In summary, the present study identified highly significant IHTTs to unilaterally-presented stimuli in both healthy individuals and chronic schizophrenia patients. IHTT (calculated from the P1 component) from left-to-right hemisphere was found to be significantly faster than from right-to-left hemisphere, across groups. The schizophrenia patients did not exhibit abnormalities in either the magnitude or asymmetry of their IHTTs, nor did they exhibit abnormalities in the diffusion properties (quantified with FA and Mode) of the visual fibers of the corpus callosum. However, linear regression indentified a significant relationship, in both groups, between IHTT and the diffusion properties of the visual callosum fibers, such that participants with the lowest FA and highest Mode exhibited the longest IHTTs. If such a relationship held in such frontally-projecting fasciculi – fasciculi that have consistently been found to be structurally abnormal in schizophrenia – this would imply the presence of conduction delays along these fibers in schizophrenia patients. Such conduction delays could potentially disrupt neural coherence, which could represent the neural basis of the ‘cognitive dysmetria’ that has been proposed to underlie the disease (Andreasen et al., 1999).
