Foundations of Medical Imaging and Signal Recording - Biomedical Signal Analysis: Contemporary Methods and Applications - page 5

Figure 1.1
EEG signal processing. The EEG signal is displayed in the upper right corner, and
the filtered signals averaged is shown below [243].
Magnetoencephalogram (MEG)
The magnetoencephalogram is a technique that records based on ul-
trasensitive superconducting sensors (SQUIDS), which are placed on a
helmet-shaped device. The magnetic fields generated by the neural ac-
tivity thus allow clinicians to monitor brain activity at different locations
and represent different brain functions. As with EEG, the magnetic fields
result from coherent activity of dendrites of pyramidal cells. The pro-
cessing methods are the same as in EEG in regard to both spontaneous
and averaged activity. Both EEG and MEG have their own advantages.
In MEG, the measured magnetic fields are not affected by the conduc-
tivity boundaries, as is the case with EEG. On the other hand, EEG,
compared to MEG, enables the localization of all possible orientations
of neural sources.
Electrocardiogram (ECG)
The electrocardiogram (ECG) is the recording of the heart's electric ac-
tivity of repolarization and depolarization of the atrial and ventricular
chambers of the heart. Depolarization is the sudden influx of cations