Dynamic regulation of the siphon withdrawal reflex of Aplysia californica in response to changes in the ambient tactile environment

The state of an animal's environment can be viewed as a source of informati on that can be used to regulate both ongoing and future behavior. The prese nt work examined how the ambient environment can regulate the Aplysia sipho n withdrawal reflex (SWR) by changing the environment between calm and turb ulent. Results indicate that the SWR is dynamically regulated on the basis of variations in external conditions, so that responsiveness (measured as b oth reflex duration and threshold) is matched to the state of the environme nt. Prior exposure to a noxious stimulus (tailshock) has selective effects on this regulation, suggesting the existence of multiple regulatory mechani sms. Further, neurophysiological correlates to behavioral observations were measured in sensory and motor neurons. This will allow for a detailed cell ular analysis of environmental information-processing in this system.