ABSTRACT
The modification of the efficacy of synaptic transmission is considered to be one of the mechanisms underlying the storage of information. Long-term potentiation (LTP) and long-term depression (LTD) in the efficacy of excitatory synaptic transmission have been observed in the neocortex, hippocampus, cerebellum, thalamus and others structures of the central nervous system (CNS) (Bliss and Collingridge, 1993; Bear and Malenka, 1994; Weber et al., 1984; Silkis, 1994b, 1996b, 1997a; Ito and Karachot, 1992). Properties of LTP and LTD such as their duration, input specificity, associativity and dependence on previous synaptic efficacy (Abraham and Bear, 1996; Linden, 1994; Tsumoto, 1992) are most important with respect to their participation in the learning. The necessity for pre-and postsynaptic cells to be coactive for an increase in synaptic efficacy to occur was postulated by Hebb (1949), and is known as the Hebbian rule.
