activity in prestriate areas concerned with basic visual processing. Imaging and cellular studies are delineating the networks of anatomical areas that serve as the source of attentional modulation and have suggested that these networks are anatomically distinct from the sites of the resulting amplifications. Cognitive studies of visual search have explored the role of these amplified computations in the integration of visual features into objects. Attentional effects in normal subjects, and their disruption following brain injury, have revealed the mental representations upon which attention operates.
Two dichotic listening experiments were performed in which stimulus and task conditions were optimized for the early selection of inputs. Subjects listened selectively to sequences of rapidly presented tone pips in one ear while ignoring tone pips of a different pitch in the opposite ear. In both experiments, an enhanced positivity between 20 and 50 msec (the 'P20-50') was observed over central and frontal sites in the ERPs to the attended-channel tone pips. At longer latencies, the effects of attention appeared to include an amplitude modulation of several exogenous ERPs, including subcomponents of the central N1 (60-150 msec) and P2 (170-230 msec) waves and the temporal T complex (80-150 msec). In contrast, the attention effect prefrontally consisted of a broad negativity that appeared to be largely endogenous. A signal processing technique (Adjar) was employed to correct for distortion of mutually overlapping ERPs elicited by successive stimuli presented at short interstimulus intervals (ISIs). It was confirmed that the P20-50 attention effect was not the result of differential overlap from previous ERPs. In addition, this technique allowed an analysis to be made of the effects of the preceding stimulus type and ISI on the attention-sensitive ERPs, which provided further support for the view that highly focused selective attention can directly modulate exogenous components of the auditory ERP. Moreover, these sequence-dependent ERP modulations were paralleled by variations in target discrimination performance. Taken together, these results provide strong support for the early selection hypothesis that attention can serve to selectively bias or gate stimulus processing before full perceptual analysis has occurred.
The effect of selective attention on activity of the right human auditory cortex was studied with a 24-channel planar SQUID-gradiometer. Two conditions were used, favoring either a late attention effect following N100m, or an early effect, overlapping with N100m. In experiment 1 (15 subjects), a randomized tone sequence of 1 and 3 kHz tones was delivered to the left ear with a constant interstimulus interval (ISI) of 405 msec. The subjects' task was to count infrequent longer tones of one of these pitches among shorter standards. An attention effect, called magnetic difference (Md), was found when the responses to the irrelevant standards were subtracted from those to the relevant standards. Md peaked at about 220 msec for the 1 kHz tones and at 195 msec for the 3 kHz tones. The equivalent source of Md was in the supratemporal auditory cortex, about 1 cm anterior to the source of N100m, and in the same location as the source of P200m. In experiment 2 (8 subjects) the paradigm was similar, except that the 1 kHz and 3 kHz tones were led to different ears with a random ISI of 240-300 msec. In this case Md started already at 30-40 msec, adding to the N100m deflection, and the sources of N100m and Md overlapped. Present results show that attention can modify the activity of two different areas in the supratemporal auditory cortex. We interpret both attention effects as alterations of the exogenous evoked response components: the earlier effect as changed activity in neurons underlying N100m to relevant tones and the later effect as a modification of P200m to irrelevant tones.
Article
Positron emission tomography (PET) was used to measure changes in regional cerebral blood flow of normal subjects, while they were discriminating different attributes (shape, color, and velocity) of the same set of visual stimuli. Psychophysical evidence indicated that the sensitivity for discriminating subtle stimulus changes was higher when subjects focused attention on one attribute than when they divided attention among several attributes. Correspondingly, attention enhanced the activity of different regions of extrastriate visual cortex that appear to be specialized for processing information related to the selected attribute.
Article
Event-related brain potentials (ERPs) were recorded in response to unilateral arrays of letters flashed in rapid, randomized sequences to left and right visual field locations. Subjects were required to focus attention exclusively on either left or right field stimuli, or to divide attention in different proportions between the two fields, with the aim of detecting infrequent target letters. Both d' and percent hits for target detections increased significantly as attentional allocation to a stimulus location increased. Attention operating characteristic (AOC) curves for the target detection scores were highly similar in form to those for the amplitudes of the long-latency, endogenous ERP components--N350-650 and P400-800 (P300). All of these measures showed gradual, nearly rectangular tradeoff functions. In contrast, the AOC curves for the early sensory-evoked components displayed steep, nearly linear amplitude tradeoffs as attention was increasingly allocated to one visual field at the expense of the other. The early and late ERP components were considered as indices of separate but interacting levels of attentional selection having different operating principles.
The maturational changes in auditory, somatosensory, and visual evoked potential latencies are re-analyzed using a simple developmental model. It is assumed that latency changes between birth and adulthood can be described by a sum of decaying exponential functions. Curve fitting procedures resulted for all 3 stimulus modalities in 3 exponential functions. The rates of decay, interpreted as representing specific maturation rates, can be described with time constants of about 4 weeks, about 40 weeks, and about 4 years. For the short time constant process the growth spurt in myelination as well as that in increasing synaptic density can be held responsible. Evidence is provided that the medium time constant process parallels a slower myelination stage. Using the above described model, the maturational changes in evoked potentials for the 3 stimulus modalities, both for short and long latency evoked potentials, can be unified.
Article
The contribution of the event-related potential (ERP) research to understanding human selective attention will be evaluated. A closely related issue, the starting point of the present treatment, involves the nature and extent of automaticity in information processing. The mismatch-negativity component of the ERP suggests that the basic, obligatory, processing of the physical features of auditory stimuli is unaffected by the direction of attention. These data also reveal a possible mechanism for attention switching to stimulus change occurring in the unattended input, observed by cognitive psychologists. The N1 wave of the ERP might in turn provide a data base for explaining similar attention switches to stimulus onsets after breaks in stimulation and to offsets of long-duration stimuli. With regard to selective attention, the processing negativity might make it possible to delineate the central principle of stimulus selection in attention, a goal probably inaccessible to non-physiological attention research. In the visual modality, cognitive psychologists have found that spatial attention is more fundamental and powerful in stimulus selection than any other form of visual selective attention. Consistently, ERP data show that the exogenous components in vision are enhanced by spatial selective attention but not when attended and unattended stimuli are not spatially separated. Also, ERP data (the P3 wave) give support to certain forms of resource-allocation theories of attention. In addition, with regard to the currently popular distinction between automatic versus controlled processing, these data strongly suggest that extended consistent-mapping training does not lead to a "genuine" automatization of a search process in the sense of independence of a limited-capacity system.
Findings from the experiments summarized above indicate that the MRL components, Pa and P1, are differentially affected by several functional and parametric variables, suggesting that each of these components reflects a separate and distinct generator system. Moreover, the similarities between the human Pa and the cat wave 7 suggest an auditory cortex origin of this component. The similarities between the human P1 and the cat wave A suggest that in the human, as in the cat, this potential may be generated by a component of the ascending reticular activating system.
Article
The need for a simply applied quantitative assessment of handedness is discussed and some previous forms reviewed. An inventory of 20 items with a set of instructions and response- and computational-conventions is proposed and the results obtained from a young adult population numbering some 1100 individuals are reported. The separate items are examined from the point of view of sex, cultural and socio-economic factors which might appertain to them and also of their inter-relationship to each other and to the measure computed from them all. Criteria derived from these considerations are then applied to eliminate 10 of the original 20 items and the results recomputed to provide frequency-distribution and cumulative frequency functions and a revised item-analysis. The difference of incidence of handedness between the sexes is discussed.
Article
Steps in brain information processing are reflected on the scalp as changes of the electric potential which is evoked by the stimulus. However, for a given recording point on the scalp, there is no absolute amplitude or phase information of the electric brain potential. This means that the shape of an evoked potential waveform which is recorded from a given scalp location crucially depends on the location of the chosen reference. Only unbiased results of evoked potential data evaluation can be hoped to elucidate or map successfully into information processing models established by other methods, e.g. behavior measurements. Conventional recordings vs a common reference contain only one of many possible sets of waveshapes. In order to avoid ambiguities or bias of results, the entire evoked potential data set firstly must be analysed over space, and reference-independent parameters must be extracted. For each time point, the spatial distribution of the potentials is viewed as field map. The parameter extraction in a direct approach at each time point includes, e.g. locations of field peaks and troughs, voltage and gradient between them, and global electrical field power; or