Orientation/direction selectivity

Here is a video showing sinusoidal gratings drifting in different directions. Each "click" indicates the actual spike of a neuron in primary visual cortex that is responding to the grating.

Below the video is the "tuning curve", or the averaging firing rates (in spikes/second) during the presentation of the grating. Note that the cell responds much more strongly for movement to the upper left and lower right; that is, it prefers bars that are about 45 degrees like this: \