Dopamine release and its control over early Pavlovian learning differs between the NAc core and medial NAc shell

Abstract

Dopamine neurons respond to cues to reflect the value of associated outcomes. These cue-evoked dopamine responses can encode the relative rate of reward in rats with extensive Pavlovian training. Specifically, a cue that always follows the previous reward by a short delay (high reward rate) evokes a larger dopamine response in the nucleus accumbens (NAc) core relative to a distinct cue that always follows the prior reward by a long delay (low reward rate). However, it was unclear if these reward rate dopamine signals are evident during early Pavlovian training sessions and across NAc subregions. To address this, we performed fast-scan cyclic voltammetry recordings of dopamine levels to track the pattern of cue and reward-evoked dopamine signals in the NAc core and medial NAc shell. We identified regional differences in the progression of cue-evoked dopamine signals. However, reward rate encoding was not evident in either the NAc core or NAc shell during early training sessions. Pharmacological experiments found that dopamine-sensitive conditioned responding emerged in the NAc core before the NAc shell. Together, these findings illustrate regional differences in NAc dopamine release and its control over behavior during early Pavlovian learning.

Parental Education and Functional Connectivity between Nucleus Accumbens (NAcc) and Frontoparietal Network (FPN)

“…The Nucleus Accumbens (NAcc), a subcortical brain structure located within the ventral striatum serving as a key limbic-motor interface, holds an important role in Pavlovian learning (Ferrario, 2020;Stelly, Girven, Lefner, Fonzi, & Wanat, 2021). This means that the NAcc regulates emotional and motivation processing (Salgado & Kaplitt, 2015), incentive salience (Olney, Warlow, Naffziger, & Berridge, 2018), and pleasure, reward, and reinforcement (Boissoneault, Stennett, & Robinson, 2020).…”

“…This means that the NAcc regulates emotional and motivation processing (Salgado & Kaplitt, 2015), incentive salience (Olney, Warlow, Naffziger, & Berridge, 2018), and pleasure, reward, and reinforcement (Boissoneault, Stennett, & Robinson, 2020). In addition, neural reactivity to food-and/or drug-related reward cues could evoke robust dopamine responses in the NAcc (Stelly et al, 2021). As such, the NAcc is a part of the brain reward system, reflecting how an individual responds to cues that signal a potential reward (Stelly et al, 2021).…”

“…In addition, neural reactivity to food-and/or drug-related reward cues could evoke robust dopamine responses in the NAcc (Stelly et al, 2021). As such, the NAcc is a part of the brain reward system, reflecting how an individual responds to cues that signal a potential reward (Stelly et al, 2021). Because the NAcc has various functions, it is unsurprising that the NAcc has been implicated in several psychological disorders and conditions impacting health, such as obsessive-compulsive disorder (Chen et al, 2021;Zhang et al, 2020), anxiety (Zhang et al, 2020), depression (Heshmati et al, 2020), obesity (Ferrario, 2020;Rapuano et al, 2020), food addiction (Domingo-Rodriguez et al, 2020), tobacco abuse, and alcohol and drug-seeking behaviors (Boissoneault, Lewis, & Nixon, 2019;Buck, Torregrossa, Logan, & Freyberg, 2021;Sousa et al, 2020).…”