Weakened Center-Surround Interactions in Visual Motion Processing in Schizophrenia

Abstract

Schizophrenia is often accompanied by a range of visual perception deficits, with many involving impairments in motion perception. The presence of perceptual abnormalities may impair neural processes that depend on normal visual analysis, which in turn may affect overall functioning in dynamic visual environments. Here, we examine the integrity of suppressive center-surround mechanisms in motion perception of schizophrenic patients. Center-surround suppression has been implicated in a range of visual functions, including figureground segregation and pursuit eye movements, visual functions that are impaired in schizophrenia. In control subjects, evidence of center-surround suppression is found in a reduced ability to perceive motion of a high-contrast stimulus as its size increases. This counterintuitive finding is likely a perceptual correlate of center-surround mechanisms in cortical area MT. We now show that schizophrenic patients exhibit abnormally weak center-surround suppression in motion, an abnormality that is most pronounced in patients with severe negative symptoms. Interestingly, patients with the weakest surround suppression outperformed control subjects in motion discriminations of large high-contrast stimuli. This enhanced motion perception of large high-contrast stimuli is consistent with an MT abnormality in schizophrenia and has a potential to disrupt smooth pursuit eye movements and other visual functions that depend on unimpaired center-surround interactions in motion.

Altered Center-Surround Motion Inhibition in Schizophrenia

“…Studies in aging found age-associated decreases in GABA mediated inhibition [17] and reduced surround suppression on motion perception [18]. The increased surround suppression, found in this study, and the reduced surround suppression, found in a previous study, in schizophrenia suggest that abnormalities in inhibitory control of motion processing are multi-faceted in nature [14,19].…”

“…The dependence of surround modulation on signal strength is analogous to the finding that center-surround interaction in schizophrenia is weakened for high contrast stimuli [14]. Both results suggest that suppressive surround modulation is abnormal in schizophrenia when salient motion stimuli (such as those with high contrast or intermediate motion coherence) adequately activate the neural circuitry.…”

“…In a previous study [14], controls, but not patients, were less sensitive in detecting a large sized moving grating. Since only large-sized stimuli activate the center-surround mechanism, this result suggests that the center receives less suppression from the surround in schizophrenia (i.e.…”

“…When the center and the surround moved in opposite directions, decreased and increased surround facilitation would yield a perceptual shift towards the opposite and the same direction of central motion, respectively. Given that decreased surround suppression in schizophrenia was reported [14,15], we hypothesize that patients would show a perceptual shift towards central motion.…”

Motion detection, noise reduction, texture suppression, and contour enhancement by spatiotemporal Gabor filters with surround inhibition

“…For instance, it has been reported that surround suppression mechanisms in old people and patients with schizophrenia are weak. At the same time, they experience difficulties in segregating figure from background (Betts et al 2005;Tadin et al 2006), a finding that underlies the importance of surround mechanisms.…”