Is there a cell-biological alphabet for simple forms of learning?

Recent studies such as that by the 1st author and colleagues (1983) indicate that the cellular mechanism underlying classical conditioning of the mollusc Aplysia's siphon withdrawal reflex is an extension of the mechanism underlying sensitization. This finding suggests that the mechanisms of yet higher forms of learning may similarly be based on the mechanisms of these simple forms of learning. This hypothesis is illustrated by showing how several higher-order features of classical conditioning, including generalization, extinction, 2nd-order conditioning, blocking, and the effect of contingency, can be accounted for by combinations of the cellular processes that underlie habituation, sensitization, and classical conditioning in Aplysia. (64 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).