Left anterior prefrontal activation increases with demands to recall specific perceptual information

Results from neuroimaging studies have led to competing theories regarding the contributions of prefrontal regions to memory formation and retrieval. To investigate this issue, we used event-related functional magnetic resona nce imaging to assess prefrontal activation during encoding and retrieval o f pictures of objects. Responses to studied and unstudied objects at retrie val were compared between two tests with differing demands for the specific ity of information to be retrieved (source vs old-new recognition). Results showed that bilateral ventral [Brodmann's areas (BA) 44, 45, and 47] and r ight dorsal (BA 9) prefrontal regions were activated during both encoding a nd retrieval, but activity in these regions was not reliably modulated by t he specificity of information to be retrieved. A region in left anterior pr efrontal cortex (BA 10/46) was reliably activated during retrieval trials, and activation in this region increased with demands to retrieve perceptual ly detailed information about studied objects. Our results show that left a nterior prefrontal cortex is engaged during the monitoring and evaluation o f specific memory characteristics at retrieval-a process critical for accur ate episodic remembering.