EXCEED THE SPACE PROVIDED. The long term objectives of this project are to describe and analyze the development and maturation of neural, anatomical, and molecular substrates for hearing in an animal that undergoes metamorphosis as a normal part of its development. During metamorphosis, the bullfrog, Rana catesbeiana, transforms from an aquatic, free-swimming, mute larva (tadpole) to a partly terrestrial, highly vocal adult. Metamorphosis involves the reorganization of the auditory system from one optimized for detecting underwater sound to one more sensitive to atmospheric sound; molecular, anatomical, and functional changes are involved in this reorganization. Results in the previous funding period emphasized the considerable plasticity of the auditory nervous system during the tadpole/frog transition, and the relationship of developmental changes in the auditory system to that in the closely-related vestibular system. We also proposed a model of how auditory system reorganization might occur in response to changing environmental demands. This proposal outlines a series of experiments using physiological, anatomical and immunohistochemical/molecular techniques designed to test specific hypotheses about the emergence of different aspects of auditory function across normal development. We will compare neural information processing, and how this processing develops and matures, in the dorsal medulla, focusing on nuclei that subserve either auditory or vestibular function in the adult. We will also perform electrophysiological experiments examining how different components of sounds (pressure and particle movement) are coded in the developing medulla, and how these two modes of stimulation might interact to guide behavior. Immunohistochemistry and in situ hybridization will be performed to analyze the expression of candidate molecules and hormones (in particular, thyroid hormone) important both for auditory function and for normal growth and development. As there are environmental, physiological and anatomical parallels between metamorphosis and mammalian intrauterine sensory development, our findings from the frog will be useful for understanding early auditory development in humans. This research program will also contribute to the study of plasticity in general, by exploiting a model system that naturally reorganizes across life. PERFORMANCE SITE ========================================Section End===========================================
| Simmons, Andrea Megela; Warnecke, Michaela; Vu, Thanh Thao et al. (2015) Flow sensing in developing Xenopus laevis is disrupted by visual cues and ototoxin exposure. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 201:215-33 |
| Simmons, Andrea Megela (2015) Representation of particle motion in the auditory midbrain of a developing anuran. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 201:681-9 |
| Simmons, Andrea Megela (2013) ""To ear is human, to frogive is divine"": Bob Capranica's legacy to auditory neuroethology. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 199:169-82 |
| Simmons, Andrea Megela; Flores, Victoria (2012) Particle motion is broadly represented in the vestibular medulla of the bullfrog across larval development. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 198:253-66 |
| Schmidt, Brian P; Knowles, Jeffrey M; Simmons, Andrea Megela (2011) Movements of Rana catesbeiana tadpoles in weak current flows resemble a directed random walk. J Exp Biol 214:2297-307 |
| Simmons, James A; Megela Simmons, Andrea (2011) Bats and frogs and animals in between: evidence for a common central timing mechanism to extract periodicity pitch. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 197:585-94 |
| Horowitz, Seth S; Simmons, Andrea Megela (2010) Development of tectal connectivity across metamorphosis in the bullfrog (Rana catesbeiana). Brain Behav Evol 76:226-47 |
| Bates, Mary E; Cropp, Brett F; Gonchar, Marina et al. (2010) Spatial location influences vocal interactions in bullfrog choruses. J Acoust Soc Am 127:2664-77 |
| Megela Simmons, Andrea; Simmons, James A; Bates, Mary E (2008) Analyzing acoustic interactions in natural bullfrog (Rana catesbeiana) choruses. J Comp Psychol 122:274-82 |
| Simmons, Andrea Megela; Horowitz, Seth S; Brown, Rebecca A (2008) Cell proliferation in the forebrain and midbrain of the adult bullfrog, Rana catesbeiana. Brain Behav Evol 71:41-53 |
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