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Natasha Djordjevic

Student , Prirodno-matematicki fakultet

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How can we say for sure that these hallucinations aren't the product of our experiences or memories?

We do't know half the thing our brain does especially when it comes to how it stores memories. What evidence then do we have that any hallucination isn't the product of our own memories, except the explanation that the person doesn't remember any of the characters in the hallucination? And if they indeed aren't coming from memories, then where are they coming from?

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    Jun 9 2011: A hard question Natasha...

    I can't say I have a definite answer, but there are some hypotheses about it.

    A hallucination can happen in any form of senses (or combined), but let's take a visual as example.
    When you think of a person, a lot of neurons in your brain get activated. Some of them are the same as when you see that person... our brain uses the recognition neurons for evoking an image as well as perceiving the image.

    Other parts of our brain show indicate that what we see/imagine is real or not (this can be severely impaired or dysfunction during psychosis for example).

    So when we hallucinate, and see a person that is not there, but when the "this is real" brain-part is active, you do experience it as real.

    You can imagine unexciting persons (e.g. recombining features of different persons together), so during a hallucination, it is possible to see unknown people.

    Most probable, our (visual) memories are sets of neurons (or rather matrix patterns over a lattice of neurons) that activate all parts of the (visual) brain, needed to evoke the image.

    If you are hallucinating, you might find clues it is a hallucination even if experienced (in feeling) as real. For example you see things that are in conflict with laws of nature or other forms of in-congruence .
    In the film 'a beautiful mind' Nash realizes that some of the people he sees are illusions. While not being able to suppress them, he ignores them (he found out they did not age or could not eat real food). So he had very vivid hallucinations, bet did manage to distinguish them from reality (through reason).

    I hope this sounds plausible, but I assume there are more nuanced versions of this theory.
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      Jun 9 2011: Thanks so much for this incredible answer. It is a very interesting theory and I will look more into it. Maybe you can suggest some TED talks or websites or books that I can find on this subject... Thanks again for your answer.
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        Jun 9 2011: Natasha,
        The answer was derived from what I learned during college and what I read... Not just one book alas... And I don't know all the sources (nor can I provide a list of all the papers I read)

        but:
        Try Dennet, Damasio on TED

        http://cognet.mit.edu/library/books/topic?key=Neuroscience is a list (didn't read them myself, but I studied neurobehavioural sciences as a major).

        Shapiro and Luria are great authors in the field as well...
        And surely read some Sachs: he writes so good, and the cases he describes are amazingly fascinating!
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    Jun 11 2011: At some point would not all hallucinations have to be based on some reality. One hallucination may be a cut up collage consisting of many different memories, but I doubt if I could hallucinate something I had no prior experience of. If however through brain scans we wound no excess activity in parts of the brain associated with memory retrieval, it might imply that creativity is based on a mental glitch.
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    Jun 9 2011: That's difficult in real sense, if we could really be sure about those , we need redefine SANITY and INSANITY ..........

    What we call insane behavior due to some mental conditions (as those are considered unreal unusal response) are actually real experience to those conditions which includes delusions, hallucination ..... due to specific kind of neurotransmission of brain .