title: Forward acoustic masking enhances the auditory brainstem response in a diotic, but not dichotic, paradigm in salicylate-induced tinnitus.
abstract: We recently reported that forward acoustic masking can enhance the auditory brainstem response (ABR) in rats treated with a high dose of sodium salicylate (NaSal), a tinnitus inducer, when tested in open acoustic field (Liu and Chen, 2012, Brain Research 1485, 88-94). In the present study, we first replicated this experiment in closed acoustic field under two conditions: (1) the forward masker and the probe were presented to both ears (diotic paradigm); (2) the forward masker was presented to one ear and the probe to the other ear (dichotic paradigm). We found that only when the stimuli were presented by using the diotic, rather than the dichotic, paradigm could forward acoustic masking enhance the ABR in the rat treated with NaSal (300 mg/kg). The enhancement was obvious for ABR waves II and IV, but not for wave I, indicating a central origin. The enhancement occurred at the high frequencies (16, 24, 32 kHz) at which the animals demonstrated a tinnitus-like behavior as revealed by using the gap prepulse inhibition of acoustic startle paradigm. We then administered vigabatrin, a GABA transaminase inhibitor, in the animals to suppress NaSal-induced tinnitus. The vigabatrin treatment successfully prevented forward acoustic masking from enhancing the ABR. These findings demonstrate that the observed enhancement of ABRs by forward acoustic masking originates in the central auditory pathway ipsilateral to the stimulated ear. We propose that the enhancement is closely associated with NaSal-induced tinnitus.
authors: Center for Biomedical Engineering, School of Information Science and Technology, University of Science and Technology of China, Hefei 230027, China.
authors: Xiao-Peng
authors: XP
authors: Liu
authors: CAS Key Laboratory of Brain Function and Diseases, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China; Auditory Research Laboratory, University of Science and Technology of China, Hefei 230027, China. Electronic address: linchen@ustc.edu.cn.
authors: Lin
authors: L
authors: Chen
mesh_terms: D000612:4-Aminobutyrate Transaminase / Q000037:antagonists & inhibitors / Q000378:metabolism; D000161:Acoustic Stimulation / Q000379:methods*; D000818:Animals; D001299:Audiometry; D001306:Auditory Pathways / Q000503:physiopathology; D001307:Auditory Perception; D001309:Auditory Threshold; D001933:Brain Stem / Q000187:drug effects / Q000503:physiopathology*; D004007:Dichotic Listening Tests; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects; D005260:Female; D008297:Male; D009622:Noise / Q000009:adverse effects*; D010470:Perceptual Masking; D017208:Rats, Wistar; D012980:Sodium Salicylate; D013997:Time Factors; D014012:Tinnitus / Q000139:chemically induced / Q000503:physiopathology* / Q000517:prevention & control / Q000523:psychology*; D020888:Vigabatrin / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D000612:4-Aminobutyrate Transaminase; D020888:Vigabatrin; D012980:Sodium Salicylate