Presentation Title

The Mesolimbic Dopamine Pathway: Sign Trackers and Goal Trackers Encode Incentive Salience Differently

Start Date

November 2016

End Date

November 2016

Location

HUB 302-49

Type of Presentation

Poster

Abstract

Through exploration of incentive salience, the attribution of motivational value to reward-paired cues, we gain a deeper understanding of compulsive behaviors in animals. This investigation of motivation utilizes a Pavlovian approach task (PCA), which pairs a discrete cue (an illuminated lever) presented for 8 seconds, with rewards (palatable banana pellets). The cue is a conditioned stimulus (CS), and the reward is an unconditioned stimulus (UCS). Animals trained under PCA typically display one of two phenotypic traits, sign tracking or goal tracking. Sign trackers (STs) present a motivation to interact with stimuli presented, such as levers, whereas goal trackers (GTs) typically focus on the location in which a reward is deposited. We hypothesize that the individual differences in the attribution of incentive salience to reward-paired cues have a relationship to the neural firing pattern differences between these animals. The system of interest, the mesolimbic dopamine pathway, is implicated in reward and comprises connections between the ventral tegmental area (VTA) and other brain regions. Not only do STs and GTs exhibit differences in behavioral patterns and response to stimuli, but they also have notable changes in the ventral pallidum (VP) and VTA. Our findings show that both STs and GTs have an enhanced firing to CS onset in the VP, but only STs show an extended response during the entire time that the CS is presented. Additionally, the same patterns were seen from dopaminergic neurons within the VTA. These results support the role for dopamine in motivation and cue-related behaviors.

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The Mesolimbic Dopamine Pathway: Sign Trackers and Goal Trackers Encode Incentive Salience Differently

HUB 302-49

Through exploration of incentive salience, the attribution of motivational value to reward-paired cues, we gain a deeper understanding of compulsive behaviors in animals. This investigation of motivation utilizes a Pavlovian approach task (PCA), which pairs a discrete cue (an illuminated lever) presented for 8 seconds, with rewards (palatable banana pellets). The cue is a conditioned stimulus (CS), and the reward is an unconditioned stimulus (UCS). Animals trained under PCA typically display one of two phenotypic traits, sign tracking or goal tracking. Sign trackers (STs) present a motivation to interact with stimuli presented, such as levers, whereas goal trackers (GTs) typically focus on the location in which a reward is deposited. We hypothesize that the individual differences in the attribution of incentive salience to reward-paired cues have a relationship to the neural firing pattern differences between these animals. The system of interest, the mesolimbic dopamine pathway, is implicated in reward and comprises connections between the ventral tegmental area (VTA) and other brain regions. Not only do STs and GTs exhibit differences in behavioral patterns and response to stimuli, but they also have notable changes in the ventral pallidum (VP) and VTA. Our findings show that both STs and GTs have an enhanced firing to CS onset in the VP, but only STs show an extended response during the entire time that the CS is presented. Additionally, the same patterns were seen from dopaminergic neurons within the VTA. These results support the role for dopamine in motivation and cue-related behaviors.