Ph.D., Princeton University
Professor
Department of Neuroscience
366 Sidney Frank Hall of Life Sciences
Tel: (401) 863-1542
Email: James_Simmons@Brown.edu

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. Presently, 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 presently 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 largescale parallel, distributed model of the bat’s sonar receiver to identify critical parameters of neural responses which 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.

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. 121, 3001-3010.

Au, W. W. L., and Simmons, J. A. (2007) Echolocation in dolphins and bats. Physics Today, in press.

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.

Sanderson, M.I. & 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: 3353-3361.

Eastman, K.M. & Simmons, J.A. 2005. A method of flight path and chirp pattern reconstruction for multiple flying bats. Acoustics Research Letters Online 6: 257-262.

Simmons, J.A., Neretti, N., Intrator, N., Altes, R.A., Ferragamo, M.J. & Sanderson, M.I. 2004. Delay accuracy in bat sonar is related to the reciprocal of normalized echo bandwidth or Q. Proc. Natl. Acad. Sci. USA 101: 3638-3643.

Horowitz, S.S., Cheney, C.A. & Simmons, J.A. 2004. Interaction of vestibular, echolocation, and visual modalities guiding flight by the big brown bat, Eptesicus fuscus. J. Vestibular Res. 14: 17-32.

Sanderson, M.I., Neretti, N., Intrator, N. & Simmons, J.A. 2003. Evaluation of an auditory model for echo delay accuracy in wideband biosonar. J. Acoust. Soc. Am. 114: 1648-1659.

Simmons, J.A., Ferragamo, M.J. & Sanderson, M.I. 2003. Echo delay versus spectral cues for temporal hyperacuity in the big brown bat, Eptesicus fuscus. J. Comp. Physiol. A. 189: 693-702.

Neretti, N., Sanderson, M.I., Intrator, N. & Simmons, J.A. 2003. Time-frequency computational model for echo-delay resolution in sonar images of the big brown bat, Eptesicus fuscus. J. Acoust. Soc. Am. 113: 2137-2145.

Sanderson, M.I. & Simmons, J.A. 2002. Selectivity for echo spectral shape and delay in the auditory cortex of the big brown bat, Eptesicus fuscus. J. Neurophysiol. 87: 2823-2834.

Simmons, J. A., Eastman, K. M., and Horowitz, S. S. (2001) Versatility of biosonar in the big brown bat, Eptesicus fuscus. Acoustics Research Letters Online, 2, 43-48.

Wotton, J. A., and Simmons, J. A. (2000) Spectral cues and perception of the vertical position of targets by the big brown bat, Eptesicus fuscus. J. Acoust. Soc. Am. 107, 1034-1041.

Sanderson, M. I., and Simmons, J. A. (2000) Neural responses to overlapping FM sounds in the inferior colliculus of echolocating bats. J. Neurophysiol. 83, 1840-1855.

Simmons, A. M., Eastman, K. M., and Simmons, J. A. (2000) Autocorrelation model of periodicity coding in bullfrog auditory nerve fibers. Acoustics Research Letters Online, 2, 1-6.

Simmons, J. A., Ferragamo, M. J., and Moss, C. F. (1998) Echo-delay resolution in sonar images of the big brown bat, Eptesicus fuscus. Proc. Nat. Acad. Sci. 95, 12647-12652.