What Defines Human Consciousness?

Don't like to read?


What defines human consciousness? The world recently learned that human consciousness can be switched off and on by scientists; but what constitutes being conscious? What does consciousness imply? Consciousness resides in that mysterious and marvelous organ – the brain. Consisting of three pounds of mostly fatty material and containing 100 billion neurons, the brain is the seat of human awareness and identity. The brain has 100,000 miles of blood vessels, generates enough electricity to power a light bulb, and uses 20 percent of the body’s oxygen. For each neuron there are 1,000 to 10,000 synapses: tiny spaces between neurons through which the neurotransmitters jump carrying all the messages of the human body. One of the best things about the brain is that it works like a muscle. Mental activity can create new neurons and recalling memories creates new connections. One of the most interesting things about the brain is that it generates more active brain waves while we are asleep.

This all leads back to the original question – what defines human consciousness? If the brain is more active while people sleep, or are unconscious, then is consciousness linked intrinsically to physical brain activity? What separates moments of consciousness and unconsciousness?

Generally defined as a state of awareness, people attribute their individuality and sense of self to being conscious of the world around them. People believe they have a unique experience of the world made up of both personal interactions and a singular brain configuration. What happens in the brain, in the thinking, feeling and reacting, is the essence of self. Being conscious implies that people are acknowledging our surroundings; that they are taking in new information, making new memories, learning new material and thinking new thoughts. Consciousness, as awareness of the world, produces an individual response to it. Consciousness is what defines people’s humanity, sets them apart from the world and one another, and draws them together again in a common human experience. What in the brain causes awareness to occur and what happens if it can be turned off?

Recently, a team of neurological researchers led by Mohamed Koubeissi of George Washington University was accidentally successful in inducing a state of unconsciousness in a female patient by stimulating her claustrum which lies deep in the brain. The woman suffers from severe epilepsy so the researchers had attached electrodes to various parts of her brain. By turning an electrical signal on and off the scientists hoped to pinpoint the location that triggered her seizures and provide targeted treatment. Surprisingly, they were able the turn the woman’s consciousness off when they activated the claustrum. The study, titled Electrical Stimulation of a Small Brain Area Reversibly Disrupts Consciouness, was published in the August volume of Epilepsy and Behavior. The paper describing the two days of experimentation and the remarkable discovery looks at the claustrum as a possible key to what defines human consciousness.

The claustrum is a very thin sheet of gray matter lodged vertically deep in the brain between several white matter tracts. Gray matter generally makes up the cerebral cortex which surrounds the brain and performs the actual processing of information. The amount of gray matter a person has relates to the amount of information that person can process. Being gray matter, the claustrum has also been thought to play a role in processing or coordinating information, but its location has inhibited study. The true function of the claustrum has remained as mysterious as consciousness itself.

Scientists have known that the claustrum helps link the two hemispheres of the brain together. It may cause the parts of the brain to pay attention to the same thing; to create unity. The claustrum is also unique because it is mostly made up of one type of cell. This singularity of form may aid it in synchronizing the different portions of the brain. For example, as the brain gathers information and attempts to make sense of it, it needs to know whether the information came from a single source; for example, hearing a bird and seeing a bird utilize two different parts of the brain. The claustrum may function to bring this information together to describe one event. However, too much synchronicity between the various aspects of the brain can have a negative impact. Overly synchronizing the brain can stop meaningful experiences of events. People’s brains need the jumble of sensory information and random thoughts to make us uniquely conscious of an experience. Stimulating the claustrum may increase synchronicity to the point where the brain is no longer aware of its surroundings – no longer conscious.

Francis Crick who won the Nobel Prize for his work on the structure of DNA, spent his later years obsessed with theoretical neurobiology and the study of what defines consciousness. He and his partner, Christof Koch of the Allen Institute of Brain Science in Seattle, were confident that the claustrum was integral to human consciousness. Crick and Koch theorized that the claustrum was comparable to a conductor in an orchestra. They believed it was responsible for organizing and coordinating the information collected and processed by all the various brain components. Koubeissi’s recent study supports their theory. Perhaps stimulating the claustrum is similar to an orchestra playing a single note. The stimulation of the claustrum may focus the brain so much that it stops taking in and processing new information.  Or, possibly it is like an orchestra going silent with the claustrum allowing or disallowing consciousness according to its activity. Either way, the music is no longer an organized blend of sounds.

What defines human consciousness? Maybe the claustrum is like a gate between consciousness and unconsciousness that divides one from the other. The human experience distinguishes between these states clearly. Either one is awake or one is asleep; but then there is hypnosis. There is some research to support the use of hypnosis, which is observed by outsiders as a trance-like or sleepy state, for some conditions. It is described by the medical field and trained hypnotists as a state of being hyper-aware, but also hyper-relaxed. It is most similar to being completely focused on one activity such as reading, painting, playing music, etc., to the point of losing awareness of the outside world. Research suggests that people under hypnosis may be so focused on relaxation that they may become highly amenable to suggestions and directions. A study published in the European Society of Anaesthesiology concluded that using hypnosis in combination with anesthetic medications may reduce pain, shorten surgery time, and speed recovery. It works best in tandem with known drugs and a trained anesthesiologist because people can take themselves out of hypnosis.

Many people find it fascinating to imagine the benefits of being able to completely switch the consciousness off. According to Koubeissi, his patient did not experience any side effects from her periods of unconsciousness. She was awake, but completely unaware of and unresponsive to her surroundings. This is a state of being unfamiliar to most people. When the stimulation of the claustrum was stopped, she became instantly conscious and felt fine. The study has ramifications not only for medical procedures, but the entire mental health industry. Could the claustrum be used as a reset button? If doctors can induce a coma, maybe they can also wake a patient. Approximately 50 million Americans suffer from neurological disorders. Could switching consciousness off treat diseases such as Parkinson’s, Turret’s syndrome, depression, schizophrenia or even Alzheimer’s? The possibilities are intriguing to scientists, but, they say, vast amounts of further research need to be completed. Questions remain about the effect of stimulating the claustrum on different people, and the long term effects of inducing unconsciousness this way. Finding volunteers for brain experimentation may be difficult.

What defines human consciousness? Koubiessi and Koch have made an important leap in knowledge about how the brain works and how consciousness is defined. If their research is repeatable in a larger population it may prove that consciousness is simply an amalgamation of the physical workings of the brain. Although each person has a unique compilation of brain functions, and although science, so far, shows that consciousness lies solely within the brain, some people claim that there may be something outside the physical aspect of the brain that establishes human identity. Psychologists disagree about the nature of consciousness. Outside of the world of studies and hard data, there are many ideas about human consciousness. Physicalism holds that consciousness is simply an arrangement of atoms and neurons. Functionalism posits that mental activity exists in causal relationships to other mental activity. Dualism insists there is something beyond a physical explanation for consciousness. In addition to solving the debate on human consciousness, looking at the claustrum can determine how consciousness is defined in other living beings. The claustrum in other species, even other primates, seems to have a different structure and function. Will the claustrum be a key to determining who, or what, has consciousness? Although a long way from settling the debate, finding that human consciousness can be switched off and on provides greater insight into the hidden workings of the human brain. Neuroscientists may be one step closer to unveiling the secret of what defines human consciousness.

By: Rebecca Savastio


Science Direct

Psychology Today


New Scientist

Oxford Journals




American Psychological Association