Redundancy gain in the acallosal brain.
The authors measured simple reaction time (RT) to visual stimuli, presented either singly to 1 or the other visual field or in bilaterally presented pairs, to 2 women with callosal agenesis. The stimuli were either white against a black background or gray against an equiluminant yellow background. RTs to bilateral pairs were decreased beyond predictions based on a simple race between independent unilateral processes, implying interhemispheric neural summation. This effect was enhanced under equiluminance in the participant M.M. whose anterior commissure was within normal limits, but not in the participant J.P. whose anterior commissure was enlarged. The anterior commissure may act, relative to its size, to inhibit cortical activation to bilateral pairs, which then acts to decrease subcortical neural summation.
Barr
Melodie S
MS
Research Centre for Cognitive Neuroscience, Department of Psychology, University of Auckland, New Zealand. m.barr@auckland.ac.nz
Corballis
Michael C
MC
D000328:Adult; D061085:Agenesis of Corpus Callosum; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007361:Intelligence Tests; D008959:Models, Neurological; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology*; D014057:Tomography, X-Ray Computed; D014794:Visual Fields / Q000502:physiology*