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James Simmons, PHD, MA

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James Simmons

Title: Professor of Biology
Department: Neuroscience

James_Simmons@Brown.EDU
+1 401 863 1542

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Overview | Research | Grants/Awards | Teaching | Publications

I'm interested in understanding how the bat's sonar works and how the bat's brain makes sonar images. They make sounds, listen to echoes, and then see objects. To study echolocation, we go into the field and videotape bats using sonar for different purposes. These observations tell us in what situations bats use their sonar, and what sorts of sounds they use. If we know where the objects are in the videos, we can figure out what sounds get back to the bats.

Biography

My laboratory studies the biological sonar systems of bats, in recent years using the big brown bat, Eptesicus fuscus, as the example. Eptesicus is a species that emits ultrasonic, frequency-modulated (FM) echolocation sounds and exhibits unusually sophisticated real-time signal-processing techniques for auditory representation of FM echoes. I am interested in orientation by echolocation and the neural mecha¬nisms for perception by acoustic images that have evolved in bats, especially FM bats because the theoretical basis for understanding the bat's performance is made unusually strong by the large applied-math literature on radar and sonar receivers. The principal goal of my work is to learn how echolocation "works"—to understand how natural images are created in perception from neural reconstruction of the target scene by the bat's brain.

Lab Website:
neuroscience.brown.edu/simmonslab/

Institutions

Bu

Research Description

I'm interested in understanding how the bat's sonar works and how the bat's brain makes sonar images. They make sounds, listen to echoes, and then see objects. To study echolocation, we go into the field and videotape bats using sonar for different purposes. These observations tell us in what situations bats use their sonar, and what sorts of sounds they use. If we know where the objects are in the videos, we can figure out what sounds get back to the bats. We then use a computer to generate these sounds and play them to the bats while we record responses from their brains. We want to know what the neurons in the bat's auditory system do to process the echoes to allow the brain to see. We also train bats in the lab to respond to computer-generated echoes, so we can tell something about the images the bat perceives. We are developing a computer model of how the bat's brain processes the echoes to see if the model produces the same kind of images the bat perceives. This model is part of a project to design new high-performance sonar for the U.S. Navy.

My laboratory studies the biological sonar, or echolocation, of bats as an auditory imaging system. The research uses behavioral, neurophysiological / neuroanatomical, and modeling techniques to learn how bats process echoes of their ultrasonic sonar transmissions to perceive the location and identity of the flying insects they prey upon. The approach is a combination of neuroethology and systems neurobiology, with sonar signal-processing as a theoretical tool. Currently, we are carrying out experiments on target ranging by the big brown bat, Eptesicus fuscus, to characterize the images bats perceive along the dimension of echo delay or target distance. Eptesicus transmits frequency-modulated (FM) sonar sounds and perceives the delay of echoes from the timing of neural discharges they evoke in the auditory system. The bat perceives the shape of targets from the spectrum of echoes, but the images themselves consist of a reconstruction of the differences in range to the different parts of the target (for example, an insect's head and wing). Thus, the image has echo delay as its primary dimension, both for determining how far targets are from the bat and for determining their shape. The auditory cortex of Eptesicus appears to carry out the neural computations that transform the echo spectrum into estimates of the distance to the different parts of the target, and we are currently investigating the response properties of cortical neurons in relation to the delay and spectrum of FM echoes. This problem is of considerable theoretical interest because the bat carries out parallel time-domain and frequency-domain transforms to form its images of targets. We use a large-scale parallel, distributed model of the bat's sonar receiver to identify critical parameters of neural responses that are relevant for carrying out these transforms, and then we record the responses of cortical neurons to sonar signals and echoes as a means of evaluating the model.

Lab Website:
neuroscience.brown.edu/simmonslab/

Awards

NIMH Research Scientist Development Award (Level II)
Elected Fellow of the Acoustical Society of America
Elected Fellow of the American Association for the Advancement of Science
Member, Technical Committee on Animal Bioacoustics, Acoustical Society of America
Associate Editor, Animal Bioacoustics, Journal of the Acoustical Society of America
Silver Medal in Animal Bioacoustics, Acoustical Society of America

Affiliations

Acoustical Society of America
Animal Behavior Society
Association for Research in Otolaryngology
American Association for the Advancement of Science
Society for Neuroscience
International Society for Neuroethology
North American Bat Research Symposium

Teaching Experience

BN65 Biology of Hearing (current)
BN01 Introduction to Neuroscience (lectures on hearing) (current)
BN 19640b Neuroethology (Undergraduate Seminar)(current)

View My Full Publication List in pdf format

Selected Publications

  • Bates, M. E., and Simmons, J. A. (2010) Effects of harmonic filtering of biosonar echoes on delay acuity by FM big brown bats (Eptesicus fuscus). J. Acoust. Soc. Am. (in press).(2010)
  • Hiryu, S., Bates, M. E., Simmons, J. A., and Riquimaroux, H. (2010) FM echolocating bats shift frequencies to avoid broadcast-echo ambiguity in clutter. Proc. Nat. Acad. Sci. (in press).(2010)
  • Petrites, A. E., Eng, O. S., Mowlds, D. S., Simmons, J. A., and Delong, C. M. (2009). Interpulse interval modulation by echolocating big brown bats ( Eptesicus fuscus ) in different densities of obstacle clutter. J. Comp. Physiol.-A. 195, 603-617.(2009)
  • DeLong, C. M., Bragg, R., and Simmons, J. A. (2008). Evidence for spatial representation of object shape in echolocating bats (Eptesicus fuscus). J. Acoust. Soc. Am. 123, 4582-4598.(2008)
  • Horowitz, S. S, Stamper, S. A., and Simmons, J. A. (2008). Neuronal connexin expression in the cochlear nucleus of big brown bats. Brain Research 1197, 76-84.(2008)
  • Stamper, S. A., Simmons, J. A., DeLong, C. M., and Bragg, R. (2008). Detection of targets co-localized in clutter by echolocating big brown bats (Eptesicus fuscus). J. Acoust. Soc. Am, 124, 667-673.(2008)
  • Bates, M. E., Stamper, S. A., and Simmons, J. A. (2008). Jamming avoidance response of big brown bats in target detection. J. Exp. Biol. 211, 106-113.(2008)
  • Hiryu, S., Shimamoto, H., Bates, M., Stamper, S., Simmons, J. A., and Riquimaroux, H. (2008) Jamming avoidance strategy for temporal overlap of own reverberant echoes by FM echolocating bats (Eptesicus fuscus) during flight, revealed by telemetry sound recording. Trans. Tech. Comm. Psychol. Physiol. Acoust., The Acoustical Society of Japan, 36.(2008)
  • Au, W. W. L., and Simmons, J. A. (2007) Echolocation in dolphins and bats. Physics Today, .(2007)
  • Saillant, P. A., Simmons, J. A., Bouffard, F. H., Lee, D. N., and Dear, S. (2007) Sonar sounds impinging on the target during interception by big brown bat, Eptesicus fuscus. J. Acoust. Soc. Am. in press.(2007)
  • Eastman, K. A. and Simmons, J. A. (2005) A method of flight path and chirp pattern reconstruction for multiple flying bats. Acoustics Research Letters Online, 6, 257-262.(2005)
  • Simmons, J. A. (2005) Big brown bats and June beetles: multiple pursuit strategies in a seasonal acoustic predator-prey system. Acoustics Research Letters Online, 6, 238-242.(2005)
  • Sanderson, M. I. and Simmons, J. A. (2005) Target representation for naturalistic echolocation sequences in single unit responses from the inferior colliculus of big brown bats. J. Acoust. Soc. Am. 118, 3352-331.(2005)