Blog Archives

Study of suppression effect in the brainstem auditory evoked potential*

the present study indicated increased latencies and reduced amplitudes of waves I, III and V with contralateral noise, when comparing the situations with and without noise. These results suggest a possible influence of the efferent auditory system on the response modulation of Brainstem auditory evoked potential when contralateral white noise is used.

from Pró-Fono

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Doing better than your best: loud auditory stimulation yields improvements in maximal voluntary force

Could task performance be constrained by our ability to fully engage necessary neural processing through effort of will? The StartReact phenomenon suggests that this might be the case, as voluntary reaction times are substantially reduced by loud sounds. Here, we show that loud auditory stimulation can also be associated with an improvement in the force and speed of force development when 18 healthy subjects are repeatedly asked to make a maximal grip as fast and as strongly as possible. Peak grip force was increased by 7.2 ± 1.4% (SEM) (P < 0.0001), and the rate of force development was increased by 17.6 ± 2.0% (P ≪ 0.00001), when imperative visual cues were accompanied by a loud auditory stimulus rather than delivered alone. This implies that loud auditory stimuli may allow motor pathways to be optimised beyond what can be achieved by effort of will alone.

from Experimental Brain Research

Pre-stimulus beta oscillations within left posterior sylvian regions impact auditory temporal order judgment accuracy

Both neural and behavioral responses to stimuli are influenced by the state of the brain immediately preceding their presentation, notably by pre-stimulus oscillatory activity. Using frequency analysis of high-density electroencephalogram coupled with source estimations, the present study investigated the role of pre-stimulus oscillatory activity in auditory spatial temporal order judgments (TOJ). Oscillations within the beta range (i.e. 18-23Hz) were significantly stronger before accurate than inaccurate TOJ trials. Distributed source estimations identified bilateral posterior sylvian regions as the principal contributors to pre-stimulus beta oscillations. Activity within the left posterior sylvian region was significantly stronger before accurate than inaccurate TOJ trials. We discuss our results in terms of a modulation of sensory gating mechanisms mediated by beta activity.

from the International Journal of Psychophysiology

Malformation of the human superior olive in autistic spectrum disorders

Autistic spectrum disorders (ASD) comprise a continuum of psychosocial disorders clinically characterized by social difficulties, impaired communication skills and repetitive behavioral patterns. Despite the prevalence of ASD, the neurobiology of this disorder is poorly understood. However, abnormalities in neuronal morphology, cell number and connectivity have been described throughout the autistic brain. Further, there is ample evidence that auditory dysfunction is a common feature of autism. Our preliminary investigation of neuronal morphology in the auditory brainstem of individuals with ASD focused on the medial superior olive (MSO) and revealed that neurons in this region were significantly smaller and rounder than in controls. In this report, we expand our investigation to examine all nuclei within the human superior olivary complex (SOC), an important auditory brainstem center. We examine neuronal morphology and neuronal number in four control (average age = 15 years) and 9 autistic brains (average age = 15 years). This detailed investigation supports our previous descriptions of the MSO, and also reveals significant dysmorphology in five other SOC nuclei. Moreover, we provide evidence of a consistent and significant decrease in the number of SOC neurons in the autistic brain. Our studies implicate an extensive malformation of the auditory brainstem in the hearing and language difficulties in individuals with ASD. The results from this investigation suggest that neonatal testing of auditory function may aid in the identification of individuals with ASD earlier than presently possible.

from Brain Research

An investigation of prototypical and atypical within-category vowels and non-speech analogues on cortical auditory evoked related potentials (AERPs) in 9 year children

The present study examined cortical auditory evoked related potentials (AERPs) for the P1-N250 and MMN components in children 9 years of age. The first goal was to investigate whether AERPs respond differentially to vowels and complex tones, and the second goal was to explore how prototypical language formant structures might be reflected in these early auditory processing stages. Stimuli were two synthetic within-category vowels (/y/), one of which was preferred by adult German listeners (“prototypical-vowel”), and analogous complex tones. P1 strongly distinguished vowels from tones, revealing larger amplitudes for the more difficult to discriminate but phonetically richer vowel stimuli. Prototypical language phoneme status did not reliably affect AERPs; however P1 amplitudes elicited by the prototypical-vowel correlated robustly with the ability to correctly identify two prototypical-vowels presented in succession as “same” (r = -.70) and word reading fluency (r = -.63). These negative correlations suggest that smaller P1 amplitudes elicited by the prototypical-vowel predict enhanced accuracy when judging prototypical-vowel “sameness” and increased word reading speed. N250 and MMN did not differentiate between vowels and tones and showed no correlations to behavioral measures.

from the International Journal of Psychophysiology

Clinical neurophysiology of visual and auditory processing in dyslexia: A review

Neurophysiological studies on children and adults with dyslexia provide a deeper understanding of how visual and auditory processing in dyslexia might relate to reading deficits. The goal of this review is to provide an overview of research findings in the last two decades on motion related and contrast sensitivity visual evoked potentials and on auditory event related potentials to basic tone and speech sound processing in dyslexia. These results are particularly relevant for three important theories about causality in dyslexia: the magnocellular deficit hypothesis, the temporal processing deficit hypothesis and the phonological deficit hypothesis. Support for magnocellular deficits in dyslexia are primarily provided from evidence for altered visual evoked potentials to rapidly moving stimuli presented at low contrasts. Consistently ERP findings revealed altered neurophysiological processes in individuals with dyslexia to speech stimuli, but evidence for deficits processing certain general acoustic information relevant for speech perception, such as frequency changes and temporal patterns, are also apparent.

from Clinical Neurophysiology

Superior voice recognition in a patient with acquired prosopagnosia and object agnosia

Anecdotally, it has been reported that individuals with acquired prosopagnosia compensate for their inability to recognize faces by using other person identity cues such as hair, gait or the voice. Are they therefore superior at the use of non-face cues, specifically voices, to person identity? Here, we empirically measure person and object identity recognition in a patient with acquired prosopagnosia and object agnosia. We quantify person identity (face and voice) and object identity (car and horn) recognition for visual, auditory, and bimodal (visual and auditory) stimuli. The patient is unable to recognize faces or cars, consistent with his prosopagnosia and object agnosia, respectively. He is perfectly able to recognize people’s voices and car horns and bimodal stimuli. These data show a reverse shift in the typical weighting of visual over auditory information for audiovisual stimuli in a compromised visual recognition system. Moreover, the patient shows selectively superior voice recognition compared to the controls revealing that two different stimulus domains, persons and objects may not be equally affected by sensory adaptation effects. This is also implies that person and object identity recognition are processed in separate pathways. These data demonstrate that an individual with acquired prosopagnosia and object agnosia can compensate for the visual impairment and become quite skilled at using spared aspects of sensory processing. In the case of acquired prosopagnosia, it is advantageous to develop a superior use of voices for person identity recognition in everyday life.<p><p>from <a href=”http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T0D-511R9X0-1&_user=108452&_coverDate=09%2F17%2F2010&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_acct=C000059732&_version=1&_urlVersion=0&_userid=108452&md5=b8367be9e9acc9d929d3ec793dd0ee4a&searchtype=a”><em>Neuropsychologia</em></a></p&gt;

Sound localization difficulty affects early and late processing of auditory spatial information: Investigation using the dipole tracing method

Conclusions
Difficulty of sound localization may affect brain function related to analyzing features of the spatial cue, eventually identifying the spatial location, and attention.

from Clinical Neurophysiology

Speech-feature discrimination in children with Asperger syndrome as determined with the multi-feature mismatch negativity paradigm

Conclusions
Cortical speech-sound discrimination is aberrant in children with Asperger syndrome. This is evident both as hypersensitive and depressed neural reactions to speech-sound changes, and is associated with features (frequency, intensity) which are relevant for prosodic processing.

from Clinical Neurophysiology

Effects of DBS on auditory and somatosensory processing in Parkinson’s disease

Motor symptoms of Parkinson’s disease (PD) can be relieved by deep brain stimulation (DBS). The mechanism of action of DBS is largely unclear. Magnetoencephalography (MEG) studies on DBS patients have been unfeasible because of strong magnetic artifacts. An artifact suppression method known as spatiotemporal signal space separation (tSSS) has mainly overcome these difficulties. We wanted to clarify whether tSSS enables noninvasive measurement of the modulation of cortical activity caused by DBS. We have studied auditory and somatosensory-evoked fields (AEFs and SEFs) of advanced PD patients with bilateral subthalamic nucleus (STN) DBS using MEG. AEFs were elicited by 1-kHz tones and SEFs by electrical pulses to the median nerve with DBS on and off. Data could be successfully acquired and analyzed from 12 out of 16 measured patients. The motor symptoms were significantly relieved by DBS, which clearly enhanced the ipsilateral auditory N100m responses in the right hemisphere. Contralateral N100m responses and somatosensory P60m responses also had a tendency to increase when bilateral DBS was on. MEG with tSSS offers a novel and powerful tool to investigate DBS modulation of the evoked cortical activity in PD with high temporal and spatial resolution. The results suggest that STN-DBS modulates auditory processing in advanced PD. Hum Brain Mapp, 2010. © 2010 Wiley-Liss, Inc.

from Human Brain Mapping

Random gap detection test and random gap detection test-expanded: Results in children with previous language delay in early childhood

The children with PLD have difficulties in perception of speech sounds at a certain rate, even they have not language learning difficulties. Therefore, difficulty in distinguishing of speech sounds may cause especially receptive language development delay.

We believe that perception of the speech sounds and language in a certain speed; and temporally degraded speech programmes should be incorporated into the training programme and may help to prevent delays.

from Auris Nasus Larynx

Random gap detection test and random gap detection test-expanded: Results in children with previous language delay in early childhood

We believe that perception of the speech sounds and language in a certain speed; and temporally degraded speech programmes should be incorporated into the training programme and may help to prevent delays.

from Auris Nasus Larynx

Language-dependent pitch encoding advantage in the brainstem is not limited to acceleration rates that occur in natural speech

Experience-dependent enhancement of neural encoding of pitch in the auditory brainstem has been observed for only specific portions of native pitch contours exhibiting high rates of pitch acceleration, irrespective of speech or nonspeech contexts. This experiment allows us to determine whether this language-dependent advantage transfers to acceleration rates that extend beyond the pitch range of natural speech. Brainstem frequency-following responses (FFRs) were recorded from Chinese and English participants in response to four, 250-ms dynamic click-train stimuli with different rates of pitch acceleration. The maximum pitch acceleration rates in a given stimulus ranged from low (0.3 Hz/ms; Mandarin Tone 2) to high (2.7 Hz/ms; 2 octaves). Pitch strength measurements were computed from the FFRs using autocorrelation algorithms with an analysis window centered at the point of maximum pitch acceleration in each stimulus. Between-group comparisons of pitch strength revealed that Chinese exhibit more robust pitch representation than English across all four acceleration rates. Regardless of language group, pitch strength was greater in response to acceleration rates within or proximal to natural speech relative to those beyond its range. Though both groups showed decreasing pitch strength with increasing acceleration rates, pitch representations of the Chinese group were more resistant to degradation. FFR spectral data were complementary across acceleration rates. These findings demonstrate that perceptually salient pitch cues associated with lexical tone influence brainstem pitch extraction not only in the speech domain, but also in auditory signals that clearly fall outside the range of dynamic pitch that a native listener is exposed to.

from Brain and Language

The effects of cortical ischemic stroke on auditory processing in humans as indexed by transient brain responses

Left-hemispheric ischemic stroke impairs the processing of sinusoidal and speech sounds. This deficit seems to depend on the severity and location of stroke.

from Clinical Neurophysiology

The effects of healthy aging on auditory processing in humans as indexed by transient brain responses

Aging seems to affect the temporal dynamics of cortical auditory processing. The transient brain response is sensitive both to spectral complexity and aging-related changes in the timing of cortical activation.

from Clinical Neurophysiology