Alix Norton receives a UW Mary Gates Undergraduate Research Scholar Award, 2009.
The Role of Dopamine in Novelty and Taste Aversion Learning
Alix Norton, Senior, Psychology
Mentor: Sheri Mizumori, Psychology
Mentor: Min Jung Kim, Psychology
Dopamine (DA) plays a crucial role in the neurobiology of learning and memory by providing information about reward prediction error, incentive salience of environmentalcues, and the novelty value of a particular stimulus. The neural function of DA in the processing of rewards has been thoroughly explored in the last several years. More recent studies have begun to focus on the role of DA in response to aversive stimuli and conditioning.
In the current study, we explore a form of aversive conditioning known as conditioned taste aversion (CTA). CTA is a type of classical conditioning in which animals remember a taste stimulus and avoid consuming it once they have experienced the pairing of a novel taste (CS,conditioned stimulus) followed by the sensation of nausea
(US, unconditioned stimulus). In a typical laboratory experiment, a sweet taste such as saccharin is used as the CS, and LiCl (lithium chloride, a nausea-inducing agent)as the US. The dramatic changes in behavior after this
aversive taste conditioning period have been well presented in previous studies.
Our research focuses on both the dopaminergic neural activity as well as relevant behavioral reactions during the CTA process. Using a hyperdrive recording technique, neural activity of several single units can be simultaneously recorded while an animal performs a task. CTA learning targets neurons in the midbrain area, which is known to be a major source of dopamine in brain functioning. Our main interest in this study is how midbrain neurons process the same taste stimulus (e.g. saccharin) differentially according to the animal’s familiarity or novelty associated with the CS.
This study provides a new aspect of the dopaminergic role in reward processing, which can broaden our understanding in human domains of learning, such as drug addiction.