Extremely Low Frequency Magnetic Fields Do Not Affect LTP-Like Plasticity in Healthy Humans

Area of Science:

• Neuroscience
• Biophysics
• Electromagnetic field effects on biological systems

Background:

• Extremely low-frequency magnetic fields (ELF-MFs) have shown varied effects on neuronal activity and synaptic plasticity in in vitro and animal studies.
• Previous research presents conflicting results regarding ELF-MFs' impact on long-term potentiation (LTP), with some studies reporting increases and others decreases.
• The specific effects of ELF-MFs on human cortical plasticity, particularly LTP-like plasticity, remain largely uninvestigated.

Purpose of the Study:

• To investigate the impact of ELF-MFs on the human cortex's capacity for LTP-like plasticity.
• To determine if whole-brain exposure to specific ELF-MF parameters influences cortical plasticity in healthy human subjects.

Main Methods:

• A randomized, single-blind, sham-controlled, cross-over study was conducted on 10 healthy participants.
• Cortical plasticity was assessed using intermittent theta burst stimulation (iTBS) before and after a 45-minute exposure to either ELF-MFs (75 Hz; 1.8 mT) or a sham condition.
• Changes in motor-evoked potential (MEP) amplitude were measured to quantify plasticity induction.

Main Results:

• No adverse events were reported during the study, indicating a safe exposure profile.
• The application of ELF-MFs (75 Hz; 1.8 mT) did not result in any statistically significant changes in LTP-like plasticity.
• Motor-evoked potential amplitudes showed no significant alteration attributable to ELF-MF exposure compared to the sham condition.

Conclusions:

• Whole-brain exposure to ELF-MFs at 75 Hz and 1.8 mT is deemed safe for human subjects.
• This study concludes that ELF-MFs do not significantly affect LTP-like plasticity in the human motor cortex.
• The findings suggest that the investigated parameters of ELF-MFs do not interfere with key mechanisms of cortical plasticity in humans.