- A.B., 1989, Occidental College, Biology.
- M.S., 1992, University of Maine, Zoology.
- Ph.D., 1998, UCLA, Physiological Science.
- Postdoctoral research: UCLA.
Joined the department in 2004.
Associations: Faculty of Neuroscience.
College Station, TX 77843-3258
Biological Sciences Building West
Biological Sciences Building West
|Physiology and Evolution of the Vocal Motor Pathway in Mammals
Our primary line of research investigates the neurophysiology of those parts of the mammalian brain that regulate the structure and timing of syllable production in mammals. We use echolocating bats because these mammals exploit an array of auditory and somatosensory feedback cues to precisely regulate the sound of their voice. Part of our lab focuses on the organization of a brainstem vocal pattern generator that is responsible for the production of single sounds. More recently we have developed an experimental protocol for exploring the role of the mammalian striatum in the regulation of complex temporal patterns of vocal emissions. Bats often use specialized “pulse groupings” when echolocating in noisy or crowded situations. Preliminary evidence suggests that these pulse groups are created by an extrapyramidal motor loop consisting of the motor cortex, the dorso-lateral striatum and sensory-motor thalamic nuclei, to coordinate the production of these vocal sequences. This makes echolocating bats an especially useful animal model for exploring the evolution and architecture of the neural circuits that underlie human speech and language production. Analagous circuits have not been identified in rodents or non-human primates. These results have important implications for the treatment of human speech disorders, because important questions about how potentially therapeutic drugs such as striatal dopamine receptor antagonists might affect the speech motor pathways can now be tested in echolocating bats before being tested on humans.
Singing by bats
We maintain a colony of Mexican free-tailed bats (Tadarida brasiliensis), which we use to study echolocation, vocal communication and social behaviors in bats. In the spring, male free-tailed bats sing a complex, highly stereotyped courtship song intended to attract females to their private roosting sites, and males aggressively defend these sites from other intruding males. The song is of particular interest because of its remarkable similarity to the courtship songs of some birds, and because it implies that the bats possess the neural architecture necessary for coordinating long multi-syllabic vocal sequences. A plethora of current graduate and undergraduate student projects are addressing questions of how the song production is regulated (daily, seasonally, and hormonally), what parts of the brain are uniquely involved in singing, and when and if the song is a learned vocalization.
- Tressler J, Schwartz C, Wellman P, Hughes S & Smotherman M (2011) Regulation of bat echolocation pulse acoustics by striatal dopamine. J Exp Biol 214:3238-47 Full text
- Schwartz CP & Smotherman MS (2011) Mapping vocalization-related immediate early gene expression in echolocating bats. Behav Brain Res 224:358-68 Full text
- Jarvis J, Bohn KM, Tressler J & Smotherman M (2010) A mechanism for antiphonal echolocation by Free-tailed bats. Anim Behav 79:787-796 Full text
- Bohn KM, Schmidt-French B, Schwartz C, Smotherman M & Pollak GD (2009) Versatility and stereotypy of free-tailed bat songs. PLoS One 4:e6746 Full text
- Tressler J & Smotherman MS (2009) Context-dependent effects of noise on echolocation pulse characteristics in free-tailed bats. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 195:923-34 Full text
- Schwartz C, Bartell P, Cassone V & Smotherman M (2009) Distribution of 2-[I]iodomelatonin binding in the brain of Mexican free-tailed bats (Tadarida brasiliensis). Brain Behav Evol 73:16-25 Full text
- Smotherman M & Guillén-Servent A (2008) Doppler-shift compensation behavior by Wagner's mustached bat, Pteronotus personatus. J Acoust Soc Am 123:4331-9 Full text
- Schwartz C, Tressler J, Keller H, Vanzant M, Ezell S & Smotherman M (2007) The tiny difference between foraging and communication buzzes uttered by the Mexican free-tailed bat, Tadarida brasiliensis. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 193:853-63 Full text
- Smotherman MS (2007) Sensory feedback control of mammalian vocalizations. Behav Brain Res 182:315-26 Full text
- Smotherman M, Kobayasi K, Ma J, Zhang S & Metzner W (2006) A mechanism for vocal-respiratory coupling in the mammalian parabrachial nucleus. J Neurosci 26:4860-9 Full text