Immediate and cumulative effects of high-frequency repetitive transcranial magnetic stimulation on cognition and neuronal excitability in mice

Abstract

This study primarily explored the potential effects of high-frequency (20 Hz) repetitive transcranial magnetic stimulation (rTMS) with different intervention protocols on cognition and neuronal excitability in mice. Mice were randomly divided into 4 groups: a control group that received sham stimulation, an rTMS in vitro group whose acute brain slices received high-frequency stimulation, an rTMS 1 d group that received high-frequency stimulation for only 1 d, and an rTMS 15 d group that received high-frequency stimulation for 15 d. The novel object recognition and step-down tests were used to assess cognitive ability. The patch-clamp technique was used to record the membrane potentials and neural discharges of dentate gyrus granule cells to evaluate neuronal excitability. Results revealed that cognition and neuronal excitability in the rTMS 15 d group were significantly increased than that in the control and rTMS 1 d groups. The neuronal excitability in the rTMS in vitro group was also significantly increased than that in the control and rTMS 1 d groups. No significant changes were observed between the control and rTMS 1 d groups. These results suggested that high-frequency rTMS applied to the acute brain slices of mice in vitro exerted an immediate effect on increasing neuronal excitability. Chronic high-frequency rTMS applied to the brain of mice in vivo exerted a cumulative effect in improving cognition and increasing neuronal excitability.