# Distinct contributions of prefrontal, parietal, and cingulate signals to exploratory decisions

## TL;DR

This study shows how different brain regions contribute uniquely to exploratory decisions, such as seeking new options or reducing uncertainty.

## Contribution

The study identifies distinct neural signals for internal and external exploration in the IPS and ACC, and a flexible value signal in the mPFC.

## Key findings

- The IPS encodes internal exploration independently of the decision type.
- The ACC encodes external exploration independently of the decision type.
- The mPFC flexibly encodes the value of exploration or reward based on the decision context.

## Abstract

Exploratory decisions could be motivated by multiple reasons, such as to reduce uncertainty of existing options (i.e. internal exploration) or to identify new alternatives (i.e. external exploration). Exploratory behaviours are related to a wide range of brain regions including the intraparietal cortex (IPS), anterior cingulate cortex (ACC), and medial prefrontal cortex (mPFC). However, whether these regions play unique roles signalling different aspects of exploration remain unclear. Here, we identified unique internal and external exploratory signals in the IPS and ACC, respectively. Crucially, these signals were invariant to the impending decisions. In contrast, the mPFC flexibly encoded the value of internal exploration, external exploration or collecting a reward based on the type of impending decision. This is consistent with the neural common currency hypothesis suggesting the mPFC’s role in signalling general decision value. Our findings contribute to the understanding of the unique roles of IPS, ACC and mPFC during exploratory decision-making.

Human fMRI reveals distinct exploration codes: IPS tracks internal exploration, ACC tracks external exploration, and mPFC flexibly encodes the value guiding choices across exploration and acceptance.