The Role of the Basal Ganglia– Anterior Prefrontal Circuit as a Biological Instruction Interpreter

Intelligent and versatile behavior requires the capability of adapting to novel and unanticipated situations. When facing novel and unexpected tasks, a fast and general solution consists in creating new declarative task representations, and subsequently acting upon them. Although this mechanism seems straightforward in general terms, it poses significant difficulties to be implemented in a biological model, and the exact neural substrates of this process are still unknown. Based on the analysis of two different computational models, we hypothesized that the brain circuit for interpreting instructions would comprise the aPFC (holding dependencies among specialized cortical areas) and the basal ganglia (orchestrating the exchange of information among regions). To verify this hypothesis, we designed and ran an fMRI experiment where participants had to perform changing tasks that consisted of different combinations of atomic cognitive operations. Both models and experimental data suggest that the aPFC is critical in representing abstract knowledge that reflects planned cognitive operations. This is consistent with the late appearance of aPFC in the evolution of the human brain, and its role in enabling human intelligence and culture. On the other hand, results and simulations show that the effect of this cortical region is made possible by the contribution of the basal ganglia circuit, which works as a general-purpose interpreter of declarative knowledge.