Abstract
Recent theories propose that the prefrontal cortex (PFC) is organized in a hierarchical fashion with more abstract, higher level information represented in anterior regions and more concrete, lower level information represented in posterior regions. This hierarchical organization affords flexible adjustments of action plans based on the context. Computational models suggest that such hierarchical organization in the PFC is achieved through interactions with the basal ganglia (BG) wherein the BG gate relevant contexts into the PFC. Here, we tested this proposal using functional magnetic resonance imaging (fMRI). Participants were scanned while updating working memory (WM) with 2 levels of hierarchical contexts. Consistent with PFC abstraction proposals, higher level context updates involved anterior portions of the PFC (BA 46), whereas lower level context updates involved posterior portions of the PFC (BA 6). Computational models were only partially supported as the BG were sensitive to higher, but not lower level context updates. The posterior parietal cortex (PPC) showed the opposite pattern. Analyses examining changes in functional connectivity confirmed dissociable roles of the anterior PFC-BG during higher level context updates and posterior PFC-PPC during lower level context updates. These results suggest that hierarchical contexts are organized by distinct frontal-striatal and frontal-parietal networks.
Highlights
A hallmark of intelligent behavior is the ability to flexibly adjust action plans based upon the context
Mounting evidence suggests that the balance of stability and flexibility involves interactions between the prefrontal cortex (PFC) and basal ganglia (BG)
Accuracy was near ceiling indicating that subjects adequately understood instructions and appropriately maintained contextual information in working memory (WM)
Summary
A hallmark of intelligent behavior is the ability to flexibly adjust action plans based upon the context. Whereas one might typically turn right at an intersection to drive home, one might instead turn left if intending to first pick up groceries. Such rule-based behavior depends on a balance between stable maintenance of contexts and flexible updating. Excessive stability can lead to perseveration, while excessive flexibility can lead to distractibility. Mounting evidence suggests that the balance of stability and flexibility involves interactions between the prefrontal cortex (PFC) and basal ganglia (BG). PFC–BG interactions may be critical for the representation of appropriate contexts online in working memory (WM) to guide flexible behavior
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