biomagnetism

Biomagnetism is the study of magnetic fields produced by living organisms and the use of magnetic fields to study biological processes. It encompasses the generation, detection, and interpretation of endogenous magnetic fields as well as the application of magnetic techniques to biomedical research and clinical practice. The magnetic fields produced by biological activity are extremely weak, typically in the femtotesla to picotesla range for brain signals and higher for cardiac signals.

The brain, heart, and other excitable tissues generate electrical currents that produce magnetic fields. Noninvasive measurement of these fields allows functional imaging and physiological assessment without direct contact. The most prominent clinical and research tool is magnetoencephalography (MEG), which uses highly sensitive sensors to detect the brain’s magnetic activity. Magnetocardiography (MCG) records the heart’s magnetic field. More recently, atomic or optically pumped magnetometers have begun to supplement or replace some superconducting devices.

Applications include mapping brain function, localizing epileptogenic zones, studying sleep, and assessing cardiac electrophysiology. Biomagnetic techniques also support basic research in muscle physiology, neurovascular coupling, and sensory processing. In addition, some organisms exhibit magnetoreception—navigation guided by magnetic fields—an area of biomagnetic interest.

Therapeutic magnets marketed to treat various conditions are controversial and not supported by robust evidence. Biomagnetism as a scientific field emphasizes measurement, interpretation, and modeling of biological magnetic phenomena, with clinical utility evolving as technology improves.