Temporal dissociations within the core recollection network.

We investigated whether time courses of fMRI BOLD activity in recollection-sensitive brain regions varied according to the time over which recollected information was maintained. Human subjects studied word-picture pairs and were subsequently tested with studied and unstudied pictures during a scanned test phase. The test requirement was to judge whether each picture was old or new and, if old, to retrieve its study associate and hold it in mind until a response cue appeared. The interval between the test item and cue varied between two and eight seconds. Separate responses were required when items were deemed new or the associate was not retrieved. Whereas recollection-related activity in the posterior cingulate, medial temporal, and medial prefrontal cortices was transient and unrelated to the maintenance interval, activity in the left anterior angular gyrus (aLAG) tracked the interval. Thus, as in a prior study, recollection-sensitive regions could be temporally dissociated.