Top-Down Control in Contour Grouping

• DOI: 10.1371/journal.pone.0054085
• Publication Date: 2013-01-10T17:13:38Z
• Authors: Gregor Volberg; Andreas Wutz; Mark W. Greenlee
• Keywords: Stimulus (psychology)

Human observers tend to group oriented line segments into full contours if they follow the Gestalt rule of 'good continuation'. It is commonly assumed that contour grouping emerges automatically in early visual cortex. In contrast, recent work animal models suggests requires learning and thus involves top-down control from higher brain structures. Here we explore mechanisms perceptual by investigating synchronicity within EEG oscillations. participants saw two micro-Gabor arrays a random order, with task indicate whether first (S1) or second stimulus (S2) contained collinearly aligned elements. Contour compared non-contour S1 produced larger posterior post-stimulus beta power (15-21 Hz). S2 was associated pre-stimulus decrease alpha (11-12 Hz) fronto-posterior theta (4-5 phase couplings, but not increase power. The results subjects used prior knowledge processing for grouping. Expanding previous on oscillations, propose long-range synchrony shapes neural responses groupings regulating lateral inhibition