Disorders of compulsivity: a common bias towards learning habits

Area of Science:

• Neuroscience
• Cognitive Psychology
• Computational Psychiatry

Background:

• Decision-making involves goal-directed (model-based) and habitual (model-free) systems.
• The habitual system is implicated in maladaptive, repetitive behaviors.
• Understanding the computational basis of these systems is key to explaining compulsive disorders.

Purpose of the Study:

• To investigate the contribution of model-based versus model-free learning in compulsive behaviors.
• To identify the neurobiological correlates of habit formation bias.
• To explore a common neurocomputational mechanism underlying diverse compulsive disorders.

Main Methods:

• Utilized a decision task to quantify model-based and model-free learning contributions.
• Examined individuals with disorders characterized by repetitive behaviors (binge eating, methamphetamine use disorder, obsessive-compulsive disorder).
• Correlated learning biases with gray matter volumes in specific brain regions using neuroimaging.

Main Results:

• Demonstrated a significant bias towards model-free (habit) learning in all studied compulsive disorders.
• Found that this habit formation bias is associated with reduced gray matter volume in the caudate and medial orbitofrontal cortex.
• Highlighted a potential shared neurocomputational deficit across various compulsive conditions.

Conclusions:

• A bias in learning mechanisms, favoring habit formation, may underlie the repetitive behaviors seen in compulsive disorders.
• Dysfunction in a common neurocomputational pathway involving the caudate and medial orbitofrontal cortex could be a unifying factor in these conditions.
• These findings offer insights into the neural basis of compulsion and potential targets for intervention.