Activation of the prefrontal cortex during judgments of recency

Animal and human lesion studies have consistently shown that damage to the prefrontal lobe disrupts performance on tasks requiring memory for temporal context. In this study, functional magnetic resonance imaging (fMRI) was used to explore the brain regions associated with judgements of relative recency in healthy humans. Bilateral dorsolateral prefrontal cortex (Brodmann's area BA 9) was more active during a verbal recency judgment task than during a non-mnemonic control task. Activation related to temporal context recognition was also observed in midline supplementary motor area (BA 6) and left precuneus (BA 7). This study provides further evidence that memory for temporal context requires the prefrontal cortex and is the first to demonstrate this association in healthy humans. The current findings also suggest the possibility that recognition of context and recognition of episodic content may involve similar brain systems.