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Uri Polat, Ativ Levi, Anna Sterkin, Revital Amiaz; Abnormal contour filling-in process in patients with depression. Journal of Vision 2006;6(6):377. doi: https://doi.org/10.1167/6.6.377.
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© ARVO (1962-2015); The Authors (2016-present)
Cardinal signs of depressive disorder are impairment of cognitive tasks and symptoms that may be mediated by an impairment of the brain reward system (that involved in decision making). We showed (Polat & Sagi, VSS 2005) that collinear interactions (YES-NO paradigm) induce high rate of false alarms (FA) in the Mix by trials condition, probably due to lateral excitation, inducing illusory percepts when targets are not present. Here, we probe the filling in process in three groups; hospitalized patients with depressive symptoms (N=26), out patient (N=6) and control (N=15). We measured sensitivity (d'), response criterion, FA and Hit rate for a Gabor target with different target-flankers separations of 3–12λ (wavelength). In the control group, the probability of reporting target present (FA and Hit) was very high at the shorter separations (3,4λ) and decreased with increasing separation. The performance of the patients is similar to the control group in d', FA and Hit for the larger separations, but FA is reliably different at the short separations (3,4λ;). Response criterion at 3λ is significantly increasing with increasing depression level and thus, becomes more different than the control group. Since the differences are restricted for the short separations, global cognitive dysfunction in depression cannot account for the reduced filling in. Rather, it may suggest that the filling in process is compromised,probably due to reduced excitation between neurons. Neural excitation is a key factor in the neural processing involving in the reward system and decision making.
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