LSD HALLUCINATIONS AS A MODEL FOR
ALTERED STATES OF CONSCIOUSNESS
by Don DeGracia, BSc, PhD(Cand.)  August 1995

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 bulblike 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 1 which is the file DEGFIG.GIF in the SMN library in the
New Age B forum on CompuServe [GO NEWBAGE]).    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 1 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 1 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" [3,6].  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.

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For further information contact:-
Don DeGracia, 72662,1335