Neuromodulatory systems and memory storage: role of the amygdala

This article reviews findings of research examining the interaction of peripheral adrenergic systems with cholinergic, opioid peptidergic and GABAergic systems in modulating memory storage. It is well established that retention is enhanced by posttraining systemic or intra-amygdala injections of adrenergic agonists, opiate antagonists and GABAergic antagonists. These influences appear to be mediated by activation of NE receptors within the amygdala, as intra-amygdala injections of beta-adrenergic antagonists block the memory-modulating effects of hormones and drugs affecting these systems. Furthermore, these influences also appear to involve, at a subsequent step, activation of a cholinergic system: atropine blocks the memory-enhancing effects of adrenergic agonists and opiate and GABAergic antagonists and oxotremorine attenuate the memory-impairing effects of opiate agonists and GABAergic agonists. These findings suggest that the amygdala integrates the memory-modulating effects of neuromodulatory systems activated by learning experiences.