期刊
MOLECULAR PSYCHIATRY
卷 21, 期 7, 页码 946-955出版社
SPRINGERNATURE
DOI: 10.1038/mp.2015.73
关键词
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资金
- Groupe Pasteur Mutualite
- Fondation pour la Recherche Medicale
- Fondation Bettencourt Schueller
- Marie Curie Intra-European fellowship (FP7-PEOPLE-IEF)
- National Health and Medical Research Council [1050504, 1066779]
- Australian Research Council Future Fellowship [FT130100589]
- Wellcome Trust
- Bernard Wolfe Health Neuroscience Fund
- Medical Research Council [MC_UU_12012/5/B, G0001354, G1000183B, G0001354B] Funding Source: researchfish
A state of pathological uncertainty about environmental regularities might represent a key step in the pathway to psychotic illness. Early psychosis can be investigated in healthy volunteers under ketamine, an NMDA receptor antagonist. Here, we explored the effects of ketamine on contingency learning using a placebo-controlled, double-blind, crossover design. During functional magnetic resonance imaging, participants performed an instrumental learning task, in which cue-outcome contingencies were probabilistic and reversed between blocks. Bayesian model comparison indicated that in such an unstable environment, reinforcement learning parameters are downregulated depending on confidence level, an adaptive mechanism that was specifically disrupted by ketamine administration. Drug effects were underpinned by altered neural activity in a fronto-parietal network, which reflected the confidence-based shift to exploitation of learned contingencies. Our findings suggest that an early characteristic of psychosis lies in a persistent doubt that undermines the stabilization of behavioral policy resulting in a failure to exploit regularities in the environment.
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