Recent research from the National Institute on Alcohol Abuse and Alcoholism (NIAAA) sheds new light on habitual behaviors, specifically the circuits in the brain that allow mice to break from routine actions. Such shifting between old habits and new behavior aimed at accomplishing a particular goal are critical to flexible decision-making in everyday life. It also has important implications for mental health and substance abuse interventions. The inability to shift between routine behavior and new goal-directed actions may underlie disorders such as addiction and obsessive compulsive disorder.  

“While habits are important to efficient-decision making, we encounter situations in which it is necessary to ‘break habits’ and re-evaluate actions based on their consequences,” said the study’s first author, Dr. Christina Gremel of the NIAAA Laboratory for Integrative Neuroscience. “These findings give us insight into the neural basis of such adaptability.”

In the study, published in Nature Communications, researchers set out to identify the neural circuitry involved in the shift between habit and goal-directed behavior. Previous studies indicate the involvement of two neighboring regions in the forebrain – the dorsal medial striatum is necessary for goal-directed actions, while the dorsal lateral striatum is needed for habitual actions.

In the present study, researchers found that the orbital frontal cortex, a region associated with obsessive compulsive disorder, is critical to shifting to goal-directed actions.  

To uncover this finding, researchers developed an instrumental feeding task in which mice would shift between habitual and goal-directed behavior. Use of this newly-developed procedure allowed the researchers to probe the brain mechanisms involved when the animals shifted action strategies.

The researchers found that using light to activate individual neurons in the orbital frontal cortex, a process known as optogenetics, increased goal-directed actions in the mice. Inhibiting these neurons using a chemical and genetic approach interfered with the shift to goal-directed behavior, leaving the mice acting out of habit.  

“Our findings indicate that shifts in activity of the orbital frontal cortex and the striatum mediate the shifting between goal-directed and habitual actions,” said the study’s senior author, Rui Costa, Ph.D., of the Champalimaud Foundation, in Portugal and a guest researcher at NIAAA. “Interestingly, these neural circuits appear to work in parallel, enabling both automatic and goal-directed actions to be learned.”