Control of semantic interference in episodic memory retrieval is associated with an anterior cingulate-prefrontal activation pattern

Prefrontal activation is a consistent finding in functional neuroimaging st udies of episodic memory retrieval. In the present study we aimed at a furt her analysis of prefrontal neural systems involved in the executive control of context-specific properties in episodic memory retrieval using an event -related fMRI design. Nine subjects were asked to learn two 20-item word li sts that consisted of concrete nouns assigned to four semantic categories. Ten items of both word lists referred to the same semantic category. Subjec ts were instructed to determine whether nouns displayed in random order cor responded to the first 20-item target List. The interference evoked by the retrieval of semantically related items of the second list resulted in sign ificantly longer reaction times compared to the noninterference condition. Contrasting the interference against the noninterference retrieval conditio n demonstrated an activation pattern that comprised a right anterior cingul ate and frontal opercular area and a left-lateralized dorsolateral prefront al region. Trial averaged time series revealed that the PFC areas were sele ctively activated at the interference condition and did not respond to the familiarity of learned words. These findings suggest a functionally separab le role of prefrontal cortical areas mediating processes associated with th e executive control of interfering context information in episodic memory r etrieval. (C) 2001 Wiley-Liss, Inc.