The purpose of the research is to investigate the complexity alterations of normal brain aging on the resting-state and metal calculation-state.15 healthy young people and 13 healthy old people were recruited, and their EEG recordings on the resting-state and mental calculation-state were analyzed using multiscale sample entropy (MSE) methods. The results showed that on the same state, the resting-state MSE values for old people were higher than young people in most of the whole brain, but the mental calculation-state MSE values for old people were lower than young people in most of the whole brain. However, the differences between old people and young people were not statistically significant. On different states, the mental calculation-state MSE values for young people and old people were lower than the resting-state in most of the whole brain. The differences were statistically significant for old people almost covering the whole brain particularly in the prefrontal lobe regions, but did not existed for young people. Therefore, it can be concluded that the alterations in brain functional complexity of normal brain aging were not obvious, but comparing with the resting-state, the mental calculation-state could better reflect the effect of aging on the complexity of brain function and the prefrontal lobe might be the regions of normal brain aging and memory function.

resting-state; mental calculation-state; multiscale sample entropy; normal brain aging; complexity; prefrontal lobe