Dangerous Desire : Central Amygdala Excitation Amplifies Attraction Towards Aversive Stimuli
Dandar, Christina M.
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The survival of an organism depends on its ability to consume natural rewards and avoid aversive stimuli. However, maladaptive pursuits of pleasure can result in affective disorders, such as drug addiction. Here I examined the role of the central nucleus of the amygdala (CeA) in detecting an environmentally salient stimulus: a shock prod. I paired optogenetic channelrhodopsin (ChR2) stimulation in the CeA of male and female rats with a shock prod. When rats entered a l-in. radius around the shock prod, they received 40 Hz of optogenetic blue laser stimulation to the CeA. A second group received no optogenetic stimulation. I predicted that both groups would exhibit fearful behavior. Surprisingly, CeA ChR2 rats did not fear the shock prod. Instead, they pursued it, demonstrating consummatory behaviors towards the prod. By comparison, rats without CeA excitation feared the shock prod, exhibiting defensive behaviors, such as treading. The consummatory behaviors demonstrated by the CeA ChR2 group suggest that incentive salience was attributed to the shock prod, transforming it into an attractive, attention-grabbing object. Fos expression in various brain regions was compared between the two groups and results identified two structures that may explain the difference in behavior between the two groups: the basolateral amygdala (BLA) and ventral pallidum. The results confirm that optogenetic activation of CeA-related circuitry produces narrowly focused yet intense motivation to pursue a reward. However, it also suggests a 'maladaptive' feature of this CeA-generated intense motivation that might be shared with addiction, as the motivation enhancement was towards a threatening and harmful stimulus.