Directionally selective cells in the locust medulla.

Intracellular recordings of a distinctive class of directionally selective cell from the medulla of the locust, Locusta migratoria, optic lobe are described. Dye marking shows that these cells arborize in the distal part of the medulla, and project through the lobula complex. The cells are excited by upward movement and have receptive fields of about 20 degrees in diameter. They are sensitive to a wide range of angular velocities from 0.02 degrees/s to over 200 degrees/s. The cells are sensitive to stationary flicker and have different latencies to dimming and brightening. Evidence is presented which suggests that directional computation depends, at least in part, on an inhibitory interaction between flicker sensitive channels.