How the Brain Does Consciousness: Biological Research Perspectives

[Piggy]

In light of that, I thought I'd post a small bit of the interview with Christof Koch that I linked to above.

Koch: There is no conscious entity inside my head that serves the role of conductor. That's not to say that there may not be places in the brain that act akin to a conductor, that sort of synchronize and that coordinate the various parts of the brain that fire independently, because one of the remarkable phenomena of consciousness is, everything's integrated.

When I look at you and you talk, your voice comes out of your mouth. When you move, the motion I perceive is attached to your head. Now in the brain, all those things are analyzed in different parts of the brain. So you need some sort of entity that pulls all these different networks of the brain together.

RL: Is there a place in the brain that does that?

Koch: Well, Sir Francis Crick and I think so.... There's this odd structure in the brain called the claustrum.... and it's a small area, it's sort of an elongated sheet-like structure beneath the cerebral cortex -- you have two of them, one on the left and one on the right -- and what's remarkable about it, indeed this structure receives input from almost every cortical area, so it seems to be in an ideal position if you want to go to the metaphor of synchronizing all the different activities and making sure they're all in some sort of lock step.

A couple of relevant points from the Wiki article relating Koch with (upcoming) Gazzaniga:

Integration of modalities

Through a number of different studies, summed up succinctly by Crick and Koch, it has been found that the claustrum is, it seems, crucial in modality integration. Objects in real life have many different simultaneous characteristics such as: sound, shape, color, speed, weight, smell, etc. It is necessary for us to take in all of this information and integrate it together to potentially one object. In doing so, processing can take place, and the brain can determine the necessary actions to take. If this integration did not take place, one would not be able to converge all the information into a single percept, and would thus be perpetually confused. The claustrum is crucial in this process.

Role in Functional timing

Perhaps just as important as the ability to take in multiple modalities is the claustrum's capacity for functional timing. Few latency experiments have been performed (more would definitely be useful), but it is clear that the claustrum in one way or another is a big part of taking all the different sources of information and integrating them together so they are processed at the same time. Without this ability, the inherent differences in processing timing for vision vs. hearing and other types would take over and one would never be able to combine information and have a single percept.

However, adequate studies are still lacking, and more research will be needed in order to attain the necessary detail and confidence regarding the claustrum.

 

[INRM]

What about the Centromedian Nucleus? Does it receive input from every cortical area too; furthermore, are there connections between it and the Claustrum?

 

[Dancing David]

It certainly seems to be the case for snakes.

Also, I recently read about a study on wombats who have been isolated from predators on an island for nearly 10,000 years, and they still have a freeze response to stuffed predators but not to other stuffed animals or objects.

Citation?

 

[Piggy]

Citation?

I was wrong about the wombats, it was wallabies.

Dan Blumstein did the study. "Insular tammar wallabies (Macropus eugenii) respond to visual but not acoustic cues from predators". Behavioral Ecology 11:528-35.

ETA: I'll have to dig further for the snake studies.

 

[Piggy]

What about the Centromedian Nucleus? Does it receive input from every cortical area too; furthermore, are there connections between it and the Claustrum?

I'm sure there are folks here who can tell you more, in the meantime here's the wiki:

It sends nerve fibres to the subthalamic nucleus and putamen. It receives nerve fibres from the cerebral cortex, vestibular nuclei, globus pallidus, superior colliculus, reticular formation, and spinothalamic tract.

Its physiological role involves attention and arousal, including control of the level of cortical activity. Some frequencies of extracellular electrical stimulation of the centromedian nucleus can cause absence seizures (temporary loss of consciousness) although electrical stimulation can be of therapeutic use in intractable epilepsy and Tourette's syndrome. General anaesthetics specifically suppress activity in the ILN, including the centromedian nucleus. Complete bilateral lesions of the centromedian nucleus can lead to states normally associated with brain death such as coma, death, persistent vegetative state, forms of mutism and severe delirium. Unilateral lesions can lead to unilateral thalamic neglect.

Some have suggested the controversial notion that human consciousness resides fully or at least mainly in the centromedian nucleus, since damage or change to the area alters consciousness significantly.

It is not noted who "some" are.

 

[Piggy]

What about the Centromedian Nucleus? Does it receive input from every cortical area too; furthermore, are there connections between it and the Claustrum?

Btw, the Centromedian Nucleus is part of the ILN that Gazzaniga is talking about in my earlier citations.

 

[Jeff Corey]

That's how it is in the Harper Collins edition of Human. Could be that the words "one half of" were omitted ("by giving a visual command to one half of the eye") and not noticed, or that only one eye was used... I'm pretty sure I recall Gazzaniga using equipment to present commands to half the visual field.

Well, your book is clearly wrong on that point. And, yes, I linked to Sperry's tachistoscope set up when I first raised this point. I notice errors like that because they are cues to the reliability of the information posted. Information available in any good intro psych text.

 

[Dancing David]

I was wrong about the wombats, it was wallabies.

Dan Blumstein did the study. "Insular tammar wallabies (Macropus eugenii) respond to visual but not acoustic cues from predators". Behavioral Ecology 11:528-35.

ETA: I'll have to dig further for the snake studies.

Thanks!

 

[Piggy]

Well, your book is clearly wrong on that point. And, yes, I linked to Sperry's tachistoscope set up when I first raised this point. I notice errors like that because they are cues to the reliability of the information posted. Information available in any good intro psych text.

Well, it's certainly a clue regarding that one particular phrase in the book and whether or not it may be in error. But I don't see that this casts any real doubt on the split brain studies themselves, which is what's important here. Or are you suggesting that an apparent error in one phrase of one sentence discounts Gazzaniga's entire book?

 

[Piggy]

Well, your book is clearly wrong on that point. And, yes, I linked to Sperry's tachistoscope set up when I first raised this point. I notice errors like that because they are cues to the reliability of the information posted. Information available in any good intro psych text.

Btw, a couple more points....

You do realize that Gazzaniga worked with Sperry on the original experiments, no?

Secondly, here's an image from Dr. G's "The Split Brain Revisited" (1998) describing the experimental set-up.

Here is Dr. G's response to a viewer question from Scientific American Frontiers' "Ask the Scientist" sometime in the late '90s:

Q: If the right brain tells us what faces look like, what happens if we shut our left eye when looking at an Arcimboldo painting?

A: Remember how the visual system works. Each eye sends information to both half brains and the information is divided up in the following way. If you fixate a point, everything to the left of fixation goes the right brain and everything to right of fixation goes to the left brain. So, what you means to ask is, what happens when you place the Arcimboldo pictures to the left of fixation? In normals, not much since their corpus callosum is still intact.

Notice the typo: means instead of mean. Despite that, it's clear that Gazzaniga is not at all confused about how the visual system works.

Now, are you still going to try to suggest, based on what appears to be an error in one sentence in one book, that Gazzaniga is somehow generally unreliable? Or that he doesn't know the information in intro psych texts (despite editing this graduate text)?

I'll see if I have time tonight to look the passage up again, btw, and make sure I didn't mistranscribe it. But even so, I don't think it's a problem if we're focusing on the results of the studies and what they imply about consciousness and the brain.

 

[Piggy]

And one more thing, Jeff Corey....

Here's what I should have said about this whole thing to begin with....

Wow, that's a doozy! Thanks for pointing it out.

I think I'll write the author and publisher and let them know so they can correct it.

Amazing that this book came out in 2008 and no one's caught that yet.​

Would have saved a lot of trouble.

Anyway, got to work late today, might post more chapter 8 stuff later if I can.

 

[TmoonII]

How can someone dismiss philosophy while actually doing philosophy?

Probably a short communication span.

 

[Piggy]

Then there's being conscious of something, better known as "attention."

Because of a recent gripe by Beelzebuddy that I may not have been following links, I decided to do a little back-reading and respond to anything I might have shrugged off.

In this post there were several cites, but not all of them dealt with consciousness -- e.g. the discussion of whisker response in mice... it is doubtful that all input from the whiskers is consciously experienced.

But this bit here relates to other posts as well, in which Beelzebuddy attempts to deny the validity of research into consciousness on the grounds that only sub-processes can actually be identified in the brain.

Before posting cites from Koch which demonstrate that this is not accurate, I'd like to note that this specific claim regarding attention is incorrect.

I'll begin with a cite from the same chapter in Human that I've been citing in recent posts:

You should note here an important point: Attention and consciousness are two separate animals. First off, cortical processors control the orientation of attention. Although there may be top-down voluntary control, there may also be bottom-up nonconscious signals of such strength that they can co-opt attention. We experience this all the time. You may be consciously thinking about the project that you are working on, when off go your thoughts to somewhere else, seemingly beyond your control. Second, although attention may be present, it may not be enough for a stimulus to make it to consciousness. You are reading that article about string theory, your eyes are focused, you are mouthing the words to yourself, and none of it is making it to your conscious brain, and maybe never will.

There is also a large body of research that depends on the fact that attention and consciousness are not equivalent, studies involving the processing of "subliminal" visual cues which are perceived and understood by the brain, and used in later tasks, but which were not consciously perceived at the time and cannot be consciously recalled later.

The problem with trying to do away with "consciousnes" is the same as trying to do away with the concept of "running".

Sure, if we study the physiology of running, we are always going to encounter more granular processes such as muscle cell contraction and relaxation, the firing of neurons, the flexing of tendons and ligaments, changes in the articulation of joints and the spatial relationships of bones, and so forth.

But we cannot understand running merely by understanding these, because these same sub-processes are involved in bodily functions other than running. We can understand everything about them and still not understand running.

No, to understand running, we have to study running. And to understand consciousness, we have to study consciousness -- studying memory, language, attention, emotions, and so forth by themselves will not suffice.

Furthermore, there is no need to "find" consciousness "in the brain", for the same reason that there's no need to "find" running "in the legs". Running and consciousness are behaviors, not tissues, although they are both the direct result of the action of certain tissues in the body. To figure out how the body performs either behavior, we have to study the relevant body parts in action as they perform the behavior.

The existence of consciousness is not something that needs to be theoretically proven, just as the existence of running is not something that needs to be theoretically proven -- they are confirmed by simple observation.

The principal difference is that we currently know so little about the physical mechanisms that cause conscious experience that we cannot yet even produce a satisfactory definition of what it is we're observing -- Koch calls the current state of research "the inchoate science of consciousness". (This thread, btw, does not attempt to provide a more systematic view of consciousness than is available from the research itself.)

However, Koch does have a few observations (which can be drilled into if anyone cares to) regarding what is known [from "The Neurobiology of Consciousness" in The Cognitive Neurosciences (2009), verbatim]:

• Interaction with the world is not required for consciousness
• Consciousness does not require self-consciousness, introspection, or language
• Consciousness and attention are independent processes

Which brings us back to the claim that we can only find subprocesses going on in the brain, but not activity that distinguishes conscious processes from non-conscious ones.

As it turns out, experiments have been designed that do in fact distinguish between conscious and non-conscious activity in the brain at that level of granularity.

Koch cites studies into humans and monkeys (who are trained to respond to images on a screen) in which competing images are shown to each eye. Although the stimulus to each eye is constant, the conscious perception of what is seen flickers back and forth between the two. It is then possible to have human and animal subjects respond to what they think they see rather than what their eyes perceive. "In this manner the neural mechanisms that respond to the subjective percept rather than the physical stimulus can be isolated, permitting the footprints of visual consciousness to be tracked in the brain."

Pretty cool!

As it turns out, "monkeys and humans experience the same basic phenomenon", which helps answer rocketdodger's question about animal consciousness, at least in part.

Here's an excerpt from Koch's comments on the studies:

In primary visual cortex (V1), only a small fraction of cells weakly modulate their response as a function of the percept.... The majority of cells responded to one or the other retinal stimulus with little regard to what the animal perceived at the time. In contrast, in a high-level cortical area such as the inferior temporal (IT) cortex along the ventral pathway, almost all neurons responded only to the perceptually dominant stimulus, that is, to the stimulus that was being reported.... This result implies that the NCC [neural correlates of consciousness] involve activity in neurons in inferior temporal cortex.

Clearly this does not imply that the NCC are local to IT. Given known anatomical connections, it is likely that specific reciprocal interactions bettween IT cells and neurons in parts of the prefrontal cortex are necessary for the NCC. This possibility is compatible with the widely accepted notion that the NCC involve positive feedback to ensure that the neural activity is persistent and strong enough to exceed some threshold and to be distributed to multiple cognitive systems, including working memory, planning, and language.

In short, although consciousness cannot be "found in the brain" in the way that, say, the liver can be "found in the abdomen", it is incorrect to claim that consciousness is equivalent with any subprocess such as attention, and it is incorrect to claim that conscious and non-conscious processing cannot be distinguished in brain activity as conscious/non-conscious processing without resorting to subroutines.

 

[Beelzebuddy]

Second, although attention may be present, it may not be enough for a stimulus to make it to consciousness. You are reading that article about string theory, your eyes are focused, you are mouthing the words to yourself, and none of it is making it to your conscious brain, and maybe never will.

Yeah, that's attention, not consciousness. Here I sit streaming nerdrage onto the internet, right? Meanwhile Beelze**** is off in the background nattering on about something. Probably drapes. I'm not paying attention to her. She knows I'm not paying attention to her. In a minute or two she's going to pause meaningfully, and I will be expected to calmly recite her last sentence verbatim. Husbands have and will be doing this for millenia, though probably not with the mental sound effect of a rewinding cassette tape.

I don't know what part of this process Gazzaniga attributes to consciousness, but it's attention I'm not giving her, and it's attention that will flood my temporal cortex to rewind a bit and drive it to my speech areas. Until then, I attend here.

Same for subliminal messages - you're neither conscious of nor are you paying attention to them, so how does that mean the two concepts are separate?

It seems that you're begging the question, piggy. You're certain consciousness exists, so logically it must. Your pal Koch can't even define it.

As it turns out, experiments have been designed that do in fact distinguish between conscious and non-conscious activity in the brain at that level of granularity.

Koch cites studies into humans and monkeys (who are trained to respond to images on a screen) in which competing images are shown to each eye. Although the stimulus to each eye is constant, the conscious perception of what is seen flickers back and forth between the two. It is then possible to have human and animal subjects respond to what they think they see rather than what their eyes perceive. "In this manner the neural mechanisms that respond to the subjective percept rather than the physical stimulus can be isolated, permitting the footprints of visual consciousness to be tracked in the brain."

Pretty cool!

Yeah that's not consciousness either. That's two stimulus patterns competing for one brain region. You can do that to earlier regions and it's called an "optical illusion."

For example, in area MT (face recognition):
image

it is incorrect to claim that consciousness is equivalent with any subprocess such as attention, and it is incorrect to claim that conscious and non-conscious processing cannot be distinguished in brain activity as conscious/non-conscious processing without resorting to subroutines.

I'm not claiming either. I'm claiming consciousness doesn't exist at all.

 

[Piggy]

I'm not claiming either. I'm claiming consciousness doesn't exist at all.

And you are absolutely wrong. You might as well claim that running does not exist. It's this kind of nonsense that this thread is specifically designed not to get bogged down in, so unless you have some brain research to cite....

 

[Piggy]

Same for subliminal messages - you're neither conscious of nor are you paying attention to them, so how does that mean the two concepts are separate?

The research clearly indicates that you are indeed paying attention to them.

 

[Piggy]

It seems that you're begging the question, piggy. You're certain consciousness exists, so logically it must. Your pal Koch can't even define it.

First off, Koch is not my pal. We've never met.

Second, we know consciousness exists because we observe it. It has nothing to do with any process of abstractly deducing anything through formal logic.

Third, if we refuse to admit the existence of everything we have no formal definitions for, then we will never arrive at any formal definitions because we will never investigate any phenomena for which we do not have explanations readily at hand.

 

[Piggy]

Yeah that's not consciousness either. That's two stimulus patterns competing for one brain region. You can do that to earlier regions and it's called an "optical illusion."

Yes, those are called optical illusions. This is precisely what Koch calls them in the subhead to that section of his essay.

But you fail to address the significant aspect of the research here, which is that the experiment objectively distinguishes between the brain processes involved in perception and those involved in conscious awareness.

 

[Beelzebuddy]

It's this kind of nonsense that this thread is specifically designed not to get bogged down in, so unless you have some brain research to cite....

Yeah, it doesn't work that way. You have to show that consciousness exists. I've just gotta stand here with my arms crossed until you do. And no, the very next sentence of Michael Gazzaniga's book Human will probably not do it.

The research clearly indicates that you are indeed paying attention to them.

You mean "perceiving them," I presume. There is a difference, you can perceive things and act on them without paying attention to either, it's how you can drive and carry on a conversation without running off the road.

Second, we know consciousness exists because we observe it. It has nothing to do with any process of abstractly deducing anything through formal logic.

Same can be said for the id, the soul, and body thetans. When you move an arm, the only thing that can be observed is that you moved an arm. Nothing about "why," though of course you're free to make wild guesses. But then you can track down the causes of arm motion a bit at a time, then track down what caused them, etc. When the causes and supercauses bypass the need for your pet theory, you discard it. Consciousness was a nice idea, but it's not evident and not required.

Third, if we refuse to admit the existence of everything we have no formal definitions for, then we will never arrive at any formal definitions because we will never investigate any phenomena for which we do not have explanations readily at hand.

There is no phenomena of consciousness. There is nothing you can point at and go "THIS. THIS IS CONSCIOUSNESS." It relies solely on an arbitrary definition that you can't provide, so you just equivocate. That's all you've done in this thread. When you "move an arm," there's your definition: you moved an arm. Now we can move forward to how and why. How do you do consciousness to something in an observable manner?

But you fail to address the significant aspect of the research here, which is that the experiment objectively distinguishes between the brain processes involved in perception and those involved in conscious awareness.

You failed to post a citation, but I suspect no, it doesn't. It objectively distinguishes between low level perception and high level perception.

 

[Piggy]

Yeah, it doesn't work that way. You have to show that consciousness exists. I've just gotta stand here with my arms crossed until you do.

Do you promise? Because that would be wonderful.

But seriously, no, that's not going to happen.

I mean, if there's a thread on oceanography, and someone chimes in that, in his opinion, oceans do not exist -- only the stuff in them does, like water and sand and fish and corals and whales and so forth -- that's not a point that deserves any serious discussion.

To prove oceans exist, all you have to do is drive to the beach.

Proving consciousness exists is even simpler -- wake up.

So if you intend to wait for me to "prove" that consciousness exists, you're going to have a long wait. I'm not going to waste my time on such nonsense.