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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)
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