Dennis Choi, PhD

Postdoctoral Associate

Research Interests:

My major research interests lie in ascertaining the psychological and neural mechanisms of fear and stress. Dysregulation of these mechanisms are implicated in psychiatric disease states such as post-traumatic stress disorder, depression, and anxiety. In January 2007, I received my Ph.D. in neuroscience at the University of Cincinnati under the mentorship of Dr. Jim Herman. My dissertation work primarily focused on limbic regulation of the HPA axis in response to stress. Recently, I started a postdoctoral fellowship in the laboratory of Dr. Kerry Ressler at Emory University to further pursue my interest in the central regulation of conditioned fear learning and extinction. Since disorders such as PTSD appear to reflect a dysfunction in the ability to modulate learned fear, further understanding of the mechanisms involved in fear inhibition may be critical in providing potential therapies for PTSD patients.

A major goal of my project will be to understand how primary sensory systems are altered by and contribute to the fear and stress response. Previous work in the Ressler lab has demonstrated that mice can acquire classic Pavlovian fear conditioning using odor as a conditioned stimulus. Additionally, intense training to the odor stimulus resulted in long-lasting changes in the size of the glomerulus in the olfactory bulbs and olfactory sensory neuron population specific to the trained odor. Since the basolateral amygdala is well established to be a key modulator of the acquisition of fear, we hypothesize that olfactory neuronal adaptations following fear conditioning to an olfactory-conditioned stimulus are amygdala-dependant. Using the combination of fear conditioning behavior with anatomical, molecular, and pharmacological techniques, we aim to answer a number of questions including 1) Is the basolateral amygdala or other brain regions necessary in regulating olfactory structural plasticity?; 2) What neurotransmitter/neuropeptide systems are specifically involved in this phenomenon?; 3) Are these structural changes long-lasting or can they also be reversed by conditioned fear inhibition behavior? Overall, these studies aim to increase our understanding of a novel system in which conditioned fear behavior to odor can lead to long-lasting neuronal plasticity. In doing so, we hope to further understand the mechanisms involved with regulating long-term memory and the stress response.

Dennis Choi's CV