Biology subjects

Hughes, B. L.

Publications and source records attributed to Hughes, B. L..

3 recordsLinked to original sources

bioRxiv2020

Causal inference gates corticostriatal learning

Attributing outcomes to your own actions or to external causes is essential for appropriately learning which actions lead to reward and which actions do not. Our previous work showed that this type of credit assignment is best explained by a Bayesian reinforcement learning model which posits that beliefs about the causal structure of the environment modulate reward prediction errors (RPEs) during action value updating. In this study, we investigated the neural circuits underlying reinforcement learning that are influenced by causal beliefs using functional magnetic resonance imaging (fMRI) while human participants (N = 31; 13 males, 18 females) completed a behavioral task that manipulated beliefs about causal structure. We found evidence that RPEs modulated by causal beliefs are represented in posterior putamen, while standard (unmodulated) RPEs are represented in ventral striatum. Further analyses revealed that beliefs about causal structure are represented in anterior insula and inferior frontal gyrus. Finally, structural equation modeling revealed effective connectivity from anterior insula to posterior putamen. Together, these results are consistent with a neural architecture in which causal beliefs in anterior insula are integrated with prediction error signals in posterior putamen to update action values. Significance StatementLearning which actions lead to reward - a process known as reinforcement learning - is essential for survival. Inferring the causes of observed outcomes - a process known as causal inference - is crucial for appropriately assigning credit to ones own actions and restricting learning to effective action-outcome contingencies. Previous studies have linked reinforcement learning to the striatum and causal inference to prefrontal regions, yet how these neural processes interact to guide adaptive behavior remains poorly understood. Here, we found evidence that causal beliefs represented in the prefrontal cortex modulate action value updating in posterior striatum, separately from the unmodulated action value update in ventral striatum posited by standard reinforcement learning models.

neuroscience↗

bioRxiv2018

Neurocomputational mechanisms underlying motivated seeing

People tend to believe their perceptions are veridical representations of the world, but also commonly report perceiving what they want to see or hear, a phenomenon known as motivated perception. It remains unclear whether this phenomenon reflects an actual change in what people perceive or merely a bias in their responding. We manipulated the percept participants wanted to see as they performed a visual categorization task for reward. Even though the reward maximizing strategy was to perform the task accurately, this manipulation biased participants perceptual judgments. Motivation increased activity in voxels within visual cortex selective for the motivationally relevant category, indicating a bias in participants neural representation of the presented image. Using a drift diffusion model, we decomposed motivated seeing into response and perceptual components. Response bias was associated with anticipatory activity in the nucleus accumbens, whereas perceptual bias tracked category-selective neural activity. Our results highlight the role of the reward circuitry in biasing perceptual processes and provide a computational description of how the drive for reward can lead to inaccurate representations of the world.

neuroscience↗

bioRxiv2018

Wanting to like: Motivation influences behavioral and neural responses to social feedback

Human beings revel in social approval and social connection. For example, individuals want to be liked, and frequently surround themselves with people who provide such positive reinforcement. Past work highlights a \"common currency\" between social rewards like social approval, and non-social rewards like money. But social and motivational contexts can reshape reward experiences considerably. Here, we examine the boundary conditions that deem social approval subjectively valuable. Participants received feedback about their attractiveness from others. Neural activity in reward-related brain structures (e.g., ventral striatum) increased in response to positive feedback, but only when such feedback came from well-liked targets. These heightened reward responses predicted increases in subsequent attraction to well-liked targets. This work suggests that motivational contexts amplify or diminish the value of social approval in a target-specific manner. The value of social approval is thus defined by the extent to which these experiences bring us closer to people we like.

neuroscience↗