A recent review of neuroimaging studies suggested that right
prefrontal cortex (PFC) is recruited during heuristic evaluation of
episodic memories and that left PFC is engaged in episodic
remembering when more complex or systematic retrieval and/or
evaluation is required (Nolde, Johnson, & Raye, 1998).
Consistent with this, a previous fMRI study comparing old/new
recognition with more specific decisions about the source of
memories (picture, word or new) found no difference between old/new
recognition and source identification conditions in activation of
right PFC, but greater left PFC activation during the source task
than the recognition task (Nolde, Johnson, & D'Esposito, 1998).
The current study extended this finding holding the number of
response options constant. Again, left PFC was responsive to the
difference between old/new recognition and more specific source
identification. Taken together, these findings suggest that when
tasks involve more difficult or more specific access and evaluation
during episodic remembering, more left PFC and/or more cooperative
interactions between right and left PFC may be required.