Why some people struggle more with habits than others: Unlocking the brain's dual habit circuits
The age-old advice to 'repeat it until it turns automatic' may be a simplified approach to understanding habit formation. A recent study in mice reveals a more intricate process, suggesting that habits are governed by two distinct brain circuits, each playing a unique role in the transition from routine to compulsion.
The Two Habit Circuits
The research, conducted by scientists at Kyoto University, uncovers a fascinating dichotomy in the brain's habit formation process. One circuit, originating from the anterior cingulate cortex and extending to the retrosplenial cortex, assesses the value of an action relative to its cost. This circuit strengthens as the animal learns the goal-directed task, but weakens as the habit takes hold, reflecting the animal's evolving strategy.
In contrast, the second circuit, running from the lateral orbitofrontal cortex to the central striatum, influences the intensity of the habit. The strength of connections in this pathway determines the volume of the habit, with stronger responses leading to higher pressing rates and weaker responses resulting in reduced pressing.
Unraveling Individual Differences
What makes this discovery even more intriguing is the variability in habit execution among individual mice. Despite identical initial behaviors and rewards, some mice increased their pressing after the switch to the habitual task, while others decreased sharply. This suggests that the 'volume dial' of the orbitofrontal pathway may be set differently in each individual, influencing the strength of the habit.
From Routine to Compulsion
The study's implications extend beyond the lab, as compulsive disorders often involve overactivity in the orbitofrontal to striatal connections. This pathway, crucial for setting the execution level of habits, may be a key target for treating compulsive behaviors. However, the research also highlights the complexity of habit formation, suggesting that a treatment restoring flexibility may only address half the problem.
Unlocking the Mystery of Habits
As study co-author Nozomi Asaoka notes, habits are indeed one of the brain's most mysterious functions. By understanding the dual circuits involved, researchers may eventually find ways to take control of habits rather than being controlled by them. The study's findings open up new avenues for exploration, raising questions about the factors that set the 'volume dial' and the potential for personalized habit management strategies.
This research, published in the journal Nature Communications, not only sheds light on the neural mechanisms of habit formation but also offers a promising direction for developing more effective interventions for those struggling with habit-related challenges.
