Biomagnetics: An interdisciplinary field where magnetics, biology and medicine overlap

Biomagnetics is an interdisciplinary field where magnetics, biology and medicine overlap. It has a long history since 1600, when William Gilbert published his book De Magnete. Recent advances in biomagnetics have enabled us not only to detect extremely weak magnetic fields from the human brain, but also to control cell orientation and cell growth by extremely high magnetic fields. Pulsed magnetic fields are used for transcranial magnetic stimulation (TMS) of the human brain, and both high frequency magnetic fields and magnetic nanoparticles have promising therapeutic applications for treatments of cancers and brain diseases such as Alzheimer’s and Parkinson's. On the imaging front, magnetic resonance imaging (MRI) is now a powerful tool for basic and clinical medicine. New methods of MRI based on the imaging of impedance of the human body, called impedance MRI, and the imaging of neuronal current activities in the human brain, called current MRI, are also being developed.

This lecture focuses on the advances in biomagnetics and bioimaging obtained mostly in our laboratory in recent years. The lecture describes: (1) a method of localized magnetic stimulation of the human brain by TMS with a figure-eight coil; (2) magneto-encephalography (MEG) to measure extremely weak magnetic fields produced from brain electrical activity using superconducting quantum interference device (SQUID) systems; (3) impedance MRI and current MRI; (4) cancer therapy and control of iron-ion release from, and uptake into, ferritin, an iron-storage protein, by using both high frequency and pulsed magnetic fields and magnetic nanoparticles; and (5) magnetic control of biological cell orientation and cell growth by strong static magnetic fields. These new biomagnetic approaches will open new horizons in brain research, brain treatment, and regenerative medicine.