A and B, mean excitatory conductance (Ge, black, ±s.e.m.) and mean inhibitory conductance (Gi, grey, ±s.e.m.) in 7 ON DSGCs (A) and 6 ON–OFF DSGCs (B) in response to gratings moved at different velocities through the receptive field. C and D, integral excitatory conductance (GE, black, ±s.e.m.) and integral inhibitory conductance (GI, grey, ±s.e.m.) for the same data sets as A and B.