Figure 1.

Classification of primary afferents. (A) Typical responses of rapidly (RA) and slowly adapting (SA) primary afferents to a ramp-and-hold stimulus in the preferred direction of the cell. (B,C) Discriminative responses of RA and SA units to sine waves of different amplitude and peak frequency. (B) Slow, high amplitude sine waves are not responded by RAs but by SAs. (C) Fast, low amplitude sine waves evoke responses in both cell classes. (D) A number of preliminary recordings were used to delineate the responses of RA and SA cells to the two sine wave stimuli (light red and blue background). The units reported in this study are labeled by a number. The numbering of cells and coloring (red/blue) according to cell class is consistent throughout all figures to allow the cross referencing of individual cells.