Independent Encoding of Position and Orientation by Population Responses in Primary Visual Cortex

摘要

The primary visual cortex (area V1) encodes visual attributes such as direction of motion, orientation, and position through the activity of populations of neurons. We asked how this activity is affected by different combinations of these attributes. We measured population responses by imaging voltage-sensitive dye fluorescence in area V1 of anesthetized cats with dye RH-1692 in response to stimuli that are both oriented and localized in space. We tested whether the resulting activation could be explained by a simple rule of combination that assumes the activation is a point-by-point multiplication of the map of orientation preference with a blurred prediction of the stimulus' footprint in cortex derived from a map of retinotopy. This simple rule of combination provided good fits of the responses and implies that the effects of stimulus orientation and position on population responses are independent.