Responses of lateral line receptors to water flow in the Antarctic notothenioid, Trematomus bernacchii

The response properties of anterior lateral line afferent neurones in Trematomus bernacchii were recorded extracellularly while stimulating the fish with unidirectional water flows of varying velocity. Afferent neurone responses were either flow-sensitive or flow-insensitive. Flow-sensitive neurones showed linear increases in response magnitude with increasing flow rate and tonic non-adapting response properties. These findings indicate that flow-sensitive afferent neurones originate from lateral line receptors that detect absolute flow velocity. The likely explanation is that flow-sensitive afferent neurones innervate neuromasts located superficially on the skin and flow-insensitive neurones innervate neuromasts situated in sub-epidermal fluid-filled canals.