Bioelectromagnetics: Encyclopedia - Bioelectromagnetics

Bioelectromagnetics

Bioelectromagnetics is the study of how electromagnetic fields interact with and influence biological processes. Common areas of investigation include the mechanism of animal migration and navigation using the geomagnetic field, studying the potential effects of man-made sources of electromagnetic fields, such as those produced by the power distribution system and mobile phones, and developing novel therapies to treat various conditions.

While several treatments based on the use of magnetic fields have been reported in peer-reviewed journals, the only ones that have been approved by the FDA are the use of pulsed magnetic fields to aid non-union bone fractures. Transcranial magnetic stimulation is currently under active study in multiple research centres, and will likely become an approved therapy in the future.

Bioelectromagnetics - Introduction: general features of observed interactions

Bioelectromagnetics - Thermal vs nonthermal nature

Most of the molecules that make up the human body interact only weakly with electromagnetic fields (EMF) that are in the radiofrequency or extremely low frequency bands. One basic interactiion is the absorption of energy from the EMF, which can cause tissue to heat up; more intense field exposures will produce greater heating. This heat deposition can lead to biological effects ranging from discomfort to protein denaturation to burns. Many nations and regulatory bodies (for example, the International Commission on Non-Ionizing Radiation Protection) have established safety guidelines to limit the EMF exposure to a non-thermal level, which can either be defined as heating only to the point where the excess heat can be dissipated/radiated away, or as some small temperature increase that is not detectable with current instruments (such as a heating of less than 0.1°C).

However, some research has indicated that biological effects may be present for these non-thermal exposures. Various mechanisms have been proposed to explain non-thermal exposures, and there may be several mechanisms at work underlying the differing phenomena observed.

Bioelectromagnetics - Noise-masking time and space integration cooperativity

Bioelectromagnetics - Intrinsic fields

Bioelectromagnetics - Natural fields

Bioelectromagnetics - Primary interaction mechanisms

Bioelectromagnetics - Membrane polarization

Bioelectromagnetics - Electrorotation

Bioelectromagnetics - Ion cyclotron resonance and ion parametric resonance

Bioelectromagnetics - Nonlinear kinetics

Bioelectromagnetics - Frohlich-style macro dipole interactions

Bioelectromagnetics - DNA conduction

Bioelectromagnetics - Microtubule waveguides

Bioelectromagnetics - Ferromagnetic domains

Bioelectromagnetics - Frequency selectivity from spatial features

Bioelectromagnetics - Effects on the level of a cell or below

Bioelectromagnetics - Calcium efflux

Bioelectromagnetics - Neurotransmitter systems

Bioelectromagnetics - DNA strand breaks and genotoxicity

Bioelectromagnetics - Ornithine decarboxylase

Bioelectromagnetics - Melatonin

Bioelectromagnetics - Bacterial growth and metabolism

Bioelectromagnetics - Effects on the level of an organ or system

Bioelectromagnetics - Blood-brain barrier permittivity

Bioelectromagnetics - EEG changes

Bioelectromagnetics - Wound healing regeneration and bone growth

Bioelectromagnetics - Cancer promotion

Bioelectromagnetics - Whole-organism effects

Bioelectromagnetics - Electrical sensing organs fish etc

Bioelectromagnetics - Navigation bees pidgeons etc

Bioelectromagnetics - Effects on embryonic development

Bioelectromagnetics - Behavioral effects

Many subtle, and at times, not-so-subtle effects on behaviour have been reported from exposure to magnetic fields, with a particular focus in research on pulsed magnetic fields. The specific pulseform used appears to be an important factor for the behavioural effect seen. For instance, a pulsed magnetic field originally designed for magnetic resonance spectroscopic imaging was found to alleviate symptoms in bipolar patients (Rohan et al, 2004), while another MRI pulse had no effect. A whole-body exposure to a pulsed magnetic field was found to alter standing balance (Thomas et al, 2001) and pain perception (Shupak et al, 2004) in other studies.

Bioelectromagnetics - Effects of artificial fields

Bioelectromagnetics - Powerlines

Bioelectromagnetics - CRTs

Bioelectromagnetics - Cell phones

Bioelectromagnetics - Radar

Bioelectromagnetics - Other transmitters radio TV ...

Bioelectromagnetics - Medical applications

Bioelectromagnetics - Bone fracture healing

Bioelectromagnetics - TMS and related

A strong changing magnetic field can induce electrical currents in conductive tissue, such as the brain. Since the magnetic field will penetrate tissue, it can be generated outside of the head to induce currents within, hence Transcranial magnetic stimulation. These currents will depolarize parts of the brain, leading to changes in the patterns of neural activation. Essentially, it is a form of electroconvulsive therapy using induced currents from strongly changing magnetic fields rather than inserted electrodes. This type of controlled siezure can be useful in treating disorders such as severe depression, or as a tool for inducing localized brain activation in functional imaging studies.

Bioelectromagnetics - Low-level Laser Therapy LLLT

Bioelectromagnetics - Strong magnetic pulses for disinfection

Bioelectromagnetics - Other

See also

Bioelectromagnetism

Biophysics

Unsolved problems in biology

Specific absorption rate and Electromagnetic radiation hazard.

Mobile phone radiation and health

Adapted from the Wikipedia article "Bioelectromagnetics", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki