The observed relationship between FA/Mode and IHTT could also account for our failure to identify IHTT abnormalities in the schizophrenia patients, as the schizophrenia patients did not exhibit abnormalities in either FA or Mode in their visual corpus fibers. However, as mentioned previously, there are a number of fasciculi – particularly frontally-projecting fasciculi – in which SZ patients do show consistent and substantial diffusion abnormalities. Whilst there are significant differences between the microstructural properties of these frontally-projecting fasciculi and the visual callosum fibers investigated in the present study (e.g., Cherubini et al., 2009), if a similar relationship existed between transmission velocity and FA/Mode in these frontal fasciculi, then schizophrenia patients would be expected to experience significant conduction delays in signals traveling along these fasciculi. Such conduction delays could disrupt the precise temporal synchronization that is necessary for effective communication between discrete populations of oscillating neurons (Fries, 2005) which, in line with the ‘connectivity’ theories of SZ (Andreasen et al., 1999; Bartzokis, 2002; Bressler, 2003; Phillips and Silverstein, 2003), could underpin the cognitive disorganization characteristic of the disorder.
