|
|
| [MASTER INDEX] [DATE INDEX] [THREAD INDEX] [SUBJECT INDEX] [AUTHOR INDEX] |
| [Date Prev] [Date Next] [Thread Prev] [Thread Next] |
Nov 12, 1995 01:31 PM
by Don DeGracia
LSD Hallucinations as a model for Altered States of Consciousness Don DeGracia email: 72662.1335@compuserve.com Copyright 1995. All rights reserved by the author Hallucinations are perceptions of things not presented to the senses. Hallucinations play a critical role in altered states of consciousness ASC. Some hallucinatory states are natural including dreams hypnagogia lucid dreams and synesthesia. Hallucinations can also be induced by methods including yoga brain injuries and by drugs. Hallucinations of all sensory modalities occur. Here we shall focus on visual hallucinations caused by psychedelic drugs such as LSD. Since psychedelic drugs cause the predictable formation of waking hallucinations the study of the mechanism of these drugs could illuminate the nature of hallucinations and such understanding could presumably be carried into the study of other ASC in which hallucinations play a role. Examples of psychedelic hallucinations involve perceptions of moving colored imagery behind closed eyes seeing patterns of color and light perceptions of lace ribbons geometric patterns rainbow effects flash bulb- like after images all seemingly filling the air around the subject [2 4]. The central questions are: what is the nature of and mechanism behind these hallucinations? Data from animal experiments with LSD indicate that post synaptic activity at the relay between the optic nerve and lateral geniculate nucleus LGN is suppressed [1]. However only 10-20% of presynaptic connections to the LGN are from the retina; the majority of LGN afferents nonretinal afferents come from other brain regions including the brain stem reticular formation and the occipital cortex [5]. Nonretinal afferent connections to the LGN are thought to be feedback connections that regulate the flow of visual information from the retina to the cortex. Given this data one could hypothesize that the mechanism of formation of hallucinations during psychedelic experiences involves a bleed-through of the nonretinal feedback signals to the LGN into the normal routes for transmitting retinal signals Figure 01 which is the file DEGFIG.GIF in the SMN library in the New Abe B forum on CompuServe. In the non-drug state feedback signals to the LGN serve merely to regulate retinal input but do not enter into the information stream which will ultimately be converted to visual perception Figure 01 A. However during psychedelic drug inebriation these same feedback signals may actually become a part of the retinal signal flow and are transferred to higher visual centers which interpret them as visual perceptions along with retinal input Figure 01 B. Therefore the nature of the hallucinations perceived under the influence of psychedelic drugs is that these images are visual representations of signals entering the LGN from nonretinal afferents. In the simplest of terms current evidence indicates that one is literally watching the internal "talk" of their own brain when hallucinating under the influence of psychedelic drugs. Other authors have presented this view without however a clear model of the underlying mechanism [7]. How might this model of psychedelic induced hallucinations be related to other ASC? It is known that psychedelics exert their major influence in the brain stem [4]. Presumably drug induced changes in the brain stem are responsible for altering the activity of the LGN. It is interesting to note that changes in brain stem activity occur during REM sleep [5] and also probably during yogic breathing exercises. Yogic breathing exercises alter activity of brain stem breathing centers which in turn could affect ascending brain stem pathways Both REM sleep and yoga practices lead to the formation of visual hallucinations. Thus changes in the brain stem cause changes in higher visual centers leading to the formation of visual hallucinations. Variations of imagery perceived during various ASC probably reflect subtle differences in brain stem changes and brain stem effects on higher brain centers. The above model also suggests a mechanism for a little known psychic ability called variously "anima" "micro-psi" or "magnifying clairvoyance" [36]. The nature of this psychic ability is such that it allows one to perceive minute objects such as cells or atoms objects far too small to be perceived with the naked eye. It is conceivable that the bleed-through of the nonretinal feedback on the LGN during ASC could amplify if concentrated upon. By concentrating or focusing on details of the hallucination this will alter the signals moving through the feedback loop amplifying magnifying the images focused upon and damping out the remaining hallucinatory imagery. Thus initial perceptions of the macroscopic structure of the brain will give way to perceptions of individual nerve cells. These in turn will give way to direct perception of subcellular components. These in turn will give way to direct perceptions of molecules and atoms and so on. Thus by such a mechanism is it possible to perceive objects that the retina itself cannot discern. This suggests that our ability to perceive is not limited by the physical limits of the senses and that there are mechanisms in the brain that allow us to directly perceive the components out of which our body brain and cells are constructed. The models presented above are empirically testable. They make specific predictions about the behavior of the brain. Use of current brain imaging techniques such as magnetic resonance imaging could confirm or refute the model presented above. In conclusion psychedelic drugs can be used as a model system for the study of altered states of consciousness. The above discussion focused only on visual hallucinations. Other aspects of altered states are also amenable to this model treatment such as for example the mystical experience which can be induced by psychedelic drugs. References: [1] Aaronson B. and Osmond H. Psychedelics. New York: Doubleday & Co. Inc. 1970. [2] Asaad G. Hallucinations in Clinical Psychiatry. New York: Brunner/Mazel 1990. [3] Besant A. and Leadbeater C.W. Occult Chemistry. London: Theosophical Publishing House 2nd edition 1919. [4] Hoeffer A. and Osmund H. The Hallucinogens. New York: Academic Press 1967. [5] Kandel Schwartz and Jessel. Principles of Neural Science 3rd ed.. Norwalk: Appleton and Lange. 1991 [6] Phillips S.M. Extra-Sensory Perception Of Quarks. Wheaton IL: Theosophical Publishing House 1980. [7] Watts A. The Joyous Cosmology. New York: Vintage Books 1962.