Binaural processing is important because it allows organisms to localize sounds in their environment. Evidence of this processing can be found at early levels of central auditory pathways in mammals, including nuclei of the superior olive, lateral lemniscus, and inferior colliculus. Neurons in these pathways use interaural time and level differences (ITD's and ILD'S) to compute the source of a sound. Part of this processing involves the interaction of excitatory inputs driven by one ear and inhibitory inputs driven by the other ear. In this project we will investigate which neurons in the auditory pathways provide inhibitory inputs for binaural processing, and how these inputs converge with excitatory inputs at different levels of the auditory pathway. We will relate these findings to the processing of ITD's and ILD's in nuclei of the superior olive, lateral lemniscus, and inferior colliculus. To do this, immunocytochemistry and transmitter-specific uptake will be used to identify which neurons in the nuclei of the superior olive, lateral lemniscus, and inferior colliculus may use inhibitory or excitatory transmitters. These procedures will be combined with retrograde transport of exogenously injected tracers to identify inhibitory or excitatory neurons with ascending projections. Moreover, anterograde tracing of the afferent inputs to these projection neurons will be combined with retrograde transport and immunocytochemistry. In this way we will define the chains of neurons and their inhibitory connections which are likely to be involved in the binaural processing of ITD's and ILD'S.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
5R01DC000726-02
Application #
3217413
Study Section
Hearing Research Study Section (HAR)
Project Start
1990-03-01
Project End
1993-02-28
Budget Start
1991-03-01
Budget End
1992-02-29
Support Year
2
Fiscal Year
1991
Total Cost
Indirect Cost
Name
University of Connecticut
Department
Type
Schools of Dentistry
DUNS #
City
Farmington
State
CT
Country
United States
Zip Code
06030
Saint Marie, R L; Luo, L; Ryan, A F (1999) Effects of stimulus frequency and intensity on c-fos mRNA expression in the adult rat auditory brainstem. J Comp Neurol 404:258-70
Shneiderman, A; Stanforth, D A; Henkel, C K et al. (1999) Input-output relationships of the dorsal nucleus of the lateral lemniscus: possible substrate for the processing of dynamic spatial cues. J Comp Neurol 410:265-76
Saint Marie, R L; Luo, L; Ryan, A F (1999) Spatial representation of frequency in the rat dorsal nucleus of the lateral lemniscus as revealed by acoustically induced c-fos mRNA expression. Hear Res 128:70-4
Luo, L; Ryan, A F; Saint Marie, R L (1999) Cochlear ablation alters acoustically induced c-fos mRNA expression in the adult rat auditory brainstem. J Comp Neurol 404:271-83
Saint Marie, R L; Shneiderman, A; Stanforth, D A (1997) Patterns of gamma-aminobutyric acid and glycine immunoreactivities reflect structural and functional differences of the cat lateral lemniscal nuclei. J Comp Neurol 389:264-76
Ostapoff, E M; Benson, C G; Saint Marie, R L (1997) GABA- and glycine-immunoreactive projections from the superior olivary complex to the cochlear nucleus in guinea pig. J Comp Neurol 381:500-12
Saint Marie, R L; Stanforth, D A; Jubelier, E M (1997) Substrate for rapid feedforward inhibition of the auditory forebrain. Brain Res 765:173-6
Winer, J A; Saint Marie, R L; Larue, D T et al. (1996) GABAergic feedforward projections from the inferior colliculus to the medial geniculate body. Proc Natl Acad Sci U S A 93:8005-10
Saint Marie, R L (1996) Glutamatergic connections of the auditory midbrain: selective uptake and axonal transport of D-[3H]aspartate. J Comp Neurol 373:255-70
Oliver, D L; Winer, J A; Beckius, G E et al. (1994) Morphology of GABAergic neurons in the inferior colliculus of the cat. J Comp Neurol 340:27-42