Associative Learning and Synaptic Plasticity
D. O. Hebb proposed on psychological grounds the existence of synaptic modifications during learning, in the absence, then, of any physiological evidence for such modifications. The 1973 article dealt with the modeling of some psychological data on the learning of lists. T. Kohonen et al. used the terms “associative memory” and “associative learning” for two distinct yet interrelated sets of cognitive phenomena. One set of phenomena involves memory or learning of associations that develop, for example, by classical conditioning or serial learning of lists. The other set involves recollection of a total pattern if part of the pattern is perceived: the term associative memory is restricted to denote a process in which a signal pattern is recalled upon the basis of a fraction of it. After the early invertebrate work, the search for synaptic plasticity in mammals began with the hippocampus, the area involved in consolidation of short-term memory into long-term memory.