2 Neuroscience2.7 Neural circuits
2.7.1.8 Habit formation, obsessions and compulsions
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Written by Resident Doctor Committee · Published
Goal-directed action and habit
Goal-directed actions follow expected consequences and current goals, so they are flexible but slow and effortful (model-based control).
Habits are cue-response links that ignore current outcomes, so they are fast and cheap but blind to change (model-free control).
Both systems run together, and repetition strengthens habits.
Test | Manipulation | Goal-directed responding | Habitual responding |
|---|---|---|---|
Outcome devaluation | Satiety or aversive pairing | Falls | Persists |
Contingency degradation | Reward regardless of action | Falls | Persists |
The striatal shift with practice
Phase | Cortex | Striatum |
|---|---|---|
Early action-outcome learning | Prefrontal | Dorsomedial (caudate) |
Stable repeated cue | Sensorimotor | Dorsolateral (posterior putamen) |
Dorsolateral lesions preserve goal-directed control after overtraining, and dorsomedial lesions favour early habits.
Control shifts between active systems rather than a memory moving, so flexible control can return.
Dopamine prediction errors strengthen rewarded corticostriatal activity, and dopamine bursts shift to predictive cues.
What tips control towards habit
Stress and high cognitive load weaken prefrontal control through noradrenaline and glucocorticoids.
A change of context or repeated errors can restore flexible responding.
Cortico-striato-thalamo-cortical loops
Frontal cortex projects through striatum, pallidum and nigra to thalamus, which returns activity to cortex.
Component | Role in repetitive behaviour |
|---|---|
Orbitofrontal cortex | Expected value; significance of contamination or harm |
Anterior cingulate | Conflict, error and uncertainty |
Striatum | Response selection, chunking, learning from reward or relief |
Pallidum and nigra | Gate competing programmes through the thalamus |
Obsessions, compulsions and habits
Feature | Obsession | Compulsion | Habit |
|---|---|---|---|
Form | Intrusive thought, image or urge | Repeated act or mental operation | Cue-response action |
Experience | Unwanted, often distressing | Often effortful or distressing | Usually efficient |
Purpose | Intrudes, not performed | Neutralises or prevents harm | No feared consequence |
Mental compulsions are deliberate neutralising by counting, reviewing or silent reassurance.
Negative reinforcement maintains washing because it relieves anxiety, and crediting the ritual for safety prevents disconfirmation.
Evidence in obsessive-compulsive disorder
Some patient groups show reduced devaluation sensitivity, but distributions overlap and medication and illness duration affect results.
Imaging implicates orbitofrontal, cingulate, striatal and thalamic circuits but cannot separate cause from compensation or diagnose individuals.
Habits explain repetition better than they explain obsessional content.
Related condition | Different driver |
|---|---|
Tics | Sensory discomfort |
Hair pulling, skin picking | Urges and reward |
Body dysmorphic disorder | Beliefs about appearance |