Belief Updating in Subclinical and Clinical Delusions

Area of Science:

• Neuroscience
• Cognitive Psychology
• Psychiatry

Background:

• Current theories link delusions to abnormal belief updating, involving prediction error (PE) signaling and environmental volatility misestimation.
• This study investigates if belief updating signatures in behavior and neural activity are specific to delusions or broadly linked to schizophrenia.

Purpose of the Study:

• To differentiate the neural and behavioral correlates of belief updating in individuals with and without delusions, and across diagnosed schizophrenia patients versus healthy controls.
• To examine the roles of prediction error signaling and volatility estimation in the pathophysiology of delusions and schizophrenia.

Main Methods:

• A cross-sectional study with 66 participants stratified into four groups: healthy controls with minimal/strong delusional ideation, and schizophrenia patients with minimal/strong delusions.
• Participants completed a reversal learning task during fMRI, with stable and volatile environmental contingencies.
• A hierarchical Gaussian filter model was used for computational analysis of learning, focusing on outcome uncertainty, volatility beliefs, and precision-weighted PEs.

Main Results:

• Schizophrenia patients exhibited lower accuracy and increased choice switching compared to controls; delusional ideation did not significantly alter these measures.
• Individuals with delusions showed heightened neural activation in fronto-striatal regions associated with precision-weighted PEs.
• Schizophrenia patients overestimated environmental volatility and displayed attenuated neural representation of volatility in specific brain regions (anterior insula, medial frontal, angular gyrus).

Conclusions:

• Altered striatal PE-signals are associated with delusional beliefs.
• Manifest schizophrenia, distinct from delusions, appears linked to overestimating environmental volatility and reduced neural encoding of subjective volatility.