Modulation of Emotional and Nonemotional Memories: Same Pharmacological Systems, Different Neuroanatomical Systems

This chapter integrates and organizes pharmacological studies of memory by searching for generalizations or "rules" about the roles of hormonal and neurotransmitter systems in the regulation of learning and memory processes. In doing so, it is important to examine carefully the extent to which these generalizations are similar and different for results obtained with systemic injections and those obtained with direct brain injections. Consistently, systemic injections of epinephrine or of glucose, which may contribute to epinephrine effects on memory, enhance memory when administered near the time of training. Similarly, systemically administered drugs that promote the functions of central cholinergic, glutaminergic, or noradrenergic systems enhance memory on later tests. Moreover, diminished release of the neurotransmitters or pharmacological blockade of their receptors can impair memory. There also appear to be some neurochemical systems, for example, opioid and GABA, for which activation impairs, and inactivation enhances, learning and memory.