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Why do people hallucinate?

  1. Dec 16, 2004 #1
    why do people hallucinate?
    can we really answer that question. do we really know why someone hallucinates or if what they are seeing is a hallucination, just because you cant see it, doesnt make it not real, does it.
    this is sorta metaphysical, but could there be something deep down, not on a chemical level, that takes the mind and body into another visual realm, but still keeps you grounded somewhat in this world. maybe light encoded messages within the plants that we mentally and physically react too, and then produce what it produces. can we really say that what we saw was not real, even though we are seeing it right in front of us.
    plus if we say that its some type of chemical reaction that causes the hallucination, arent we making it seem that consciousness is produced by the brain, which as we all know is not yet proven to be fact, and by my humble opinion, will not be.
    so enlighten me
  2. jcsd
  3. Dec 20, 2004 #2


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    I think what it really boils down to is a matter of perception. The neurochemical modifications induced by hallucinogens such as LSD, ibogaine, peyote, etc are fairly well-defined. Alterations in central glutamatergic and serotonergic neurotransmission most likely lead to the behavioral effects of these agents.
    Having said that, these systems are widely distributed throughout the brain and are important in numerous functions, specifically regions high in a specific serotonin receptor, 5-HT2 type, such as the cerebral cortex and locus ceruleus are involved in mood, cognition, and sensory integration. From the role of these functions in behavior we can see that alterations in the neurochemical processes involved in these areas it appears that hallucinations are caused by the excitation/inhibition of specific neuronal circuitry involved in perception. If we take it down to root signals our perception of the world is based on our brain interpretation of signals coming in from numerous sensory organs. If we do something to disrupt that system, then our perception is altered an perhaps we see something that is not "there". If I knew the correct circuitry to stimulate I could probably lay open your visual nerves and make you perceive a chair that is not really there. It's all in how your brain integrates the signals and "tells" you that there is a chair in front of you.
    If you delve into the realm of brain-related disorders such as schizophrenia or other perception-altering syndromes you'll see a similar pattern of sensory-brain alterations leading to the disorder. Take a look at the books by Oliver Sacks, a brilliant neurologist who describes fascinating brain disorders in which certain brain lesions or other maladies result in the sufferers altered perception of the world (really a great read for anyone interested in the brain and people, not just for scientists). Also check out Cooper, Bloom and Roth's "The Biochemical Basis of Neuropharmacology" for a nice section on hallucinogen pharmacology.

    As far as alterations in human conscience, thats a much grayer area. My thoughts tend toward the myriad complex connections that exist within the brain and body that, as a sum, lead up to something greater than its parts. Whether such drugs affect this higher order processing, I don't know, but as far as hallucinations there may be a purely organic, brain-driven explanation.
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