Plaid and Grating Stimuli in MT

After the initial characterization of each neuron with gratings in area MT, we presented a dynamic random plaid and grating stimulus. Gratings were presented at 50% contrast, and plaids were constructed by adding two such gratings separated by 120$^\circ$ in orientation. We presented each of these two types of stimuli drifting in twelve different directions, in addition to four periods of blank (mean gray) screen. Trials lasted 45 s and consisted of all 28 of the stimuli presented in random order for 320 ms each, with five presentations of each stimulus. These trials were typically repeated 20 times, to achieve 100 presentations of each of the 28 stimuli. The actual number of presentations was chosen for each cell based on the variability of its response.