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Intrahemispheric dysfunction in primary motor cortex without corpus callosum: a transcranial magnetic stimulation
Shirley Fecteau1, Maryse Lassonde, Hugo Théoret
1Centre de Recherche en Neuropsychologie et Cognition, Département de Psychologie, Université de Montréal and Hôpital Sainte-Justine, Montreal, Canada. sfecteau@bidmc.harvard.edu
BMC Neurology
|June 23, 2006
Summary
Individuals without a corpus callosum show altered intrahemispheric motor cortex inhibition. This study used transcranial magnetic stimulation (TMS) to assess neurophysiological function in these individuals, revealing increased cortical silent period duration.
Area of Science:
- Neuroscience
- Neurophysiology
- Motor Cortex Function
Background:
- The corpus callosum facilitates communication between cerebral hemispheres.
- Individuals lacking the corpus callosum exhibit interhemispheric and intrahemispheric impairments.
- Understanding intrahemispheric function in the absence of callosal projections is crucial.
Purpose of the Study:
- To investigate intrahemispheric neurophysiological function in the primary motor cortex of individuals with complete agenesis of the corpus callosum.
- To compare motor cortex excitability between individuals with and without a corpus callosum.
Main Methods:
- Utilized transcranial magnetic stimulation (TMS) protocols.
- Assessed resting motor threshold, paired-pulse stimulation (intracortical facilitation and inhibition), and cortical silent period.
- Compared three individuals with agenesis of the corpus callosum to sixteen healthy controls.
Main Results:
- No significant differences were found in resting motor threshold, intracortical facilitation, or intracortical inhibition.
- A significant increase in cortical silent period duration was observed in individuals lacking the corpus callosum.
- This indicates abnormal intrahemispheric inhibitory function.
Conclusions:
- Individuals without a corpus callosum demonstrate abnormal intrahemispheric excitability of the primary motor cortex.
- These findings extend previous observations of impaired interhemispheric function.
- Agenesis of the corpus callosum impacts both interhemispheric and intrahemispheric neurophysiological balance.