Sensors and Sensing in Biology and Engineering

Abstract

The lateral line is a hydrodynamic receptor system that enables fishesto detect minute water motions generated by conspecifics, predatorsor prey. The sensory units of the lateral line are the neuromastswhich are dispersed over large portions of the body surface. Whereassuperficial neuromasts are freestanding on the surface of the skinand sensitive to water velocity, canal neuromasts are embedded inlateral line canals and sensitive to pressure gradients between canalpores. Superficial and canal neuromasts are innervated by distinctpopulations of nerve fibers. When goldfish are exposed to a constantbackground water flow, responses of fibers innervating superficialneuromasts to superimposed hydrodynamic stimuli are masked due tothe continuous stimulation of the neuromasts by the running water.In contrast, responses of fibers innervating trunk canal neuromastsare hardly affected by background water flow due to the filter propertiesof lateral line canals. These findings are evidence for a strongform-function relationship in the sensory periphery of the fish lateralline system. A functional subdivision similar to that in the peripherycan be found in the brainstem suggesting that to a large degree informationfrom superficial and canal neuromasts, respectively, is processedseparately at least at the first stage of central nervous integration.