Genesis of pattern and contour selectivity by intra-cortical circuits: functional implications of the pinwheel mosaic

[摘要] We distinguish shapes by contours, and surfaces by patterns and textures of multiple orientations and scales, despite retinal response compression leading to cross-orientation suppression. In striate cortex of primates and carnivores, orientation preference is arranged as iso-orientation domains that radiate circularly from pinwheel centers. Using tangential penetrations with multi-electrode arrays, we found that orientation tuning is narrower, and contrast saturation and cross-orientation suppression stronger, within iso-orientation domains than at pinwheel centers. These differences develop due to excitation (not normalization) from neighboring oriented neurons. As a result of these local intra-cortical computations, narrower tuning, greater cross-orientation suppression and higher contrast gain of iso-orientation cells, lead to extraction of object contours from images; whereas broader tuning, greater linearity and less suppression of pinwheel cells, generate selectivity for surface patterns and textures.

[学科分类] 眼科学