GOALS


The major focus of the LECOM Auditory Research Center is the auditory pathways and specifically the superior olivary complex (SOC). The SOC is an aggregation of nuclei within the mammalian brainstem with numerous function roles in auditory processing. The SOC contains two principal cell groups, the medial superior olive (MSO) and the lateral superior olive (LSO). The cells of the MSO are biased towards low-frequency sounds and encode interaural timing differences while the cells of the LSO are biased towards high-frequency sounds and encode interaural intensity differences; both cell groups play essential roles in the localization of sound sources. The organization of the PON is much more variable - the types of neurons presents and the connections they make with other brainstem structures varies between species. Animal studies even support variable functional roles between species (Kulesza et al., 2003). Unfortunately, little is known about the PON in human.

The mission of the LECOM Auditory Research Center is to understand the organization of the human SOC and the role this center plays in human auditory perception. In order to meet this goal we will require clarification of the components and organization of the human SOC with a detailed examination of the connectivity of this brainstem center with auditory and non-auditory regions. This information will be accessed through neuroanatomical techniques including, Nissl staining, immunocytochemistry, morphometric analysis and tract tracing with lipophilic tracers. The detailed knowledge obtained in the course of these studies will be essential in approaches to overcoming hearing loss.

Clinical Significance: Analysis of auditory function in patients with cochlear implants reveal deficits in temporal processing (Fu et al., 2001; Szelag et al., 2004), perception in noisy environments (Zeng, 2004) and understanding speech (Wilson et al., 2003). Thus, there is potential for improvement of current cochlear implants (Fu, 2002). Presbycusis is an age-related hearing loss partially attributed to death of inhibitory SOC neurons (rat; Caspary et al., 1990). The SOC functions in numerous capacities including temporal processing and listening in noisy environments. Thus, a detailed understanding of brainstem auditory circuits involving the SOC will be pivotal to the improvement of cochlear implants and addressing presbycusis.