One of the best known methods to record the electrical activity of human brain is the Electro Encephalogram (EEG). This method employs special sensors called electrodes which are attached to the head and hooked by wires to a computer. The latter records the brain’s electrical activity on the screen or on paper as ‘wavy’ lines, which show changes in their normal pattern in persons having an anomaly in brain functioning.
The neural activity produces tiny electrical signal called impulses. This electrical activity of the brain is seen as different types of waves: Beta waves have a frequency of 13 to 30 cycles per second, which normally occur in wakeful state. Alpha waves having a frequency of 8 to 12 cycles per second occur when the body is more relaxed, with eyes closed, but one is mentally alert. Theta waves have a frequency of 4 to 7 cycles per second, which are normally found when one is asleep. Similarly, Delta waves that have a frequency of less than 3 cycles per second are found when one is in deep sleep.
EEG is usually done to diagnose epilepsy and the type of seizures that occur in a patient. It is also used to find the underlying cause for the loss of consciousness and studying the abnormal brain activity in sleep disorders, diseases like Alzheimer’s and head injuries, while monitoring the brain activity during brain surgery. EEG would reveal no brain activity when the brain function stops, as in coma, due to lack of oxygen or blood flow inside the brain.
Computerized Axial Tomography (CT Scan)
Computed Tomography makes pictures by sending many x-rays through the body and taking views from many different angles. Thus cross-sectional images of the bones and soft tissues of the body can be generated, which help in viewing all parts of the body from different angles. This technique is commonly used to examine patients who have had internal injuries like victims of car accidents etc. this non-invasive technique helps to diagnose several medical conditions like bleeding in the brain or haemorrhage, brain tumour sinusitis, stroke etc.
Magnetic Resonance Imaging (MRI)
Magnetic Resonance Imaging uses powerful magnets and pulses of radio wave energy to take pictures of the body. It can reveal tissue damage or disease, such as infection, inflammation or a tumor in the body. MRI of the head is done, in many cases, to look for the cause of headaches. It can help to diagnose brain stroke and other conditions related to improper blood flow in the brain.
MRI is also done to ascertain changes in the brain in diseases like Huntington’s disease, Multiple Sclerosis (MS), Parkinson’s disease and Alzheimer’s disease. Besides, this technique is highly useful in diagnosing birth defects of the brain, infection and tumours, in addition to understanding the cause of muscle weakness or numbness/tingling vision, speaking and hearing difficulties. As MRI does not use any radiation, it does not pose any risk as there are no side effects from magnetic fields and radio waves. However, strong magnetic fields can affect the working of heart pacemakers and other implants.