Figure 4.

Slow excitation enhances the response of CD afferents to sinusoidal indentation. A, D, Continuous rate histograms showing the CD afferent response to the delivery of continuous, fixed-amplitude 0.3 Hz sinusoidal indentation (along the x-axis), before, during, and after a 10 efferent shock train (gray box; A) or superfusion of 50 μm muscarine (gray box; D). B, E, Corresponding phase histograms were constructed from A and D, respectively. Control, slow, and wash traces were generated from the first 18 waves, 18 waves centered on the peak efferent-mediated or muscarine-mediated slow excitation, and 18 waves at record end when discharge rates returned to near control values, respectively. Indent, Fit of indenter displacement signal. C, F, Corresponding gain measurements in CD afferents, expressed as the average difference in peak-to-peak modulation over indenter amplitude, are shown before (open symbols) and after respective treatments (filled symbols). Triangles and dashed lines represent units shown in B and E, respectively.