Prefrontal cortex state representations shape human credit assignment

Abstract

People learn adaptively from feedback, but the rate of such learning differs drastically across individuals and contexts. Here we examine whether this variability reflects differences in what is learned. Leveraging a neurocomputational approach that merges fMRI and an iterative reward learning task, we link the specificity of credit assignment-how well people are able to appropriately attribute outcomes to their causes-to the precision of neural codes in the prefrontal cortex (PFC). Participants credit task-relevant cues more precisely in social compared to nonsocial contexts, a process that is mediated by high-fidelity (i.e., distinct and consistent) state representations in the PFC. Specifically, the medial PFC and orbitofrontal cortex work in concert to match the neural codes from feedback to those at choice, and the strength of these common neural codes predict credit assignment precision. Together this work provides a window into how neural representations drive adaptive learning.

The challenge of learning adaptive mental behavior.

“…In contrast, the performance of a cognitive operation might disrupt the ability to attribute prediction errors to the cognitive action itself. Broadly consistent with this, prior work suggests that people ascribe credit not only to outcome-relevant aspects of their actions, but also incorrectly to irrelevant aspects that are entailed by the action (such as spatiomotor aspects orthogonal to reward; Shahar et al, 2019; see also Jocham et al, 2016;Lamba et al, 2023).…”

Belief updates, learning and adaptive decision making

“…In humans, latent state representations have been observed in both orbitofrontal cortex (Jocham et al, 2016;Nassar, McGuire, et al, 2019;Schuck et al, 2016) as well as in dorsolateral prefrontal cortex (Vaidya & Badre, 2022). The precision of state representations in frontal cortical regions predicts the specificity of credit assignment across individuals (Jocham et al, 2016) and task conditions (Lamba et al, 2023) in simple experimental paradigms suggesting a functional role in the credit attribution process. Nonetheless, our understanding of how the brain represents the state of the world more in complex situations akin to the real world remains somewhat rudimentary and is an active area of research.…”