Spectrotemporal receptive field, from the second-order Wiener kernel for a seismic unit from the bullfrog lagena. The vertical axis
represents time
prior to the occurrence of a spike, the horizontal axis represents frequency. The image was formed by taking the difference between the
short-term power spectral densities of the noise stimuli in general and the noise stimuli that preceeded spikes. Thus zero (light
blue-green) represents no difference. The darker blue areas show regions of time and frequency where the intensity of the spike-producing
noise-stimulus intensity was well below the mean level (making the difference negative); the yellow-red areas show regions where it was
well above the mean level (making the difference positive). We take the image to imply that a stimulus that occurred between 2 and 7 ms
ago, centered about 125 Hz, would tend to produce a spike now, and that a stimulus in the same frequency range, but occurring 10 to 20 ms
ago would tend to inhibit the occurrence of the spike now. We intepret this inhibition to be among those phenomena commonly
labeled "adaptation." This sort of blue, adaptation pattern was not present in saccular units.
Last updated 12/27/2010
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