Gap detection deficits in rats with tinnitus: A potential novel screening tool.

Abstract

The study describes a novel method for tinnitus screening in rats by use of gap detection reflex procedures. The authors hypothesized that if a background acoustic signal was qualitatively similar to the rat's tinnitus, poorer detection of a silent gap in the background would be expected. Rats with prior evidence of tinnitus at 10 kHz (n = 14) exhibited significantly worse gap detection than controls (n = 13) when the gap was embedded in a background similar to their tinnitus. No differences between tinnitus and control rats were found with 16 kHz or broadband noise backgrounds, which helped to rule out explanations related to hearing loss or general performance deficits. The results suggest that gap detection reflex procedures might be effective for rapid tinnitus screening in rats.

Mice with behavioral evidence of tinnitus exhibit dorsal cochlear nucleus hyperactivity because of decreased GABAergic inhibition

“…2A). The hypothesis is that the chronic tinnitus partially masks the silent gap perception, and therefore, mice show reduced ability to detect the silent gap and less inhibition of startle reflex (8). In the present study, gap detection performance was assessed before noise induction and 2-9 wk postnoise induction.…”

“…Tinnitus is often induced after intense sound exposure, and therefore, we used a noise-induced animal model of tinnitus. We used a protocol [unilateral, 45-min exposure to 116-dB sound pressure level (SPL), 1-kHz band noise centered at 16 kHz] that does not lead to permanent hearing threshold shifts (8). To assess behavioral evidence of tinnitus, we used a reflex-based gap detection method (8).…”

“…We used a protocol [unilateral, 45-min exposure to 116-dB sound pressure level (SPL), 1-kHz band noise centered at 16 kHz] that does not lead to permanent hearing threshold shifts (8). To assess behavioral evidence of tinnitus, we used a reflex-based gap detection method (8). According to this paradigm, normal hearing animals exhibit an inhibited reflex to a startling sound (115 dB for 20 ms) when a silent gap (50 ms long) is embedded in a constant background sound ( Fig.…”

“…Animal models of tinnitus have contributed significantly to the understanding of the pathophysiology of tinnitus (2)(3)(4)(5)(6)(7)(8). An emerging pattern associated with tinnitus pathology indicates that intense noise exposure leads to cochlear damage and hearing loss, which often is not clinically detected.…”

Enhanced GABAA-Mediated Tonic Inhibition in Auditory Thalamus of Rats with Behavioral Evidence of Tinnitus

“…The gap detection reflex method was adapted from Turner et al (2006) and , and was based upon the ability of the acoustic startle reflex to be reduced when preceded by a silent gap in a constant acoustic background. As detailed in Wang et al (2009), behavioral testing used Kinder Scientific startle reflex hardware and software, which was customized for this application.…”