6 Applications and Methods in Biosignal Processing

In this chapter practical examples for the application of the methods of biosignal pro-

cessing are presented. In principle, the methods are also applicable to other biosig-

nals, which is why some electrical biosignals and their meaning are listed again here.

Commonly used procedures are:

–

Electrocardiogram (ECG): measurement of muscle excitation in the heart;

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Electroencephalogram (EEG): measurement of nerve activity in the brain;

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Electromyogram (EMG): measurement of muscle excitation in general;

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Electroretinogram (ERG): measurement of light stimulation of the eye. The essen-

tial information is in amplitudes and latencies of the detected waves;

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Electrooculogram (EOG): measurement of motor influences on the eye position.

Less frequently used methods are:

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Electroolfactogram: recording of the stimulation of the sense of smell;

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Electrogastrogram: recording of the activity of the stomach muscles;

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Elektrohysterogram: recording of the activity of the uterine musculature;

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Electrodermatogram: recording of electrical potential distribution on the skin;

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Electroneurogram: recording of intracellular electrical potentials.

6.1 Signals of the Brain

The brain is part of the central nervous system. In humans, it consists of about 10 bil-

lion individual brain cells (nervous tissue). The nervous tissue is in turn composed of

neurons (nerve cells) and glial cells. Important functions of neurons of the brain are

reception, processing and transmission of stimuli. Glial cells act, among other things,

as supporting cells of neurons. Functionally, a brain neuron is divided into a multitude

of tentacle-like dendrites for the reception of stimuli, the nucleus and the elongated

axon for the transmission of stimuli. The axon branches in the terminal region to sev-

eral synapses, which transmit a stimulus to another cell. The enormous performance

of the brain is based on the strong interconnection of the individual neurons. In the

area of the cerebral cortex (cortex), each neuron is connected with 1000 to 100,000

synapses. The transmission of stimuli from one cell to the next takes place chemically

by the release of neurotransmitters from the synapse, which are taken up by dendrites

of the next cell via receptors. As in all cells, the activity of neurons is accompanied

by a change in transmembrane voltage, which is summarized under the term action

potential. In the area of the dendrites, the neurotransmitters control the protein chan-

nels in the cell membrane and thus the action potential. There are both activating and

inhibitory neurotransmitters. Since there are several synapses at the dendrites that

simultaneously release neurotransmitters, it is the sum of all incoming stimuli that

https://doi.org/10.1515/9783110736298-006