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New
New summaries and reviews of papers, articles, books etc.
1.) The World in Your Head - Steven Lehar - added 1 March 2010 (under Neuroscience 4) - Argues against the concept of the brain as a conventional computer.
2.) Indeterminism in neurobiology - Weber, M. - added 22 February 2010 (under Mainstream 15) - Climbs the wrong mountain in associating quantum consciousness with chance events.
3.) Consciousness: Creeping up on the Hard Problem - Jeffrey Gray - added 17 February 2010 (under Mainstream 15) - Criticises functionalism from a mainstream point of view
4.) QUANTUM COHERENCE IN PROTEIN AT ROOM TEMPERATURE Coherently wired light-harvesting in photosynthetic marine algae at ambient temperature - Elisabetta Collini, Cathy Wong, Krystyna Wilk, Paul Curmi, Paul Brumer & Gregory Scholes - added 8 February (under Protein&coherence 2) - Collini demonstrates quantum coherence in photosynthetic protein at room temperature undermining a key argument against quantum consciousness.
5.) A model of ionic wave propagation along microtubules - Satiric, M. et al - added 5 February 2010 (under Danko Georgiev 2) - Further model for possible basis of quantum information processing in microtubules
6.) Coherence in stable microtubules - Danko Georgiev - added 3 February 2010 (under Danko Georgiev 2) - Discusses computation in microtubules in relation to the electric field and elastic energy in the microtubule lattice
7.) Solving the binding problem: cellular adhesive molecules and their control of the cortical quantum entangled network - Danko Georgiev - added 27 January 2010 (under Danko Georgiev 2) - Proposal for quantum coherence extending between neurons via the synaptic cleft.
8.) Neuroligins and neurexins - Thomas Sudhof - added 22 January 2010 (under Danko Georgiev 2) - Relates to ideas on coherence between neurons
Other recent reviews:- 1.) Neurophysics of consciousness - John, E. - added 2 Feb 2010 (under General Articles 4) (2.) Consciousness not yet explained - Tallis, R. - added 23 Jan 2010 (under Philosophy 3) (3.) Molecular biology and biophysics of microtubules - Georgiev, D. et al - added 13 Jan 2010 (under Danko Georgiev 2) (4.) Why physicalism entails panpsychism - Strawson, G. - added 10 Jan 2010 (under Other Quantum 5) (5.) Dissipationless waves for
information transfer in neurobiology - Georgiev, D. - added 6
Jan 2010 (under Danko Georgiev 2) (6.) Consciousness - Revonsuo, A. - added 2 Jan 2010 (under Mainstream 14) (7.) On the dynamic timescale of mind-brain interaction - Georgiev, D. - added 23 Dec 09 (under Danko Georgiev) (8.) Electric and magnetic fields
inside neurons - Georgiev, D. - added 21 Dec 09 (under Danko Georgiev) (9.) Analysis of quantum decoherence in the brain - Georgiev, D. - added 15 Dec 09 (under Danko Georgiev) (10.) Mental causation: Libet
& Soon - Batthyany, A. - Dec 09 (under
Freewill 4).) (11.) Synaptic Self - Le Doux, J. - added 4 Dec 09 (under Neuroscience 3) (12.) Examination of
quantum coherence in a photosynthetic system at physiological
temperature - added 27 Nov 09 (under Protein&Coherence 2) (13.) Seeing Red - Humphery, N. - added 19 Nov 09 (under Mainstream 13) (14.) Brain Coherence and
Entanglement in the 21st Century - added 12 Nov. 09 (under Protein&coherence 2) (15.) Falsification of
Hameroff-Penrose model of consciousness - Georgiev, D. - added 5 Nov. 09 (under Other Quantum 4) (16.) Penrose's Godelian argument - Feferman, S. - added 3 Nov. 09 (under Penrose & Hameroff 8) (17.) Godel's First Incompleteness
Theorem - added 30 Oct. 09
(under Penrose & Hameroff 8) (18.) The Illusion of Conscious Will - Wegner, D. - added 23 Oct. 09 (under Mainstream 12) (19.) Conditions for coherent vibrations in the cytoskeleton - Pokorny, J. - added 4 Oct. 09 (under Protein&Coherence) (20.) The Root of Thought - Koob, A. - added 3 Oct. 09 (under Neuroscience 3)
1.)
The World in Your Head: A
Gestalt View of the Mechanism of Conscious Experience
Steven Lehar,
Schepens Eye Research Institute
Lawrence Erlbaum (2003)
INTRODUCTION: Lehar makes a good case against the computer/AI model of
the brain, by highlighting the inability of computers to differentiate
the edges needed to construct a model of the world, from the mass of
less important input. He contrasts this with the ability of biological
vision to deduce information from very flimsy inputs. The Gestalt
methods suggested for achieving what the brain can do are not entirely
convincing, as a means of sorting the mass of data input, and thus
avoiding the combinatorial explosions implied by the requirements of
visual perceptions. In this respect, a quantum computing approach might
look to have a greater chance of success. Further to this, a weakness
of the book is the lack of much attempt to relate what is proposed to
the physical components and processing of the brain.
Lehar
approaches consciousness from the angle of the relationship between
visual image processing and artificial intelligence (AI). A computer
has all the data relative to an image in the form of numerical data.
However, turning this into usable information in AI/robotics has proved
an intractable problem. Computers can detect features such as edges,
but the problem is that they can detect too many of such features.
Their edge detection includes details of texture, surface fragmentation
and shadows, but fails to pick out those edges that are relevant for
the outlines or volumes of an object. Further, there is no apparent
algorithm to deal with occluded objects, where a small object obstructs
the view of part of a larger object, but it can be deduced that the
larger object continues behind the smaller object. This is taken to
mean that the information of global significance for understanding the
image is not available in the local edges.
Computers have problems
with the spatial structure of visual scenes, and as a result difficulty
in navigating in an environment of irregular forms, which, by contrast,
present little problem for biological vision. Lehar points out that the
retinal image is two-dimensional, but is perceived as
three-dimensional, and that therefore the three-dimensional depth of
the image must be the result of cortical processing. A basic function
of visual perception is argued to be the transformation from a
two-dimensional retinal image to a three-dimensional perception in the
brain. Apart from inserting spatial structure into an initially
two-dimensional image, the brain must also decompose this image into
coherent objects with volume within the spatial structure. From this it
is argued that the brain must operate a spatial algorithm, in order to
produce this three-dimensional image. What computers have had
difficulty in achieving is not receiving the visual data, but in
developing the sort of processing that allows the brain to turn this
data into a conscious image.
The literature relative to these
problems concentrates on restricted domains, with separate algorithms
for extracting shape from shading, for motion or for lines. However,
the problem of dealing with shape of the conformation of objects that
reflect light has remained largely unresolved. This divergence in
relative performance is argued to show that the basis of biological and
computer vision are very different from one another.
Conscious
images: Lehar takes the view that the conscious image is assembled in
the brain, in response to data from the external world. This is
described as 'indirect realism,' in contrast to 'direct realism' or
'naive realism', in which it is believed that we perceive the external
world as it actually is. The author thinks that discussions in
neuroscience are often implicitly based on direct realism, but he
argues that this view is based on false assumptions. The visual
experience is at odds with scientific reality, because the subjective
world is experienced, as if it were outside the brain, whereas visual
processing occurs inside the brain. The causal chain of vision is one,
in which the brain can only process material that has already been
picked up by the sensory organs. Consciousness is therefore necessarily
confined to the experience of internally constructed models. Lehar goes
back to Kant, who distinguishes between the 'nouminal' world of light
signals etc. and the phenomenal world of internal conscious perception.
The 'nouminal' world is only perceived within the phenomenal world.
The author argues that the properties of subjective experience are
inconsistent with the present neuroscientific thinking, based on the
semi-independent sequential operation of billions of individual
neurons. In contrast, our experience is mainly of stable and solid
volumes, rather than billions of abstract features. The author accuses
the neuroscientific community of evading this problem by assuming the
'naive realism' view, and ignoring subjective experience. This attitude
is partly blamed on the mid-twentieth century advent of single-cell
recording, which shifted the emphasis from assembly-wide features
towards single-cell features. In the same period, the digital computer
became a major part of technology, and was seen as an analogy of the
brain. At this stage, AI researchers thought that they had the problem
of vision solved, and that they could implement robotic vision without
paying any attention to biological systems.
Famous Dalmatian: The
author discusses the well-known picture of a Dalmatian dog against a
speckled background. Much of the dog is missing, and some of the edges
that are there are locally indistinguishable from the background. Much
of the edge of the dog is missing and some of the edges that are there
are locally indistinguishable from the background. The main point about
this is that the local information does not allow the observer to
distinguish the dog from the background, but when the picture is viewed
as a whole, the dog is clearly distinguishable. Lehar argues that this
indicates that perception is based on global brain activity, rather
than the sequential processing of individual neurons. He claims that no
algorithm has ever come close to handling the ambiguity of the
Dalmatian dog picture. Furthermore, the picture is viewed as
demonstrating, in exaggerated fashion, the principles that underlie
biological visual processing. One argument tries to evade this
conclusion, by suggesting that an image such as this is a special case
that does not apply to normal visual processing. However, Lehar
counters that studies that restrict the view of pictures to just a few
edges show that humans cannot distinguish between edges that are
important to the outline or form of objects, and edges that are just
texture or shadows.
Kaniza triangle: Lehar discusses visual
figures, such as the Kaniza triangle, where the mind automatically
perceives a triangle, although all that is physically there on the
printed paper is three black Pacman features. Thus, the observer
perceives edges and a brighter white ground than the surrounding area,
where neither exists on the paper. Again, this is argued to be a global
processing of the image, rather than derived from the examination of
individual edges.
Rubin vase/faces: The same is true of other
well-known examples such as the Rubin face/vase illusion. A black
figure on a page may be perceived, as either a vase or the profiles of
two faces opposite one another. The brain jumps from one perception to
the other, without ever offering a hybrid picture, and can as quickly
reverse its perception. It is argued from this that visual recognition
is not the result of feed-forward processing of a visual input leading
to a perceptual output, as is often assumed in computer models of the
brain, but instead involves a dynamic process that is not completely
stable. P. Invariant perception: Lehar also discusses the problem of
the invariance of our perception of objects, in that they can be
recognised from different angles and in different lights, as the same
objects, in a way that is not easily achievable by the analysis of
individual edges. Conventional computing could only manage this by
having a detector for each possible position, which could produce a
combinatorial explosion or NP hard problem, where classical computing
might only resolve the problem in a time that was longer than the life
of the universe. There have been suggestions that local elements of the
object are first recognised, and later put together, but this does not
take into account instances, where what are actually different elements
may form an image of the same object.
Visual agnosia: The
distinction between being able to detect individual features, and
gaining a practically useful model of the world can also be
demonstrated from human pathology in the form of visual agnosia. There
are two forms of this; in a condition known as apperceptive agnosia,
the patient can see individual objects, but cannot integrate these
features into a spatially coherent three-dimensional whole. The
opposite condition is associative agnosia agnosia, where the patient
perceives a coherent world, but cannot identify individual objects.
This medical finding is argued to contradict the 'naive realism' claim
that the brain is just seeing what is out in the world, in which case
the whole spatial environment should be perceived.
Gestalt theory
attempts to solve the problem of visual recognition by parallel
processing, in which the solutions to each part of the visual
recognition problem depend on one another, and thus constrain the
possible solutions for one another, thus closing in on a single
solution. Lehar also proposes the idea of 'harmonic resonance'. This
involves resonance between different modules in the brain, with
resonance ultimately being communicated to all the relevant systems in
the brain. This is seen as a solution to the 'binding problem' or an
explanation of the unity of different modalities in conscious
experience. This of course relates to the EEG recordings of gamma
frequency synchrony in the brain.
Conclusion: It is not clear that
these Gestalt proposals involve sufficient processing capacity to
overcome the likely combinatorial explosions/NP hard problems implied
by perception. Lehar does relatively little to link his ideas to the
physical components and processing of the brain. From the look of it, a
quantum computing process would have more chance of bridging the gap
between classical computing capacity and the requirements of visual
perception as highlighted by Lehar.
2.)
Indeterminism
in Neurobiology
Weber, M.
philsci-archive (2005)
This paper
is really an example of something which is all two frequent in
consciousness studies, where a researcher makes an assumption about
what is being proposed in quantum consciousness theories, and proceeds
to attack what has been assumed without making contact with any real
theories of quantum consciousness.
Weber's paper essentially
addresses the wrong problem. He is mainly discussing whether the
overall development of the universe and within it of large biological
structures is influenced by chance events, as a result of wave function
collapses at the quantum level.
Unfortunately, this debate is of
little interest in respect to quantum consciousness. Early on in his
first book, Penrose pointed out that the randomness of the wave
function collapse was of little use to mathematical understanding. It
was from here that he went on to propose the idea of objective
reduction, which is hypothesised to give access to the geometry of
spacetime. Weber's search for chance events in the brain is irrelevant
to Penrose's and other versions of quantum consciousness theory.
Weber adopts what is essentially the Tegmark approach to quantum
coherence in biological matter, arguing that biological systems are
macroscopic, interact with the environment, and by implication
therefore decohere and behave in a classical/deterministic manner. This
paper was written before Engel et al (2007) and Collini et al (2010)
demonstrated the existence of quantum coherence in some proteins, and
the latter of the two papers demonstrated coherence at room
temperature. However, even when the paper was published in 2005, a
discussion of Hameroff's proposals for shielding microtubule protein
from decoherence would have seemed relevant.
Another unusual feature
is the treatment of the possibility of chance events at the synaptic
level. This is not in fact a proposition made by Penrose/Hameroff,
where dendritic gap junctions are the focus of attention, but given
that it is discussed, it is very surprising that Weber does not mention
the fact that only 15-30% of axon potentials result in the synapse
firing. However, Danko Georgiev, who is critical of the Hameroff model,
has recently proposed that neurotransmitter release could be influenced
by coherence extending from microtubules via presynaptic scaffold
proteins.
Weber also discusses randomness in ion channels, and here
too, it is surprising that he does not refer to the work of Gustav
Bernroider, who seeks to demonstrate coherence within ion channels and
possibly entanglement between them. Bernroider was sympathetic to David
Bohm's idea of an implicate order, but it seems possible that his ion
coherence could be linked into a Penrose type theory.
3.)
Consciousness:
Creeping up on the hard problem
Jeffrey Gray
Oxford University Press
(2004)
INTRODUCTION: This book is worth reading for a number of interesting
areas of discussion. It attempts to use aspects of synaesthesia to refute the
still dominant functionalist theory of consciousness. It argues that
intentionality or meaning arises from unconscious processing, and also that
there is no true representation of the external world in the brain. Because of
these last two points, it is argued that much of the philosophical baggage of
consciousness studies can be left behind, and discussion of consciousness should
be focused purely on qualia. Gray does not think we yet have an explanation for
qualia. He takes the possibility of quantum consciousness, at least in the
Penrose form more seriously than most mainstream investigators, although he
argues that it contains no explanation for the selection of particular qualia.
He sees conscious as being selected for by evolution, because it is causal, but
causal in a sense that does not involve agency or freewill. Unconscious systems
are claimed to respond to conscious perception, but only in the sense that our
brains can respond to a sketch as a reminder, with the sketch having no agency
of its own. This part of the discussion seems rather incomplete. Gray has
relatively little to say about cognitive processing, the conscious emotional
aspects of the brain, or the relationship between these two, which is known to
be crucial in determining preferences for action and behaviour.
Gray
stresses that conscious experience has no scientifically understood links with
neuroscience or behavioural science. Without such links, there can be no
understanding of the interaction of consciousness with the physical world. Neuroscience
has built up a detailed knowledge of neurons, but this is viewed here as having
made no contribution at all to explaining consciousness. Most neuroscience
experimentation has not been aimed at understanding consciousness, but at understanding
the movement of energy in the brain. Biology as such makes do with two systems,
firstly the laws of physics and chemistry, and secondly feedback mechanisms
that respond to a variable, which is being controlled. In fact, neuroscience
has created a complete outline of brain processing without involving
consciousness. There is nothing for consciousness to do within conventional
neuroscience, and the existence of consciousness is something of an
embarrassment to the theory. But Gray argues that while experimentation has
shown much of what we perceive to be an illusion, we should hold onto the fact
of conscious experience, for without conscious experience, it would be
impossible to have an illusion in the first place. The unconscious mind is
argued not to be capable of having an illusion, but only of making an error. In
contrasts to an error, an illusion continues even when it is known to be an
illusion. Thus knowing that a film is a series of frames does not prevent us
from seeing it as continuous.
Refuting functionalism: Gray goes on to discuss functionalism, which
he views as the dominant form of consciousness theory. According to
functionalism, consciousness is the nature of certain complex systems,
regardless of whether they are is made of neurons, silicon chips or some other
material. The underlying tissues or machinery is irrelevant. Further to that,
consciousness relates only to functions performed by the brain or other system,
and does not arise as a result of anything that is non-functional. In looking
at the qualia red and green, functionalism says that all that exists are
responses, by which the individual's behaviour demonstrates the capacity to
discriminate between red and green. For any discriminated difference in qualia,
there must be a difference in function. It is also claimed that for every
discriminated difference in function, there is a difference in qualia.
Gray
claims to refute functionalism, on the basis of data from research into
synaesthesia performed at the Institute of Psychiatry in London. In discussing
this question further, Gray looks at synaesthesia, where modalities become
mixed, as when numbers or sounds are experienced with colour. Extensive
experimentation in recent years has demonstrated that synaesthesia is a real
and observable brain state, and is most likely the consequence of abnormal
projections into the V4 colour region of the visual cortex from other parts of
the brain. Brain scanning studies showed that when words were spoken, in
addition to the normal activity in the auditory cortex, the V4 colour vision
area in the visual cortex became active, in a way which did not occur in normal
subjects. There was no related activation in V1 or V2, the earlier stages of
the visual pathway. The conclusion drawn from a whole series of experimentation
was that the 'word-colour' type of synaesthete has an abnormal projection from
the auditory cortex into the visual cortex causing the V4 colour area to
produce consciousness of colour. However, there is no evidence that this colour
sensation has any function. Thus, there is no relationship between the
occurrence of the synaesthete's colour experiences and the linguistic function
that triggers them. Gray argues that this phenomena refutes the functionalist
theory's analysis of conscious experience.
Intentionality and the
unconscious brain: Gray argues that a
large proportion of the brain's activity is unconscious. Consciousness is
commonly estimated to lag about 250 milliseconds behind an event being
registered by the sense organs, but much action and behaviour takes place more
rapidly than this. He also discusses the existence of separate systems for
conscious and unconscious processing. This is the case in the visual system,
where there is a ventral stream that underlies conscious perception, and a
dorsal stream that underlies rapid but unconscious actions.
Conscious
experience or more specifically the contents of consciousness are usually about
something, and this is described as 'intentionality', whereas movements of
energy in the brain are just themselves, and are not about anything.
Intentionality is another aspect of the 'binding problem', as to how the different
modalities, such as sight and hearing, are bound together into a single
conscious experience. Gray points out that without binding, eating a banana
could involve seeing yellow, feeling a surface and tasting something without
the unifying awareness of a particular object known as a banana. Intentionality
can also be referred to as meaning, the meaning of the yellow colour etc. is a
banana. Without this binding, things would be just meaningless shapes, edges,
colours etc. Consciousness appears to arise where modalities come together.
This also involves the idea of categories that usually bridge two or more
modalities, as with the example of the banana, as a particular category of
object.
Gray sees the unconscious brain as containing subsystems that can be
regarded as what he calls servomechanisms dedicated to controlling a particular
variable, such as the distance between a hand and an object that is going to be
grasped. These servomechanisms are often linked to actions. In contrast,
conscious perception can be just about perception, such as looking at a sunset.
Despite this distinction, Gray argues that intentionality is based on
unconscious processing. The processing in the visual cortex that underlies
conscious perception is not itself conscious. Instead, the perception springs
into consciousness fully-formed, including the intentionality of what the
perception is, or is about. To prove this point, Gray use the example of
pictures that can be either of two things, such a duck or a rabbit. They are
never hybrid, but are always completely duck or completely rabbit. The perception of a duck or rabbit is argued to
be constructed unconsciously up to the last moment. The actual process of
binding, as in the binding problem, is also suggested to be an unconscious
result of synchronous firing within and between brain regions. Gray's
conclusion from this part of his discussion is that intentionality arises from
the physical and chemical structure of the brain, but also that if
intentionality can be constructed out of unconscious processing, it is unlikely
to produce a solution to the 'hard problem' of how consciousness arises.
Representation:
Gray goes on to discuss the question of the representation of the external
world in the brain. First of all, he reminds us that the external world is
nothing like what it appears like in conscious perception. The external world
is bits of energy fluctuating in the vacuum, with none of the qualities of
solidity, colour etc. attributed to the perceived world. But the author goes
further than this. He dismisses what he calls the fall back position, which is
to think that the perception of something, a cow for example, is a
representation, in the sense of resembling the cow as it really exists. Gray
argues that our only direct knowledge of the cow is a brain state. We have has
no direct knowledge of the cow as it really is, and it is therefore meaningless
to argue that the cow brain-state is a representation of the real cow.
Gray
argues the conscious perceptions should be treated as signals. Signals have no
need to resemble the thing about which they communicate. A whistle might warn
thieves of the approach of a policeman, but a whistle is nothing like a policeman.
Perceptual experiences are seen as signals, about what observers might expect
about their environment. However, he stresses that these perceptual signals
arise in the brain, and do not have any kind of external existence. This is not
to say that we cannot deduce useful information about the real world from
perception. Thus for example visual perception is a good guide to the
reflectance of surfaces, which in turn often has survival value for an
organism. Thus there is a 'fit' between the external world and the model
constructed in the brain, otherwise we would not have much success in
interacting with the world.
Gray also emphasises that conscious perception
is not voluntary. Perceptions just pop into consciousness, and are argued here
to come from unconscious processing. Furthermore, it is claimed that only a
tiny proportion of the data that could potentially enter consciousness actually
does. It is possible to distinguish between two types of unconscious
processing. Firstly, processing that can never come into consciousness, and
secondly processing which is potentially conscious but remains unconscious.
Philosophical
Baggage: Gray's message is that we can
dispense with much of the philosophical baggage of modern consciousness studies,
as regards intentionality and representation, because these are either
unconscious or non-existent. Given the reams that have been written on these
subjects, and the meagre gains in our understanding of consciousness, many
might be glad to dispense with this baggage train. Instead, Gray says we should
concentrate on the qualia of subjective conscious experience, as the only
aspect of the brain that involves consciousness.
Function of consciousness
as comparator and late detector: Gray
views the function of consciousness as a 'late error detector'. The brain is
argued to be a 'comparator' system that predicts what should happen and detects
departures from that prediction. It is suggested that consciousness is
particularly concerned with novelty or error. It is also viewed as something that
causes us to review past actions, and to learn from errors in these actions. Late
error detection permits more successful adaption, if a similar situation
emerges in the future. Gray looks at the question of pain. We remove our hands
from a hot surface before consciously feeling the pain of touching it. The pain
involves is argued to be a rehearsal of the action that led to it, and has the
survival advantage of making a repetition of the damaging action less likely.
Gray accepts that there are many unconscious systems that detect errors, so
this on its own does not produce a survival value for consciousness. However,
he distinguishes consciousness as being multi-modal, and as directing us
towards whatever is most novel within several modalities. The brain takes account
of plans as to what to do next, plus memories of past regularities, in assessing
what is likely to be the next stage of a particular process. These predictions
are submitted to a comparator, but still at an unconscious stage. Only the
unexpected outcomes, or feedback for the continuation of motor action enters
consciousness. We are only conscious of things that change unexpectedly, or
things that are particularly important at the moment.
Gray views the
function of consciousness as the construction of relatively constant
perceptions from ever-changing sensory inputs. The trick is the transmutation
of the ever-changing into the constant. The survival value of consciousness is
seen as the ability to take a second look, where actions or predictions have gone
wrong. The actual detection of departure from prediction is argued to be at the
unconscious level, and the perception of error then just jumps into
consciousness.
The perceptual system is said to construct a relatively
stable picture of the external world, against which unconscious processing by
the comparator reports expectations, error and change. Experimental data
suggests this is useful with navigation. A route once learnt can be re-used
without trial and error on the basis of a few major land marks. Similarly in
other circumstances such as physical actions, consciousness can act by
providing information on key variables, which feed back into action.
Gray
goes on to make the distinction between egocentric and allocentric views of the
spatial world. The egocentric is concerned with action, and is centred on parts
of the body. Conscious perception, however, uses an allocentric system where
the relationship between objects is independent of the conscious observer. Damage
to the inferior parietal lobule, as in Balint's syndrome, leads to errors in
binding together the different features of a single object. This is related to
the parietal's involvement with spatial perception, and is taken to suggest
that binding requires that objects are attributed to a particular spatial
location. Egocentric space is suggested to be unconscious in the parietal
lobule, with a projection to the hippocampus, which supports conscious
allocentric space.
Medium of display:
Gray regards consciousness as a medium of display created by unconscious
processing. The standard objection to this is that it creates an infinite
regress because there has to be a conscious homunculus viewing the display in
the Cartesian theatre, and then an homunculus within that homunculus and so on ad
infinitum. However, Gray argues that the conscious display is used by
unconscious systems, as in the example of unconscious aversion to a food
associated with a gastric illness. Conscious perception is in this theory
created by unconscious systems, and used by other unconscious systems to respond
to late errors, unexpectedness or novelty.
Consciousness – causal but
without agency: Gray likens the
conscious perception to a sketch made of a particular scene that is retained
for use as a record or reminder of the scene. In this way, the sketch is causal
in the sense that it performs the function of recalling or assisting memories,
but it is not directly active in the brain. In Gray's consciousness model, the
conscious perception plays much the same role as the sketch in his analogy. Consciousness
is causal, in the sense that downstream unconscious systems respond to it,
mainly in the area of error correction. However, this conscious aspect of the
brain has no agency or freewill with which to initiate or inhibit actions,
anymore than the sketch on a piece of paper can initiate can initiate actions
independently of our brain.
Incompleteness: I think that although there is
much of interest in Gray's analysis of intentionality, representation and the
unconscious, his analysis is nevertheless incomplete in important ways. In
discussing the unconscious nature of rapid response actions, he adopts the
conventional but superficial approach to the Libet experiments. When he
describes how these showed that trivial (automatic pilot type) actions are
initiated in the brain before the awareness of the decision to make the action,
he appears to simply assume without further discussion that this must apply to
more deliberative or strategic decisions that by their nature takes a longer
time to reach a conclusion.
In line with this, he also makes no extended to
attempt to discuss either cognitive activity or the impact of emotions, and
more importantly the interaction between the prefrontal cognitive areas and the
areas of the brain processing emotions. It might be possible to argue there are
unconscious systems making the actual decisions in these areas of the brain,
but if Gray did want to establish this point, he needed to discuss his model in
terms of these systems, which have a central role in determining actions. In
particular, he needed to pin down the role of our subjective experience of
emotion in determining preferences and actions, if he wanted to justify the
dominance of the unconscious in actual decision taking.
What are
qualia: Gray poses the question, as to
how the brain creates and inspects the display medium of conscious perception.
In asking this question, he makes the assumption that consciousness is
different from either behaviour or brain activity. He views this as a 'hard
problem', in the sense of the term coined by the philosopher, David Chalmers.
He considers that for all of biology, except for the question of consciousness,
the laws of physics and chemistry, plus natural selection and the internal
feedback mechanisms selected for by natural selection are sufficient
explanation. He considers that consciousness has sufficient causal effects to
justify it being selected for by evolution. The hard problem is seen as being
the difficulty of locating consciousness qualia within physics.
Amongst
researchers within mainstream neuroscience, Gray is unusual in not finding the
idea of quantum states being relevant to neural activity as ridiculous. However,
his discussion of the Penrose's version of the theory is not really complete,
in that he concentrates entirely on Hameroff's propositions for quantum
activity in the brain, rather than Penrose's original reason for looking to the
quantum level in the first place. Penrose's suggestion was that a special form of
quantum wave reduction was the only thing that could explain mathematical
understanding, when it goes further than what can be determined by the axioms
of any formal theorem. This might been seen to answer one of Gray's main
objections to the theory, which is as to why particular wave function collapses
should select for any one particular qualia. Gray also questions the temporal
aspect of Hameroff's model, where the proposed 25 milliseconds to wave function
collapse equates to the 40 Hz gamma synchrony, which is possibly the best known
correlate of consciousness. Gray argues that this does not work very well
because it takes at least ten times as long as this for a conscious perception
to form. However, this does not seem an insuperable problem given that there is
strong support for the idea of a connection between gamma synchrony and
consciousness. This is the case even in conventional neuroscience, which suggests
some physical link between synchrony and the time to conscious perception,
whether at the classical or the quantum level. Gray's final word on the subject
is that at least Penrose tries to explain qualia, which is seen as an advance
on Dennett and functionalism, which essentially deny the data that we all have
as to the existence of conscious experience or qualia, and which any valid
theory of consciousness should attempt to explain rather than deny.
4.)
ROOM TEMPERATURE QUANTUM
COHERENCE IN PROTEIN
Coherently wired light-harvesting in
photosynthetic marine algae at ambient temperatures
Elisabetta
Collini, Cathy Wong, Krystyna Wilk, Paul Curmi, Paul Brumer &
Gregory Scholes
Universities of Toronto, New South Wales and Padua
Nature, 463, pp. 644-7, 4 February 2010 doi:10.1038/nature08811
INTRODUCTION: This low-key paper may in time come to be seen as one of
the decisive studies of the 21st century. The paper shows that room
temperature quantum coherence can occur in biological matter. In 2007,
Engel et al had shown that coherence was possible in organic matter,
but this was only demonstrated at very low temperatures, whereas the
Collini study demonstrates similar activity at ambient temperature. The
paper and related commentaries makes no mention of consciousness,
although a relevance to quantum computing is suggested, which is a
possible step towards discussing consciousness. The main plank of the
arguments against quantum consciousness relates to the speed of
decoherence in biological matter being too quick for coherence to be
relevant to processing, particularly neural processing, in such matter.
This argument looks to have been substantially undermined by the recent
study.
Antenna proteins are an essential part of the photosyntetic
process, which absorbs light and transmits the resulting excitation
between molecules to a reaction centre. Recent research has
concentrated on determining the mechanisms that support a very high
level of efficiency in this energy transport. Light-harvesting antennas
are comprised of eight pigment-molecules, with different pigments
absorbing different frequencies of light. The route the energy takes
across the molecule is important in terms of energy efficiency. Studies
have documented the fact that light-absorbing molecules in some
photosynthetic proteins transfer energy according to quantum mechanical
rather than classical laws even at ambient temperature. This
contradicts the 20th century dogma that long-range quantum coherence
would always decohere in the temperatures found found in biological
systems.
This paper by Collini et al describes X-ray crystallography
studies of two types of marine cryptophyte algae that have long-lasting
excitation oscillations and correlations and anti-correlations,
symptomatic of quantum coherence even at ambient temperature. Distant
molecules within the photosynthetic protein are thought to be connected
to quantum coherence, and to produce efficient light-harvesting as a
result. The cryptophytes can photosynthesise in low-light conditions
suggesting a particularly efficient transfer of energy within protein.
According to the traditional theory, this would imply only small
separation between chromophores, whereas the actual separation is
unusually large.
In this study, performed at room temperature, the
antenna protein received a laser pulse, which results in a coherent
superposition in the protein. The experimental data of the study shows
that the superposition persists for 400 femtoseconds and over a
distance of 2.5 nanometres. Quantum coherence occurs in a complex mix
of quantum interference between electronic resonances, and decoherence
caused by interaction with the environment. The authors think that
long-lived quantum coherence facilitates efficient energy transfer
across protein units.
The authors remains uncertain, as to how
quantum coherence can persist for hundreds of femtoseconds in
biological matter. One suggestion is that the expected rate of
decoherence is slowed by shared or correlated motions in the
surrounding environment. Where light-harvesting chromophores are
covalently bound to the protein backbone, it is suggested that this may
strengthen correlated motions between the chromophores and the protein.
In the same issue of 'Nature' that published Collinis study, the
'News and Views' section of the journal also comments on her paper. It
emphasises that this is the first study in which quantum coherence in
photosynthetic proteins has been observed at room temperature. It
comments on the remarkable efficiency of energy transfer, between the
antennas that guide excitation energy from hundreds of light-absorbing
pigment molecules towards the subsequent reaction centres that drive
biochemical events. Collini is suggesting that quantum coherence could
be a factor in this efficiency.
Earlier studies had observed
coherent behaviour in green sulphur bacteria, but at very low
temperatures. Collini et al observed quantum coherence in the antenna,
and found that this persisted over 400 femtoseconds, in contrast to an
expectation in traditional theory of only 100 femtoseconds. Coherence
was observed between widely separated pigment molecules. This has also
been observed in bacterial light-harvesting complexes. However, this
was at very low temperatures, while the Collini study was at room
temperature. Engel et al, who were responsible for some of the earlier
studies, have speculated that quantum coherence allows antennas to
search for the lowest energy state of the complex more efficiently,
thus enhancing the energy transfer to the reaction centre. Coherence
might help excitations to avoid local energy traps or minima, on their
way to the reaction centre. Covalent binding to the protein backbone is
speculated to make coherence longer lasting.
Perhaps the most
surprising aspect of this latest paper on coherence in proteins is the
speed with which news of the development has made its way to the level
of more popular science, in the form of a useful full page summary by
Kate McAlpine in the 'New Scientist'. She mentions that Gregory Engel,
who was respnsible for the earlier low temperature studies of coherence
in bacterial proteins, is enthusiastic about the Collini result. Engel
and his group have also performed a study at 4 degrees centigrade, much
above previous levels, although below the 21 degrees of the Collini
study. Engel is also quoted as saying that this work could have
implications for quantum computing, where a core problem has been to
operate at the very low temperatures that are usually thought necessary
to prevent quantum decoherence. The speed with which this work has been
picked up and given prominence in a popular science magazine suggests a
background change of attitude to coherence in protein. The vexed
question of quantum consciousness is not mentioned, but the suggestion
of activities within protein as a model for quantum computing is moving
is in that direction.
5.)
A
non-linear model of ionic wave propagation along microtubules
Sataric, M., Tuszynski, J. et al, University of Novi Sad and Cross
Cancer Institute
European Biophysical Journal (2009) 38:637-47, DOI
10.1007
The cytoskeleton is a major component of all cells including
neurons. It is comprised of actin filaments, intermediate filaments and
microtubules, which are comprised of subcomponents of tubulin protein
dimers, formed from an alpha and a beta monomer. These structures are
organised into networks interconnected by proteins, with specific roles
to play in the functioning of the cell. The microtubule is usually
formed from 13 protofilaments. Each monomer of the tubulin dimer has a
C-terminal helix, plus an amino acid sequence, projecting 4-5
nanometres out from the microtubule, and referred to as a tubulin tail
(TT)
These TTs are involved in interaction with motor proteins and
with the microtubule associated proteins (MAPs) that cross-link the
microtubules. The alpha tubulin monomer TT is 19 amino acids long, with
ten negatively charged residues. The TT on the beta monomer is nine
amino acids longer. The detailed charge distribution on the tubulin
surface results in a peak in electrostatic potential at every
protofilament and a trough in the areas between them. The microtubule
as a whole is suggested to be a 'cable' conducting 13 parallel ionic
flows. The flow of ions along the microtubules is postulated to be
mainly channelled through valleys in the electrical potential running
parallel to each of the protofilaments. It is suggested that the TTs
could significantly influence ionic current flow. The ions are
suggested to flow at a radial distance from the surface of the
microtubules.
The model proposed here is that microtubules with
brush-like tubulin tails and surrounded by solvent ions in the cytosol
act as electrical transmission lines. It is suggested that this model
could provide some insight into a role for microtubules in information
processing within neurons.
6.)
Coherence
in stable microtubules
Danko Georgiev, School of Medical Science,
Kanazawa University
Neuroquantology, December 2009, vol. 7, 4, pp.
538-47
Stable microtubules comprise a large proportion of neurons,
and are the main component of the cytoskeleton, which supports the
extended dendritic arborisation and the axons of the neurons. Most
neuron microtubules are stabilised by the cross-linking of microtubule
associated proteins (MAPs), and the capping of the ends of proteins,
both of which suppress frequent assembly and disassembly of the
microtubules. This greater stability in neuron microtubules answers the
often asked question, as to why non-brain microtubules are not seen as
a basis of consciousness. But this does not prevent the
non-consciousness of microtubules outside the brain being trundled out
as an argument against quantum consciousness.
In dendrites,
cross-linking is performed by MAP2 and in axons by MAP-tau. The author
argues that the GDP and GTP molecules are not able to provide energy
for computation within the microtubule, and energy from their processes
is argued to go into the microtubule wall, as a result of the
stretching of pre-existing bonds between the tubulin dimer
subcomponents in the microtubule lattice. The microtubules are composed
of 13 protofilaments. The tubulin subcomponents or dimers are connected
by longitudinal bonds within the same protofilament and lateral bonds
between dimers in different protofilaments. Here, chemical energy has
been transduced into stored elastic energy. The author considers that
this stored elastic energy might be important for the microtubular
functioning within cells. He suggests that microtubular computation
might be driven by interaction between the electric field inside
neurons and the charged elastic brain microtubules.
Reference: Caplow, M. et al - Free energy stored in the microtubule lattice -
Journal of Cell Biology, 127, pp. 1918-24
7.)
Solving
the binding problem: cellular adhesive molecules and their control of
the cortical quantum entangled network
Danko Georgiev, Medical
University of Varna
Cogprints: 2 May 2003
INTRODUCTION: The
author proposes a model by which quantum coherence arises in the
cytoskeleton, is transmitted to the synapse, and from there to
neighbouring neurons via the neurexin-neuroligin complex in the
synaptic cleft. This is suggested to bring a large group of neurons
into quantum entanglement, and to provide a solution for the binding
problem.
The article proposes a possible process to support quantum
entanglement between neurons, based on neurexin and neuroligin. This
involves the 20-30 nanometre wide synaptic cleft, which is filled with
electron-dense material. The presynaptic side has an active zone
containing vesicles of neurotransmitters. Apart from signalling
processes, there is also an adhesive junction at the synapse formed by
neurexins and neuroligins. These are brain specific molecules, which
bind to one another, and are part of a family of molecules known as
CAMS, which are often present at synapses. The author claims growing
evidence for the role of CAMs in modulating both short and long lasting
plasticity. Receptors required for longer term potentiation (LTP) may
be linked to the modulation of the cell adhesion proteins. Adhesion
proteins could modulate glutamate receptors, possibly by altering the
width of the synaptic cleft, and the size of the pre and post synaptic
active zones, and also by altering glial cell processing around the
edge of the synapse. Neurexin and neuroligin appear well suited to link
pre and postsynaptic signalling mechanisms. The C-termini of
neuroligins are inside the postsynaptic neuron and bind to the PDZ,
which is thought to act as a nexus for receptors and signalling
molecules on the postsynaptic side. The C-termini of the neurexins
binds to CASK another PDZ containing protein on the presynaptic side.
The author relates these structures to the proposal that the
cytoskeleton is important to the processing of incoming information in
the brain, and that macroscopic quantum coherence arises in the
cytoskeleton. Beyond this, he is looking for a means by which coherence
passes from one neuron to another. He has rejected the Hameroff
proposal that this happens via gap junctions between dendrites.
There is a thickening of the cell membrane on both sides of the
synapse. The postsynaptic density (PSD) has been proposed to be a
protein lattice that organises receptors, ion channels and signalling
molecules. The proteins in the lattice contain PDZ domains involving
PSD-95 that can bind to many types of synaptic proteins, including
receptors for the main excitatory synapse. CASK, a presynaptic protein
and PSD-95 stabilise the synapse by interacting with neurexin and
neuroligin cell adhesion molecules, or by indirectly linking synaptic
proteins to the cytoskeleton. CASK is tethered to the cytoskeleton by
an actin binding protein. The author suggests that the
neurexin-neuroligin cell adhesion complex could be connected indirectly
to the cytoskeleton and mediate interneuronal quantum entanglement
across the syanptic cleft. This is suggested to allow coherence across
a large group of neurons, as a way of solving the binding problem.
8.)
Neuroligins
and neurexins
Thomas Sudhof, Stanford University
Nature, vol.
455, 16 October 2008, doi:10.1038
INTRODUCTION: Although it is not
part of Sudhof's article, it has been separately suggested that the
neurexin/neuroligin complex could allow quantum coherence that is
proposed to arise around microtubules, and might also involve
presynaptic scaffold proteins, to pass through the synaptic cleft to
subsequent neurons, and thus presumably a whole neuronal assembly. This
has been put forward as an alternative to Hameroff's suggestion that
coherence is transmitted across a whole neuronal assembly via gap
junctions.
Neurexins and neuroligins are cell-adhesion molecules
that connect the presynaptic area of one neuron with the postsynaptic
area of another, mediate signalling across the synaptic cleft, and
specify syanptic functions. The complex is suggested to be important in
the maturation of synapses, and in specifying the properties of
particular circuits. Studies suggest that neurexin and neuroligin are
not, however, essential for synaptic formation, but may be for
subsequent maturation and function. Synapses have high plasticity, and
changes in them can alter the relative contribution of synapses in a
circuit. These changes probably depend on the action of the cell
adhesion molecules, neurexin and neuroligin. These molecules probably
bind to one another, and interact with proteins within the neurons.
Current studies suggest that they mediate signalling between
presynaptic and postsynaptic areas. Neurexins come in many isoforms,
and it is suggested that these could code for different interactions at
the synapses.
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