Huiming Zhang
Department of Biological Sciences

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Huiming Zhang
401 Sunset Avenue
Windsor, ON Canada N9B 3P4
(519) 253-3000 ext. n/a

© Copyright 2020
University of Windsor

The Structure and Function of the Descending Neural Projections from the Auditory Cortex

The capability to recognize and localize sounds of interest in the presence of background noises is important for behavioral needs of mammals. This capability is dependent on the central auditory system which consists of a group of hierarchically organized neural structures with the auditory cortex being at the highest level. The auditory cortex receives ascending neural projections from subcortical neural structures and provides descending projections to these structures. This fact indicates that the auditory cortex contributes to hearing not only by processing neural signals that it receives but also by controlling subcortical neural responses.

We are investigating whether descending projections from the auditory cortex serve to gate neural signals in thalamic and midbrain auditory structures, so that only information related to sounds of interest but not background noises can be relayed from low to high structures. We are also studying how this gating is dependent on the neurotransmitter receptors that mediate the descending projections. Our research will provide knowledge about neural mechanisms of hearing, especially those related to selective auditory attention.

Tinnitus and the Expression of Neurotransmitter Receptors

Tinnitus is the perception of sounds without the presence of external acoustic stimuli. It is estimated that this phantom auditory perception affects as much as 15% and severely annoys or debilitates as much as 2% of the general population. The impact of tinnitus will be even more severe in the coming decades as people increasingly expose themselves to tinnitus-inducing factors such as intense sounds including those from portable audio devices and ototoxic drugs including salicylate (a major component of Aspirin).

We are investigating how intense-noise exposure and salicylate injection alter the level and function of excitatory/inhibitory neurotransmitter receptors in central auditory structures. We are also studying the mechanisms by which the tinnitus-inducing factors alter the level and function of these receptors. Furthermore, we are examining how this alteration affects neural activity in auditory structures. Results from this research will provide implications for developing clinical methods to regulate the level and distribution of neurotransmitter receptors and to restore normal neural activity in auditory structures of tinnitus patients.