Electroencephalography

Electroencephalography is the study in which it records all the electrical activity of the scalp. Electroencephalography which is shortened as EEG would be used to measure voltage fluctuations from ionic current flows. These ionic current are from the neurons of the brain. In clinics, Electroencephalography records the brain's sudden electrical activity within short period of time 20–40 minutes. These are recorded from multiple electrodes fixed on the scalp. In neurology, the most important application of Electroencephalography is in the epilepsy. Electroencephalography can also be used to diagnose brain death, coma and encephalopathies. When temporal resolution with millisecond range is required, Electroencephalography is commonly used.

Electroencephalography was first tested on dogs in 1912 to capture and record the brain waves. But it came into use widely from the year 1950.  Electroencephalography is the test which is powerful in finding how the brain functions over time. Thus Electroencephalography plays a vital and important role in evaluating the various disorders of brain. Electroencephalography is generally used to display the type and location of the various activity performed in the brain during a seizure. The people who might have brain functioning problems like the tumors, confusion, long-term difficulties with thinking or memory, coma or strokes get more advantage of the Electroencephalography.

Source of EEG activity

Now let us discuss on how the Electroencephalography activities came into being. To know about this we need to understand what neurons are. As you all know the electrical charge of the brain is maintained by various numbers of neurons. These neurons are electrically charged by membrane transport proteins. These in fact pump ions across their membranes. When these neurons exchange ions, ions with like charge repel each other to push the neighbors leading to the process known as volume conduction. Metal on the electrodes conducts the push or pull of electrons when the wave of ions reaches the electrodes on the scalp. A voltmeter is used to measure the voltage difference in the push.  Thus Electroencephalography was introduced to record these voltages.
Electroencephalography activity always produces the summation of the synchronous activity of all the neurons.  Ions do not line up, if the cell does not have same spatial orientation. Due to this waves that are to be detected are also created. Pyramidal neurons of the cortex produce the most Electroencephalography signal. This is due to the fact that they are well-aligned and fire together. Scalp Electroencephalography activity gives various frequency oscillations. These oscillations would be having various frequency ranges and spatial distributions.  They represent synchronized activity in a network of neurons with different states of brain functioning. Power of surface Electroencephalography is in two bands such as gamma and delta.
Uses of Electroencephalography
There are various uses related to Electroencephalography. Here we discuss some of the common uses of Electroencephalography. They are as follows:

1.     Electroencephalography is used to monitor certain procedures which include:

·      The depth of anesthesia

·      Indirect indicator of cerebral perfusion in carotid endarterectomy

·      Amobarbital effect during the Wada test

2.     Electroencephalography could also be used for brain function monitoring in the intensive care units:

·      Non-convulsive seizures/non-convulsive status epilepticus

·      Sedative/anesthesia patients in medically induced coma

·      Secondary brain damage in subarachnoid hemorrhage

3.     Electroencephalography is also used in:

·      clinical diagnosis and conventional cognitive neuroscience

·      Long-term EEG recordings in epilepsy for seizure prediction

·      Neurofeedback and in brain computer interfaces

·      In the field of neuromarketing

During the Electroencephalography preparation, certain precautions need to be taken. They include stop taking seizure medications 1-2 days before the test, stop consuming caffeine before the test and avoid hair styling products.