Voluntary action as problem-solving: an fMRI study

The capacity to pursue a goal, across a complex series of intermediate stages, is a distinctive achievement of human cognition. Scientific investigations of goal-directed action have emphasized either of two rather different aspects of this capacity. Research on executive function has described coordination of extended action sequences that solve multi-part problems. Meanwhile, research on voluntary action has emphasized the processes of endogenous generation and autonomy, which are essential for many complex problems, particularly those involving creativity and insight. Because many complex problems can be solved in several ways, choosing and generating a path through the problem space requires a convergence of executive intelligence and volitional control. Here we use neuroimaging (fMRI) to explore the links between volition and problem-solving in the human brain. Participants performed the Tower of London task (a classical neuropsychological problem-solving challenge) either by generating their own solutions or by following stepwise instructions for each move. We confirmed behavioural signatures of action planning, associated with a distributed network of frontal and parietal activations, when participants generated their own solutions. We also confirmed the crucial role of medial frontal cortex, traditionally associated with endogenous generation of very simple willed actions, in goal-directed problem-solving, based on its connectivity with a wider prefrontal network. Combining voluntariness with intelligence yields a multiplier effect for sophisticated behavioural control. Our results point to the brain mechanisms underpinning this powerful cognitive combination.