Peripheral catecholaminergic and hormonal responses to training can modulate (enhance or impair) memory storage. In particular, we have found that (1) peripheral catecholamine injections can enhance and impair memory, (2) peripheral sympathetic and adrenal medullary release of epinephrine and norepinephrine is correlated with later retention performance, and (3) peripheral injections of adrenergic antagonists can attenuate amnesia and facilitation produced by several other treatments. This proposal contains three major sets of experiments. (1) Because peripheral epinephrine does not itself enter the brain in large amounts but does affect memory and some central neurobiological systems, we plan to continue our examinations of the mechanisms by which peripheral epinephrine can affect memory. Specifically, we will study epinephrine effects on rats which are vagotomized (eliminating a major source of sympathetic afferent information) or which have brain lesions intended to disrupt processing of afferent visceral information. (2) We plan to use relatively specific adrenergic agonists and antagonists to attenuate amnesia. These studies may provide information about the peripheral mechanisms by which catecholamines act on memory. Also, we will test the possibility that adrenergic antagonists act presynaptically to promote release of epinephrine and norepinephrine. (3) Memory modulation experiments have in the past focussed primarily on avoidance training procedures. We plan here to examine memory for appetitive tasks by using traditional treatments (supraseizure electrical stimulation of the brain, amphetamine) and peripheral hormonal injections to modulate later retention performance and by measuring peripheral adrenergic responses to appetitive training. These experiments will contribute to our understanding of the roles of neuroendocrine systems in the modulation of memory storage. The study of memory modulation has widespread implications for many areas of memory research. For example, impaired modulatory systems may explain memory deficients following some forms of neural injury and dysfunction, as well as altered memory abilities during development and aging. Also, an understanding of memory modulation by neuroendocrine systems suggests possible means of pharmacological intervention to ameliorate memory impairments.
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