Human brain is the most complicated organ in human body. Despite centuries of advancements in medical sciences, the complete activity of the brain remains a riddle for medical experts. Like for example the level of consciousness of the human being is unanswerable to a large extent.

There has been a case study. After extreme cerebrum harm, patients remain in oblivious state but recently neuroscientists have found that in some of those cases patients might be conscious. Figure below shows a new way of analyzing EEG recordings depicts a striking difference between the brain activity of two injured brains (left & middle one). Despite unresponsive, the middle patient had brain activity similar to that of a healthy individual (right most brain activity). The height of the arcing lines indicates the strength of the connection between the brain regions at either ends. (Figure Reference: www.wired.com)

So if there is a device that could give information about the conscious state of the patients, doctors will find such device extremely handy and useful.

Basic Structure of the Brain

Brain has three vital structures. The largest among them is cerebrum and is the centre for cognitive functioning. The second structure is the cerebellum and is at the back of the skull. It helps to maintain the balance of the body and because of it we humans stand and not fall down. The third structure is the medulla, a stem driving into the spinal segment, which helps to manage automatic functioning like respiration.

What is EEG?

EEG stands for Electroencephalography. It is a non-invasive method to detect the electrical activity of the brain using small metal electrodes that are attached to the scalp. The principle is that brain communicates using electrical pulse and is active all the time. The EEG records these electrical pulses. It is a very well know and widely used technique.

EEG for Conscious Level Detection

A technique showing the consciousness level of human brain is developed by neuroscientist Dr. Srivas Chennu, University of Cambridge and has claimed to measure exactly how aware you are of your own existence. He combines conventional EEG with graph theory (“pair wise relation between objects”) and developed a software. When somebody is conscious, there are arrangements of synchronised neural actions racing across the brain that can be identified using EEG and evaluated or computed using the software. According to him, “Doctors can use it to measure the consciousness level of their patients. This can then be used to make the best possible choices for the patient and their family”.

A healthy, conscious brain has a signature which looks like a periodically raging ocean of waves, stemming from the neutron activity of understanding, integrating and storing. During sleep the waves become a calm sea with the occasional dream bump.

Following are the four states of the brain as concluded in the study.

In a Vegetative State the person is still unconscious. He has no awareness of himself or his environment. Locked-in syndrome (LIS) is a state in which a person is aware but cannot move or speak because of complete paralysis of muscles in the body except for vertical eye movements and blinking. Minimally conscious state (MCS) is defined as a state of extremely modified awareness in which insignificant however definite behavioural proof of self or natural mindfulness.

By:- Ms. Monika Parmar – Asst. Prof. Department of ECE, Chitkara University H.P.

References:-

• https://en.wikipedia.org/wiki/Locked-in_syndrome
• https://en.wikipedia.org/wiki/Minimally_conscious_state
• https://www.cs.kent.ac.uk/people/staff/sc785/selpub.html