Research Interests
In our laboratory, we are interested in understanding the neural mechanisms used by bats and mice to analyze complex sounds. Most of the work we have previously done has focused on how echolocating bats process information related to target distance. Echolocating bats obtain information by listening to echoes of their own vocalizations. One type of information bats obtain from echoes is the distance to a target. To obtain this information, neurons in the auditory system of the mustached bat encode the delay between the emitted call and the returning echoes. The population of these “delay-tuned” neurons responds over a range of echo delays that corresponds to behaviorally relevant foraging distances of the bat. Delay-tuned neurons in the mustached bat also respond to specific elements in the echolocation call and echoes; namely, the first harmonic frequency-modulated (FM) sweep in the emitted call and a higher harmonic FM in the returning echoes. Thus, these neurons are integrating both temporal and spectral information in the complex sound. Recent evidence suggests that this integrative response property is created in the auditory midbrain, the inferior colliculus. Neurons in the inferior colliculus may also be integrating spectral and temporal information in different types of complex sounds. For example, mustached bats emit a rich repertoire of social vocalizations. These calls typically contain multiple harmonics, and neurons in the inferior colliculus may be integrating information in these multiple harmonics to selectively encode specific calls. Our current research is presently focused on understanding how neurons in the inferior colliculus of the mustached bat encode social vocalizations. Studies on mice serve as a comparison to our studies on the mustached bat. The mouse is considered to have a more "typical" auditory system so we are examining whether neurons in the mouse inferior colliculus use the same type of spectral integrative neural strategy to process complex sounds. Our experiments with mice are just starting.
Representative Publications
Portfors, C.V. and Wenstrup, J.J. (2002). Excitatory and facilitatory frequency response areas in the inferior colliculus of the mustached bat. Hearing Research, 168, 131-138.
Portfors, C.V. and Wenstrup, J.J. (2001). Responses to combinations of tones in the nuclei of the lateral lemniscus. Journal of the Association for Research in Otolaryngology, 2, 104-117.
Portfors, C.V. and Wenstrup, J.J. (2001). Topographical distribution of delay-tuned responses in the inferior colliculus of the mustached bat. Hearing Research, 151, 95-105.
Portfors, C.V., Fenton, M.B., Aguiar, L.M.S., Baumgarten, J.E., Vonhof, M.J., Bouchard, S., de Faria, D.M., Pedro, W.A., Rautenbach, I.L., and Zortea, M. (2000). Bats from Fazenda Intervales, southeastern Brazil – species account and comparison between different sampling methods. Revista Brasileira de Zoologia, 17, 533-538.
Portfors, C.V. and Wenstrup, J.J. (1999). Delay-tuned neurons in the inferior colliculus of the mustached bat: Implications for target distance analyses. Journal of Neurophysiology, 82, 1326-1338.
Fenton, M.B., Whitaker Jr., J.O., Vonhof, M.J., Waterman, J.M., Pedro, W.A., Aguiar, L.M.S., Baumgarten, J.E., Bouchard, S., Faria, D.M., Portfors, C.V., Rautenbach, I.L., Scully, W. and Zortea, M. (1999). The diet of bats from southeastern Brazil: the relation to echolocation and foraging behaviour. Revista Brasileira de Zoologia, 16, 1081-1085.
Fenton, M.B., Portfors, C.V., Rautenbach, I.L. and Waterman, J. (1998). Compromises: Sound frequencies used in echolocation by aerial feeding bats. Canadian Journal of Zoology, 76, 1174-1182.
Fenton, M.B., Rautenbach, I.L., Rydell, J., Arita, H.A., Ortega, J., Bouchard, S., Hovorka, M.D., Lim, B.K., Ogdren, E., Portfors, C.V., Scully, W.M., Syme, D.M. and Vonhof, M.J. (1998). Emergence, echolocation, diet and foraging behaviour of Molossus ater (Chiroptera: Molossidae). Biotropica, 30, 314-320.
Fenton, M.B., Cumming, D.H.M., Rautenbach, I.L., Cumming, G.S., Cumming, M.S., Ford, G., Taylor, R.D., Dunlop, J., Hovorka, M.D., Johnston, D.S., Portfors, C.V., Kalcounis, M.C., Mahlanga, Z. (1998). Bats and the loss of tree canopy in African woodlands. Conservation Biology, 2, 399-407.
Cumming, D.H.M., Fenton, M.B., Rautenbach, I.L., Taylor, D., Cumming, G.S., Cumming, M.S., Dunlop, J.M., Ford, G., Hovorka, M.D., Johnston, D.S., Kalcounis, M., Mahlanga, Z. and Portfors, C.V. (1997). Elephant impacts on biodiversity of miombo woodlands in Zimbabwe. South African Journal of Science, 93(5), 231-236.
Courses
Comparative Physiology (BIOL 350)
Animal Behavior (BIOL 438/538)
Behavioral Neurobiology (ZOOL 490) |
