Recollection and familiarity processes in probable Alzheimer's disease: an fMRI study

Cerebral activity associated with recollection and familiarity in 28 patients with Alzheimer’s disease (AD) and 17 healthy controls was directly measured in an event-related fMRI experiment during performance of a recognition memory task with the process dissociation procedure. Brain regions associated to recollection were evidenced by contrasting activations for inclusion and exclusion conditions whereas brain regions related to familiarity were explored with the mean effect of the two conditions (at P < .05 corrected). Twelve patients had null recollection estimates (AD-), whereas 16 patients did experience some recollection although significantly less than controls (AD+). In AD+ and controls, recollection activated the posterior cingulate cortex (PCC). In contrast, familiarity estimates were equivalent in the 3 groups and were associated with brain activations around the intraparietal sulcus (IPS). Thus, in AD, impaired recollection is related to damage of the PCC whereas preserved familiarity is supported by the IPS.