Fig. 2.

Extracellular recording from DCMD in response to object approach (l/‖v‖ = 45 msec). Top panel, Time course of size of the approaching object on the stimulation screen, as monitored by TTL synchronization pulses. Bottom panel, Extracellular recording from the contralateral connective, showing DCMD as the largest unit. Note the short interruption in spiking during approach (curved arrow). Thick,thin solid lines, dashed line, Estimate of the instantaneous firing frequency obtained by smoothing the response with 20, 15, and 10 msec Gaussian windows, respectively. *Peak firing rate. Note that in this example, peak firing time is not determined with great certainty because of the two local maxima separated by the short interruption (arrow). For this experiment, l/‖v‖ = 45 msec was the least favorable stimulus parameter to estimate the peak, as can be seen from the error bars for the point l/‖v‖ = 45 msec in Figure 4A. Left inset, 20 msec Gaussian window used to smooth the spike rasters (same horizontal time scale as the extracellular trace, not drawn to scale in the vertical direction). spk, Spike.