Dissociable neural correlates of uncertainty underlie different exploration strategies

• Published in: Nature communications Vol. 11; no. 1; p. 2371
• Main Authors: Tomov, Momchil S., Truong, Van Q., Hundia, Rohan A., Gershman, Samuel J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 12.05.2020; Nature Publishing Group; Nature Portfolio
• Subjects: 631/378; 631/477; Adolescent; Adult; Analysis of Variance; Choice Behavior - physiology; Computer applications; Cortex (motor); Expected values; Exploitation; Exploration; Exploratory Behavior - physiology; Female; Functional magnetic resonance imaging; Humanities and Social Sciences; Humans; Magnetic Resonance Imaging; Male; Models, Neurological; multidisciplinary; Neighborhoods; Prefrontal cortex; Prefrontal Cortex - diagnostic imaging; Prefrontal Cortex - physiology; Restaurants; Science; Science (multidisciplinary); Uncertainty; Young Adult
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-15766-z

Most real-world decisions involve a delicate balance between exploring unfamiliar alternatives and committing to the best known option. Previous work has shown that humans rely on different forms of uncertainty to negotiate this "explore-exploit” trade-off, yet the neural basis of the underlying computations remains unclear. Using fMRI ( n  = 31), we find that relative uncertainty is represented in right rostrolateral prefrontal cortex and drives directed exploration, while total uncertainty is represented in right dorsolateral prefrontal cortex and drives random exploration. The decision value signal combining relative and total uncertainty to compute choice is reflected in motor cortex activity. The variance of this signal scales with total uncertainty, consistent with a sampling mechanism for random exploration. Overall, these results are consistent with a hybrid computational architecture in which different uncertainty computations are performed separately and then combined by downstream decision circuits to compute choice. Humans explore the world by optimistically directing choices to less familiar options and by choosing more randomly when options are uncertain. Here, the authors show that these two exploration strategies rely on distinct uncertainty estimates represented in different parts of the prefrontal cortex.