Synaptic Mechanisms of Induction and Maintenance of Long-Term Sensitization Memory in Aplysia

The marine snail Aplysia californica exhibits a simple defensive withdrawal reflex that can undergo several forms of learning. In particular, the reflex can exhibit long-term sensitization (LTS), a form of nonassociative memory. LTS is mediated by long-term facilitation (LTF) of the monosynaptic connection between the sensory and motor neurons that mediate the withdrawal reflex. LTS and LTF represent one of the best understood model systems of long-term memory extent. Furthermore, discoveries from work on this system have provided fundamental insights into the cellular and molecular mechanisms that mediate the induction and maintenance of long-term memory. This chapter reviews this work; it concludes with a discussion of recent studies of the role of protein kinase M in the persistence of the long-term memory and of memory reconsolidation in Aplysia. It is suggested that the study of LTS and LTF can provide important mechanistic information on these two intriguing memory phenomena. © 2013 Elsevier B.V