Professor of Biology
Ph.D., Washington University, St. Louis
A.B., University of Chicago
Director, Cellular & Behavioral Neurobiology Graduate Program
How does an animal’s nervous system select and generate an appropriate behavior for each circumstance the animal faces? Our research addresses this general question through neurophysiological, neuroanatomical, and pharmacological experiments on an especially suitable model system: the turtle spinal cord. The turtle spinal cord can produce three distinct types of rhythmic scratching movements of a hindlimb, each targeted to a different region of the body, as well as two types of rhythmic swimming movements of the hindlimbs, and limb withdrawal (flexion reflex). The programs for generating these movements and for choosing among them reside in the spinal cord: the animal can produce these movements appropriately even when all input from the brain is cut off. This means we can focus attention on a relatively small subset of the central nervous system and study the electrical activity, morphology, and pharmacology of individual spinal cord neurons, to reveal the kinds of neural circuitry that allow the spinal cord to select and generate appropriate movements. We have found in recent years that the spinal cord selects and generates these distinct movements using a combination of multifunctional and specialized spinal cord interneurons.
My lab’s research currently focuses on the following questions:
1) What mechanisms do multifunctional interneurons use to contribute to multiple kinds of limb movements?
2) What mechanisms do scratch-specialized interneurons use to affect scratching but not swimming?
3) What mechanisms do flexion reflex-selective interneurons use to affect flexion reflex (limb withdrawal), but not swimming or scratching?
4) How are behaviorally specialized interneurons inhibited during competing behaviors?
5) How do the spinal cord circuits for swimming, scratching, and flexion reflex interact?
6) Do neuromodulators alter swimming, scratching, and flexion reflex in the same or different ways?
7) How does the spinal cord summate gentle foot stimuli that are seconds apart to trigger a strong flexion reflex?