Intense noise exposure alters peripheral vestibular structures and physiology.

Area of Science:

• Neuroscience
• Auditory and Vestibular Systems Research
• Sensory Physiology

Background:

• Otolith organs are crucial for balance and posture, detecting linear acceleration and gravity.
• Some vestibular afferents are sensitive to sound and vulnerable to noise overstimulation.
• Previous studies showed noise exposure abolishes vestibular short-latency evoked potential (VsEP) responses and damages calyceal terminals.

Purpose of the Study:

• To determine the effect of noise exposure on VsEP responses using large head-jerk stimuli in rats.
• To investigate if noise induces a stimulus threshold shift for VsEP responses.
• To correlate VsEP changes with calyceal terminal and hair cell counts post-noise exposure.

Main Methods:

• Utilized an established noise exposure paradigm in rats.
• Measured VsEP responses using small and large head-jerk stimuli.
• Quantified calyceal terminals and hair cells in noise-exposed and control tissues.
• Assessed calretinin immunolabeling in the striolar region of the sacculus.

Main Results:

• Intense noise exposure significantly reduced VsEP responses to large stimuli and abolished responses to small stimuli.
• A shift in the minimum stimulus required to evoke VsEP responses was observed in noise-exposed rats.
• Noise exposure reduced calyx-only afferent terminals, specifically those expressing calretinin, without affecting overall calyces or hair cells.

Conclusions:

• Noise-induced damage to the vestibular periphery necessitates larger stimuli to elicit measurable VsEP responses.
• Reduced calretinin-labeled calyceal-only afferent terminals in the sacculus striolar region are linked to altered VsEP responses.
• Noise exposure may impair synaptic function in calyx-only afferents, offering insight into noise-induced vestibular changes.