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The Human Brain Encodes Event Frequencies While Forming Subjective Beliefs

d’Acremont, Mathieu and Schultz, Wolfram and Bossaerts, Peter (2013) The Human Brain Encodes Event Frequencies While Forming Subjective Beliefs. Journal of Neuroscience, 33 (26). pp. 10887-10897. ISSN 0270-6474. PMCID PMC4293915. doi:10.1523/JNEUROSCI.5829-12.2013.

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To make adaptive choices, humans need to estimate the probability of future events. Based on a Bayesian approach, it is assumed that probabilities are inferred by combining a priori, potentially subjective, knowledge with factual observations, but the precise neurobiological mechanism remains unknown. Here, we study whether neural encoding centers on subjective posterior probabilities, and data merely lead to updates of posteriors, or whether objective data are encoded separately alongside subjective knowledge. During fMRI, young adults acquired prior knowledge regarding uncertain events, repeatedly observed evidence in the form of stimuli, and estimated event probabilities. Participants combined prior knowledge with factual evidence using Bayesian principles. Expected reward inferred from prior knowledge was encoded in striatum. BOLD response in specific nodes of the default mode network (angular gyri, posterior cingulate, and medial prefrontal cortex) encoded the actual frequency of stimuli, unaffected by prior knowledge. In this network, activity increased with frequencies and thus reflected the accumulation of evidence. In contrast, Bayesian posterior probabilities, computed from prior knowledge and stimulus frequencies, were encoded in bilateral inferior frontal gyrus. Here activity increased for improbable events and thus signaled the violation of Bayesian predictions. Thus, subjective beliefs and stimulus frequencies were encoded in separate cortical regions. The advantage of such a separation is that objective evidence can be recombined with newly acquired knowledge when a reinterpretation of the evidence is called for. Overall this study reveals the coexistence in the brain of an experience-based system of inference and a knowledge-based system of inference.

Item Type:Article
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URLURL TypeDescription DOIArticle CentralArticle
Bossaerts, Peter0000-0003-2308-2603
Additional Information:© 2013 the authors. Received Dec. 18, 2012; revised April 23, 2013; accepted May 20, 2013. Author contributions: M.d., W.S., and P.B. designed research; M.d. performed research; M.d. and P.B. analyzed data; M.d., W.S., and P.B. wrote the paper. This work was supported by the Swiss National Science Foundation (PA00P1-126156) and the William D. Hacker endowment to the California Institute of Technology.
Funding AgencyGrant Number
Swiss National Science Foundation (SNSF)PA00P1-126156
William D. Hacker EndowmentUNSPECIFIED
Issue or Number:26
PubMed Central ID:PMC4293915
Record Number:CaltechAUTHORS:20130822-132327100
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:40906
Deposited By: Tony Diaz
Deposited On:23 Aug 2013 19:29
Last Modified:10 Nov 2021 04:23

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