Quantum Biology

Date: Fri, 30 Aug 1996 13:30:45 -0700 (PDT)
From: Caroline Lewis <clewis@einstein.ph.utexas.edu>
To: quantum-d@teleport.com
Subject: Quantum Biology

Dear Rhett and Colleagues,

Greetings from the land of relativity. I thought I would leave a few
thoughts with you and all before I start my travels to Canada and
Trinidad (where I can only check the email occasionally for the next
while). I leave next Monday so here goes. Mainly I think it time
to look for open-minded labs (or create them!) which could start
looking for effects associated with large scale quantum effects in
living cells. Any ideas one and all?

I am posting some experimental thoughts I have:

Quantum Biology

Caroline M. Lewis, Center for Relativity
Physics Department, University of Texas,
Austin, Texas, 78712.

Very exciting work on microtubules and consciousness has been
presented by Hameroff and Penrose (1996, ``Toward a Science of
Consciousness Proceedings,'' MIT Press) which brings together
fundamental physics and biology. A key question in this work
is whether or not there are large scale quantum effects which
directly affect biological processes such as brain function. I
propose what I would call indicative experiments to test for
quantum effects in living cells: conceptually simple experiments
which could indicate whether or not it was worthwhile to do
more sophisticated tests.

The Hameroff-Penrose conjecture is that there is a gravitationally
induced quantum coherence in arrays of microtubules (nanometer-sized
components of the cytoskeleton of the cell which are particularly
suited to hosting quantum effects because of their crystal-like
lattice structure, hollow inner core, control of cell division and
movement and their capacity to process information) at the onset of
consciousness. They use the time-energy uncertainty relation with
a time scale (``preconscious to conscious transition time,'' 500
milliseconds) derived from psychological experiments to calculate
that assemblies of about ten thousand neurons acting in quantum
concert could mediate consciousness. Another important time scale
in this work is the nanosecond time scale associated with protein
conformation changes studied by Herbert Frohlich in his prediction
that cooperative quantum effects in and amongst cells would give
rise to coherent oscillations in the 10^9-10^11 Hz frequency range.
This constitutes a large scale quantum biological phenomena analogous
to superconductivity. With this in mind, let me briefly outline the
experimental ideas:

(i)The first idea is to do microwave maps. If microtubules undergo
coherent Frohlich oscillations in order to mediate consciousness (as
in the Hameroff-Penrose suggestion), then it makes sense that there
should be a correlation between the the density of microtubules in
the human body and the intensity of microwaves at 10^11 Hz radiating
from the body, on average. Roughly speaking, there had better be more
microwave radiation coming from the area of the head (the brain contains
the highest concentration of microtubules in the body according to
B. Alberts et al., 1994, ``Molecular Biology of the Cell'', Garland
Pub.), than anywhere else for the Hameroff-Penrose scenario to fly.
Also, what are the changes in the microwave readings during anesthesia
and during sleep?

(ii)In talking about biological superconductivity, what you are talking
about is an electronic phase transition. This phase transition will
change the magnetic properties of a system and one great instrument we
have for the study of living systems is the highly sensitive and non-
invasive SQUID (Superconducting Quantum Interference Device) magneto-
meter. There are present-day SQUID arrays which are capable of measuring
the magnetic field down to 10 femtoTeslas produced by collections of
10^4 dendrites active in a 1 mm square area of the cortex (J. Wiksuo,
IEEE Transactions on Applied Superconductivity, Vol. 5, No. 2, June
1995, is the key reference on SQUIDs and biomagnetism). A transition
from incoherence to quantum coherence within the microtubules of the
neuronal assembly would be reflected in a change in the magnetic field
of the neuronal assembly. In normal superconductivity the magnetic field
is expelled at the onset of the transition. A helmet array of SQUID
magnetometers surrounding the head could monitor the changes in magnetic
field strength of cell assemblies as the subject underwent anesthesia.
Particularly large and sharp changes in the magnetic field strength of
localized assemblies of about ten thousand neurons would help validate
the Hameroff-Penrose conjecture.

(iii)New techniques in biophysics may prove useful in looking for direct
quantum effects in microtubules. For example, optical tweezers (S. Block
et al., Science, V 270, p. 1653, 1995), can measure the picoNewton forces
with which a motor protein, kinesin, slides along a single microtubule
or the enzyme RNA polymerase slides along a DNA strand. The technique
involves fastening the far end of the microtubule or DNA to a polystyrene
bead 0.5 micrometers in diameter. This bead is held in a laser interfero-
meter-based trap (the optical tweezers) and the motor protein tugs the bead
until the resistance level of the laser beam matches the tugging power of
the motor protein. A photodetector within the apparatus measures the dis-
placement of the bead which is then used to calculate the motor force. One
of the most interesting aspects observed in the real-time dynamics of the
RNA polymerase and DNA system is that there may be jumps in the position
of the RNA polymerase, as well as pauses and reversals in the motion.
The onset of quantum coherence should have an effect on the position of
motor molecules sliding along the microtubule strands; regular patterns
may be observed in the distribution of jumps which would not be expected
from thermal perturbations and which could be different from the ``knocks''
expected in traveling over bumpy macromolecules.

(iv)Biological perturbation systems: Genetically engineer clean background
systems of microtubules which can then be perturbed by varying the tem-
perature, the number of microtubule associated proteins (MAPs), the ions
present and all the other parameters of a very complex system. Real cells
are too complicated a physical system to answer a lot of the detailed
questions concerning quantum coherence in microtubules: do MAPs help
establish the large scale quantum coherence? What effect do calcium and
other ions have on the behaviour of the microtubules? Can we observe the
onset of states without thermal loss? Progress might be made through
studying the simpler system.

There are profound consequences to a quantum theory of biology. Who knows
what insights into our perceptions, our state of health and new ways of
interacting with the environment could emerge from this study (perhaps
sensitive biosensors could help us to detect those elusive gravitational
waves thinks the millennial relativist)? It is time to start the experiments.


Regards,  Caroline Lewis.