Abstract: The spontaneous behavior and the learning memory retention of aged-mice were assessed using open field and one-trial passive avoidance task after atmospheric (101.3kPa)oxygen or hyperbaric (253.3kPa)oxygen treatment (HBOT),At the same time, the synaptosomal free calcium concentration in some main brain regions (cerebral probe [Ca2+],indicat or Fura-2/AM and an AR-CM-MIC cation measurement system The results showed that the spontaneous behavior and explorative response in the openfield significantly increased and the memory retention was remarkably elevated. The high synaptosomal free Ca2+ concentration caused by decrepit was decreased afteratmospheric oxygen or HBOT, and there was a better inhibiting action of HBOT on high level of calcium in the brain, Memory declination was closely related with hypercalcemic phenomenon in the brain. It indicated that the senile memory impediment can be treated by HBOT through decreasing the synaptosomal free Ca2+ concentration.

Key words: hyperbaric oxygenation, open field, one-trial passive avoidance, calcium ion