Transient- and sustained-type afferent neurons have preferential responses to pLiFU and cwLiFU. (A), (D) Transient-type afferents respond preferentially and phase-lock to pLiFU at 100 and 20 pps, respectively. Stimulus triggered histogram of action potential times in (A) shows preference for pLiFU with most action potentials being fired within 10 ms of pulse onset and random firing to cwLiFU. (D) Unit was silent at rest. (B), (E) Sustained-type afferents modulating firing rate with high gain to cwLiFU at 2 and 0.5 Hz, respectively, and exhibiting no phase-locking to pLiFU. Stimulus triggered histogram of action potential times in (B) shows firing rate modulation with cwLiFU and random firing to pLiFU. (C) Afferent responds with high gain to both pLiFU at 100 pps and cwLiFU at 2 Hz.