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Medical Science Of Hallucinating

  1. Dec 22, 2006 #1
    When we're hallucinating is it the same part of our brain we use normally that hallucinating or another? Is our subconscious mind seeing things also?
     
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  3. Dec 24, 2006 #2
    Guess no one does psychedellics.
     
  4. Dec 24, 2006 #3

    sog

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    You don't have to be on psychedellics.

    I seen a mirage in the desert. I think a mirage is a hallucination. I don't take psychedellics.
     
  5. Dec 27, 2006 #4

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    I think the answer is yes, the same areas of the brain we normally use are active – at least some of them. There are many types of hallucinations and I am not sure the brain mechanisms behind the different kinds are well understood yet. In 2005, there was a study done with people who suffered from musical hallucinations. When the hallucinations were occurring, PET scans of subjects showed a pattern of brain activity that was similar to normal subjects who were listening to music, but with an important difference:

    http://www.nytimes.com/2005/07/12/h...en=6ad31758c7334d06&ex=1278820800&partner=rss
    I'm not sure what you mean by that.

    A mirage is an optical phenomenon, not a hallucination.
     
    Last edited: Dec 27, 2006
  6. Dec 28, 2006 #5
    SO if a person is have a total hallucination, one where there's no input from their eyes or ears just out of their mind..............are they using the normally active parts of the visual cortex?
     
  7. Dec 28, 2006 #6

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    I'm not clear on what you mean by a "total" hallucination, but if a person is having a visual hallucination, yes, most likely some part of the visual cortex is active during the experience. Parkinson's Disease patients who sometimes suffer from visual hallucinations are thought to have these occurrences due to visual cortex malfunctions. There are "normal" parts of the brain's vision system working, but in an abnormal way - some portions are overworking, others are underworking.

    If you've ever hit the back of your head and seen "stars", that's an example of your visual cortex activating independently of the normal sensory input from your eyes. The jolt of mechanical energy to the back of your skull is enough to cause some neurons to begin firing in the brain's vision processing areas and you see "lights" which obviously aren't really there.
     
  8. Dec 29, 2006 #7
    Is it your perception of reality that is distorted or are your sensations of reality actually distorted as well, while tripping on psychedelics?
     
  9. Dec 30, 2006 #8

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    Both are possibilities. LSD, for example, is known to produce both delusions (false beliefs or incorrect inferences about external reality) and (typically visual) hallucinations.
     
  10. Dec 30, 2006 #9
    When I say total hallucination I mean in a totally different world. Some people have hallucinations where the normals world get's distorted, odd colored, or see objects and people that aren't there.

    I'm talking about an entiley mental genreated hallucination. No input from your eyes ears, etc. I mean you're in another reality, dimension, the way dreams are.
     
  11. Dec 31, 2006 #10

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    Even if we're talking about visual and auditory hallucinations in a person who is shut off from all light and sound stimulation, say in a sensory deprivation tank, I'm still certain the experience is a result of the normal visual and auditory neural systems functioning abnormally for whatever reason. There is not some "not normally used" separate brain area dedicated to hallucinations. But if you find any research that makes a different claim, and it's from a credible source, please do share.:smile:
     
  12. Dec 31, 2006 #11
    Why would Parkinson's Disease cause hallucination?

    It is caused by a lack of dopamine in the brain to the striatum...

    Whereas I thought hallucinations are thought to occur due to a release of glutamate or an effect on serotonin (5-HT)
     
  13. Dec 31, 2006 #12
    Nuklear,

    The following links are to some research on auditory verbal hallucinations in schitzophrenic subjects that I came across looking into another thread in this forum. What I do know is that our neurons have a base rate of firing and information is coded and transmitted by the rate of fire, the number of neurons firing, and which particular neurons are firing. So psychedellics could cause the brain to misinterperate this internally-produced information, much like a schitzophrenic subject.

    http://www.julianjaynes.org/pdf/bentaleb-beauregard-liddle-stip_hallucinations.pdf

    http://www.julianjaynes.org/pdf/lennox-bert-park-jones_spatialtemporalmapping.pdf

    http://www.julianjaynes.org/pdf/shergill-bullmore-simmons-murray-mcguire.pdf

     
  14. Dec 31, 2006 #13
    I've had hallucinations. A couple of times I've seen these little lifgts going at diagnal angles on and off a few seconds in my eyes, swarms of the them baracading me at a time.
     
  15. Dec 31, 2006 #14

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    It's an interesting question – not an association I would have immediately made either. Unfortunately, 20-40% of Parkinson's patients develop cognitive disturbances, sometimes including hallucinations. Visual hallucinations apparently occur in about 25% of individuals with Parkinson's (Aarsland et al., 1999, Fénelon et al., 2000). Source of citations: http://brain.oxfordjournals.org/cgi/content/full/125/2/391

    As you mentioned there is a degeneration in the dopamine production regions, and patients are treated with drugs like Levodopa to boost dopamine levels and compensate for the loss. Visual and auditory hallucinations occur sometimes as a side effect of this treatment, although I do not know the specific mechanisms behind it.

    Other than that, the pathology of the disease itself may be to blame. One of the nasty things that can happen in the course of Parkinson's is a build-up of Lewy bodies in the neurons. http://en.wikipedia.org/wiki/Lewy_body I was just reading a study published in 2002 examining the brains of deceased individuals who had suffered from Parkinsons (no dementia), Dementia with Lewy Bodies (DLB), or Parkinson's Disease with Dementia (PDD). Of particular interest was the concentration and distribution of Lewy bodies (LB) in the brain and the relationship to (reported) hallucinations that the patient had suffered from while alive.
    http://brain.oxfordjournals.org/cgi/content/full/125/2/391
    So, I read that and said, "fair enough, but what's the specific relationship to the vision system?" And I thought this would be of interest to you because you had asked about specific neurotransmitters.
    However, I was thinking of a more recent fMRI study when I originally posted the comment about Parkinson's and visual hallucinations:
    http://neuro.psychiatryonline.org/cgi/content/abstract/18/3/402
    Anyway, I don't know very much about the role of specific neurotransmitters during hallucinations so maybe I can pick your brain on this - pun intended. :biggrin: I would like to learn more if you have any studies/links you could direct me to.
     
  16. Dec 31, 2006 #15

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    Were you looking at the daytime sky when this happened? Or some kind of blue background? When I am outdoors on a sunny day and look at the sky, I see something similar. Tiny bright squiggles jiggling and flying around in random directions. This is not a hallucination, but an entoptic (generated by the eye) phenomenon called Scheerer's Phenomenon:
    http://en.wikipedia.org/wiki/Blue_field_entoptic_phenomenon
    I've seen it when I've been indoors, as well, often when I am looking at a sunbeam coming through a window.
     
  17. Jan 1, 2007 #16
    lol... no problem...

    You reminded me about levodopa - and it explains fairly simply why giving it to people with Parkinson's causes schizophrenia symptoms (like halluccinations)

    Parkinson's => Too low levels of dopamine

    Therefore to treat Parkinson's you want to increase the levels of dopamine in the body... The reason you don't give dopamine is that it cannot pass through the blood brain barrier (so can't pass into the central nervous system)... and this is why you give the lipid soluble precursor of dopamine, levodopa... and so it can pass through the blood brain barrier into the CNS where it is then metabolised to dopamine... so levodopa is a prodrug...

    Schizophrenia => Too high levels of dopamine

    And so if you give too much levodopa, you naturally will cause too much dopamine and therefore would cause the symptoms of schizophrenia...

    Incidentally, the treatment of schizophrenia is simply to block dopamine receptors in the central nervous system - e.g. chlorpromazine blocks D2 receptors...

    I can do a bit more detail about receptors... I've just had a quick glance at lecture notes...

    There are basically two theories as to the mechanism behind halluccination causes...

    1) Activation of the serotonin 2A receptor (5-HT2A)... LSD causes hallucinations by activation of this receptor...

    2) Activation of the dopamine 2 (D2) receptor... This is the cause of schizophrenia...

    I do warn that this is a complicated area of pharmacology... There are about 10 different types of dopamine and 10 different types of serotonin receptor... and that drugs such as chlorprozamine seem are very unspecific and block loads of receptors having multiple actions and multiple side effects...
     
    Last edited: Jan 1, 2007
  18. Jan 1, 2007 #17

    Yes I was looking at the sky and I was triped out cause I thought they were realy. I was 20 and that kind of thing had never happened to me.
     
  19. Jan 1, 2007 #18

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    But doesn't chlorpromazine also block serotonin 5-HT2 receptors?
     
  20. Jan 1, 2007 #19
    Well what are Serotonin and DOpamine's roles?
     
  21. Jan 1, 2007 #20
    Yes, you are correct... This is another way it will prevent hallucinations and it is another way anti-psychotics drugs work...
     
    Last edited: Jan 1, 2007
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