Interneuronal communication, in the form of synaptic transmission, may be a process that is fundamental to memory. Persistent modifications of synaptic transmission that are induced by neuronal activation are emphasized in certain neurobiological models of memory. It is very likely that such use-induced, long-lasting modifications involve both an enhancement (potentiation) or reduction (depression) of synaptic transmission. Dr. Dahl will investigate a possible physiological basis for the induction of synaptic potentiation or depression. He will be testing two specific hypotheses in the CA1 region of the hippocampus: 1) postsynaptic depolarization coupled with neuronal activation may be a necessary condition for potentiation of synaptic transmission, and 2) postsynaptic hyperpolarization couple with neuronal activation may be necessary for the induction of depression. The results of this work may provide a basis for study of intraneuronal processes that are voltage-dependent, and may underlie synaptic potentiation and/or depression. Furthermore, the results may be generally applicable to cortical information processing.***//