Seminars in Hearing Research at Purdue (SHRP)

Title:  Short-Term and Long Term Sub-Cortical Auditory Pathophysiology Following Mild Blast Induced Trauma

Speaker: Emily X. Han, Ph. D. student (PI: Ed Bartlett)

Date: February 13, 2020

Time: 10:30 – 11:20 am

Location: LYLE 1150

Abstract: 

Blast-induced hearing difficulties affect thousands of veterans and civilians each year. The long-term impact of blast exposure on the central auditory system (CAS) can last months, even years, without major external injury, and is hypothesized to contribute to many behavioral complaints associated with mild blast traumatic brain injury (bTBI). Our group has previously documented the short-term (two-weeks) and longer-term (one month) effects of acute blast and non-blast acoustic impulse trauma on click/tone pip and sinusoidally amplitude modulated (AM) carriers in adult rats. However, the mechanisms that underlie these long-term impairments are still poorly understood. Specifically, many measures of auditory function, including thresholds and DPOAEs either recover or exhibit subclinical deficits, thus masking deficits in processing complex, real-life stimuli under challenging contexts. Examining the acute time course and pattern of neurophysiological impairment (within the first two weeks), as well as the underlying molecular and anatomical post-injury environment, is therefore critical to better understanding and intervention towards bTBI-induced CAS impairments. This study aims to uncover central neurophysiological deficits related to “hidden hearing loss” in acute blast and non-blast acoustic impulse trauma in adult Sprague-Dawley rat model over the course of the first two weeks. Here, we recorded the changes in auditory brainstem response (ABR) and auditory evoked potential (AEP) response to amplitude modulation (AM) and speech-like stimuli (iterated rippled noise pitch contours) in acute mild blast and non-blast acoustic impulse exposed adult Sprague-Dawley rat over the course of two months. In conclusion, the current study suggests that primary, physical damage and secondary, biochemical damage, while related, may take effect on auditory pathophysiology at different time courses. We confirmed that CAP deficits can be better elucidated by increasingly complex processing tasks. Ultimately this research can inform improved diagnostic and therapeutic strategies for bTBI related deficits.

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