CHANGES OF AUDITORY EVOKED POTENTIALS IN GUINEA PIGS UNDER HYPERBARIC OXYGEN CONDITIONS

Changes of auditory nerve action potential (AP), brainstem evoked potential (BSEP) and auditory cortical evoked potential (ACEP) in guinea pigs were studied before, during and after hyperbaric oxygen(HBO) exposure at 2 atm (absolute). In comparison with the pre-exposure levels, the amplitudes of AP and BSEP during the stay of HBO were significantly increased. The amplitude of ACEP under HBO conditions, however, did not show synchronous change-completely with the amplitudes of AP and BSEP. In about half of the animals, the ACEPs showed increase in amplitude, but in others the ACEPs showed decrease or on changes in amplitude, even though the AP ans BSEP manifested synchronous increase in amplitudes. This seems to indicate that the cortex is more sensitive to HBO and the sensitivity varied with the individual. animals. The experiments suggest that breathing HBO at 2 atm (absolute) for 1 hour is beificial to the improvement of the auditory functions.