X-Message-Number: 222
From: Kevin Q. Brown
Subject: Muscle Memory 
Date: 11 Sep 1990

One of the longstanding controversies within the cryonics community is
whether neurosuspension is better than whole body suspension or vice-versa.
Advantages of neurosuspension over whole body include:

  (1) better perfusion of the brain (because of more rapid cooldown and a
      protocol that does not have to be a compromise between the brain and
      the remainder of the body),
  (2) better portability, due to smaller size, which is important during
      threats to the storage facility (such as fire, crazed mobs, etc.), and
  (3) at facilities that provide it, neurosuspension is cheaper than the
      whole body option at the same facility.

Whole body advocates point out not only its aesthetic (and PR) advantages, but
also that its conservation of the entire body helps ensure that nothing
important gets lost.  Furthermore, reanimation of a whole body suspendee does
not raise some of the ethical questions arising from one of the proposed
methods of reanimating neurosuspendees, namely the raising of an anencephalic
clone to provide a body to insert the reanimated brain into.  (Another
proposed method of reanimation, growing a new body from the head, does not
raise this ethical question.)  Also, as the damage from cryonic suspension
is reduced (so that fixing the damage from the suspension itself is no longer
as difficult as reconstructing a new body), the level of technology required
for reanimation will decrease and whole body suspension eventually will become
favored, even if it is not now.  (Thus, even neurosuspension proponents should
have enough funding for a whole body suspension because they might live long
enough for whole body suspension to become the preferred method of suspension.)

I recently ran across another argument for the whole body advocates, suggesting
not that neurosuspendees may lose more memories than whole body suspendees,
but that they may lose ACCESS to more memories than whole body suspendees.
Then before I got around to publicizing that argument, I read it again in the
article "The Case for Whole Body Suspension" by Micheal B. O'Neal, pp. 21-26
Vol 11(7), July 1990, Cryonics.  Here is my interpretation of the issue (but
not my interpretation of O'Neal's article):

We are all familiar with our thoughts and feelings resulting in muscle
movements, but we are not as familiar with muscle manipulations resulting in
thoughts and feelings.  But that is exactly what we should expect from an
associative memory, which is one of the aspects of human memory.  How does
that relate to neurosuspension versus whole body suspension?

If you have any "weak" memories that require some assistance to be brought to
consciousness, then muscle-related associations may be an important source of
"ticklers" to get those memories back in working order after reanimation.
(Videotapes of yourself, personal mementos, diaries, friends, and pets can
provide plenty of "ticklers," too.)  A person who chose neurosuspension may
lose these important muscle-related associations.  Of course, in theory, one
can stimulate some of the neurons leading to the brain to simulate those same
muscle manipulations, thereby making the actual body unnecessary for provoking

the muscle-related associations.  In practice, though, it may be more difficult,
as a consequence of two factors (as pointed out by Michael B. O'Neal):

  (1) the experiences one has throughout life change the body so that the
      body stores important clues to (gain access to) one's experiences and
      identity, and
  (2) the DNA does not completely determine the body; "identical twins" with
      the same DNA have quite similar, but not identical, bodies.

An obvious effect of factor (1) is that backup information gets lost.  (Since
we do not know for certain what aspects of the body will be needed or useful
for reanimation, the conservative thing to do would be to save it all.)
Furthermore, loss of information about the body adds uncertainty about the
patterns of signals sent from the body to the brain.  For example, someone
with a slightly injured foot may walk with a slight pain in that foot.  That
slight pain during walking may form part of the context of some important
memories.  Reconstruction of a brand new body with a sound foot (or simulation
of that body) will lose that part of the context and possibly thereby lose
access to those memories.

The effect of factor (2) may be to increase the computational complexity of
reanimation.  To understand why that may be, recall that the game of chess
theoretically can be solved completely, but the combinatorial explosion in the
game tree renders a complete solution impractical (within the anticipated
lifetime of this universe anyway).  Could the number of possible ways the DNA
allows us to connect the neurons of the body to the brain and the number of
possible ways of stimulating those neurons (with a body) be too large and
varied to allow a practical way to simulate the muscle-related neurons closely
enough to stimulate the old, muscle-related memories?  I do not know.  Perhaps
someone with more knowledge of neurophysiology will know.

That is as strong as I can state the case for whole body suspension.  These
latest theoretical limitations to the effectiveness of neurosuspension seem
rather subtle, though, which makes me wonder how important they might be.
In particular, quadraplegics are essentially animate neuropatients and they
reportedly do not thereby suffer gross lapses in memory.  Is there anything
important in this issue that I am missing?

                                       - Kevin Q. Brown

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