PALMER, L. M.; MENSINGER, A. F.; University of Minnesota, Duluth; University of Minnesota, Duluth: Sensitivity of the anterior lateral line to complex stimuli in free swimming Oyster Toadfish, Opsanus tau

The lateral line of fishes consists of mechanoreceptive hair cells that function in schooling behavior, localization of underwater objects, rheotaxis and prey detection. Hair cells are grouped into sensory neuromasts located either upon the skin surface (superficial neuromasts) or enclosed within subdermal canals (canal neuromasts). Both neuromast types are innervated by primary afferents of the lateral line nerve. Previous investigations of the lateral line nerve have been limited by the need to restrain the experimental animals. Therefore, despite recent advancements in the understanding of the lateral line system, the neural activity of the lateral line in response to complex stimuli is largely unknown. To address such issues, we developed an inductive telemetry technique that enables extended recording from free swimming fish. This technique was employed to determine the neural activity of the anterior lateral line nerve in free swimming toadfish (Opsanus tau). Afferent anterior lateral line nerve spontaneous discharge rates were determined and the neural response to water flows varying in velocity and intensity were recorded in a quasi-natural environment. The firing rates were shown to be correlated with the distance between the water flow source and the innervated neuromasts. The results of this study enhance the knowledge of the lateral line system by providing insight into how fish interpret complex water flow. Additionally, the telemetry system provides researchers with an advanced tool for neural response analysis of aquatic animals.