Differential Contributions of Lateral Prefrontal Cortex Regions to Visual Memory Processes

The prefrontal cortex (PFC) is the seat of higher level control operations, with recognition and working memory processes critical to those operations. While not strictly organized by the principle of localization, certain functions are clearly more associated with one region than another within PFC dynamic systems. We set out to test the hypothesis that active visual memory comparison (making judgments of novelty) was most associated with the ventrolateral prefrontal cortex (VLPFC), while the monitoring and manipulation of visual information was most associated with the mid-dorsolateral prefrontal cortex (mid-DLPFC). The current study used magnetic resonance volumetry to define the VLPFC and mid-DLPFC as regions of interest (ROIs), and analyzed those in relation to types of visual memory processes. We observed a functional dissociation of working memory within the PFC corresponding to comparison versus monitoring processes. One of the blocks of the monitoring and manipulation task showed a significant positive relationship with left, right, and total mid-DLPFC volume, with no significant relationship to the VLPFC. Performance on a memory comparison task bore a significant positive relationship with right and total VLPFC volume, and no relationship with the mid-DLPFC.