Recollection and familiarity in recognition memory: An event-related functional magnetic resonance imaging study

The question of whether recognition memory judgments with and without recol lection reflect dissociable patterns of brain activity is unresolved. We us ed event-related, functional magnetic resonance imaging (fMRI) of 12 health y volunteers to measure hemodynamic responses associated with both studying and recognizing words. Volunteers made one of three judgments to each word during recognition: whether they recollected seeing it during study (R jud gments), whether they experienced a feeling of familiarity in the absence o f recollection (K judgments), or whether they did not remember seeing it du ring study (N judgments). Both R and K judgments for studied words were ass ociated with enhanced responses in left prefrontal and left parietal cortic es relative to N judgments for unstudied words. The opposite pattern was ob served in bilateral temporoccipital regions and amygdalae. R judgments for studied words were associated with enhanced responses in anterior left pref rontal, left parietal, and posterior cingulate regions relative to K judgme nts. At study, a posterior left prefrontal region exhibited an enhanced res ponse to words subsequently given R versus K judgments, but the response of this region during recognition did not differentiate R and K judgments. K judgments for studied words were associated with enhanced responses in righ t lateral and medial prefrontal cortex relative to both R judgments for stu died words and N judgments for unstudied words, a difference we attribute t o greater monitoring demands when memory judgments are less certain. These results suggest that the responses of different brain regions do dissociate according to the phenomenology associated with memory retrieval.