The role of hippocampus and frontal cortex in age-related memory changes: a PET study.

The purpose of this study was to examine the neuroanatomical correlates of explicit retrieval of episodic memories in older and young adults. We used an experimental paradigm that allowed us to separate the effort involved in attempting to retrieve a recently studied word from the actual recollection of the item. Both older and younger adults showed hippocampal blood flow increases in association with recollection of a studied word. In contrast, younger but not older adults showed bilateral blood flow increases in anterior prefrontal cortex during retrieval attempts: older adults showed more posterior frontal lobe activations during attempted retrieval. We conclude that the hippocampus activations may reflect a commonality in the way that older and younger adults remember past events, whereas differences in frontal activation may reflect age-related changes in their retrieval strategies.