Consciousness is a state? Or a sequence of events?
Stuart Hameroff
Andrew Brook
> Sure, if all the inputs and outputs to a certain
> important set of neurons are there, a conscious state could be there,
> maybe even would be there. But the conscious state could just as well
> extend over the whole system: inputs, neurons, and outputs. There is no
> reason that I know of, no reason from brain imaging for sure, to view
> conscious states as not highly distributed representations.
Agreed...consciousness usually involves activity in varying regions (though it
may also be localized, as in Zeki's V4 study). But why assume consciousness is
a state? Consciousness is, by all accounts, a process...specifically sequences
of discrete events...probably at gamma synchrony (~40 Hz)
Consciousness as a sequence of events (rather than a continuous state) is
consistent with ideas put forth by many people including Whitehead, William
James, Buddhists, Nancy Woolf, me, Christof Koch, Rufus van Rullen, ...among
many others..
If you say consciousness is a state, ..a condition of...the brain...what does
that tell us? what kind of condition? A conscious condition? Circular, to say
the least unless you characterize better. If you say, well neural
activity...what specific neural activity?
OK, if you say consciousness is a sequence of events, then what kind of event?
Well, possibly quantum state reductions...(Recent work shows macroscopic
quantum processes and entanglement at warm temperatures - the decoherence
problem is evaporating). But conscious events could also be classical
events...some threshold effect..
Andrew Brook
> All imaging
> tells us is that having state X
(or having a sequence of events X)
> is correlated with some region of the
> brain (actually, it is almost always multiple regions of the brain)
> using ever so slightly more oxygen or .... than background. Well,
> background activation is still activation. Who knows over what range of
> neurons X extends?
This is a very good point. Imaging shows only relative changes...More
importantly, we dont know if the metabolic demands increasing oxygen
utilization or blood flow which give the imaging signal relate to the specific
activities directly
responsible for consciousness or not. In other words we dont know whether
consciousness itself is the largest consumer of energy among activities related
to consciousness, as opposed to activities broadcasting the results of conscious
processes. Plus the signals occur after consciousness...probably
as a result of consciousness.
Gamma synchrony EEG is far and away the best neural correlate of consciousness.
Gamma synchrony derives from local field potentials driven by
dendritic-dendritic gap junction networks (which can encompass large regions of
brain). So consciousness could be sequences of events (corresponding with gamma
synchrony) occurring with low energy consumption in dendrites, leading to high
energy axonal spike activities to convey the results....There is no evidence
that axonal spikes are *directly* responsible for consciousness.
Jonathan Edwards
> A juicy pyramidal neuron, I am told, has a ~40,000 bit input. If it
> makes analogue use of phase, and short term retention phenomena, like
> dendritic spine twitching,
By the way, dendritic spine actin filaments which do the twitching are connected
to microtubules in the dendrite...you're getting warmer...
>....it could front an experience worth a
> significantly greater number of bits, but I doubt we go that much
> beyond the preferred number - 100,000. How the heck you get the Mona
> Lisa let's put to one side because its tricky however we try. But we
> must remember that all we need is enough bits to encode; the
> presentee can turn it into what might appear to be megabytes of
> pixels, just as Word gives you a massive pdf.
I assume the presentee is whatever entity in the brain experiences
consciousness. Baloney. The experiencer/presentee is the process/event itself.
> The trouble with groups of cells is that they cannot have a richer
> input bitscore because nothing (no presentee) gets more bits than one
> cell.
If we recast presentee as the neural structure(s) having the experience (the
NCC), then I beg to differ. If the NCC is groups of neuronal dendrites
(pyramidal cells, cortical GABAergic interneurons etc) gamma synchronized by
gap junctions, then the the input bitscore, as you put it, is much larger. Like
100,000 neurons worth, many of which are pyramidal cells.
> And we do not want too much input (40,000x10,000 say). There is no
> reason to think that sentient units in a brain would be designed to
> receive signal and noise (or duplication) and filter out. It is much
> easier to envisage input as just signal - so more than 100,000 bits
> would be embarasse de richesse. Assuming biological efficiency, we
> are looking for 'just enough' and no more please.
Which is why the quantum approach works perfectly. The embarasse de richesse
involves unconscious quantum information which...at the instant of state
reduction/conscious event...chooses a subset to become classical perception (or
manifest willfil action)
By the way, new results show entanglement transfer and entanglement of
macroscopic objects at warm temperaure.
> So having one experience 'extend over a system' cannot work.
Gap junctions allow continuous membrane and cytoplasm, so gap junction-connected
neurons behave like one giant neuron, as Kandel described them, and have been
termed hyper-neurons, or dendritic webs which do, in fact, extend over the
system.
> extension of
> experience over a large area cannot, as James's argument
> devastatingly shows, be many cells sharing one experience, unless you
> concoct some new physical processes which would require neuroscience
> to be trashed and rewritten.
Like quantum computation in microtubules?
Actually, the Penrose-Hameroff Orch OR model is perfectly consistent with
neuroscience. There is no need to trash neuroscience, just modernize it and
dont stop at the membrane. And think about dendritic webs or hyper-neurons as
the NCC.
The analogy of axo-dendritic, chemical synapse bits to classical computers to
account for consciousness is beyond stale and just doesnt jive with the data
(e.g. gamma synchrony as the NCC). These processes are essential to brain
function, but, for example, continue during general anesthesia.
My paper in Anesthesiology last August ....see
http://www.quantumconsciousness.org/documents/twined_000.pdf
deals with the mechanisms of anesthetic
gases which selectively affect consciousness, sparing evoked potentials,
sub-gamma EEG and various autonomic drives. nesthetic gases act exclusively by
quantum interactions.
cheers
Stuart
Stuart Hameroff M.D.
Professor, Anesthesiology and Psychology
Director, Center for Consciousness Studies
The University of Arizona, Tucson, Arizona
www.consciousness.arizona.edu/hameroff
Andrew Brook
of conscious 'states' as processes of some kind than as either momentary
or unchanging states. I tend, not too perspicuously, to use 'state' as a
standin for everything but objects: events, processes, properties, ... .
I should be more careful, though such care does come at a price: clunky
English. .
Andrew
--
Andrew Brook
Chancellor's Professor of Philosophy
Director, Institute of Cognitive Science
Member, Canadian Psychoanalytic Society
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