People / FacultyGloria Choi, Ph. D.
Assistant Professor of Neuroscience
Department of Brain and Cognitive Sciences
My research addresses the mechanisms by which the brain learns to recognize olfactory stimuli and to associate them with appropriate behavioral responses.
Features central to perception in vision, touch, and hearing are topographically ordered in the sense organ and this order is maintained from the periphery to primary sensory cortices. This has led to the prevailing view that early sensory processing in these sensory modalities is mediated by developmentally programmed neural circuits. In contrast, olfactory features cannot be meaningfully represented along continuous dimensions and odorant responses in piriform display no spatial order. These observations have suggested a model in which piriform cells receive convergent input from random collections of glomeruli. As a consequence, odor representations could only be afforded behavioral significance after experience.
While in Dr. Richard Axel's laboratory, I developed an experimental strategy that permited us to ask whether the activation of an arbitrarily chosen subpopulation of neurons in piriform cortex could elicit different behavioral responses dependent upon experience. Indeed we observed that activation of an ensemble of piriform neurons expressing channelrhodopsin, when paired with foot shock or water reward, elicited either aversive or appetitive behaviors. Moreover, we demonstrated that different subpopulations of piriform neurons expressing channelrhodopsin could be discriminated and independently entrained to generate distinct behaviors.
In my own lab at MIT, I plan to dissect the brain circuits underlying this learned behavior, to understand how representations in piriform cortex can drive downstream targets to generate behavioral responses as a function of learning. I also plan to extend my approach to study social behavior, which in rodents is strongly affected by olfactory cues. One important modulator of social behavior is the hormone oxytocin, and I plan to study how oxytocin may control the mechanisms by which animals learn to attribute social significance to olfactory stimuli.
Choi, G.B., Stettler, D., Kallman, B., Shaskar, S., Fleishman, A. and Axel, R. Driving opposing behaviors with ensembles of piriform neurons. Cell. 2011 146: 1004-15