FIG. 5.

Simultaneous recording of two saccular afferents in response to pLiFU at 5 pps. (A) Individual units were identified by spike sorting (#1 blue, #2 red) and fired action potentials at winding ratios k = 1–2 (#2) and k = 2–3 (#1). (B), (C) Changing LiFU packet PW revealed that action potentials in unit #1 were triggered by the onset of the LiFU packet (#1, 2.5 ms latency re: On), and that action potentials in unit #2 were triggered by termination of the LiFU packet (#2, 3.2 ms latency re: Off). Afferents were triggered by the rate-of-change in force or, in terms of gravito-inertial stimuli, the rate-of-change in acceleration (termed “jerk”). These jerk sensitive afferent neurons are analogous to the auditory-frequency sensitive irregularly discharging afferents in mammals (transient-type neurons).