Representation of shape by medial axis in cerebral cortex (ヒューマンインフォメーション立体映像技術)

概要

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Daily life presents us with a wide variety of shapes that we recognize immediately even if the figures are occluded partially. Physiological studies with macaques suggested the presence of Medial Axis (MA) transform for shape coding in the cortical area V1. We propose that onset synchronizations among V1 cells and among border-ownership (BO) cells in V2 evoke the responses corresponding to MA through feedback and horizontal connections. To test this hypothesis, we developed a biophysically detailed, computational model of the cortical areas V1 and V2. The model is designed to reproduce the onset synchronizations among border-ownership (BO) selective cells in V2, as has been reported in a recent physiological study, as well as among V1 cells. The V1 cells receive signals from the BO cells via feedback connections, and from other V1 cells via horizontal connections. We carried out simulations of the model with various stimuli including natural images to test whether these few constraints are capable of coding shape with MA. The model encoded successfully 2D shapes through MA representation with reconstruction error of 5〜35%. The results suggest that early visual areas are capable of coding shape by MA with a few known physiological constraints including onset synchronization.
2010-03-01