Tinnitusisasubjectiveperceptionofphantomsoundthatcurrentlycannotbeobjectivelymeasured.However,thereisgrowingevidencesuggestingthatthebiologicalsourceoftinnitusmayexistinoneormorethanoneplaceintheauditorypathway.Recentstudieshavefoundthatneurotransmittersormodulators,suchasglutamate,γ-aminobutyricacid(GABA),serotonin,dynorphin,dopamine,neurosteroid,acetylcholine(ACh)andsubstanceP,areinvolvedintinnitusgeneration.Animalandhumanstudieshaveshownthatsomeoftheseneurotransmittersandtheagonistsorantagonistsoftheirreceptorseitheraffecttinnitusbehaviorsordemonstratesomedegreeoftreatmenteffectsontinnitus.However,duetotheunclearbiologicalmechanismsoftinnitusandsideeffectsofthesedrugs,thevalueofclinicalusageofsuchdrugsintreatingtinnitusisyettobeestablished.Revealingtherelationshipbetweentinnitusandneurotransmitterreceptorfunctionswillhelpidentifymoreeffectivedrugsfortinnitustreatment.Thisarticlereviewstheliteratureofneurophysiologicalstudiesontinnitusinbothanimalandhumansubjectstudiesatvariouslevelsoftheauditorypathway.
