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01/2011: pages -;
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01/2010: pages 327-343;
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01/2010: pages 362-390;
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01/2010: pages 202-250;
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ABSTRACT: Perceptual studies have indicated that basal ganglia dysfunctions such as Parkinson's disease (PD) and Huntington's disease (HD) may give rise to impaired prosodic speech modulation (dysprosodia, aprosodia). The available parametric data, however, are sparse. In the present study declarative, affectively neutral test sentences were used to investigate the production of sentence accent in PD and HD subjects. Reduced durational, pitch and loudness changes concomitant with accent realization could be disclosed in HD, whereas the PD group presented with slightly decreased durational stress contrast only. Both patient groups showed preserved categorical aspects of pitch accent signalling. Most presumably, speech motor deficits rather than disturbances of supramodal processing of prosody are responsible for the observed deviations of sentence accent production.
09/2009; 7(4):285-297.
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ABSTRACT: The flame tube is an important functional component of burners using the concept of the flame tube stabilised combustion. Under typical combustion conditions the material of the flame tube is exposed to high temperatures (≥900 °C) and to corrosion attack by the combustion gases. Furthermore as the burners are generally operated intermittently, the material suffers from extreme temperature and atmosphere changes. For flame tubes, a lifetime of approximately 8000 h is desired. Predominantly metallic high temperature materials are used. The scope of the present work was to test—under application conditions and for maximum material temperatures exceeding 900 °C—alternative high temperature alloys for use as tube material. The corrosion resistance of the austenitic Ni–Cr-based alloys (601, 602 CA, 617 and 693) has been investigated in a burner rig at maximum material temperatures of 950 and 1000 °C and with exposure times from 50 to 3000 h. The chromium content of the alloys was between 20 and 30 wt% and that of aluminium between 1 and 3.4 wt%. Metallographic cross-sections of samples of the alloys were analysed by electron microprobe yielding information about the microstructure and composition of the oxides in the surface zone and variations during exposure time. This study focuses on the observed specific effects of the alloying element aluminium on the development of the oxide scale and on the lifetime of the alloys. At the alloy surface after 500 h exposure time a chromium oxide scale had formed with aluminium oxides underneath predominantly along grain boundaries. For the alloys with the lower aluminium content, the aluminium oxides built up an open network but not a closed layer. For the alloy with the highest aluminium content (alloy 693) after 50 h two different characteristic microstructures at the surface were found. In one case, the grains at the surface were covered with chromium oxide on top and the remaining grain surface was completely enclosed by aluminium oxides. In the other case, the aluminium oxide formed a thin layer directly below the chromium oxide scale. After 500 h exposure time, a significantly thinner chromium oxide scale and massive internal chromium oxides were observed. Catastrophic corrosion, formation of internal oxides and aluminium nitrides started even after 500 h. It will be demonstrated that the early breakdown of alloy 693 is linked to the aluminium oxides which act as a barrier constricting the diffusion of chromium from the alloy matrix towards the surface. Under the conditions of extreme temperature changes given in the burner the aluminium oxide layer on its part did not provide corrosion protection.
Materials and Corrosion 05/2008; 59(5):380 - 388. · 1.17 Impact Factor
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ABSTRACT: The present paper focuses on two aspects: the service conditions of a flame tube in a low-NOx recirculation burner (maximum temperature experienced by the material: 1000 °C) and the interrelationship between service conditions and both the structure and growth of the oxide scale. The flame tube is exposed to extreme thermal and atmospheric conditions during service. Due to the short burner operation time followed by a pause, rapid changes of the temperature and gaseous environment occur. Three Ni-based alloys (alloy 602 CA, alloy 603 XL and alloy 693) were investigated in cyclic oxidation tests under typical conditions for the combustion of fuel oil. Flame tube temperature measurements in both the axial and the tangential directions are presented together with results concerning the influence of the fuel quality, duration of the air ventilation after burner shut down and temperature on the thickness and composition of the oxide scale.
Materials and Corrosion 02/2006; 57(2):122 - 127. · 1.17 Impact Factor
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ABSTRACT: During acoustic communication in humans, information about a speaker's emotional state is predominantly conveyed by modulation of the tone of voice (emotional or affective prosody). Based on lesion data, a right hemisphere superiority for cerebral processing of emotional prosody has been assumed. However, the available clinical studies do not yet provide a coherent picture with respect to interhemispheric lateralization effects of prosody recognition and intrahemispheric localization of the respective brain regions. To further delineate the cerebral network engaged in the perception of emotional tone, a series of experiments was carried out based upon functional magnetic resonance imaging (fMRI). The findings obtained from these investigations allow for the separation of three successive processing stages during recognition of emotional prosody: (1) extraction of suprasegmental acoustic information predominantly subserved by right-sided primary and higher order acoustic regions; (2) representation of meaningful suprasegmental acoustic sequences within posterior aspects of the right superior temporal sulcus; (3) explicit evaluation of emotional prosody at the level of the bilateral inferior frontal cortex. Moreover, implicit processing of affective intonation seems to be bound to subcortical regions mediating automatic induction of specific emotional reactions such as activation of the amygdala in response to fearful stimuli. As concerns lower level processing of the underlying suprasegmental acoustic cues, linguistic and emotional prosody seem to share the same right hemisphere neural resources. Explicit judgment of linguistic aspects of speech prosody, however, appears to be linked to left-sided language areas whereas bilateral orbitofrontal cortex has been found involved in explicit evaluation of emotional prosody. These differences in hemispheric lateralization effects might explain that specific impairments in nonverbal emotional communication subsequent to focal brain lesions are relatively rare clinical observations as compared to the more frequent aphasic disorders.
Progress in brain research 02/2006; 156:249-68. · 3.04 Impact Factor
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ABSTRACT: During acoustic communication among human beings, emotional information can be expressed both by the propositional content of verbal utterances and by the modulation of speech melody (affective prosody). It is well established that linguistic processing is bound predominantly to the left hemisphere of the brain. By contrast, the encoding of emotional intonation has been assumed to depend specifically upon right-sided cerebral structures. However, prior clinical and functional imaging studies yielded discrepant data with respect to interhemispheric lateralization and intrahemispheric localization of brain regions contributing to processing of affective prosody. In order to delineate the cerebral network engaged in the perception of emotional tone, functional magnetic resonance imaging (fMRI) was performed during recognition of prosodic expressions of five different basic emotions (happy, sad, angry, fearful, and disgusted) and during phonetic monitoring of the same stimuli. As compared to baseline at rest, both tasks yielded widespread bilateral hemodynamic responses within frontal, temporal, and parietal areas, the thalamus, and the cerebellum. A comparison of the respective activation maps, however, revealed comprehension of affective prosody to be bound to a distinct right-hemisphere pattern of activation, encompassing posterior superior temporal sulcus (Brodmann Area [BA] 22), dorsolateral (BA 44/45), and orbitobasal (BA 47) frontal areas. Activation within left-sided speech areas, in contrast, was observed during the phonetic task. These findings indicate that partially distinct cerebral networks subserve processing of phonetic and intonational information during speech perception.
NeuroImage 03/2005; 24(4):1233-41. · 5.89 Impact Factor
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ABSTRACT: There are few data on the cerebral organization of motor aspects of speech production and the pathomechanisms of dysarthric deficits subsequent to brain lesions and diseases. The authors used fMRI to further examine the neural basis of speech motor control.
In eight healthy volunteers, fMRI was performed during syllable repetitions synchronized to click trains (2 to 6 Hz; vs a passive listening task). Bilateral hemodynamic responses emerged at the level of the mesiofrontal and sensorimotor cortex, putamen/pallidum, thalamus, and cerebellum (two distinct activation spots at either side). In contrast, dorsolateral premotor cortex and anterior insula showed left-sided activation. Calculation of rate/response functions revealed a negative linear relationship between repetition frequency and blood oxygen level-dependent (BOLD) signal change within the striatum, whereas both cerebellar hemispheres exhibited a step-wise increase of activation at approximately 3 Hz. Analysis of the temporal dynamics of the BOLD effect found the various cortical and subcortical brain regions engaged in speech motor control to be organized into two separate networks (medial and dorsolateral premotor cortex, anterior insula, and superior cerebellum vs sensorimotor cortex, basal ganglia, and inferior cerebellum).
These data provide evidence for two levels of speech motor control bound, most presumably, to motor preparation and execution processes. They also help to explain clinical observations such as an unimpaired or even accelerated speaking rate in Parkinson disease and slowed speech tempo, which does not fall below a rate of 3 Hz, in cerebellar disorders.
Neurology 03/2005; 64(4):700-6. · 8.31 Impact Factor
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ABSTRACT: In addition to the propositional content of verbal utterances, significant linguistic and emotional information is conveyed by the tone of speech. To differentiate brain regions subserving processing of linguistic and affective aspects of intonation, discrimination of sentences differing in linguistic accentuation and emotional expressiveness was evaluated by functional magnetic resonance imaging. Both tasks yielded rightward lateralization of hemodynamic responses at the level of the dorsolateral frontal cortex as well as bilateral thalamic and temporal activation. Processing of linguistic and affective intonation, thus, seems to be supported by overlapping neural networks comprising partially right-sided brain regions. Comparison of hemodynamic activation during the two different tasks, however, revealed bilateral orbito-frontal responses restricted to the affective condition as opposed to activation of the left lateral inferior frontal gyrus confined to evaluation of linguistic intonation. These findings indicate that distinct frontal regions contribute to higher level processing of intonational information depending on its communicational function. In line with other components of language processing, discrimination of linguistic accentuation seems to be lateralized to the left inferior-lateral frontal region whereas bilateral orbito-frontal areas subserve evaluation of emotional expressiveness.
Cerebral Cortex 01/2005; 14(12):1384-9. · 6.54 Impact Factor
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Neurology 12/2004; 63(10):1932. · 8.31 Impact Factor
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ABSTRACT: Danksagung Die Untersuchungen unserer Arbeitsgruppe wurden unterstützt durch die Deutsche Forschungsgemeinschaft (Schwerpunktprogramm ¹Sprachproduktionª und Sonderforschungsbereich 550 ¹Erkennen, Lokalisieren, Handeln: Neurokognitive Mechanismen und ihre Flexibilitätª) und durch die Heidelberger Akademie der Wissenschaften Korrespondenzadresse Prof. Dr. Hermann Ackermann, M. Zusammenfassung Mit dem Begriff der Prosodie wird die Modulation von Tonhöhe, Lautstärke, Sprechrhythmus und Stimmqualität im Verlauf sprachlicher ¾uûerungen bezeichnet. Neben einer Vielzahl lin-guistischer, z. B. Wort-und Satzakzent, und pragmatischer Funk-tionen, z. B. die Spezifizierung von Sprechhandlungen, spiegeln prosodische Merkmale auch aktuelle Stimmung und Befindlich-keit (affektive Prosodie) eines Menschen wider und tragen in Verbindung mit Gestik und Mimik zum nonverbalen Ausdruck von Emotionen bei. Klinische Untersuchungen führten zu diskre-panten Modellen der zerebralen Organisation stimmlich-voka-len emotionalen Verhaltens, z. B. in Bezug auf die Hemisphären-lateralität dieser Leistungen. Funktionell-bildgebende Studien stellen einen weiterführenden Untersuchungsansatz dar. Die vorliegenden Arbeiten weisen auf zwei sukzessive Stufen der Wahrnehmung affektiver Prosodie hin: a) eine vorwiegend rechtshemisphärische Enkodierung von Intonationskonturen, ein akustisches Korrelat affektiver Prosodie, im Bereich posterio-rer Anteile des Gyrus temporalis superior und b) eine im We-sentlichen an orbitofrontale Strukturen beidseits geknüpfte Evaluation von Art und Ausprägung der durch affektiv-prosodi-sche Merkmale des Sprachsignals vermittelten Emotionen. Der Befund einer vorwiegend rechtshemisphärisch-temporalen hä-modynamischen Aktivierung im Rahmen der Verarbeitung von Abstract Besides a sequence of words, spoken utterances are characteriz-ed by prosodic (suprasegmental) qualities such as a distinct into-nation contour (¹speech melodyª), loudness variations, and a rhythmic structure. In addition to a variety of linguistic and prag-matic functions, these features may reflect a speaker's mood and, thus, contribute, concomitant with facial and gestural move-ments, to the nonverbal expression of emotions (affective proso-dy). Clinical studies yielded discrepant data on the cerebral cor-relates of the processing of affective prosody. Functional imaging provides a more recent approach to the analysis of brain-behav-iour relationships. The available investigations indicate two suc-cessive stages of the perceptual encoding of affective prosody: (a) predominant right-hemisphere processing of intonation con-tours within posterior parts of the superior temporal gyrus, (b) evaluation of the conveyed emotion at the level of bilateral orbi-tofrontal cortex. These findings corroborate and extend the mo-del of a more proficient analysis and short-term storage of tonal information within the right cerebral hemisphere.
Aktuelle Neurologie 11/2004; 31(1). · 0.32 Impact Factor
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ABSTRACT: Appreciation of the emotional tone of verbal utterances represents an important aspect of social life. It is still unsettled, however, which brain areas mediate processing of intonational information and whether the presumed right-sided superiority depends upon acoustic properties of the speech signal. Functional magnetic resonance imaging was used to disentangle brain activation associated with (i) extraction of specific acoustic cues and (ii) detection of specific emotional states. Stimulus material comprised pairs of emotionally intonated utterances, exclusively differing either in pitch range or in the length of stressed vowels. Hemodynamic responses showed a dynamic pattern of cerebral activation including sequenced bilateral responses of various cortical and subcortical structures. Activation associated with discrimination of emotional expressiveness predominantly emerged within the right inferior parietal lobule, within the bilateral mesiofrontal cortex and--with an asymmetry toward the right hemisphere--at the level of bilateral dorsolateral frontal cortex. Lateralization did not depend upon acoustic structure or emotional valence of stimuli. These findings might prove helpful in reconciling the controversial previous clinical and experimental data.
NeuroImage 05/2002; 15(4):856-69. · 5.89 Impact Factor
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ABSTRACT: Rhythm in terms of the modulation of syllable durations represents an information-bearing feature of verbal utterances contributing both to the meaning of a sentence (linguistic prosody) as well as a speaker's emotional expression (affective prosody). In order to delineate the neural structures subserving rhythmic shaping of speech production, functional magnetic resonance imaging (fMRI) was performed during (a) monotonous syllable repetitions and (b) production of syllable triplets with lengthening either of the initial or final unit. The latter pattern of syllable durations can be considered the prototypical rhythmic structure contributing both to linguistic and affective prosody. A cognitive subtraction approach (rhythmic versus monotonous iterations) revealed activation of right-sided perisylvian areas (superior temporal gyrus, Broca analogon and adjacent premotor cortex) as well as contralateral subcortical structures (putamen and thalamus). Presumably, these responses reflect a righthemisphere rehearsal mechanism of rhythmic patterns and lefthemisphere monitoring of verbal output.
04/2002;
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ABSTRACT: Eight volunteers underwent fMRI during passive listening to click trains. Using a parametric approach, rate-response profiles across the frequency band considered (2-6 Hz) were determined. Several cerebral structures outside the central-auditory pathways and target areas displayed distinct activation patterns each: rate-response profiles resembling high-pass (left side) or low-pass filtered (right side) signal series emerged at the level of the anterior insula, band-pass like characteristics (center frequency: 3-4 Hz) were observed within the left inferior frontal gyrus, and click train rates > 4 Hz yielded enhanced activation of the right cerebellar hemisphere. A variety of clinical and experimental data indicate that the left and right cerebral hemispheres act as high- and low-pass filters, respectively, on auditory input (double filtering by frequency theory). In light of the present fMRI data, the anterior insula contributes to the assumed double filtering by frequency functions. Furthermore, these intrasylvian areas seem to join up with the right cerebellum and the left inferior frontal gyrus to a network subserving parsing/timing functions within the auditory-verbal domain.
Neuroreport 12/2001; 12(18):4087-92. · 1.66 Impact Factor
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ABSTRACT: Humans show a stronger cortical representation of auditory input at the opposite hemisphere each. To specify the temporal aspects of this contralaterality effect within the domain of speech stimuli, the present study recorded a series of evoked magnetic fields (M50, M100, mismatch field) subsequent to monaural application of stop consonant-vowel syllables using whole-head magnetoencephalography (MEG). The M50 components exhibited a skewed shape of cross-symmetrical distribution in terms of an initial maximum peak succeeded by a knot over the contralateral and a reversed pattern over the ipsilateral temporal lobe. Most presumably, this pattern of evoked fields reflects two distinct stages of central-auditory processing: (a) initial excitation of the larger contralateral and the smaller ipsilateral projection area of the stimulated ear; (b) subsequent transcallosal activation of the residual neurons, i.e. the targets of the non-stimulated ear, at either side. Previous studies using non-speech stimuli found contralaterality of central-auditory processing to extend to the M100 field. In contrast, a larger amplitude of ipsilateral M100 as compared to the respective opposite deflection emerged after stimulation of either ear. Finally, the computed magnetic analogues of mismatch negativity failed any significant laterality effects. These data provide first evidence for a distinct pattern of hemispheric differences at the level of the M50/M100 complex subsequent to monaural application of speech stimuli.
Neuroreport 07/2001; 12(8):1683-7. · 1.66 Impact Factor
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ABSTRACT: Simultaneous experience of the same acoustic stimulus in two distinct phenomenological modes, e.g. as a speech-like and as a non-speech event, is referred to as duplex perception (DP). The most widely investigated DP paradigm splits each of the stop consonant-vowel (CV) syllables /ga/ and /da/ into an isolated formant transient (chirp) and the remaining sound structure (base). The present study recorded mismatch fields in response to a series of dichotically applied base and chirp components using whole-head magnetencephalography (MEG). Preattentive mismatch fields showed larger amplitudes in response to contralateral deviants. During attention to the fused percept /da/, the left ear deviants chirps elicited an enhanced and posteriorly shifted dipole field over the ipsilateral hemisphere. These data provide first neurophysiological evidence that the integration of acoustic stimulus elements into a coherent syllable representation constitutes a distinct stage of left-hemisphere speech sound encoding.
Neuroreport 04/2001; 12(3):501-6. · 1.66 Impact Factor
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ABSTRACT: In order to delineate the neuroanatomical correlates of speech motor control, functional magnetic resonance imaging was performed during silent repetitions of the syllable "ta" at three different rates (2.5, 4.0, and 5.5 Hz). Spatial extent and magnitude of hemodynamic responses at the level of the motor cortex showed a positive correlation to production frequencies. As concerns the basal ganglia, the lower rates (2.5 and 4.0 Hz) gave rise to higher magnitudes of activation within the left putamen as compared to the 5.5 Hz condition. In contrast, cerebellar responses were rather restricted to fast performance (4.0 and 5.5 Hz) and exhibited a shift in caudal direction during 5.5 as compared to 4.0 Hz. These findings corroborate the suggestion of a differential impact of various cortical and subcortical areas on speech motor control.
NeuroImage 02/2001; 13(1):101-9. · 5.89 Impact Factor
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ABSTRACT: Voiced and unvoiced sounds, characterized by a periodic or aperiodic acoustic structure, respectively, represent two basic information-bearing elements of the speech signal. Using whole-head magnetencephalography (MEG), magnetic fields (M50/M100) in response to synthetic vowel-like as well as noise-like signals matched in spectral envelope were recorded in 20 subjects. Aperiodic events gave rise to increased M50 concomitant with reduced M100 activity as compared to their periodic cognates. Attention toward the auditory channel enhanced the effects of signal periodicity. These data provide first evidence that speech-relevant acoustic features differentially affect evoked magnetic fields as early as the M50 component. Conceivably, the M50 field reflects an ongoing monitoring process whereas the M100 component is bound to more specific operations such as detection of signal periodicity.
Neuroreport 01/2001; 11(18):4017-20. · 1.66 Impact Factor
