Date of Award

Spring 4-11-2025

Document Type

Thesis (Ph.D.)

Department or Program

Integrative Neuroscience

First Advisor

Kyle Smith

Abstract

Maladaptive reward-seeking behavior can be driven by one of several different components including excessive craving elicited by cues that predict rewards, failing to effortfully pursue rewards when it is beneficial to do so, and compulsively seeking rewards when it is no longer advantageous to do so. This thesis includes experiments focusing on these three different components of reward-seeking behavior to better understand how reward-seeking can become maladaptive. First, we wanted to examine the role that sex plays in the acquisition and compulsiveness of sign-tracking behavior in the Long Evans rat, a strain that is commonly used as the background for transgenic rats. We found that males and females in the Long Evans strain acquire sign-tracking behavior similarly and showed similar sign-tracking levels following outcome devaluation; neither males or females were compulsive. Second, we wanted to chemogenetically inhibit cholinergic ventral pallidum cells across several different Pavlovian and Instrumental tasks to see if they play a role in cue-induced craving or in effortful reward-seeking. We found that these neurons play a role in the motivation to effortfully pursue the reward itself, and, by inhibiting these cells during learning, cues have an impaired ability to acquire their craving-inducing potential. Third, we wanted to disconnect the nucleus accumbens  ventral pallidum cholinergic cell pathway to see if it plays a role in cue-induced craving. We encountered some issues with this last experiment, but it seems that this pathway does not play a role in cue-induced craving but could potentially play a role in the motivation to pursue reward. Our findings demonstrate the importance of sex and strain when trying to model human behaviors and disorders while also highlighting a potential cellular target for the treatment of maladaptive reward-seeking specifically within the context of effortful reward-seeking.

Original Citation

The role of sex on sign-tracking acquisition and outcome devaluation sensitivity in long evans rats. E. Bien, K. Smith. 2023, Behav. Brain. Res., Vol. 445, (Web).

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