Fig. 8. Response of an M1 and an M2 neuron to (A) a flash of light, (B) a laterally moving object and (C) an approaching object. (A) The horizontal open bar below the traces represents 1 s duration of light stimulation (200 mW m^–2 at the crab eye). (B) The black bar represents 1 s motion of a black square object moving laterally to the crab. (C) The curved line represents the time course of expansion of the looming stimulus as described in Fig. 7. Arrows in the traces mark the approximate moment at which the neurons began to respond to the looming stimulus by increasing their synaptic activity or spike rate above resting level.