Research in the neuropsychology of aging is concerned with changes in behavior with age that are related to corresponding changes in the nervous system. In recent years, this field of research has become so vast as to encompass the full range of behaviors and their presumed neurological substrates. A comprehensive coverage of the current status of this field is well beyond the scope of this chapter. Our plan, instead, is to focus on a single function, memory. Failing memory is one of the chief complaints of elderly people. Indeed, the decline of memory with age is a robust phenomenon that has been documented extensively in the Literature. We also can draw on a large theoretical and empirical literature on memory in younger adults as well as a rapidly growing literature on memory disorders in a neurological population. Research on neurological patients has identified a number of structures that, when damaged, lead to a variety of memory disorders. Principal among these is the hippocampus and associated medial temporal cortex as well as anatomically related structures in the limbic system and diencephalon.'Damage to any of these structures can lead to a deficit in encoding and retention of new information and, perhaps, to impairment of some aspects of retrieval. There also has been a growing appreciation

'although a variety of structures are involved, for the purpose of this chapter we will typically not distinguish among them but consider them as part of the hippocampal or medial.~