Figure 4. Further examples of excitatory contra- and ipsilateral inputs.

A, representative PSTHs taken form the full range of spot sizes tested, showing the responses of a second OFF centre cell to contralateral (left column) and subsequent ipsilateral (right column) stimulation. Note the similarity in response pattern with a characteristic secondary burst of activity, seen with stimulation of both contra- and ipsilateral eyes. B, responses of an ON centre cell to a patch of drifting grating of 0.01 cycle deg⁻¹ at ∼4 Hz, repeated 10 times for each PSTH. The stimulus was first shown to the ipsilateral eye then in rapid sequence to the contralateral and repeated to the ipsilateral eye. Bin size 25 ms, Y axis = firing rate in hertz.