The Hard Problem of Gravity

[Nick227]

You're going to have to explain what you mean by that because the situation is much more complicated than you seem to imply. Do you, for instance, know that someone can be in deep coma and have an alpha rhythm in their frontal region? Do you know that folks with Parkinson's disease can walk around with a 6 Hz background, while the same activity in another is associated with stupor?

Are these examples statistically meaningful? Is there a general pattern where frequency relates to mental state?

Nick

 

[PixyMisa]

So you're saying that if pretty much your whole consciousness is filled with sound or light of a certain frequency and your eyes are shut then there's no effect on conscious report or EEG?

Not that there is no effect, but that there is no general correlation between the frequency of the sound or the light and the frequency of the brainwave. It just doesn't work - with the possible exception (I don't know enough about this) of photic epilepsy.

And I don't think that seizures are the goal here.

 

[Ichneumonwasp]

So you're saying that if pretty much your whole consciousness is filled with sound or light of a certain frequency and your eyes are shut then there's no effect on conscious report** or EEG? I used to have one of the machines and it did seem pretty relaxing. I did also have a primitive EEG thing about 15 years ago, electrodes on the temples, but I can't recall if I connected it up at the same time. I recall that it seemed to be possible to alter the brainwaves consciously, through inducing relaxation via deeper breathing.

** aside of saying my eyes are filled with light!

Nick

What? No. Look, changes in the environment change what happens in the brain. Saying so is trivial at best.

Flashing sound has no effect on the EEG. Flashing lights at best might produce a photic driving response. There is no big change in what happens in the EEG or the person as a mere result of these stimuli. If you want to relax with some sort of sound or light, then you relax. Relaxation is reflected in the EEG, but that is different from saying that flashing lights or sounds change the EEG.

I appreciate that you have played with a few electrodes on your head, but I read EEGs for a living. I look at them every day (except some weekends).

 

[Ichneumonwasp]

Are these examples statistically meaningful? Is there a general pattern where frequency relates to mental state?

Nick

I don't understand what you mean by statistically meaningful. There is a close association between decreased dominant frequencies in the EEG and Parkinson's disease and there is a one to one correspondence between upper brainstem damage and alpha, theta, or spindle coma patterns on the EEG.

There is no general pattern that relates to all mental states. The EEG is, at best, a very gross measure of activity. People with certain degenerative processes regularly walk around with very slow EEG backgrounds -- the same sort of background that in an otherwise normal person would be associated with stupor or coma.

For a dramatic example, say a Parkinson's patient with a 6 Hz background suffers severe anoxic injury. There are several possible EEG patterns that may result, but one of them is diffuse, unreactive alpha (8-12 Hz) activity. So this person may move from a diffusely slow background while being conscious to a faster frequency while being in a coma.

 

[westprog]

:Looks around thread and at the destruction wrought by himself, hands on head:

Oh my lovely goddesses, was I doing jello shots yesterday?
Where are my car keys?

And whose monkey is this?

I did notice a slight difference in tone all right.

I know what it's like. There's a stage in the evening when you're leaving the bar, you're not sleepy and you say "Time to hit the philosophy forum."

 

[porch]

No, I mean that the subject is not dealt with in Physics texts. I'm not making some argument on philosophical principle, I'm addressing the scientific consensus.

And it's easily rebutted by anyone who has a chapter on subjective experience in his physics textbook.

Ah, yes, just like the Hard Problem of Bile Production. Or is there some wiseacre out there who can show me a chapter on bile production in his or her physics textbook?

 

[Nick227]

What? No. Look, changes in the environment change what happens in the brain. Saying so is trivial at best.

Flashing sound has no effect on the EEG. Flashing lights at best might produce a photic driving response. There is no big change in what happens in the EEG or the person as a mere result of these stimuli. If you want to relax with some sort of sound or light, then you relax. Relaxation is reflected in the EEG, but that is different from saying that flashing lights or sounds change the EEG.

I totally agree.

I was not saying that entrainment takes place, as one would anyway need I imagine a stimulous that did not so overwhelm consciousness (as flashing light or sound does) to try and demonstrate this. It would have to be more subtle and ideally not consciously reportable.

I am saying that if consciousness is largely filled with a certain sound or light frequency for a period of time, then it seems reasonable to me that the frequency of brainwaves will align with this. I mean, I do not know enough about how these waves are created by neurons but this seems to me reasonable. I imagine the principle factor that determines whether this happens is how much of consciousness is overtaken by the frequency. If someone is flashing a strobe in the background whilst you're carrying on a conversation then I guess not much. If you relaxing with eyes closed and a sound of specific frequency is pretty much all your aware of, then I imagine it's much more likely.

Nick

 

[PixyMisa]

I am saying that if consciousness is largely filled with a certain sound or light frequency for a period of time, then it seems reasonable to me that the frequency of brainwaves will align with this.

This does not happen.

 

[Belz...]

No, I mean that the subject is not dealt with in Physics texts. I'm not making some argument on philosophical principle, I'm addressing the scientific consensus.

But when one brings into play qualia, then we immediately see the dualistic assumptions that underly that hypothesis.

So, what do you think of qualia ?

 

[Ichneumonwasp]

I totally agree.

I was not saying that entrainment takes place, as one would anyway need I imagine a stimulous that did not so overwhelm consciousness (as flashing light or sound does) to try and demonstrate this. It would have to be more subtle and ideally not consciously reportable.

I am saying that if consciousness is largely filled with a certain sound or light frequency for a period of time, then it seems reasonable to me that the frequency of brainwaves will align with this. I mean, I do not know enough about how these waves are created by neurons but this seems to me reasonable. I imagine the principle factor that determines whether this happens is how much of consciousness is overtaken by the frequency. If someone is flashing a strobe in the background whilst you're carrying on a conversation then I guess not much. If you relaxing with eyes closed and a sound of specific frequency is pretty much all your aware of, then I imagine it's much more likely.

Nick

You can think it's reasonable, but it doesn't happen. When, during an EEG, photic stimulation is used, the person's whole attention is focused on the flashing light (they are asked to open and close their eyes throughout the procedure and they have this very irritating flashing light source right in front of them). Some people will show a driving response and some will not; the driving response has nothing to do with consciousness of the stimulus. It's just the way that some folks occipital lobes are set up.

ETA:

I just went back and checked the EEGs I have read today. We've only had three so far. One had a photic driving response and two did not. There was no other change in the EEG during photic stimulation with any of them. Whatever you want to believe you can believe, but the data suggest otherwise.

 

[Belz...]

For a dramatic example, say a Parkinson's patient with a 6 Hz background suffers severe anoxic injury. There are several possible EEG patterns that may result, but one of them is diffuse, unreactive alpha (8-12 Hz) activity. So this person may move from a diffusely slow background while being conscious to a faster frequency while being in a coma.

That is absolutely fascinating. I just love this forum, don't you ?

 

[Ichneumonwasp]

That is absolutely fascinating. I just love this forum, don't you ?

Yes. I've learned a ton from so many folks, including you, I can't even begin to quantitate it.

Messing up on what EEGs can and can't do and what they represent is one of my pet peeves I'm afraid.

 

[westprog]

But when one brings into play qualia, then we immediately see the dualistic assumptions that underly that hypothesis.

So, what do you think of qualia ?

Qualia are what happen when you think about qualia. So the dualistic assumptions seem fairly prevalent.

 

[Nick227]

I don't understand what you mean by statistically meaningful. There is a close association between decreased dominant frequencies in the EEG and Parkinson's disease and there is a one to one correspondence between upper brainstem damage and alpha, theta, or spindle coma patterns on the EEG.

There is no general pattern that relates to all mental states. The EEG is, at best, a very gross measure of activity. People with certain degenerative processes regularly walk around with very slow EEG backgrounds -- the same sort of background that in an otherwise normal person would be associated with stupor or coma.

For a dramatic example, say a Parkinson's patient with a 6 Hz background suffers severe anoxic injury. There are several possible EEG patterns that may result, but one of them is diffuse, unreactive alpha (8-12 Hz) activity. So this person may move from a diffusely slow background while being conscious to a faster frequency while being in a coma.

Fair enough. Thanks.

I would love to understand more about these common references to brain frequencies seen in all this consciousness research-related literature. Firstly, there seem to be these "brainwaves." Then these French neuroscientists talk often about a "self-sustained reverberant state of coherent activity that involves many neurons distributed throughout the brain," or similar words. Then I read about the RAS and its role in creating neuronal oscillation. It's a bit confusing for me, though I note that the French guys also sum up...

"In the light of these considerations, the present study of neuronal oscillations should be considered as an exploration of a broad theoretical proposal, rather than an assessment of a precisely articulated prediction. Actually, theoretical considerations by other groups [55,56], as well as recent experimental measurements [57–62], suggest that for distant cortical areas, synchrony cannot be easily achieved in the high-frequency range, where the oscillation period is short relative to corticocortical transmission delays. Thus, these articles would predict that long-distance synchrony associated with conscious access should preferentially occur in the beta frequency range (13–30 Hz), whereas local recurrence would mostly concern the gamma range (>30 Hz), even for masked stimuli [7]."

Can you shed more light?

Nick

 

[Ichneumonwasp]

Fair enough. Thanks.

I would love to understand more about these common references to brain frequencies seen in all this consciousness research-related literature. Firstly, there seem to be these "brainwaves." Then these French neuroscientists talk often about a "self-sustained reverberant state of coherent activity that involves many neurons distributed throughout the brain," or similar words. Then I read about the RAS and its role in creating neuronal oscillation. It's a bit confusing for me, though I note that the French guys also sum up...

"In the light of these considerations, the present study of neuronal oscillations should be considered as an exploration of a broad theoretical proposal, rather than an assessment of a precisely articulated prediction. Actually, theoretical considerations by other groups [55,56], as well as recent experimental measurements [57–62], suggest that for distant cortical areas, synchrony cannot be easily achieved in the high-frequency range, where the oscillation period is short relative to corticocortical transmission delays. Thus, these articles would predict that long-distance synchrony associated with conscious access should preferentially occur in the beta frequency range (13–30 Hz), whereas local recurrence would mostly concern the gamma range (>30 Hz), even for masked stimuli [7]."

Can you shed more light?

Nick

Sure. Short story -- they're speculating.

Long story -- they're still speculating. All that paragraph says is that you can't expect a relay loop from brainstem to cortex to cycle in the 40 Hz range because of the distances involved (not to mention that most info from brainstem to cortex passes through the thalamus, so there's the synaptic connection there to contend with). I'd have to work out the math, but that's probably correct. I don't think anyone suspects that 40 Hz event related potentials involve any sort of brainstem cortical loop. Instead, those sorts of potentials (and to see them requires all sorts of filtering and very special, controlled situations -- you don't see these sorts of potentials in routine EEGs) depend on local cortico-cortical loops (neurons near one another in the cortex).

The problem with discussing all this stuff still is that we mean so many things by 'consciousness'. There is the consciousness that results from activation of the RAS (reticular activating system for anyone who does not know), and this mostly consists in being awake and probable aware to some extent. Then there is the whole issue of directed awareness, which depends critically on parietal lobes and to some extent the frontal lobes (where working memory seems to take place). Then there is the issue of emotion/feeling, which involves the limbic system. Then there is the issue of the contents of consciousness, etc, etc.


"self-sustained reverberant state of coherent activity that involves many neurons distributed throughout the brain" is speculation about what is going on but probably reflects the reality fairly closely (though the 'self-sustained' label is unnecessary). this just means that a bunch of neurons are involved in some type of neural network performing some function. It's a very vague phrase that tells us nothing more than what we already knew about how the brain works.

'Brainwaves' just means that we see something looking sinusoidal on an EEG; but what is really going on is that there are local differences in the activity of neurons reflected in the number and intensity of EPSPs and IPSPs in different brain regions over time (that is what EEGs measure).

In other words, they are speaking at a very gross level in very abstract terms that doesn't really help much.

EEGs are not going to give anyone the answer to consciousness.


ETA:

I guess I should also add that most of the frequencies reflected in the EEG are thought to arise from local cortico-cortical and thalamo-cortical loops. Sleep spindles (the characteristic feature of stage 2 NREM sleep; they are also present in deeper stages but not as easy to see) seem to result from a particular thalamo-cortical loop. Most of the beta range activity is thought to arise not from brainstem cortical but from cortico-cortical activity -- stroke, for instance knock out this activity because they undercut the cortico-cortical connections. All of this is speculation, bt we do know that if you isolate a particular part of cortex from it's surrounding that it will produce very slow (delta) activity (1-3 Hz). Whether that is due to the fact that the cortex is not communicating with neighboring cortex, brainstem, or thalamus is anyone's guess.

 

[rocketdodger]

So you want every possible difference in behaviour between a drop of water and a snowflake? That would take a book. There are many, many differences.

No, I don't really care. I just wanted you to finally admit that there are indeed differences.

What isn't happening is some fundamental physical process that occurs in the one and not the other. Neither one is more random or more deterministic than the other.

Right. But there are differences -- you just admitted it.

So guess what, genius? Whatever you want to call those differences between a drop of water and a snowflake, and it doesn't matter what you call them because they exist nonetheless, those are the same types of differences that people refer to with the term computation.

It's both a meaningless question and not relevant to my assertion that there is no process going on in a working computer that isn't also going on in a heap of components lying on the floor, and the idea that there is something called "computation" that is happening in the one and not the other is not a physical theory.

Wrong.

There are clearly differences between the two systems. Just like there are between a drop of water and a snowflake.

Educated people call some of those differences computation.

For you to assert that such a thing does not exist in a "physical" sense is utter stupidity, especially in light of the fact that you just admitted such physical differences exist.

 

[Nick227]

Sure. Short story -- they're speculating.

Long story -- they're still speculating. All that paragraph says is that you can't expect a relay loop from brainstem to cortex to cycle in the 40 Hz range because of the distances involved (not to mention that most info from brainstem to cortex passes through the thalamus, so there's the synaptic connection there to contend with). I'd have to work out the math, but that's probably correct. I don't think anyone suspects that 40 Hz event related potentials involve any sort of brainstem cortical loop.

OK, thanks. All great stuff. Thanks for taking the time to write it out so thoroughly.

Nick

 

[Belz...]

Yes. I've learned a ton from so many folks, including you, I can't even begin to quantitate it.

People learn from ME ? I thought I was just here for the pith.

 

[Belz...]

Qualia are what happen when you think about qualia.

Turtles all the way down, eh ?

Seems to be like "qualia" are not only unfalsifiable and undefined, they also don't answer the question of what consciousness is.

 

[Belz...]

It's both a meaningless question and not relevant to my assertion that there is no process going on in a working computer that isn't also going on in a heap of components lying on the floor, and the idea that there is something called "computation" that is happening in the one and not the other is not a physical theory.

Wait, wait. There are NO differences between computer components and a working computer ?

Dammit. Why did I even bother assembling it, then ?