Behavioral testing is the gold-standard for assessment of hearing loss and tinnitus.
Turner Scientific offers an unmatched expertise in automated reflex-based behavioral testing to determine hearing thresholds and the presence of tinnitus. Often used as an early tool for assessing auditory function, behavioral testing offers numerous advantages:
- Cost-effective screening done in a “high throughput” manner
- Capable of detecting subtle effects of drug treatment
- Necessary when electrophysiological testing (ABR) is not possible due to potential interactions with drug treatment
- Highly efficient, because it uses a reflex, extensive animal training is not required
Behavioral testing is based on the analysis of each animal’s startle reflex. A loud sound presented to a test animal will elicit a startle response that can be accurately quantified. When a second sound is presented to the animal approximately 100 ms prior to the startle trigger, the degree of startle is reduced (i.e. – inhibited). Essentially, the behavioral audiogram is conducted by altering the pitch and/or intensity of this pre-startle stimulus to assess its ability to inhibit on the actual startle reflex. This method of testing allows for analysis of several auditory dysfunctions, such as hearing loss, hyperacusis, and presbycusis.
Alternatively, rather than delivering a pre-pulse of sound prior to the startle trigger, a pre-pulse gap in background noise can be presented to evaluate the presence of tinnitus. Much like the pre-pulse stimulus described above, a period of silence against a continuous background noise can also inhibit the startle reflex in normal hearing animals. Using this technique, a brief period of silence is presented to an animal approximately 100 ms prior to the startle trigger. If the animal is experiencing tinnitus, its brain will not be as effective at processing the silent cue, and the subsequent startle reflex will not be inhibited effectively. This objective technique to evaluate tinnitus was co-invented by Jeremy Turner and is now one of the most widely used methods for tinnitus measurement in laboratory animals around the word Turner et al, 2006).
Reference:
Turner, J.G., Brozoski, T.J., Bauer, C.A., Parrish, J.L., Myers, K., Hughes, L.F., & Caspary, D.M. (2006). Gap detection deficits in rats with tinnitus: a potential novel screening tool. Behavioral Neuroscience, 120(1), 188-195.