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ERIC Number: EJ869767
Record Type: Journal
Publication Date: 2009-Oct
Pages: 6
Abstractor: As Provided
Reference Count: 0
ISBN: N/A
ISSN: ISSN-0278-2626
A Choice Reaction Time Index of Callosal Anatomical Homotopy
Desjardins, Sameul; Braun, Claude M. J.; Achim, Andre; Roberge, Carl
Brain and Cognition, v71 n1 p46-51 Oct 2009
Tachistoscopically presented bilateral stimulus pairs not parallel to the meridian produced significantly longer RTs on a task requiring discrimination of shapes (Go/no-Go) than pairs emplaced symmetrically on each side of the meridian in Desjardins and Braun [Desjardins, S., & Braun, C. M. J. (2006). Homotopy and heterotopy and the bilateral field advantage in the Dimond paradigm. Acta Psychologica, 121, 125-136]. This was explained by the fact that there are more homotopic than heterotopic fibers in the corpus callosum. However: (1) different parts of the visual field were not equiprobably stimulated, possibly causing subtle biases, (2) the predicted cost of vertical asymmetry was tested only with bilateral stimuli, and (3) interstimulus distance was at the outer limit of callosal midline fusion (10.6[degrees]). Here, a tachistoscopic experiment with 24 normal participants replicated the between-field vertical symmetry advantage [Desjardins, S., & Braun, C. M. J. (2006). Homotopy and heterotopy and the bilateral field advantage in the Dimond paradigm. Acta Psychologica, 121, 125-136.], but without irrelevant stimulation conditions and with more proximal stimuli. In addition, a significant specific cost of vertical asymmetry of 7 ms was found for between-field integration over within-field integration. As far as we know, this is the first demonstration of an effect of callosal anatomical homotopy with reaction time. (Contains 2 figures.)
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Publication Type: Journal Articles; Reports - Research
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A