Microelectrode penetrations nearly normal to the layers of foveal striate cortex in awake, behaving monkeys reveal a shift in orientation preference between cells in the upper and lower layers. Mean shift size for 57 penetrations is 54.8 °, with 70% of the penetrations showing shifts of 45-90 °. Marking lesions localize the shift to the border between layers 4C and 5. The data are suggestive of inhibition between the upper and lower layers within an "orientation column".
- Visual cortex