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Biology 202
1998 Second Web Reports
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Hallucinations and the Human Consciousness

HimaBindu Krishna

The idea of consciousness has been contemplated throughout the course of neurobiology and behavior. When does it begin or end? And what, precisely, is consciousness? Though researchers may only approximate the answers to these questions, a few things may be inferred. Since the subconscious mind is the sleeping mind, the conscious mind can be thought of as the awakened mind, the mind which shows itself to others most often. (1) This is not to say that the conscious mind is reality, because (as will later be explained) reality is quite subjective. (1) It is just that the conscious mind is the one most people associate with reality. For example, people who experience an event while dreaming will refer to it as a dream, because it occurred in their subconscious. Whereas, if the event had occurred while they were awake-in their conscious mind-frame, then it would be considered as an actual experience.

The designation between subconscious and conscious or reality and dreamlike states seem to be cut and dry. However altered mind-sets confuse the line and cause hallucinations. When we dream, our thinking is mostly pictorial and depends on memory. (1) We may hear words, but we understand most of the dream through pictures and people from the past or present. As we awaken, our mind switches from pictorial thinking to word-based thinking. (1) Hallucinations occur when the mind does not completely switch, or switches back, to the conscious state. (1,2)

The first thing to note about hallucinations is that they have long been associated with mental illness because many people become confused as to what they are seeing or experiencing. (2) Though hallucinations do occur in mentally ill people (most commonly in people with schizophrenia or bipolar disorder), they can occur in "normal" people as well. (1,2) Since there are many causes of hallucinations--lack of sleep, drugs, certain types of epilepsy, and prolonged meditation-not all causes are related to psychological disorders. (1) The second important issue concerning hallucinations is that people who experience hallucinations experience a lapse in perception. (1,2,3) People who hallucinate often know what they are experiencing is caused by external factors. Therefore their perception of events is being altered, but not to the extent where they believe in a different reality. (An alteration of reality is referred to as a delusion, which is more serious than a hallucination.) (2)

Our perception is not absolutely real. Our brain filters the environment through sensory areas. The brain's cognitive ability allows us to organize the stimulus from the external world and perceive it as the "real" world. Basically, our perception is only an approximation of reality. Since we are already constantly thinking through representations and symbols, it is not that difficult for our perception to be skewed into hallucinations. While hallucinating, the sensory regions of the brain are overridden by the memory areas of the brain. (1) The memory areas are now in charge and call upon the sensory areas to deliver a hallucination with feeling, smell, sight, etc. Since all the senses as well as familiar memories are involved in hallucinations (unlike dreams), perception is distorted for a short while. (1)

There are several suggestions as to how this confusion between the word-based consciousness and the pictorial subconscious occurs. Some neurochemists feel that there is a neural gate regulating the brain's arousal in certain areas. (1,3) The gate, the attenuator, opens during the night (or when it is time for sleep) and activates the visual area of the brain. (1,3) When the person wakes, the attenuator shuts on the visual area and opens the word-based area of the brain for conscious use. If, for example, people were fatigued, it would be simple for the brain to confuse the exhaustion with a nap and allow the attenuator to activate the visual area of the brain. Or, if someone is under the influence of a drug (i.e. peyote), the brain can react the same way. The cerebral cortex and the limbic system are the areas of the brain specifically involved because they are the centers for familiarity and meaningfulness of situations. (3) When the brain exhibits a hallucination, and triggers a memory of a past representation, the person becomes more confused because there is an added reality to the hallucination through past experience. (1)

Many people purposefully try to lapse into their subconscious or escape from reality into hallucinations. (3) Among these people are not only drug users, but also serious meditators. (3) The concept of nirvana, for example, in Buddhism revolves around a stage of enlightenment. (3) This enlightenment is only experienced through repetitive and concentrated meditation. People who reach nirvana realize that they have removed themselves from their normal perception of reality into a new state of mind.

Nirvana demonstrates how hallucinations are not necessarily negative events. Though the mind is being distorted to a certain degree, the cause of the hallucination is more important than the hallucination itself. If drug use or a mental illness brings about the hallucination, the causes themselves are problematic. However, if one chooses to hallucinate because of a culture or religion, as in the cases of meditation and peyote, their behavior is justified. There is still much to be researched in this area of neurobiology and behavior. Not only because little is known, but also because it is far more common than most people would like to think, since psychologically and biologically ill people as well as normal people may hallucinate from time to time.


1.Medscape -- (free) membership necessary to read article

2.Medscape -- (free) membership necessary to read article

3.The homepage of Chris Burdess

4.The Effects of Hallucinogenic Drugs on The Brain by Alicia Ebbitt

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