Ph.D., Harvard University
Professor
Departments of Psychology and Neuroscience
306 Hunter Laboratory
Tel: (401) 863-2283
Email: Andrea_Simmons@Brown.edu
Go to lab web page

In my laboratory, we study the normal development, adult function, and damage-induced plasticity of the auditory system of the bullfrog, Rana catesbeiana. These frogs undergo a developmental process called metamorphosis, during which the totally aquatic tadpole transforms into a partly terrestrial adult. This process involves considerable anatomical and functional reorganization of the auditory and vestibular systems. Using both immunohistochemical and neurophysiological techniques, we have identified major periods of plasticity in auditory system development, correlated with the development of the behavioral ability to hear sounds in air. We also examine expression of various factors implicated in these developmental changes. In adult frogs, we analyze how acoustic features of complex communication sounds, such as “pitch” and “timbre,” are represented in the auditory system. Our experiments show that “pitch” is represented in the frog’s inner ear by a temporal mechanism based on synchronous neural activity, and we have developed a computational model describing this process. Currently, we are using both spectral, temporal and combined time-frequency algorithms to model central processing of peripheral activity. In a third project, we are examining the molecular basis of recovery of auditory and vestibular function after damage to the eighth cranial nerve. Frogs have the ability to regenerate damaged cranial nerves; in our experiments, we are identifying gene products that may be involved in this regenerative process.

Simmons, A.M., Eastman, K. and Simmons, J.A. (2001) Autocorrelation model of periodicity coding in bullfrog auditory nerve fibers. Acoustic Research Letters Online 2, 1-6.

Horowitz, S.S., Chapman, J., Kaya, U. and Simmons, A.M. (2001) Metamorphic development of the bronchial columella of the larval bullfrog (Rana catesbeiana). Hearing Research, 154: 12-25.

Simmons, A. M. & Bean, M.E. (2000). Perception of mistuned harmonics in complex sounds by the bullfrog, Rana catesbeiana. Journal of Comparative Psychology, 114: 167-73.

Boatright-Horowitz, S.L., Horowitz, S.S. & Simmons, A.M. (2000) Patterns of vocal interactions in a bullfrog (Rana catesbeiana) chorus: Preferential responding to far neighbors. Ethology, 106: 701-712.

Simmons, A.M., Sanderson, M. I. & Garabedian, C.E. (2000) Representation of waveform periodicity in the auditory midbrain of the bullfrog, Rana catesbeiana. Journal of the Association for Research in Otolaryngology1,2-24.

Boatright-Horowitz, S.S. and Simmons, A.M. (1997) Transient “deafness” accompanies auditory development during metamorphosis from tadpole to frog. Proceedings of the National Academy of Sciences USA, 94, 14877-14882