A transient dopamine signal represents the value of avoidance in negative reinforcement

Abstract

The mesolimbic dopamine (DA) system has traditionally been examined under a reward based context. While accumulating evidence supports that DA release events represent the value of predicted rewards, there is little known about its role in avoidance. To investigate dopamine's role in the valuation of signaled operant avoidance, we developed an economics‐based shock avoidance task in which rats were given the opportunity to avoid (signaled by the presentation of a cue light) electrical foot‐shock across epochs wherein the unit price (response requirement over mA shock) to avoid or escape increases. After developing this task, we first used fast‐scan cyclic voltammetry (FSCV) to measure DA release events in vivo as the animals performed across a range of prices. We observed that the concentration of DA decreased with price, though both DA and avoidance were initially suppressed at session onset. To establish a causal role, we then used optogenetics to augment DA release at either the presentation of the cue signal or upon successful avoidance of the foot‐shock. Increasing release at the cue made avoidance more sensitive to price; whereas increasing release at successful avoidance made it less sensitive to price. We conclude that this is likely because the neural representation of the value to avoid is greater than predicted at successful avoidance, and worse than expected at the cue on trials in which foot‐shock is administered. We will next assess the role of the rostromedial tegmental nucleus (RMTg), a neural structure known to cause prediction errors, in the valuation of avoidance.Support or Funding InformationFunding for the project was provided by NSF grant IOS‐1557755, NIH grant R03DA038734, Boettcher Young Investigator Award and NARSAD Young Investigator Award to EBO and an institutional UROP to KJP.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.