It begins with an historical account of the many innovations and innovators on whose work the field rests. This is accompanied by a discussion of both the theories and experiments which were contributed to the development of the field. The physiological origin of bioelectric and biomagnetic signal is discussed in detail. The sensitivity in a given measurement situation, the energy distribution in stimulation with the same electrodes, and the measurement of impedance are related and described by the electrode lead field. It is shown that, based on the reciprocity theorem, these are identical and further, that these procedures apply equally well for biomagnetic considerations. The difference between corresponding bioelectric and biomagnetic methods is discussed.
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Biological phenomena[ edit ] Short-lived electrical events called action potentials occur in several types of animal cells which are called excitable cells, a category of cell include neurons, muscle cells, and endocrine cells, as well as in some plant cells. These action potentials are used to facilitate inter-cellular communication and activate intracellular processes. The physiological phenomena of action potentials are possible because voltage-gated ion channels allow the resting potential caused by electrochemical gradient on either side of a cell membrane to resolve.
In the late eighteenth century, the Italian physician and physicist Luigi Galvani first recorded the phenomenon while dissecting a frog at a table where he had been conducting experiments with static electricity. Galvani coined the term animal electricity to describe the phenomenon, while contemporaries labeled it galvanism.
Galvani and contemporaries regarded muscle activation as resulting from an electrical fluid or substance in the nerves. In an extreme application of electromagnetism, the electric eel is able to generate a large electric field outside its body used for hunting and self-defense through a dedicated electric organ. This can lead to biological effects ranging from muscle relaxation as produced by a diathermy device to burns.
This can be defined as either heating only to the point where the excess heat can be dissipated, or as a fixed increase in temperature not detectable with current instruments like 0. Biological effects of weak electromagnetic fields are the subject of study in magnetobiology.
The specific pulseform used appears to be an important factor for the behavioural effect seen; for example, a pulsed magnetic field originally designed for spectroscopic MRI , referred to as Low Field Magnetic Stimulation , was found to temporarily improve patient-reported mood in bipolar patients,  while another MRI pulse had no effect. A whole-body exposure to a pulsed magnetic field was found to alter standing balance and pain perception in other studies. Since the magnetic field penetrates tissue, it can be generated outside of the head to induce currents within, causing transcranial magnetic stimulation TMS.
These currents depolarize neurons in a selected part of the brain, leading to changes in the patterns of neural activity. Instead of one strong electric shock through the head as in ECT, a large number of relatively weak pulses are delivered in TMS therapy, typically at the rate of about 10 pulses per second.
If very strong pulses at a rapid rate are delivered to the brain, the induced currents can cause convulsions much like in the original electroconvulsive therapy.
Bioelectromagnetism: Principles and Applications of Bioelectric and Biomagnetic Fields
Vobar Mathematically Modelling the Electrical Activity of the Heart: The difference between corresponding bioelectric and biomagnetic methods is discussed. For the scientific journal, see Bioelectromagnetics journal. Subthreshold Membrane Phenomena 4. This is accompanied by a discussion of both the theories and experiments which were contributed The book includes about carefully bioellectromagnetism illustrations and references. The physiological origin of bioelectric and biomagnetic signal is discussed in detail.
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