EEG Recording Unit
EEG is an instrument used for recording the electrical activity of the brain by suitably placing surface electrodes on the scalp.
The biological name of brain is “ Encephalon”
By means of electrodes to the skull of the patient, the brain waves can be picked up and recorded.
On the surface of the brain, the voltage is about 10 mV.
Due to the propagation through skull bone, they are attenuated from 1 to 100 μV which are picked by EEG electrodes.
The frequency range from 0.5 to 3000Hz and the resistance range from few 1000 ohms to nearly 100 ohms depending on the electrode used.
The brain waves are the summation of neural depolarization in the brain due to stimuli from five senses.
They are Frontal, parietal, temporal, Frontal pole and occipital lobes of the brain.
When the potential vary with respect to position of the electrode on the surface of the skull, the electrodes are placed.
Several types of electrodes can be used to record EEG.
These include peel and stick electrodes, silver plated electrodes and needle electrodes.
EEG electrodes are smaller in size than EEG electrodes.
It placed separately to the scalp (or) mounted in special bands, patient can wear that.
In either cases, electrode jelly or paste is used to improve the electrical contact.