Electroencephalography
is a method to record the macroscopic electrical activity by placing electrodes
on the scalp. These are called brain
waves and can be observed through the skull by using microelectrodes placed
at different regions of head.
The EEG can easily indicate 5 waves.
1. Alpha waves
2. Beta waves
3. Theta waves
4. Delta waves
5. Gamma waves
Alpha Waves
Alpha state is a small state
where our conscious mind almost becomes calm. These are visible in the EEG of a
normal awakened person and their frequency is 8-13cycles/second. These waves
disappear during sleep. It helps in increasing our memory power. Intact
thalamocortical connection required.
Beta waves
They appear during nervous
activities involving mental tasks.
That is the frequency of 13-32 Hz. This
waves seen in thinking and excitement. Their frequency is 14-30 cycles per
second.
Theta waves
A type of electrical
activity in the brain. Brain waves with a frequency of 4-8 Hz. They appear
during emotional stress like frustration, however they generally occur in children
in temporal and parietal regions. Their frequency is 4-7 cycles/second.
Delta waves
The lowest frequencies in
our brain are called as delta waves. They are frequency 0-3.5 Hz. They appear
during sleep, if produced in an awakened person it is indicative of brain
damage. Their frequency is 1-3 cycles/second.
Gamma waves
Gamma waves are fastest kind
of brain waves. This waves are particularly responsible or carrying out the
functions related to visual consciousness and the formation of coherent, unified
perception, also known as the problem of combination in the binding problem.
Also called as Gamma rhythm or Gamma state. Mindfulness is the key to improving
Gamma waves.
Why is an EEG test done?
EEG has been in use since 1929. It is used to detect disease
in the brain activity.
Such as : -
1. Brain
inflammation
2. Sleep
disorder
3. Epilepsy
4. Brain
tumor
5. Brain
stroke
6. Brain
dysfunction
7. EEG test
is also done on an unconscious person for information.
The correct way to do an EEG test ?
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EEG is a painless and risk-free test. In EEG we often find that people do it for 5 minutes, 10 minutes, at the most someone does it for 15 minutes and then leave it, this is a very wrong method. As per convention it is very important for the patient to sleep during EEG and both the states of going into sleep and coming out of sleep should be idle, at least otherwise we need sleep-awake recording.
Generally we
should get a minimum of 3 hours of EEG done in children. Usually the 10, 15
minutes of EEG that is done does not give us much benefit. Why is it not
useful? Suppose the shocks in the brain are coming after a long time, as we
say. Suppose they are coming at an interval of 45 minutes, then if you do a
15-minute EEG and leave it, then it is possible that it is a normal duration
EEG, your report will be normal, Still, it is possible that after seeing that
report, you may not be given any medicine, at the end of that report you may
have to undergo surgery, even if you get a major shock attack. Therefore,
whenever you get an EEG done, you should tell the technician to get it done
both while sleeping and awake and yes, keep it for at least 2-3 hours. Try to
get EEG done only when you get video EEG done. If we find something abnormal in
EEG, then by watching the video we can find out which part of our body is doing
abnormal activity at that time, so that the investigation can be done in the
best possible manner.
