Corticostriatal Connectivity Underlies Individual Differences in the Balance between Habitual and Goal-Directed Action Control.

This interesting study helps elucidate the brain mechanisms of goal-directed and habitual action control. This is important because dysfunction in these systems probably underlies disorders such as obsessive-compulsive disorder (OCD), addiction, and obesity.

So-called 'slips of action' are surprisingly common in everyday life -- for example, putting tea leaves in a cup rather than a tea pot. These errors are entirely unplanned and normally occur when pre-occupied or distracted, notably on tasks that are so highly practiced that they become automatic. Couched in animal learning theory, the explanation for action slips is that through extensive repetition of a particular behaviour, subjects develop an over-reliance on the stimulus-response habit system of the brain at the expense of the slower, but more flexible goal-directed system {1}. In other words, behaviour is then triggered by a stimulus with little or no appraisal of its outcome.

The present study demonstrates that a subset of healthy human volunteers are pre-disposed to slips of action as measured on a computerised instrumental paradigm and that this behaviour is partly predicted by altered structure and functional connectivity in a network encompassing the premotor cortex and posterior putamen. Conversely, flexible, goal-directed action control was predicted by connectivity strength between the ventromedial prefrontal cortex and caudate.

These findings are important because they demonstrate that inter-individual differences in corticostriatal connectivity may bias action control between the goal-directed and habit-based systems. This shift in neural and psychological control over behaviour may constitute a vulnerability marker for clinical disorders that involve high levels of habitual responding.