Different anisotropies of movement direction in upper and lower layers of the cat's area 18 and their implications for global optic flow processing.

Cells in Area 18 of awake and behaving cats were tested for directional preference with a large visual noise pattern. Upper and lower layer cells were found to exhibit different anisotropies for movement direction, offset by 90 degrees. These findings could reflect different functions for the global mapping and processing of optic flow field in upper and lower layers.