Cognitive aging theories emphasize the decrease in efficiency of inhibitory processes and attention control in normal aging, which, in turn, may result in reduction of working memory function. Accordingly, some of these age-related changes may be due to faster sensory memory decay or to inefficient filtering of irrelevant sensory information (sensory gating). Here, event-related brain potentials and the event-related optical signal were recorded in younger and older adults passively listening to tone trains. To determine whether age differentially affects decay of sensory memory templates over short intervals, trains were separated by delays of either 1 or 5 sec. To determine whether age affects the suppression of responses to unattended repeated stimuli, we evaluated the brain activity elicited by successive train stimuli. Some trains started with a shorter-duration stimulus (deviant trains). Results showed that both electrical and optical responses to tones were more persistent with repeated stimulation in older adults than in younger adults, whereas the effects of delay were similar in the two groups. A mismatch negativity (MMN) was elicited by the first stimulus in deviant trains. This MMN was larger for 1- than 5-sec delay, but did not differ across groups. These data suggest that age-related changes in sensory processing are likely due to inefficient filtering of repeated information, rather than to faster sensory memory decay. This inefficient filtering may be due to, or interact with, reduced attention control. Furthermore, it may increase the noise levels in the information processing system and thus contribute to problems with working memory and speed of processing.
"The elderly show lower performance in working memory tasks (Salthouse et al., 1991) and have reduced working memory capacity (at least in part) due to problems in binding multiple low-level features (Brockmole and Logie, 2013). Additionally, it has been shown that elderly have trouble inhibiting distracting information in unimodal tasks (Folk and Lincourt, 1996; Groth and Allen, 2000; Gaeta et al., 2001; Tales et al., 2002; Andrés et al., 2006; Fabiani et al., 2006; Rowe et al., 2006; Yang and Hasher, 2007), in cross-modal tasks (Alain and Woods, 1999; Poliakoff et al., 2006; Hugenschmidt et al., 2009b), and multi-modal tasks (Hugenschmidt et al., 2009a). The studies by Hugenschmidt et al. and others suggest that while elderly have trouble ignoring task-irrelevant items, they do show intact attention abilities. "
[Show abstract][Hide abstract] ABSTRACT: Cortical oscillations have been shown to represent fundamental functions of a working brain, e.g., communication, stimulus binding, error monitoring, and inhibition, and are directly linked to behavior. Recent studies intervening with these oscillations have demonstrated effective modulation of both the oscillations and behavior. In this review, we collect evidence in favor of how hypothesis-driven methods can be used to augment cognition by optimizing cortical oscillations. We elaborate their potential usefulness for three target groups: healthy elderly, patients with attention deficit/hyperactivity disorder, and healthy young adults. We discuss the relevance of neuronal oscillations in each group and show how each of them can benefit from the manipulation of functionally-related oscillations. Further, we describe methods for manipulation of neuronal oscillations including direct brain stimulation as well as indirect task alterations. We also discuss practical considerations about the proposed techniques. In conclusion, we propose that insights from neuroscience should guide techniques to augment human cognition, which in turn can provide a better understanding of how the human brain works.
Frontiers in Systems Neuroscience 06/2014; 8:119. DOI:10.3389/fnsys.2014.00119
") Similar age-related increases in the N1 amplitude have been reported (e.g., Anderer et al., 1996; Chao and Knight, 1997; Alain and Woods, 1999; Amenedo and Diaz, 1999; Harkrider et al., 2006; Ross and Tremblay, 2009; Soros et al., 2009), albeit with less consistency (for a failure to find age difference see, Pfefferbaum et al., 1980; Smith et al., 1980; Picton et al., 1984; Barrett et al., 1987; Iragui et al., 1993; Bertoli et al., 2002; Tremblay et al., 2004; Kovacevic et al., 2005; Lister et al., 2011). The effect of age on the P2 amplitude is more equivocal with some studies reporting no age difference (Ford et al., 1979; Picton et al., 1984; Barrett et al., 1987; Iragui et al., 1993; Tremblay et al., 2004) while others observing smaller (Goodin et al., 1978; Smith et al., 1980; Ross and Tremblay, 2009) or larger (Pfefferbaum et al., 1980; Ford and Pfefferbaum, 1991; Fabiani et al., 2006; Alain and Snyder, 2008) amplitudes in older adults. However, the effects of age on the P2 latency are more consistent, with most studies reporting an age-related increase in P2 latency (e.g., Goodin et al., 1978; Iragui et al., 1993; Tremblay et al., 2004; Alain and McDonald, 2007). "
[Show abstract][Hide abstract] ABSTRACT: Aging is often accompanied by hearing loss, which impacts how sounds are processed and represented along the ascending auditory pathways and within the auditory cortices. Here, we assess the impact of mild binaural hearing loss on the older adults' ability to both process complex sounds embedded in noise and to segregate a mistuned harmonic in an otherwise periodic stimulus. We measured auditory evoked fields (AEFs) using magnetoencephalography while participants were presented with complex tones that had either all harmonics in tune or had the third harmonic mistuned by 4 or 16% of its original value. The tones (75 dB sound pressure level, SPL) were presented without, with low (45 dBA SPL), or with moderate (65 dBA SPL) Gaussian noise. For each participant, we modeled the AEFs with a pair of dipoles in the superior temporal plane. We then examined the effects of hearing loss and noise on the amplitude and latency of the resulting source waveforms. In the present study, results revealed that similar noise-induced increases in N1m were present in older adults with and without hearing loss. Our results also showed that the P1m amplitude was larger in the hearing impaired than in the normal-hearing adults. In addition, the object-related negativity (ORN) elicited by the mistuned harmonic was larger in hearing impaired listeners. The enhanced P1m and ORN amplitude in the hearing impaired older adults suggests that hearing loss increased neural excitability in auditory cortices, which could be related to deficits in inhibitory control.
Frontiers in Systems Neuroscience 01/2014; 8:8. DOI:10.3389/fnsys.2014.00008
"The P2 amplitude was little affected by stimulus repetition. While the reduced P2 suppression in older adults is consistent with prior work using brief tones , the effects of stimulus repetition on N1 is at odds with studies showing either no or reduced N1 adaption to pure tone stimuli [19,20]. Specifically, the age and position interaction for the N1 amplitude was not significant in the present study. "
[Show abstract][Hide abstract] ABSTRACT: Much of what we know regarding the effect of stimulus repetition on neuroelectric adaptation comes from studies using artificially produced pure tones or harmonic complex sounds. Little is known about the neural processes associated with the representation of everyday sounds and how these may be affected by aging. In this study, we used real life, meaningful sounds presented at various azimuth positions and found that auditory evoked responses peaking at about 100 and 180 ms after sound onset decreased in amplitude with stimulus repetition. This neural adaptation was greater in young than in older adults and was more pronounced when the same sound was repeated at the same location. Moreover, the P2 waves showed differential patterns of domain-specific adaptation when location and identity was repeated among young adults. Background noise decreased ERP amplitudes and modulated the magnitude of repetition effects on both the N1 and P2 amplitude, and the effects were comparable in young and older adults. These findings reveal an age-related difference in the neural processes associated with adaptation to meaningful sounds, which may relate to older adults' difficulty in ignoring task-irrelevant stimuli.
PLoS ONE 07/2013; 8(7):e68892. DOI:10.1371/journal.pone.0068892 · 3.23 Impact Factor
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