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Michael-Paul Schallmo, Cheryl Olman, Scott Sponheim; Reduced Contextual Effects on Contrast Perception in Schizophrenia and Bipolar Affective Disorder. Journal of Vision 2015;15(12):553. doi: https://doi.org/10.1167/15.12.553.
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© ARVO (1962-2015); The Authors (2016-present)
The perceived contrast of a visual stimulus is often reduced by the presence of nearby stimuli. This effect known as surround suppression may help to distinguish stimuli from similar backgrounds. Previous work has shown that people with schizophrenia demonstrate weaker surround suppression. Studying this deficit may help to identify impaired neural processing mechanisms in schizophrenia, as the neurobiology of the visual system is relatively well understood. By examining the surround suppression effect among subjects with schizophrenia (SZ; n = 23) or bipolar affective disorder (BP; n = 19), unaffected biological relatives of SZ (n = 25) or BP patients (n = 17), and healthy controls (n = 38) we sought to determine whether diminished surround suppression was specific to SZ, and if subjects with a genetic risk for either disorder would show a similar deficit. Measuring the modulation by different surround conditions (parallel with and without a gap, drifting in the same or opposite directions, and orthogonal) allowed us to investigate how this suppression effect depends on the similarity of center and surrounding stimuli. We found weaker surround suppression among patients with SZ, regardless of surround configuration. BP subjects showed an intermediate deficit, with stronger suppression than in SZ but weaker than healthy control subjects. Relatives of patients with either disorder showed normal performance. This is the first observation that reduced surround suppression is associated with both SZ and BP, but not with a genetic risk for these disorders. Further, our results indicate a deficit in broadly-tuned (rather than sharply orientation- or direction-selective) suppression mechanisms. This deficit is consistent with impaired surround suppression at an early stage of visual processing (e.g., LGN or V1).
Meeting abstract presented at VSS 2015
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