Modulation of Visual Input in the Crayfish

Abstract

The continuous adjustment of responsiveness in sensory pathways to the changing conditions of ambient stimuli and the milieu interieur, by enabling the sensory processors to extract at any moment the most relevant information, is one of the basic operations by which the nervous system serves to optimize the coupling of the organism to the environment. It is accomplished by a wide variety of mechanisms, ranging from gross motor reactions, which modify the degree of exposure of sensory receptors to the stimuli, to the subtlest adjustments of the dynamic properties of neurons affecting specific aspects of information processing. In the crayfish, several mechanisms for modulation of visual input have been characterized, and their role in the generation of complex patterns of behavior will be discussed.