8

Bioelectromagnetism

transmission of these potential changes helps the body to coordinate the activity of all of the systems in

our body. Te body can feed the information impinging on it from both the external and internal envi­

ronments to the central nervous system, where it is processed, enabling the body to adapt in a suitable

manner to both of its environments (Kato, 2006). From the study of bioelectricity, many medical and

clinical applications such as electroencephalography (EEG), electrocardiography (ECG), electromyog­

raphy and others have been developed. Moreover, electrobiology involves the study of how various elec­

trical phenomena such as electric feld, voltages and currents afect biological systems (Popp et al., 1989).

In nature, it is known that some fsh can detect the weak electrical changes generated by bait. Tese

fsh are known to have sensory organs that detect these weak electrical changes, and this characteristic

is referred to as electroreception. It is now understood that this behavior is controlled by the response

of mechanosensory organs to electric stimuli, based on electroreception experiments with insects and

terrestrial animals.

Biomagnetism is the study of magnetic felds originating from biological systems. It also deals with

magnetic phenomena of biological systems, which can be observed at diferent intensities and frequen­

cies. For example, the so-called magnetophosphene is a visual sensation caused by exposing the head to

a low-frequency (around 10–70 Hz) magnetic feld of around 10–20 mT. Tis sensation is generated in the

retina. Te earliest magnetic stimulation was reported by Jacques-Arsene d’Arsonval. Magnetic stimu­

lation is based on Faraday’s law of induction. Tis law states how the change of an applied magnetic

feld induces an electric feld with accompanying current in the tissue. Te frst magnetic stimulation

of nerve was described by Alexander Kolin in 1959. Magnetic stimulation of the human brain and heart

has been used for the purpose of both research and clinical treatment. Te biological magnetic felds are

extremely weak compared to the geomagnetic felds. Te biological magnetic feld of the human heart,

called magnetocardiogram (MCG), was frst detected by Gerhard Baule and Richard McFee in 1963.

Te biological magnetic feld of the human brain called magnetoencephalogram (MEG) was detected

by David Cohen in 1968. Afer these pioneering studies, using superconductive quantum interference

devices techniques, the weak biological magnetic felds from the brain, heart and lung were easily mea­

sured from outside the body. Biomedical stimulation with ELF electric or magnetic felds was used

frst for clinical applications such as the healing of bone fracture. Fundamental research activities have

been carried out for the healing promotion of various tissues. However, there is still no widely accepted

mechanism by which ELF electric or magnetic felds can afect biological tissues. Te well-known inter­

action between ELF electric or magnetic felds and biological tissues is the eddy currents induced in the

tissues, which is a possible candidate mechanism. Te other candidate is the interaction of the applied

magnetic felds with an endogenous magnet such as magnetite. Because the brain is so important for

human behavior, and because the functions of the brain inherently involve a great amount of electrical

activity, since the beginning of bioelectromagnetism, it has been essential to examine the efects of mag­

netic felds, electric felds and currents, since they can induce electric felds and currents on the brain.

Magnetobiology involves the study of interaction between magnetic feld and biological systems

(Popp et al., 1989). Magnetobiology also studies the identifcation and sensitivities of biological organ­

isms to weak magnetic felds. Magnetoreception, a category of magnetobiology, is known as the sensing

of magnetic felds by biological organisms. It includes the magnetic navigation of migrating birds and

other organisms, the magnetotactic behavior of some bacteria and the magnetoreception in humans.

Te study of magnetobiology and magnetoreception has made great advances in the last 10–20 years. In

magnetobiology, the ability of birds, bees, turtles, reptiles, amphibians, plants and others to detect the

geomagnetic feld has been reported (Mafei, 2014, 2019; Wiltschko and Wiltschko, 1995). Certain crus­

taceans, lobsters and bony fsh have also been found to use magnetism-related navigations (magnetic

compass). In this sense, magnetic sensibility is common in the animal kingdom. Tus, there is no longer

any doubt that animals can sense the geomagnetic feld; however, how they sense it is still unknown.

Te geomagnetic feld is weak and is unlikely to have a direct efect on the chemical reactions in the

body. Currently, the main theory of the mechanism of action of the geomagnetic feld is that magnetite

and chemical compasses based on quantum biology are responsible for the magnetoreception. For this