| Cognitive control deficits are prevalent in schizophrenia patients (SZ). Previous research using reactive inhibition tasks has found SZ take longer to inhibit a prepared response. Abnormalities in the ventral attention network, which responds to unexpected stimuli, may play a role. The goal of this study was to examine whether structural integrity within this network is altered in SZ and relates to impaired reactive control over action in SZ. 20 SZ and 20 healthy controls (HC) performed an oculomotor variant on the stop-signal task and underwent diffusion tensor imaging. Subjects were required to make rapid eye movements to a target (T1) within an array. On some trials, the target jumped to a new location (T2), and participants were instructed to look directly at T2, inhibiting their saccade to T1. The time needed to inhibit (TSRT) was calculated. Probabilistic tractography was used to construct white matter tracts between primary visual cortex (V1), the ventral attention network (temporoparietal junction-TPJ and inferior frontal cortex-IFC), and supplementary eye fields (SEF). Microstructural integrity (FA) of these tracts was compared across groups and correlated with TSRT. Groups did not differ in speed of either STOP or GO latency. Increased positive symptoms and deceased occupational functioning predicted slower inhibition speeds in SZ. Additionally, SZ had decreased FA in V1-TPJ and IFC-SEF. Increased FA in TPJ-IFC significantly predicted decreased positive symptoms. FA of these three tracts did not predict the speed of inhibition. These findings suggest attention plays a role in inhibition tasks. However, the lack of correlations between tract integrity and performance makes it unclear whether these white matter differences are relevant to performance. |
