The chief goal of these studies is to evaluate how inputs that originate from multiple lower auditory nuclei shape the response properties of collicular neurons in the mammalian auditory system. Specifically the investigators will: 1) Determine which of the cells that project to the E1 region of the colliculus, and to the 60 kHz regions of the DNLL and INLL, are GABAergic and which are glycinergic. The DNLL and INLL are the two nuclei of the lateral lemniscus that project to the 60 kHz region of the colliculus. This will be accomplished by first, in an individual bat, identifying the appropriate region in the nucleus of interest with electrophysiological recordings, and then making a focal injection of HRP. Subsequent processing will co-localize the retrogradely transported HRP with antibodies directed against glycine, GABA and glutamate decarboxylase (GAD), the synthetic enzyme for GABA. 2) Determine the monaural and binaural response properties of INLL and DNLL neurons by recording single unit activity while presenting 60 kHz tone bursts with speakers inserted into the ears. 3) Determine the functional consequences of the inhibitory inputs to the colliculus by constructing the spatial receptive fields of 60 kHz E1 neurons from their monaural and binaural response properties, which will then be compared to the changes in receptive field properties induced by iontophoretic application of bicuculling and/or strychnine. Thus, they will assess the differential roles of GABAergic and glycinergic innervation in shaping the response properties and spatial receptive fields of collicular E1 neurons, and identify the source or sources, of the GABAergic (or glycinergic) influence. Finally, by evaluating the response properties of 60 kHz neurons in DNLL and INLL and reconstructing their receptive fields, they will obtain further insights into the transformations that occur along the neuraxis, and how lower nuclei may be exerting their inhibitory influence on their targets in the 60 kHz contour of the inferior colliculus.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
2R01DC000268-09
Application #
3216354
Study Section
Sensory Disorders and Language Study Section (CMS)
Project Start
1984-07-01
Project End
1995-06-30
Budget Start
1992-07-01
Budget End
1993-06-30
Support Year
9
Fiscal Year
1992
Total Cost
Indirect Cost
Name
University of Texas Austin
Department
Type
Schools of Arts and Sciences
DUNS #
City
Austin
State
TX
Country
United States
Zip Code
78712
Pollak, George D (2011) Discriminating among complex signals: the roles of inhibition for creating response selectivities. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 197:625-40
Bohn, Kirsten M; Schmidt-French, Barbara; Ma, Sean T et al. (2008) Syllable acoustics, temporal patterns, and call composition vary with behavioral context in Mexican free-tailed bats. J Acoust Soc Am 124:1838-48
Xie, R; Gittelman, J X; Li, N et al. (2008) Whole cell recordings of intrinsic properties and sound-evoked responses from the inferior colliculus. Neuroscience 154:245-56
Bauer, Eric E; Klug, Achim; Pollak, George D (2002) Spectral determination of responses to species-specific calls in the dorsal nucleus of the lateral lemniscus. J Neurophysiol 88:1955-67
Klug, Achim; Bauer, Eric E; Hanson, Joshua T et al. (2002) Response selectivity for species-specific calls in the inferior colliculus of Mexican free-tailed bats is generated by inhibition. J Neurophysiol 88:1941-54
Burger, R M; Pollak, G D (2001) Reversible inactivation of the dorsal nucleus of the lateral lemniscus reveals its role in the processing of multiple sound sources in the inferior colliculus of bats. J Neurosci 21:4830-43
Cometto-Muniz, J E; Cain, W S (1990) Thresholds for odor and nasal pungency. Physiol Behav 48:719-25