Figure 1. Small central stimuli generate robust NMDAR-mediated light responses.

A, OFF Alpha cell responses to a 200 ms −100% contrast pulse (i.e. full decrement from the background luminance) presented within a spot of 200 or 1000 μm diameter centred over the RF centre. Synaptic currents are shown at two indicated V_holds (of eight in total, top) and averaged responses (within grey and white boxes) at stimulus onset (grey) and offset (black) are shown in the I–V plots (bottom). B₁, averaged I–V relationship at stimulus onset for OFF Alpha cells generated by the stimuli in A. The number of cells is indicated in parentheses. Error bars indicate ±SEM across cells. B₂, as for B₁ for the response at stimulus offset. C and D, as in A and B for OFF Delta cells.