The most significant finding of this paper was the discovery of an empirical relationship between IHTT – as quantified from the asymmetry in P1 latency at electrodes P9 and P10 – and the diffusion properties of the visual callosal fibers, as quantified with the diffusion metrics of FA and Mode. Specifically, the regression model – which accounted for 28.5% of the variance in IHTT – revealed that an increase of 10 ms in IHTT was associated with a decrease of approximately 0.035 in FA (i.e., more isotropic diffusion ellipsoids) and an increase of 0.14 in Mode (i.e., more prolate diffusion ellipsoids). Whilst the relationship between Mode and white-matter integrity has not been well established – although a study by Kindlmann et al. (2007) found evidence that abnormally increased Mode was associated with abnormalities in crossing fibers – reductions in FA have consistently been associated with white-matter pathology, including in dysmyelinated mice (Harsan et al., 2006), and patients with the demyelinating disease multiple sclerosis (Roosendaal et al., 2009). Furthermore, such white-matter pathology has consistently been associated with slowed neural transmission velocity,
