Computation of value functions based on gains and losses in the cortico-striatal network

Abstract

Event Abstract Back to Event Computation of value functions based on gains and losses in the cortico-striatal network Human behaviors are not always rewarded or punished by primary reinforcers, but instead modified by the gains and losses of conditioned reinforcers, such as social praise and money. Neuroimaging studies in human subjects have identified a network of brain areas involved in the evaluation of monetary feedback. In contrast, little is known about how action-outcome associations are encoded by the individual neurons in the brain when the animal's actions lead to the gains and losses of tokens or conditioned reinforcements. In this study, we trained rhesus monkeys to perform a stochastic decision-making task under token economy, and investigated how information about the animal's choice and its outcome is processed in the medial and lateral prefrontal areas as well as the dorsal and ventral striatum. At the beginning of each trial, a circular array consisting of 0 to 5 red tokens was displayed at the center of a computer screen. These tokens were exchanged with juice reward, when the animal accumulated 6 of them. During a 0.5-s fore-period, the animal fixated a square at the center of a computer screen, and was required to shift its gaze towards one of the two peripheral targets after a 0.5 delay. After the animal fixated its chosen target for 0.5 s, the outcome of the animal’s choice was revealed by a feedback ring. The color of the feedback ring signaled an increase (gain), a decrease (loss), or no change in the number of tokens, and this was determined according to the payoff matrix of a biased matching-pennies game. A logistic regression analysis showed that the gain and loss of a token exerted a robust reinforcing and punishing effect on the animal's subsequent choices. We tested how the neural activity is influenced by the animal's choices and their outcomes, using a multiple linear regression model. The model incorporated a set of interaction terms between choices and gains or losses in the current as well as previous trial and was applied to spike rates measured for the delay period (0.5 s after target onset) and feedback period (0.5 s after feedback onset). We found that the conjunctions of choice and the outcome was more frequently encoded in the dorsomedial frontal cortex, compared to dorsal anterior cingulate cortex or dorsolateral prefrontal cortex. Within the striatum, the conjunctions were more frequently encoded by the caudate neurons compared to neurons in the ventral striatum. Furthermore, the contingency analysis revealed that neural activity during delay period signaling the conjunction of choice and gain or loss in the previous trial tends to be correlated with the difference in the action value functions between two alternative actions. These results suggest that the cortico-striatal network, in particular the dorsomedial frontal cortex and the caudate nucleus, might play a key role in adjusting animal's behaviors based on conditioned reinforcers and their losses. Conference: Computational and systems neuroscience 2009, Salt Lake City, UT, United States, 26 Feb - 3 Mar, 2009. Presentation Type: Poster Presentation Topic: Poster Presentations Citation: (2009). Computation of value functions based on gains and losses in the cortico-striatal network. Front. Syst. Neurosci. Conference Abstract: Computational and systems neuroscience 2009. doi: 10.3389/conf.neuro.06.2009.03.132 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 02 Feb 2009; Published Online: 02 Feb 2009. Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Google Google Scholar PubMed Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.