4 on
3 off

Three OFF Cells

Excitatory Raster--------------- Inhibitory Raster

Four ON Cells

Excitatory Raster----------------Inhibitory Raster

Here are examples of 4 ON cells. Excitation on the left, inhibition on the right. Vertical white lines indicate stimulus ON and OFF. One second duration. Horizontal lines indicate stimulus width: 600 microns.
Here are similar rasters for 3 OFF cells. Note that, except for the LED, excitation and inhibition are complementary in both space and time.
Click here to see how these rasters are generated