Neural dynamics of an extended frontal lobe network in goal-subgoal problem solving

Complex behavior calls for hierarchical representation of current state, goal, and component moves. In the human brain, a network of “multiple-demand” (MD) regions underpins cognitive control. We recorded from four putative homologs to human MD regions in the frontal lobe – ventrolateral (vlPFC), dorsomedial (dmPFC), dorsal premotor (dPM) and insula/orbitofrontal (I/O) cortex - as monkeys solved an on-screen spatial maze. Across regions there was wide variation in strength of encoding task features. Sensory input and current state were strongly coded in vlPFC, goal most stably in dmPFC, and move most rapidly in vlPFC and dPM. I/O responded during revision of a prepared route. Across regions, an abstract, hierarchical code of problem structure marked progress from problem start to end. We suggest that, across an extended frontal network, partially separated but widely reproduced codes build the structured control program of organized behavior.