Graduate/Undergraduate Research Highlight
Shannon Cole, 4th year biopsychology graduate student, on the work he and undergraduates, Thomas Choi and Nina Mostovoi, do in the Kent Berridge Lab:
The Berridge lab seeks to understand how emotion, motivation, and learning are produced by neural mechanisms. Specifically, they look at the neurobiological processes of how pleasure and desire are created.
Utilizing approaches such as optogenetics (using lasers to activate specific populations of neurons) or drug microinfusions paired with multiple psychological tests, they are able to determine brain regions and cellular communications responsible for generating psychological phenomena.
“My part of this research has been looking into how different cell populations and neurochemical signaling within the nucleus accumbens, an area long shown to be involved in multiple motivated behaviors (e.g., food seeking, sex, drug reward, etc.), produces both intense craving (i.e., motivation to go towards) and fear (i.e., motivation to avoid). Largely, my studies have looked into how various brain regions, pathways, and neurotransmitters (e.g, dopamine, glutamate, and GABA) communicate with specific cells within this brain region.”
In addition to several graduate students, post docs, and technicians, a large portion of the Berridge lab’s investigations are performed by undergraduate research assistants.
“I have had the privilege of mentoring Thomas Choi and Nina Mostovoi; two outstanding undergraduate thesis students working with me to understand how the brain produces desire and dread. Both students have used optogenetics and drug microinfusions within the brain to understand how neurotransmitter systems change cell activity, and how that activity is able to produce motivation.”
Nina Mostovoi is examining how the manipulation of glutamate and GABA neurotransmitter release within the nucleus accumbens produces the generation of intense eating or defensive behaviors. It was unknown how increasing or decreasing neurotransmitter signaling affects accumbens neuron activity, and how that produces these motivated states. By countering drug microinjections with optogenetic stimulation, Nina has found that pauses in glutamate signaling, which should relatively inhibit cells in the nucleus accumbens, also stops these incredibly intense motivations; by turning back on the cells turned off through drug/transmitter signaling, Nina decreased animals’ normally high motivation and demonstrated that pauses in glutamate likely induce motivation by causing decreases in cell activity.
In a complementary line of study, Thomas Choi is answering an important question of which brain regions communicate with the nucleus accumbens through neurochemical messages to produce powerful motivations. Using optogenetics to stimulate projections (specific routes of communication) to the nucleus accumbens and induce glutamate release, Thomas has discovered how specific brain regions in the cortex change activity within the accumbens and subsequently trigger or pause food ingestion and defensive behaviors. Thomas demonstrated that where chemical signals come from determines the production of these motivations.
In tandem, the remarkable work that Thomas and Nina have produced delineates how the fine interplay of chemical and electrical signals within these circuits can produce incredibly strong motivation. In this way, piece-by-piece, the lab gains new understanding of how discrete brain regions and circuits normally create natural motivations and pleasures, and how dysfunction in these systems can produce maladaptive behaviors, such as eating disorders and drug addiction.