fMRI investigations of left and right PFC contributions to episodic remembering

We used functional magnetic resonance imaging (fMRI) to investigate the rel ation between left and right prefrontal cortex (PFC) and task complexity in episodic memory. In Experiments 1A, 1B, and 1C, left PFC activity land, in Experiment 1C, right PFC as well) was greater for source identification th an for old/new recognition, indicating that left PFC is likely to be recrui ted when specific features of episodic memories are considered. In Experime nt 2, we found greater activity in PFC areas more medial or more ventral to those found in Experiments 1A-1C in successive recognition relative to for ced-choice recognition, indicating that the regions of PFC recruited depend on the nature of the task complexity. Furthermore, Experiment 2 provided e vidence consistent with the hypothesis that increased processing complexity may require interhemispheric interaction. In Experiments 1A, 1C, and 2, in creased task complexity also increased activity in anterior cingulate (ACC) , consistent with the idea that ACC interacts with PFC to control processin g during remembering.