P1.105 Tuesday, Jan. 4 Pectoral Fin Innervation and Sensation of Movement NEUBARTH, NL*; WILLIAMS IV, R; HALE, ME; Univ. of Chicago email@example.com
Pectoral fins play critical roles in the locomotor movements of fishes by generating forces to propel, maneuver and stabilize the body. Little is known of how these movements are driven by the nervous system or modulated by feedback from the physical environment. In this study, we examine whether the fins themselves may act as sensors, providing feedback on the movement of the fins during locomotion. Our work focused on bluegills (Lepomis macrochirus), a species that uses its pectoral fins extensively during swimming. We mapped the innervation of the fins through dissection and staining techniques. Sudan Black and antibody staining labeled nerve fibers proximal to and within the fin rays and membrane. We found that the fin rays and membranes are extensively innervated. Several major nerves branch to serve each of the fin rays. Many nerve fibers extend through the core of each fin ray and into distal branches. Nerve fibers are also present in the fin membrane itself and are heavily concentrated along the leading edge of the fin. Additionally, we used extracellular recordings in a fictive fin preparation to examine whether the nerves identified respond to fin bending, which would indicate mechanoreception. Physiological recordings from several nerves demonstrated little or no response to touching the fin rays but a strong response to fin ray bending. Activity was recorded in response to bending toward both the lateral surface and the medial surface of the fin. These data show that the fin is capable of acting in mechanosensation and suggest that local mechanical feedback conveyed by the nerve fibers studied here may play a role in modulating fin movement. Supported by ONR, NSF’s moto-IGERT program (DGE-0903637) and NIH R90 DA023425.