Biomedical subjects

Kimberly Giraud

Publications and source records attributed to Kimberly Giraud.

2 recordsLinked to original sources

PubMed2005

Hemispheric lateralization of voice onset time (VOT) comparison between depth and scalp EEG recordings.

Auditory-evoked potential (AEP)s elicited to French-language voiced stop consonant (/ba/) and voiceless stop consonant (/pa/) were studied in non-language-impaired epileptic patients and non-epileptic volunteers. First, depth AEPs recorded from the primary auditory cortex during pre-surgical exploration and scalp AEPs recordings using high resolution EEG (HR EEG-64 channels scalp EEG) were compared in the same patients. Both methods indicated that the processing of voiced and voiceless consonants was based on a temporal auditory coding. /Ba/ elicited a first complex (N1) at the onset of voicing and a second component [release component (RC)] time-locked to release. This processing took place specifically in the left primary auditory cortex. Source modeling of the RC showed that a left-greater-than-right amplitude of source probes (SP) both in epileptic patients with left-hemispheric language dominance [established by means of invasive tests (WADA test) and/or clinical data] and right-handed non-epileptic subjects. Our data suggest that the processing of VOT is related to hemispheric dominance for language and that scalp-recorded AEPs may represent an effective, non-invasive method to establish hemispheric dominance for language in clinical settings. This procedure could complement existing methods and could help to detect the dissociation between receptive and expressive language sometimes observed in patients with epilepsy.

Acoustic Stimulation↗

PubMed2002

Interhemispheric sensorimotor integration in pointing movements: a study on dyslexic adults.

In addition to reading disorders, numerous deficits have been found to be associated with dyslexia, suggesting that various neurological factors might be involved in its etiology. In the present study, we focused on three of the deficits which have been thought to accompany and to a certain extent, to explain dyslexia: an abnormal pattern of hemispheric asymmetry, abnormal hemispheric communication, and abnormal motor control. The aim of the present study was to determine whether adults with reading difficulties perform differently from control subjects in a visuo-manual pointing task, in which the subject was required to point with the right or the left hand to targets appearing to the right or left of a central fixation point. A total of 14 dyslexic adults and 14 control adults participated in this experiment. Motor control was assessed based on the time taken to perform the pointing task, hemispheric asymmetry in terms of the inter-hand differences in the reaction and movement times, and hemispheric communication based on the interhemispheric transfer time under crossed conditions, where the hand and the target were not on the same side. The results showed that neither hemispheric asymmetry nor interhemispheric transfer differed between dyslexic and control adults. However, the dyslexics were significantly slower when performing the pointing task. These results are in agreement with the hypothesis that dyslexia may involve a mild motor deficit.

Adult↗