Striatal dysfunction during reversal learning in unmedicated schizophrenia patients

Area of Science:

• Neuroscience
• Cognitive Psychology
• Psychiatry

Background:

• Schizophrenia is associated with deficits in reinforcement-driven reversal learning.
• The underlying neurobiological mechanisms of this deficit remain unclear.

Purpose of the Study:

• To investigate the neurobiological basis of reversal learning impairments in early, unmedicated schizophrenia patients.
• To examine the role of prediction errors and computational strategies in this deficit.

Main Methods:

• Behavioral and functional magnetic resonance imaging (fMRI) data were collected during a reversal learning task.
• Computational modeling (Hidden Markov Model) was used to analyze task-solving strategies.
• fMRI analysis focused on ventral striatum (VS) activation related to prediction errors.

Main Results:

• Schizophrenia patients exhibited reduced VS activation in response to prediction errors.
• A subgroup of patients, particularly those with more severe psychosis, failed to adjust behavior using an internal task model.
• VS dysfunction remained significant in patients and controls using similar cognitive strategies, especially during behavioral reversals.

Conclusions:

• Ventral striatum (VS) dysfunction is a core deficit linked to reward-related reversal learning impairment in early schizophrenia.
• This deficit is present even when controlling for task-solving strategies, suggesting a fundamental neurobiological issue.