# The parieto-occipital cortex is a candidate neural substrate for the human ability to approximate Bayesian inference

## TL;DR

The study identifies the parieto-occipital cortex as a brain region involved in human Bayesian inference, integrating prior beliefs with new evidence.

## Contribution

The paper identifies a specific brain region involved in integrating prior beliefs and evidence during Bayesian inference.

## Key findings

- Activation in the left parieto-occipital cortex tracks subjective posterior probability.
- The region integrates prior probability and evidence likelihood during inference.
- Individual deviations from objective probabilities are reflected in this brain area.

## Abstract

Adaptive decision-making often requires one to infer unobservable states based on incomplete information. Bayesian logic prescribes that individuals should do so by estimating the posterior probability by integrating the prior probability with new information, but the neural basis of this integration is incompletely understood. We record fMRI during a task in which participants infer the posterior probability of a hidden state while we independently modulate the prior probability and likelihood of evidence regarding the state; the task incentivizes participants to make accurate inferences and dissociates expected value from posterior probability. Here we show that activation in a region of left parieto-occipital cortex independently tracks the subjective posterior probability, combining its subcomponents of prior probability and evidence likelihood, and reflecting the individual participants’ systematic deviations from objective probabilities. The parieto-occipital cortex is thus a candidate neural substrate for humans’ ability to approximate Bayesian inference by integrating prior beliefs with new information.

Analysis of fMRI data from participants in a probability estimation task suggests that the parieto-occipital cortex is a neural substrate for humans’ ability to approximate Bayesian inference by integrating prior beliefs with new information.