Professor of Biology
3203 SE Woodstock Blvd.
Portland, OR 97202
Understanding the neural basis of behavior—focus on frog vocalizations
The overarching goal of my research is to discover mechanisms in the brain that generate behaviors. More specifically, I want to learn how behavioral variation is encoded in neural circuits. To achieve these goals, I am investigating courtship vocal behaviors of African clawed frogs, Xenopus laevis. Adults of this species exhibit a rich vocal repertoire of at least seven call types that range from rhythmically simple to temporally complex. Xenopus vocalizations are sexually differentiated; males and females produce calls with distinct temporal characteristics that are regulated by steroid hormones during development and in adulthood. This rich palette of rhythmic behaviors combined with robust hormone dependence make X. laevis vocal behaviors an ideal subject for understanding the neural basis of behavior and behavioral plasticity.
Probing neural circuits—brains in a dish
To learn how neural circuits produce motor patterns, we must first gain access to brain activity during behavior. However, recording from brains of awake and behaving animals is extremely challenging. Fortunately, we are able to elicit natural vocal-like neural activity in isolated Xenopus brains. Using this experimentally powerful “calling brain in a dish” preparation, we can employ numerous physiological, pharmacological, and anatomical techniques to record and modulate important vocal brain regions.
Some specific questions being addressed in the lab
- Do intrinsic neuronal properties directly regulate vocal patterns?
- How do structural differences in male and female vocal circuits explain differences in behavior?
- What are the hormone targets in male and female vocal circuits?
- How do hormones affect the structure and function of vocal neurons and networks?
Zornik E, Yamaguchi A. 2012. Coding rate and duration of vocalizations of the frog, Xenopus laevis. Journal of Neuroscience
Zornik E, Kelley DB. 2011. A neuroendocrine basis for the hierarchical control of frog courtship vocalizations. Frontiers in Neuroendocrinology 32(3):353 – 66
Zornik E, Yamaguchi A. 2011. Vocal pathway degradation in gonadectomized Xenopus laevis adults. Journal of Neurophysiology 105(2):601 – 614
Zornik E, Katzen AW, Rhodes HJ, Yamaguchi A. 2010. NMDAR-dependent control of call duration in Xenopus laevis. Journal of Neurophysiology 103(6):3501 – 3515
Zornik E, Yamaguchi A. 2008. Sexually differentiated central pattern generators in Xenopus laevis. Trends in Neuroscience 31(6):296 – 302
Zornik E, Kelley DB. 2008.Regulation of respiratory and vocal motor pools in the isolated brain of Xenopus laevis. Journal of Neuroscience 28(3):612 – 621
Zornik E, Kelley DB. 2007.Breathing and calling: neuronal networks in the Xenopus laevis hindbrain. Journal of Comparative Neurology 501(3):303 – 315