Fig. 4.

Averaged responses of two STC neurons whose activity was modulated by only one direction of wobble stimulation. Responses illustrated were elicited by 0.2-Hz wobble stimulation delivered at 7.5°. Averaged unit activity is indicated by traces, whereas overlain black curves are sine waves fit to the responses. A: responses of one unit prior to the administration of copper sulfate. The unit responded to clockwise (CW) wobble stimulation, but not counterclockwise (CCW) rotations (the signal-to-noise ratio was 0.82 for the CW response, and 0.01 for the CCW response). B: responses of a different unit before (top) and after (bottom) the administration of copper sulfate. During both conditions, the unit responded to CCW wobble, but not CW rotations. The response to CCW stimuli was so powerful that the activity of the unit was completely abolished during one phase of the rotation (contralateral ear down). The response gain for CCW trials was similar before (2.3 spikes·s⁻¹·deg⁻¹) and after (2.2 spikes·s⁻¹·deg⁻¹) copper sulfate administration. See Fig. 3 for definitions of abbreviations. The number of sweeps averaged to generate each trace was A: 33 (CW), 30 (CCW); B, top: 53 (CW), 51 (CCW); B, bottom: 11 (CW), 44 (CCW).