Meeting Abstract
Mechanosensory feedback has been shown to be critical to motor performance of vertebrate limbs. In fishes, the pectoral fin performs dual roles as a propulsor and a sensor. Although fins are known to be mechanosensitive, much remains to be discovered about how fin deformations are encoded in afferent responses. Here we use a suite of mechanical stimuli along spatiotemporal axes to probe the stimulus features encoded by the pectoral fin afferents of Gomphosus varius. We examine the dependence of response strength and dynamics on stimulus amplitude and examine the frequency sensitivity of individual afferents, both in the strength and phase-locking of the response to vibratory stimuli over a range of amplitudes and frequencies. Movements are encoded by afferents that can be classified as rapidly or slowly adapting, responding only during the transient phase of a stimulus, or as afferents that exhibit both adaptation properties. Our data indicate that different afferents also exhibit different frequency sensitivity profiles, with some afferents responding to frequencies greater than 20Hz, which exceeds the range of typical fin beats. Many of these afferents also exhibit precise phase-locking to vibratory stimuli across a wide range of frequencies. These data enhance our understanding of the mechanical features being encoded by pectoral fin afferents. The high temporal precision and the ability to encode frequencies well above normal fin beat frequency suggest that pectoral fin mechanosensory feedback may be used for other purposes in addition to its role in modulating fin movements and motor patterns.
