Biomagnetic Fields
The body produces its own very complex electrical activity. Wherever there is electrical activity MFs result. The body’s own magnetic fields are extremely tiny. They are so tiny that they are easily obscured by the surrounding planetary and environmental fields. These external fields have to be blocked to allow study of the body’s own magnetic fields. The endogenous electrical and magnetic fields of the body regulate all the body’s processes and interact with each other. Unlocking these secrets opens new alternatives in diagnosis and treatment.
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Biomagnetometers
There are many devices for measurement of electrical fields, including electroencephalo- grams (EEGs) and electrocardiograms (EKGs). There are significant limits to the information able to be gained from these, especially at the local cellular level. Electrical field measurement does not localize small areas of pathology as well as MF measurements can and can’t “see” as deep into the body without having to insert probes. Also, electrical measurements capture voltage but magnetic measurements say more about total current, which is more physiologically relevant. Biomagnetic fields are minimally affected by tissues along their paths, such as the skull, as opposed to bioelectric fields. Biomagnetometers, do not require electrode placement and allow intracellular currents to be measured compared to extracellular voltage charges. Thus MF measurement allows for measuring transmembrane charges without penetration of the cell membrane. It therefore becomes easier to detect electric currents flowing within a person by detecting the associated MFs than by recording surface electric charges at the skin. This allows for accurate, non-invasive assessment of function or pathology.
Magnetically shielded rooms have been created that made it possible for new devices called SQUIDS to actually measure and map the fields of the whole body and its organs.
Magnetic shielding requires the use of new artificial metals, called “mu” metals, combined with other metals, to get as close as possible to zero magnetic fields. SQUIDS are super-conducting Quantum Interference Devices. They are based on the discovery in physics of “Josephson Junctions” in super-conducting materials. The SQUIDS allow measurement of extremely tiny electrical and magnetic fields.
Magnetically shielded rooms
Laboratories are very magnetically and electrically “noisy” environments. Even, remote natural environments are still “noisy” relative to the body’s fields The sensitivity of the SQUID and the amount of shielding determine how small the fields are that can be measured.
The body’s natural MFs
The strength of the body’s fields in relation to the strength of the Earth’s magnetic field is shown in the table below.
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Strengths of endogenous magnetic fields versus Earth’s field |
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| Signal source | FemtoTesla | Gauss | Earth’s field stronger by |
| Skeletal Muscle | ~50,000 | 0.0000005 | 1 million times |
| Heart | ~500,000 | 0.000005 | 100,000 times |
| Physiologic “noise” | 50,000-5,000,000 | 0.0000005 0.00000005 | 1 – 10 million times |
| Earth’s field | 50,000,000,000 | 0.5 | |
As widely known elsewhere in science and engineering, externally applied electric and magnetic fields interact with and affect each other. The body’s own biomagnetic fields have both time-varied (frequency) and DC components. While externally applied DC fields need to be stronger than the surrounding geomagnetic field to exert additional impact on the body, time-varied magnetic fields (TMF) can be much weaker than the Earth’s background field. In fact, the lower limits of strength of weak TMFs to have biologic effects have not been defined. What is known is that TMFs much weaker than the Earth’s field have been shown to exert actions on the body, even probably to the picoTesla level, and maybe even to the femtoTesla level. Much instrumentation for treatment, including those used in the studies described in our book “Magnetic Therapy in Eastern Europe: a review of 30 years of research” uses fields that are in the mT range (10′s to 100′s of Gauss). These EMFs are 1000 to 10′s of thousands times stronger than the Earth’s magnetic field. That means, for TMFs, they are 10′s to 100′s of millions times stronger than the body’s own EMFs. The clinical use of EMFs will be dealt with in the Health Topics.
Diagnostic use of biomagnetic measurements
The finding through objective basic research of these endogenous fields not only allows us to know what their magnitudes are but also has allowed the development of new non-invasive means of measuring cellular function. The technical ability to obtain sensitive, natural biomagnetic measurements has already allowed use in medicine, especially magnetoencephalography (MEG). MEGs are used for helping neurosurgeons localize areas of the brain causing epileptic seizures. Studies are being done to evaluate cardiac function and pathology (magnetocardiography). Other applications are being considered, including measuring tissue iron loads in lung and liver. Muscle and other nerve function measurement systems are also possible in the future.
This is a website for cardiac imaging: www.lib.hut.fi
More information is available from the book “Advances in Biomagnetism” , edited by Williamson, SJ.
