A novel behavioral assay for the assessment of acute tinnitus in rats optimized for simultaneous recording of oscillatory neural activity.
BACKGROUND
Human magneto/electrophysiology studies suggest that the phantom sound of tinnitus arises from spontaneous oscillatory neural activity in auditory cortex; however, in animal models, behavioral techniques suitable for testing this hypothesis in combination with electrophysiology recordings have yet to be evaluated. While electrophysiological studies of tinnitus have been reported in passive, awake animals, these studies fail to control for attentional mechanisms likely to play a role in the perception of tinnitus.


METHODS
A novel appetitive operant conditioning, two-alternative identification task was developed for detecting acute tinnitus in rats. The procedure optimizes conditions for simultaneously recording oscillatory neural activity while controlling for the attentional state of the animal.


RESULTS
Tinnitus was detected in six of seven rats following systemic injection with sodium salicylate (200mg/kg IP), a known inducer of tinnitus. Analysis of ongoing local field potentials recorded from chronically implanted electrodes in auditory cortex of a rat reporting tinnitus revealed changes in the spectrum of ongoing neural activity. Comparison with existing method(s): Existing tinnitus-detection methods were not explicitly designed for the simultaneous recording of neural activity. The behavioral method reported here is the first to provide the conditions necessary for obtaining these recordings in chronically implanted rats.


CONCLUSIONS
The behavioral assay presented here will facilitate research into the neural mechanisms of tinnitus by allowing researchers to compare the electrophysiological data in animals with confirmed tinnitus.
Center for Hearing & Deafness, Department of Communicative Disorders and Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14215, USA; Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, Ontario N6A 5C1, Canada. Electronic address: dstolzbe@uwo.ca.
Daniel
D
Stolzberg
Sarah H
SH
Hayes
Nina
N
Kashanian
Kelly
K
Radziwon
Richard J
RJ
Salvi
Brian L
BL
Allman
D000818:Animals; D001303:Auditory Cortex / Q000503:physiopathology; D001522:Behavior, Animal; D003216:Conditioning, Operant; D004195:Disease Models, Animal; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000379:methods*; D005072:Evoked Potentials, Auditory / Q000502:physiology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D014012:Tinnitus / Q000175:diagnosis* / Q000503:physiopathology
AC; AM; Animal model; Auditory cortex; Electrophysiology; LFP; NBN; Oscillatory activity; Sodium salicylate; Tinnitus; amplitude modulated noise; auditory cortex; local field potential; narrow-band noise