Prefrontal and medial temporal lobe contributions to relational memory in young and older adults
When we remember a past event, we typically remember not only the various components of the event, or item memory (IM), but also the associations among these components, or relational memory (RM). RM is more sensitive than IM to several memory disorders, including those associated with healthy ageing. In fact, the age effects on RM are about twice as large as those on IM. Studies with animals, human patients, and neuroimaging techniques have shown that RM depends prominently on the prefrontal cortex (PFC) and the medial temporal lobes (MTLs). Although age-related RM deficits are most likely due to PFC and/or MTL dysfunction, direct evidence for this causal link is very scarce. This chapter reviews ideas and findings concerning the neural correlates of RM and how they change as a function of ageing. The first section introduces some basic concepts; the second section describes theories and evidence linking RM to PFC and MTL function; the third section considers the effects of ageing on the PFC and MTL substrates of RM. Finally, the fourth section discusses several open issues.