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Monday, April 5, 2010

Neurophysiological Explanations of Visions--Part Two

Continuing the discussion of Phillip Wiebe's Visions of Jesus: Direct Encounters from the NT to Today, I want to again examine neurophysiological explanations for the visions.

Another theory produced by neruophysiology is the perceptual release theory. This theory states that information obtained through sensory perception is stored, altered, and then "released into consciousness" at a later time and experienced as a hallucination. This mechanism has been thought to be the basis for both dreams and hallucinations (Wiebe, p. 201).

According to Ernest Hartmann (Dreams and Other Hallucinations: An Approach to the Underlying Mechanism in R.K Siegel and L. J. West, eds. Hallucinations: Behavior, Experience, and Theory), The neurophysiological activities thought to be involved are those in the brain stem, including some originating in the pontine brain stem that bombard the cerebral cortex, possibly the visual area.... defects in the norepinephrine systems involved in neurotransmission could account for some forms of hallucination, and the chemical substructure of such functions as reality testing might be found in the ascending norepinephrine systems that extend to the cerebral cortex (Wiebe, p. 202).

Another theory propounded by some neurologists is the information processing theory. Mardi Horowitz (Hallucinations: An Information Processing Approach in Siegel and West) argues that hallucinations are a form of image representation. An image is information that remains after a perceptual event has taken place, capable of being combined with other information derived from memory, thinking, and fantasy (Wiebe, pp. 202-03).

An important factor according to Horowitz is the capacity of the image forming systems to obtain information from both internal and external origins. . . . Experimental evidence shows that normal subjects can confuse internal and external signals when the latter are vague or dim (Wiebe, p. 203). According to Horowitz, hallucinations are caused by an intensification or "release" of images of internal origin when external image formation decreases but the representational system is still "on" (cited in Wiebe, p. 203). When external stimulation falls below a certain threshold, but cortical arousal remains constant, previously recorded perceptions are released into awareness and are experienced there as hallucinations (Wiebe, p. 204). This phenomena is more likely in cases where the information processing system has become impaired either through damage, intoxication, sleep deprivation, high anxiety, stress, deep depression, grief, and so on.

Another neurophysiological explanation for visions is the overactive reticular system theory advocated by Frank Fish (A Neurophysiological Theory of Schizophrenia, Journal of Mental Science). The reticular system is a tight, complex network of fibers at a point where the spinal cord ends and the brain begins. A site of vital brain activity, it is causally related to sleep and arousal, reflexes and muscle tone, and with the organization of the brain as a whole (Wiebe, p. 206).

Fish says that the hallucinations of schizophrenics occur as a result of overactivity of the reticular system, resulting in certain cell assemblies being closer than usual to their firing threshold. When a sensory event occurs, the cell assemblies that are activated acquire greater significance than they normally would, and produce a new set of cell assemblies capable of later becoming active independently of the sensory input that led to their development in the first place. Because the new set of cell assemblies is not well-integrated into the central processes that are part of normal experience, it is not associated with the sense of self that is part of the central processes. So when the new set of cell assemblies is later triggered, producing a hallucination, it is experienced as foreign (Wiebe, p. 206).

This theory may explain the out of the body sensation that some experience when having a vision. Note Paul in 2 Corinthians 12:2: I know a man in Christ who fourteen years ago was caught up to the third heaven. Whether it was in the body or out of the body I do not know-God knows. Mystics typically report out of the body sensations when they experience a vision. This experience can be seen clinically according to Fish, in both schizophrenics and amphetamines drug users. In both cases the reticular system is overactive.

Neurophysiology is still in its infancy. Much more about how the brain functions is being learned literally every day. While ancient peoples and even some people today attribute whatever they don't understand to the supernatural, it is no longer necessary. Superstition is being gradually eroded by the advances of modern science.

4 comments:

  1. The science underlying hallucinations is intriguing,i.e., the physical/chemical "how." But more intriguing, at least for me, is the "why." Why did Mother Nature, so to speak, in the form of Saint Paul's 3-pound human brain, and all it was connected to internally and externally (the universe) create an halluciantion of Jesus alive again? Was it an act of random nonsense or was there thought behind it? What was Mother Nature thinking? so to speak, if she was. Does Wiebe get into that, into equating Mother Nature, the universe, with God or a part of God and a form of consciousness, perhaps an evolving consciousness, possessing intentionality? I wonder.
    Ed

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  2. Ed,

    The "why" is an excellent question. I am sure there is a reason why our brains evolved the way they did; I suppose when we discover the correct theory of how these hallucinations originate we may be able to figure out how it helped man adapt to his enviornment. Certainly a lot of additional study is needed.

    I find it interesting that you and all of us automatically have the question of "why"? I think this is one reason why religions developed. Man has an insatiable desire to know "why" things happen the way they do. Why were we born? What is the purpose of life? Why do we die? Where do we go when we die? Men desire an answer for these questions. And most men, instead of being willing to suspend judgment until more information is in, jump to the conclusion that a supernatural entity is involved somehow and they construct their explanation around that entity and presto, we have a religion.

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  3. An excellent post on this subject can be found at Professor Matt McCormick's site, My Magical Mind and God. Matt's site is one of the best around, in my opinion.

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  4. Thank you for the link to My Magical Mind and God. It is an excellent site and very well written.

    A neurologist that I know said the brain is the last frontier of medicine. I'm enjoying reading this portion of your blog.

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