The effects of repetitive transcranial magnetic stimulation on the cognition and neuronal excitability of mice.

This study aimed to investigate the effects of repetitive transcranial magnetic stimulation (rTMS) on the cognition and neuronal excitability of Kunming mice during the natural aging of the brain. Twenty young (2-3-month-old) female mice, 20 adult (9-10-month-old) female mice and 12 aged (14-15-month-old) female mice were divided into two groups (control and rTMS treatment). rTMS-treated groups were subjected to high-frequency (20 Hz) rTMS treatment for 15 days. Novel object recognition (NOR) and step-down tests were performed to examine cognition of learning and memory. The whole-cell patch clamp technique was used to record the resting membrane potential (RMP) and action potential (AP), and the intrinsic properties of the AP were analyzed (the frequence of AP, the after hyperpolarizing potential (AHP), the AP peak amplitude, the time to AP amplitude, the average rise/down slope). Results showed that the cognition and neuronal excitability of hippocampal dentate gyrus (DG) granule cells were significantly declined only in aged animals while no statistic differences were found between young and adult animals. Chronic high-frequency rTMS could significantly improve the age-related cognitive impairment in parallel with enhancing the DG granule cells' neuronal excitability.