Project Summary
Our understanding of the mechanistic underpinnings of drug consumption and craving
has been greatly aided by the development of numerous computational models focused
on these behaviors. However, most of these models ignore the role of cost. To this end,
our proposal seeks to experimentally validate a novel computational neurobiological
model of costly drug-taking behavior centered on the striosomes of the dorsomedial
striatum (DMS). Notably, the striosomes lie at the center of the cortico-striatal-
dopaminergic circuit, which is critical for drug-seeking behavior and the evaluation of co-
occurring cost and reward. While DMS striosomes have been implicated in behaviors
such as locomotor sensitization to cocaine, no studies have investigated the
computational and experimental role of striosomes in a cost-drug tradeoff during self-
administration behavior. We recently developed a computational model of striosomal
state-switching in cost/benefit decision-making. Using this model, we have shown that
different neural ‘states’ such as stress and aging can, via striosomal circuitry, drive
distinct patterns of cost/benefit decision-making. Here, we seek to develop an expanded
version of this model to demonstrate a role for striosomal circuitry in driving drug-taking
in the face of cost. We hypothesize that the prelimbic-striosomal-substantia nigra pars
compacta circuit mediates the impact of craving on drug-cost tradeoffs and predicts
vulnerable drug-taking phenotypes associated with cost. We will assess drug-taking
using two distinct drug-taking paradigms that involve a cost: punished responding and
effortful responding. These two types of costs differentially impact drug-taking, and we
hypothesize that animals will form distinct patterns of vulnerability and resilience to
drug-taking paired with these costs. Furthermore, the neurocircuitry underlying these
two types of costs differs, and both sex and drug type (cocaine vs. opioids) differentially
interact with cost type. In total, our goal is to validate a computational model of costly
drug-taking during a craving state. Towards this goal, we will use electrophysiology,
optogenetics, and advanced modeling techniques to determine the role of the prelimbic-
striosomal (Aim 1) and striosomal-substantia nigra (Aim 2) circuits in vulnerability for
punished and effortful drug-taking behavior. Collectively, these studies will move us
towards our long-term goals of predicting individuals who are at-risk for relapse, and
providing new targets for intervention to prevent relapse.