Remembering familiar people: the posterior cingulate cortex and autobiographical memory retrieval

Most functional imaging studies of memory retrieval investigate memory for standardized laboratory stimuli. However, naturally acquired autobiographical memories differ from memories of standardized stimuli in important ways. Neuroimaging studies of natural memories may reveal distinctive patterns of brain activation and may have particular value in assessing clinical disorders of memory. This study used functional magnetic resonance imaging to investigate brain activation during successful retrieval of autobiographical memories elicited by name-cued recall of family members and friends. The caudal part of the left posterior cingulate cortex was the most strongly activated region and was significantly activated in all eight subjects studied. Most subjects also showed significant activation of the left anterior orbitomedial, anterior middle frontal, precuneus, cuneus, and posterior inferior parietal cortices, and the right posterior cingulate and motor cortices.Our findings are consistent with prior studies showing posterior cingulate cortex activation during autobiographical memory retrieval. This region is also consistently activated during retrieval of standardized memory stimuli when experimental designs emphasizing successful retrieval are employed. Our results support the hypothesis that the posterior cingulate cortex plays an important role in successful memory retrieval. The posterior cingulate cortex has strong reciprocal connections with entorhinal and parahippocampal cortices. Studies of early Alzheimer's disease, temporal lobectomy, and hypoxic amnesia show that hypometabolism of the posterior cingulate cortex is an early and prominent indicator of pathology in these patients. Our findings suggest that autobiographical memory retrieval tasks could be used to probe the functional status of the posterior cingulate cortex in patients with early Alzheimer's disease or at risk for that condition.