title: Early visual evoked potentials in callosal agenesis.
abstract: Three participants with callosal agenesis and 12 neurologically normal participants were tested on a simple reaction time task, with visual evoked potentials collected using a high-density 128-channel system. Independent-components analyses were performed on the averaged visual evoked potentials to isolate the components of interest. Contrary to previous research with acallosals, evidence of ipsilateral activation was present in all 3 participants. Although ipsilateral visual components were present in all 4 unilateral conditions in the 2 related acallosal participants, in the 3rd, these were present only in the crossed visual field-hand conditions and not in the uncrossed conditions. Suggestions are made as to why these results differ from earlier findings and as to the neural mechanisms facilitating this ipsilateral activation.
authors.affiliation: Research Centre for Cognitive Neuroscience, Department of Psychology, University of Auckland, Auckland, New Zealand.
authors.forename: Melodie S
authors.initials: MS
authors.lastname: Barr
authors.forename: Jeff P
authors.initials: JP
authors.lastname: Hamm
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Kirk
authors.forename: Michael C
authors.initials: MC
authors.lastname: Corballis
mesh_terms: D000328:Adult; D061085:Agenesis of Corpus Callosum; D001927:Brain Diseases / Q000473:pathology / Q000503:physiopathology*; D001931:Brain Mapping / Q000379:methods; D003337:Corpus Callosum / Q000503:physiopathology*; D004569:Electroencephalography / Q000379:methods; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D010775:Photic Stimulation / Q000379:methods; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology*; D013997:Time Factors