Brain frequency magnetic fields alter cardiac autonomic control mechanisms

Area of Science:

• Neuroscience
• Cardiology
• Biophysics

Background:

• Heart rate variability (HRV) reflects autonomic nervous system control of the heart.
• Previous research suggests 60 Hz magnetic fields can alter human HRV.
• Autonomic cardiac control originates centrally in the brain.

Purpose of the Study:

• To investigate if magnetic fields in the beta(1) EEG/MEG frequency range (16 Hz) are more effective at altering HRV than 60 Hz fields.
• To explore the underlying mechanisms of magnetic field-induced HRV changes.
• To determine if magnetic field exposure affects the cardiac pacemaker directly or via central nervous system (CNS) pathways.

Main Methods:

• Overnight exposure of healthy young men (n=9) to an intermittent 16 Hz magnetic field (28.3 microTesla).
• Control group (n=9) received sham exposure under blind conditions.
• Analysis of HRV frequency spectrum and heart rate.
• Phase-resetting experiments to assess direct cardiac pacemaker effects.

Main Results:

• Magnetic field exposure significantly reduced low-frequency power in the HRV spectrum (P<0.05).
• Mean heart rate decreased during magnetic field exposure.
• No evidence of direct effect on the cardiac pacemaker was found.

Conclusions:

• Magnetic field exposure at 16 Hz alters HRV through a CNS mechanism.
• The findings rule out direct effects on the cardiac pacemaker.
• Biophysical calculations support a central (brain) rather than peripheral (heart) site of action for magnetic field bioeffects.