| Research Abstract |
2002 years : We used Hartley guinea pigs. We recorded firing rates from central auditory nerve, primary auditory cortex (AI), secondary auditory cortex (AII) and cochlear nerve (CN). Recording positions in AI, AII and CN, each was injected two or three tungsten microelectrodes ad investigated about firing rates. To record from AI and AII was opened right temporal bone, and CN was opened the occipital bone through to cerebellum under the general anesthesia. TDT workstation was used to recording of firing rates from AI, AII and CN. Recently, by the development of electrophysiology, recording firing rates from cochlea nerve, auditory nerve, inferior colliculus and auditory cortex by cats was possible. However, the examination used guinea pigs was rare, reported by Wallace in 1999. We could record from AI, AII and CN, due to TDT workstation.
2003 years. Renal failure was created by amikacin hydrochloride, which was received an intramuscular infection of 750 mg/kg at 10 times every days. Firing rates of CN was abnormal ad spontaneous firing rates in AII was increased, whereas in AI reduced the spontaneous rates. The data was same as tinnitus induced salicylate and quinine. This suggests that renal failure induced disturbed homeostasis of cochlea by increasing osmotic pressure due t medium sized catabolic toxic molecules, leading ultimately to originating hearing loss and tinnitus. We suggested that it was important of AII by the mechanism of tinnits.
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