Figure 9. IR- vs. efferent-evoked afferent responses.
Responses of three different afferents to separate IR and efferent vestibular stimulation (EVS) are shown. A, one unit showed an excitatory response (a) to EVS followed by a slow adaptation to resting discharge rate. The same unit elicited a mixed-type response to IR. Unlike EVS, IR evoked a rapid inhibitory response (b) followed by excitation (c) and increased the variance of interspike interval (CV) of the afferent unit. B, a second afferentunit did not respond to EVS (d) but elicited a strong response to IR (discharge rate increased from ∼50 spikes s−1 to ∼100 spikes s−1, e). C, a third unitwas inhibited by IR (f) but did not respond to EVS. EVS did eliminate (h) the respiratory motion artifact (g) from the afferent response.