Evidence for Globalized Consciousness

Pythagorean

new article (note, the above quote is from the news article, so subject to journalist interpretations):

http://neurosciencenews.com/consciou...rontal-cortex/

peer reviewed article:

http://www.cell.com/neuron/abstract/...273(12)00380-7

madness

I don't really see how they drew this conclusion. Everything from the thalamus to the visual cortex to the parietal lobe to the frontal cortex correlates with the percept during multistable perception. (http://www.cell.com/trends/cognitive...2809%2900119-3)

zoobyshoe

This is saying that visual consciousness is located in the temporal lobes and also in the lateral prefrontal cortex. I am not seeing how this supports the view it's global, as the article asserts it does. Some piece of that reasoning is missing as far as I can see.

Pythagorean

the two camps have been localized vs. global. Global really just means not localized. I.e. distributed... that there's no "seat of consciousness"

zoobyshoe

Where do the localizers localize it to, the thalamus?

Pythagorean

I think the most famous example is Crick and Koch:

Crick and the claustrum:
http://www.nature.com/nature/journal...a.html?guid=on

But, I didn't think there's just one. I remember some noise being made about the precuneus:

The Precuneus:
http://www.ncbi.nlm.nih.gov/pubmed/17603406

There's lots of attention on the frontal lobes too.

zoobyshoe

A guy named Hypnagogue who used to post here brought the claustrum to me attention once (he'd probably been reading about Crick) but this is the first I've heard of the precuneus being a suspect. It seems that two separate things are being discussed, though. In your article the issue is consciousness of the visual field. The precuneus is asserted to have bearing on sense of self. These could both be true and non-contradictory.

madness

I also think we need to remember that localising the "seat of consciousness" is a bit of a copout. We have localised it to the brain so far but we still have no clue how it works. Localising it to an area of the brain would be much the same. It would certainly be interesting and would direct further research, but it wouldn't be much of an answer to the real mystery of consciousness.

zoobyshoe

It would only be a copout if you stopped there and thought you'd explained consciousness. If it is localized, though, you won't be able to explain anything until you find the location and analyze what's happening there.

Pythagorean

You'd have to have accepted distributed consciousness already to see consciousness as something that can be divided functionally like that :)

madness

I think that brings up a nuance in the distributed/localised debate. Different aspects could be localised in different brain areas, but there is a stronger sense of distribution in which no aspect of consciousness might be localised any single brain area. This would be the case if visual consciousness was itself distributed throughout the brain, and so was the sense of self etc. I would probably favour the stronger form of distributed consciousness. Bear in mind also that our overall consciousness seems take take place after the integration of the various senses and the sense of self etc.

zoobyshoe

You bastard! Saw right through me! :)

zoobyshoe

I don't know if there are any "schools of thought" that assert this, but my own notion is that consciousness is a collection of tiny parts, pixels as it were. A firing neuron may be the equivalent of a pixel. Groups of neurons that fire in response to the same things, say stimulation by light wavelength (color perception), constitute a kind and level of consciousness unto themselves. Were there some primitive life form that only had this kind of neuron (and accompanying receptors) we could call it conscious, but it would, of course, be a very limited consciousness compared to ours.

By this reasoning, if you cover an eye with your hand you are subtracting some consciousness. Close both eyes, you subtract more. Go to sleep and you subtract a very large chunk.

Someone could easily consider this simplistic, I'm aware. It ignores the whole issue of "intelligence" among other things.

madness

I would tend to side with the predictive models of perception (and by extension consciousness). These theories model perception as the result of an internal, heirarchical, top down set of predictions which attempt to "explain away" the incoming sense data. In this way, a group of neurons don't fire in response stimulation by a wavelength of light in a bottum up constructive manner. In fact, neural signals should represent the error between prediction and incoming data according to these models.

To me this seems to provide a more integrated and less atomistic view of consciousness. I also think it is more in line with the fact that we are conscious at all. A passive, bottom up filter between sensory input and motor output would intuitively seem less conscious than a system which generates an internal model of the external world and attempts to predict the incoming stream of sense data.

apeiron

Yes, this is simplistic.

It is not a case of local vs global but about how the two things work together. So "a state of conscious awareness" is both a highly particular state (the brain is intent on some single focal view) and also a highly general state (at the same time, it is actively pushing everything else it "knows" into the background).

So where it comes to neural firings, the dog that didn't bark, my dear Watson, is also part of the state.

All neurons are firing off all the time. Unless they are dead. But firing rates get suppressed, become unsynchronised, etc, if the brain wants to push "what they are saying" into the background.

This is why some theories of consciousness (like one of Crick's multiple attempts to locate a seat of awareness) stress the thalamus, a crucial bottleneck in orchestrating what cortical activity is currently being enhanced, and what suppressed.

But the prefrontal is also very active in this same orchestration (reaching down to the thalamus to control it) so can also seem to be a seat of consciousness (of the spotlight of attention).

So a better mental image is to think of the brain as a buzzing confusion of neural rustling - the kind of day-dreamy unfocused awareness you get when idling. Which can then be kicked into states of high-contrast representation by turning up some neurons/circuits, and suppressing the contributions of others.

In this way, consciousness is the result of local~global differentiation and integration. The whole of the brain is always involved. But locally, some activity is ramped up, other activity suppressed. And the dogs that don't bark count along with the dogs that do so far as the final experience goes.

This explains stuff like priming or the fact you only notice the hum of the fridge when it switches off. Your brain was representing the hum, but it was also suppressed to the level when it was not part of your focal spotlight. But the sudden absence of a now expected part of your mental background is the dog that stopped barking. And so the brain shifts its focus to find out what happened exactly.

zoobyshoe

This all makes sense, and it describes what my mind always seems to be up to, but it seems you are equating attention with consciousness. I would class them as two separate considerations.

apeiron

No, it would be the sucessfully attended plus the successfully ignored that adds up to some particular state of consciousness in this view. If there is a spotlight of attention, then by the same token there is the penumbra of all that is not being attended - or rather actively suppressed.

So attention leads to what is reportable. And that can seem like all that matters. But you may know from fine arts 101 that they start you off by focusing on negative space so that you "really see things". You can't have the light without the shade, the object without the context. So you have to step back and learn to clearly see all the things you had learnt to ignore.