9 research outputs found
ABR hearing thresholds for tinnitus<sup>(+)</sup>, tinnitus<sup>(-)</sup>, and control rats prior to intense noise or sham exposure, and on post-exposure day 0 and post-exposure week 7.
<p>Thresholds were elevated across all frequencies in tinnitus<sup>(+)</sup> and tinnitus<sup>(-)</sup> rats at post-exposure day 0, revealing immediate and significant hearing loss. By post-exposure week 7, however, thresholds recovered to pre-exposure levels. At all time points, thresholds were similar between tinnitus<sup>(+)</sup> and tinnitus<sup>(-)</sup> rats. There were no threshold elevations in control rats. Error bars represent standard error of the mean.</p
Licking rates during silent trials prior to injections (post-exposure week 8), as well as 3 hours and 5 days following saline (A) or salicylate (B) injections.
<p>After saline injections, no changes in licking rate were observed. Three hours following salicylate injections, however, all nine animals increased licking behavior during silent trials, though most robustly following high-frequency narrowband sound trials. The licking rates during silent trials returned to pre-injection levels by 5 days post-injection.</p
Licking rates over time for tinnitus<sup>(+)</sup>, tinnitus<sup>(-)</sup>, and control rats during narrowband sound trials (A-E).
<p>Tinnitus<sup><b>(+)</b></sup> refers to rats that later exceeded 1 lick/trial for one or more silent trial categories over weeks 5 through 7 weeks following noise exposure; tinnitus<sup><b>(-)</b></sup> refers to noise-exposed rats that did not meet that criteria. No significant changes in sound trial licking were observed for any group of rats.</p
Top and side views of the behavioral testing chamber.
<p>The horizontal waterspout is located in the front of the wire mesh chamber and connected to a syringe pump for water delivery. Speakers were mounted to the chamber walls on both sides of the waterspout, so that sound could be presented bilaterally to the animal. Sounds levels and frequencies were calibrated using a microphone (ACO Pacific, Belmont, CA) and the chamber was tested to ensure that sound presentation did not vibrate the chamber. The stainless steel grid floor was electrified to deliver footshocks. Behavioral sessions were monitored with a USB camera placed above the testing chamber.</p
Illustrations showing phase 4 behavioral training during 6–8 and 10–12 kHz sound and silent trials.
<p>The “x 3” and “x 1” notations refer to the number of spout licks required to obtain a water reward and a variable shock, respectively.</p
Baseline rates of licking during silent trials (training sessions 11–16).
<p>Tinnitus<sup><b>(+)</b></sup> refers to rats that later exceeded 1 lick/trial for one or more silent trial categories over weeks 5 through 7 week following noise exposure; tinnitus<sup><b>(-)</b></sup> refers to noise-exposed rats that did not meet that criteria. A silent trial category was determined by the narrowband sound trial that preceded it (i.e. 6–8 kHz, 10–12 kHz, 14–16 kHz, 22–24 kHz, 30–32 kHz) (A-E). From baseline test sessions 13–16, all rats exhibited stable baseline behavior (≤ 1 average lick/trial) for every silent trial category, as indicated by the dashed line and shaded area. There were no significant differences between tinnitus<sup>(+)</sup>, tinnitus<sup>(-)</sup>, or control (ctrl) rats in baseline silent trial licking.</p
Baseline licking rates of eventual tinnitus<sup>(+)</sup>, tinnitus<sup>(-)</sup>, and control (ctrl) rats during different narrowband sound trials (A-E).
<p>Tinnitus<sup><b>(+)</b></sup> refers to rats that later exceeded 1 lick/trial for one or more silent trial categories over weeks 5 through 7 weeks following noise exposure; tinnitus<sup><b>(-)</b></sup> refers to noise-exposed rats that did not meet that criteria. For all rats, licking rates did not significantly change between training sessions 14 through 16. These rates were comparable between all groups of rats.</p
Noise-exposed (Exposed) and sham-exposed (Sham) rats tested without footshocks at four weeks (A) and eight weeks (B) following exposure.
<p>The dotted line and shading indicate the silent trial licking range of sham-exposed rats. A few of the noise-exposed rats exhibited silent trial licking rates higher than those of sham-exposed rats at both four and eight weeks post-exposure. This is suggestive of tinnitus-like behavior.</p
Licking rates over time for tinnitus<sup>(+)</sup>, tinnitus<sup>(-)</sup>, and control rats during silent trials (A-E).
<p>Tinnitus<sup><b>(+)</b></sup> refers to rats that later exceeded 1 lick/trial for one or more silent trial categories over weeks 5 through 7 weeks following noise exposure; tinnitus<sup><b>(-)</b></sup> refers to noise-exposed rats that did not meet that criteria. Tinnitus<sup>(+)</sup> and tinnitus<sup>(-)</sup> rats exceeded 1 lick per each silent trial category immediately after noise exposure (D 0), except for one rat for 6–8 and another rat for 30–32 kHz silent trials. Eleven rats exceeded 1 lick per silent trial for one or more silent trial categories over at least 5 to 7 weeks post-exposure (Wk 5 –Wk 7). These increases in silent trial licking were significant relative to the last baseline training session (T16). Control rats show no significant increases in licking over time. The dashed line and gray-shaded area indicate the ≤ 1-lick/trial threshold.</p