Exploration of the dynamics between brain regions associated with the default-mode network and frontostriatal pathway with regards to task familiarity.

Specific brain regions have consistently been reported to be activated during resting state period, and they were described as being part of a particular network called the default-mode network (DMN). It has been shown that the DMN would deactivate during goal-directed tasks, but the actual relationship between them is still a matter of debate. In a previous study, we reported a specific pattern of activation of the frontostriatal regions during a set-shifting task in which these regions were increasing their activity as set-shifts were performed continuously and decreasing when the same rule was executed repeatedly. The present study aimed at assessing the relationship between the frontostriatal regions and the DMN. We hypothesized that the DMN would be anticorrelated with the frontostriatal regions so the DMN would be more deactivated as set-shifts are executed for a long period, but would start increasing when the same rule is being executed for a long period. Here, 15 participants underwent functional magnetic resonance imaging while performing a card-sorting task. We observed increased activity in the frontostriatal regions as more set-shifts are being performed while the DMN gets more deactivated. Interestingly, as decreased activity was observed in the frontostriatal regions during the execution of the same rule for a long period, the DMN showed increasing activity. We argue that there is an anticorrelation between the frontostriatal regions and the DMN, but also that the DMN could show positive activation during performance of a familiar goal-directed task.