Altered feed-forward transfer of visual motion information to association cortex in psychotic disorders: implications for visual tracking

Abstract

Objective: To identify alterations in neural networks for visual motion perception and pursuit tracking and their interrelationship in schizophrenia, and secondarily to evaluate their comparability to findings in psychotic bipolar disorder. Design, setting and participants: Untreated first-episode patients with schizophrenia (N=24) and psychotic bipolar disorder (N=13), and 20 matched healthy participants performed a passive visual motion processing task and a pursuit eye tracking task, which patients have been shown to perform as well as healthy subjects, during functional neuroimaging. Available subjects were retested after four weeks, during which both patient groups received second generation antipsychotics. Besides categorical comparisons between groups, we were especially interested in the relationship of activation in motion-sensitive extrastriate area V5 during motion processing and activation in neural systems supporting pursuit tracking. Statistical analysis included analysis of variance and post-hoc t-tests using AFNI, probability thresholds were set at pcorrected=0.013. Results: During the motion processing task, neither patient group showed reduced activation in V5, but activations in its projection fields in posterior parietal cortex were reduced in both groups. Pursuit related neural activation in both patients groups was not reduced in sensorimotor systems, but was enhanced in anterior intraparietal sulcus and insula. In schizophrenia, activation was also enhanced in dorsolateral prefrontal cortex and dorsomedial thalamus. Conclusions: Greater V5 activation during passive motion processing predicted greater activation in posterior parietal cortex during pursuit in healthy individuals but not in patients. The only significant change at follow-up was decreased anterior cingulate activation during pursuit in schizophrenia.