Neuroethology of Species Recognition in Electroreception

Abstract

Two critical stages of information processing are prelude to most sensory recognition tasks: filtering, and coding. Peripheral sensory receptors act either in unison, or as banks of stimulus filters to shape and modify stimuli, and to improve signal detection. Stimuli are then coded into nerve impulses so that information can pass to higher centers. It would be impossible to search for neural correlates for an innate releasing mechanism without knowledge of these two early, fundamental steps in the recognition process. Recognition may take place in a sequence or hierarchy of steps, and in order to understand one, the functions of the earlier stages must be known. Knowledge of the mechanisms of information processing can be used to make predictions about the effects of novel stimuli on behavior. The characteristics of sensory filtering ard coding, also shed light on the evolution of function in sensory systems. In the present study, I shall use an example of a species recognition response in an electric fish to illustrate filtering, coding, and recognition. W. Heiligenberg (this volume) has already introduced electric fish, and has discussed the sensory basis for a complex reflex known as the jamming avoidance response, JAR. I will focus on more social aspect,s of electric communication behavior, and will consider optimal designs for communication signals and signal receivers.