Department of Physiology and Biophysics

CURRENT RESEARCH

My lab is interested in the neural circuits underlying decision making and goal-directed behavior. We use electrophysiological, behavioral, molecular, and computational methods to study how rodents transform sensory – primarily olfactory – input into motor output. We aim to understand how sensory stimuli are used to select and initiate motor actions in the normal and disease states.

Identification of an olfactory-motor decision circuit

Our previous research has focused on the neural substrates underlying motor responses to olfactory stimuli. But it is not known how representations of the odor stimulus – evident in the olfactory bulb and piriform cortex – influence selection of the appropriate motor output. We are addressing this question by first using neuroanatomical tools to identify candidate pathways from known olfactory to motor regions. We will then focus neural recordings on the candidate regions in rodents performing olfactory decision tasks. Molecular tools may be useful to differentiate the role of specific cell types in the sensorimotor transformation, and data-driven computational models can be used to elucidate how olfactory representations are used to select actions.

Pathophysiology of movement disorders

We have begun applying our rodent behavior and recording paradigm to study the pathophysiology underlying the disordered initiation of movement, a prominent symptom of Parkinson’s Disease (PD). We have applied a classical rodent model of PD to rats performing an olfactory cued spatial choice task in which the rat must initiate a leftward or rightward movement to obtain a reward. We’ve found that unilateraly lesioning a dopaminergic nucleus biases the rat to initiate movements towards the lesioned side. We plan to record from critical motor nuclei in this model system in order to understand how dopaminergic cell death – as occurs in PD – affects the activity underlying movement initiation.

(A) The task environment, showing the tetrode-implanted rat in the odor port (left image) and the right reward port (right image). Mixtures in which Odor A was dominant instructed the rat to enter the left reward port, and those in which Odor B was dominant instructed the rat to enter the right reward port, for a water reward. (B) Behavioral performance. (C) Perievent histograms showing average activity across trials for an example cell, recorded from the deep layers of the left superior colliculus, that prefers upcoming rightward movement.