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. Author manuscript; available in PMC: 2012 Jan 13.
Published in final edited form as: Neuron. 2011 Jan 13;69(1):147–158. doi: 10.1016/j.neuron.2010.12.007

Figure 6.

Figure 6

A DCMD firing rate threshold contributes to triggering co-contraction (see also Supp. Fig. S4). A) Example of neural and muscle recordings in response to looming stimuli with three final angular sizes (from bottom to top: 18, 25 and 50°; l/|v|=80 ms). As the final size increases the DCMD maximum firing rate and the total number of extensor spikes increase as well. Co-contraction did not occur for a final size of 18°. B) Probability Density Function (PDF) for the DCMD maximum firing rate in trials with, and without co-contraction (red and gray, respectively). The PDF is estimated using a non-parametric fit to the firing rate histogram as the sum of Gaussian kernels with bandwidths equal to 20 spk/s. C) Correlation coefficient between DCMD firing rate and l/|v| plotted as a function of delay before co-contraction onset. The correlation coefficient equals zero 40 ms before co-contraction onset. D) At that time the DCMD firing rate does not depend on l/|v| (pKWT = 0.6), and has an average value of 225 spk/s (SD: 73). Box plots of data from 4 locusts presented with full-expansion looming stimuli.