Revealing abrupt transitions from goal-directed to habitual behavior

Area of Science:

• Neuroscience
• Behavioral Science

Background:

• The transition from goal-directed actions to habitual behaviors is a long-standing question in behavioral neuroscience.
• Understanding the speed and mechanism of habit formation is crucial for explaining behavior.

Purpose of the Study:

• To investigate whether habit formation is a slow, gradual process or a sudden transition.
• To identify the neural mechanisms underlying goal-directed to habit transitions.

Main Methods:

• Utilized an auditory go/no-go task with male mice and a citric-acid water solution to modulate reward seeking.
• Employed Hidden Markov Model-Generalized Linear Model (HMM-GLM) for transition analysis.
• Confirmed habit transition using sensory-specific outcome devaluation, DLS lesions, motor stereotypy, and pupillary responses.
• Performed dual-site fiber photometry to record neural activity in the dorsolateral striatum (DLS).

Main Results:

• Mice quickly learned task discrimination but showed fluctuating engagement, which abruptly ceased around a ~3-trial transition point.
• Evidence confirmed a goal-directed to habit transition, indicated by outcome devaluation, DLS lesions, and behavioral changes.
• Fiber photometry revealed abrupt changes in DLS activity: reduced outcome-related activity and sharpened stimulus-response activity at the transition.
• These findings suggest a switch-like mechanism rather than gradual threshold changes.

Conclusions:

• Habit formation can occur suddenly, mediated by an abrupt neural shift.
• The dorsostriatum plays a critical role, switching from outcome-based to stimulus-driven processing.
• This study challenges gradual models and supports a rapid, switch-like emergence of habits.