Local contour features contribute to figure-ground segregation in monkey V4 neural populations and human perception

Figure-ground (FG) segregation is a crucial step towards the recognition of objects in natural scenes. Gestalt psychologists have emphasized the importance of contour features in perception of FG. Recent electrophysiological studies have identified a neural population in V4 that shows FG-dependent modulation (FG neurons). However, whether the contour features contribute to the modulation of the response patterns of the neural population remains unclear. In the present study, we quantified the contour features associated with Gestalt factors in local natural stimuli and examined whether salient contour-features evoked reliable perceptual and neural responses by analyzing response consistency (stability) across trials. The results showed the tendency that the more salient contour-features evoked the greater consistencies in the perceptual FG judgments and population-based neural responses in FG determination; a greater partial correlation for curvature and weaker correlations for closure and parallelism. Multiple linear regression analyses demonstrated that the perceptual consistency depended similarly on curvature and closure, and the neural consistency depended significantly on curvature but weakly on closure. We further observed a strong correlation between the consistencies in the perceptual and neural responses, i.e., stimuli that evoked more stable percepts tended to evoke more stable neural responses. These results indicate that local contour-features modulate the responses of the neural population in V4 and contribute to the perception of FG organization.