Fig. 9. Response of M1 and M2 neurons to different types of movement. (A–E) Results with (A) the black looming stimulus, (B) the black receding stimulus, (C) the white looming stimulus, (D) the laterally moving stimulus and (E) the gradual darkening. Sample recordings from a single M1 and a single M2 neuron illustrate the type of responses of these neurons to the five different stimuli. Peristimulus time histograms show the mean spike rate recorded from 11 M1 and 13 M2 neurons from different animals (one trial per stimulus per neuron). Data are divided into 100-ms bins and are plotted as means ± s.e.m. The angular size of the looming and receding object is given in the bottom traces of each panel. Arrowheads signal the beginning of the stimulus expansion; black bars represent 1 s motion of a black square object moving laterally to the crab. The darkening bar in E represents a gradual darkening of the screen without motion components.