Nucleus Accumbens Core and Shell Differentially Encode Reward-Associated Cues after Reinforcer Devaluation

Abstract

Nucleus accumbens (NAc) neurons encode features of stimulus learning and action selection associated with rewards. The NAc is necessary for using information about expected outcome values to guide behavior after reinforcer devaluation. Evidence suggests that core and shell subregions may play dissociable roles in guiding motivated behavior. Here, we recorded neural activity in the NAc core and shell during training and performance of a reinforcer devaluation task. Long-Evans male rats were trained that presses on a lever under an illuminated cue light delivered a flavored sucrose reward. On subsequent test days, each rat was given free access to one of two distinctly flavored foods to consume to satiation and were then immediately tested on the lever pressing task under extinction conditions. Rats decreased pressing on the test day when the reinforcer earned during training was the sated flavor (devalued) compared with the test day when the reinforcer was not the sated flavor (nondevalued), demonstrating evidence of outcome-selective devaluation. Cue-selective encoding during training by NAc core (but not shell) neurons reliably predicted subsequent behavioral performance; that is, the greater the percentage of neurons that responded to the cue, the better the rats suppressed responding after devaluation. In contrast, NAc shell (but not core) neurons significantly decreased cue-selective encoding in the devalued condition compared with the nondevalued condition. These data reveal that NAc core and shell neurons encode information differentially about outcome-specific cues after reinforcer devaluation that are related to behavioral performance and outcome value, respectively.

Thalamic Regulation of Sucrose Seeking during Unexpected Reward Omission

“…Whereas the core subregion has been involved in learning and action during goal-directed behavior, the shell subregion has been implicated in processing hedonic and motivated behavior (Burton et al, 2015; Castro and Berridge, 2014; Saddoris et al, 2015; West and Carelli, 2016). Such functional differences have been attributed to distinct input sources and output targets, with the core being mainly interconnected with regions involved in motor responses and the shell being mainly interconnected with regions implicated in incentive motivation (Brog et al, 1993; Groenewegen et al, 1999).…”

Cocaine-Induced Chromatin Modifications Associate With Increased Expression and Three-Dimensional Looping of Auts2

“…Because high cell numbers are required to study chromatin interactions, we conducted the 4C experiment in rats. As NAc shell and core have different roles in cocaine and other drug responses (20–22), separate 4C libraries were made for the two subregions. Paired end sequencing of the libraries yielded fragments that are in good agreement with the 4C literature (23).…”

Striatal Local Circuitry: A New Framework for Lateral Inhibition

“…On the other hand, in vivo recordings from freely moving animals show greater evidence of synchronized firing among SPNs (Miller et al, 2008). In behaving animals, SPN firing is seen time locked to specific aspects of the behavioral task, suggesting synchronized spiking of functionally related populations (Adler et al, 2012; Barnes et al, 2005; Cacciapaglia et al, 2011; Carelli, 2002; Jin et al, 2014; West and Carelli, 2016) that are not necessarily in close proximity (Bakhurin et al, 2016). Ensembles are likely formed by sparsely distributed rather than tightly clustered neurons, and as such, the chances of simultaneously recording their firing from the same electrode array might be low.…”