Meeting Abstract
The fins of bottom dwelling fishes often touch substrate and may deform in response to that contact. Here we investigate the capability of the fin mechanosensory system to resolve fine details of associated substrate. While the tetrapod somatosensory system exhibits fine tactile sensitivity capable of resolving sub-millimeter textural features via mechanoreceptors with small diameter receptive fields, it is unknown whether fish fins can encode such detail on the shape and roughness of the substrate. Sensory feedback on surface features could modulate a variety of substrate-based behaviors such as orientation or station holding. In this study we examined the pectoral fins of the bottom dwelling Round Goby (Neogobius melanostomus), an invasive species common to sandy and rocky bottoms of Lake Michigan. Using a linear brush stimulation we identified afferents that exhibited receptive field sizes similar to those found in the mammalian system, suggesting that they have the capability to discriminate aspects of fine tactile stimuli. To examine this possibility, fin ray nerve fiber activity was recorded in response to a rotating 3D printed drum with grating and embossed dot patterns. We found that afferents encode millimeter-sized features across a range of speeds (10 – 100 mm/sec), indicating similar levels of resolution to tetrapod tactile sensation. Immunostaining revealed putative mechanoreceptors located primarily in the fin membrane directly adjacent to each ray and differences between leading and trailing edge fin rays were found. This study suggests that fins of bottom dwelling species may be well suited to encode detailed surface features of their habitat and that limb based texture perception is not a unique feature of sarcopterygians.
