How the Brain Does Consciousness: Biological Research Perspectives

[Beth]

Pulling this out because it's really the crux of yours and piggy's argument.

I'd rather you had answered my question. I am interested in hearing the answer. Do you also deny the phenomenon of sleep? After all, if consciousness doesn't exist, why should being asleep be considered something different from being awake?

Science doesn't work this way. Religion works this way.

As a scientific term, "consciousness" is meaningless drivel. It didn't have to be. Early neuroscientists firmly believed they'd quickly find a part of the brain that acted as a command and control center; the "seat of consciousness." They didn't. So some gave up, and the rest looked harder. Still didn't. Same thing, repeated a few times, and now we're down to these two guys who swear consciousness is just hiding under this next rock. Meanwhile consciousness hasn't had a jot of further definition from all their efforts, all we have are a few more (conflicting) views on what it isn't.

"Studying consciousness" is exactly the wrong way to go about the science. You aren't starting with empirical observations and deriving testable theories, you're starting from an untestable theory and trying to find observational gaps where the theory can be shoehorned in. You're arguing from what is sensible, instead of what is.

Actually, we're starting from an observation and trying to understand what produces that observation. Are you saying that you don't think that science can study the human process that we term consciousness? After all, the scientific study of sleep is fairly well underway.

 

[Piggy]

Can you provide the reference for this one? I'm particularly interested in how the study determined what he was aware of at the time of the crash.

It wasn't a study, it was a case history.

And btw, I realized I called him a NASCAR driver specifically and I don't actually remember if he was or not.

I do recall that he himself said he had no clue why he slowed down, but then realized why when watching the car cam. And given the fact that he was in a high-speed auto race at the time, and approaching a curve, it's not surprising that he was paying no conscious attention to the crowd. Would have been rather unsafe.

I believe that case was cited in Pinker's "The Blank Slate", which I have... I can try to find the reference if you like.

 

[Piggy]

Pulling this out because it's really the crux of yours and piggy's argument.

Science doesn't work this way. Religion works this way.

As a philosophical term, shorthand for, yknow, thinking and stuff, "consciousness" works fine. It doesn't need to have a real meaning, because philosophy isn't expected to have a real use.

As a scientific term, "consciousness" is meaningless drivel. It didn't have to be. Early neuroscientists firmly believed they'd quickly find a part of the brain that acted as a command and control center; the "seat of consciousness." They didn't. So some gave up, and the rest looked harder. Still didn't. Same thing, repeated a few times, and now we're down to these two guys who swear consciousness is just hiding under this next rock. Meanwhile consciousness hasn't had a jot of further definition from all their efforts, all we have are a few more (conflicting) views on what it isn't.

"Studying consciousness" is exactly the wrong way to go about the science. You aren't starting with empirical observations and deriving testable theories, you're starting from an untestable theory and trying to find observational gaps where the theory can be shoehorned in. You're arguing from what is sensible, instead of what is.

It's true that the currently leading ideas about consciousness do not involve a control center. That's been clear in the research cited thus far.

However, "consciousness" is certainly not "meaningless drivel". As I said, it refers to something we all observe, about which there is no serious doubt. If you're experiencing something -- a regular waking moment, a dream, an acid trip -- you're in some way conscious. If you're not -- e.g. you're under general anesthesia or you're in deep sleep or you're in TS's situation -- then you're not conscious.

End of story.

That's the phenomenon being studied, and to assert that no such phenomenon exists is simply ridiculous.

You've added some other dimensions to it, apparently, in your conception of it, but that has nothing to do with the research.

Which, btw, is perfectly scientific. There is no "untestable theory" and no one is searching for "observational gaps". Two sets of observations are clearly correlated -- those correlations are being explored in the hopes of developing a workable theory to explain the correlation.

Anyway, since your objections have no bearing on the actual research because they do not describe the research, I'm really going to have to let this drop and get back to the point of the thread.

 

[Piggy]

Here's a bit from another section in Koch ("The Neurobiology of Consciousness", citations omitted), a passage that deals both with the distinction and relationship between consciousness and attention and with the question of what consciousness is, in functional terms. (Emphasis added)

Many actions in response to sensory inputs are rapid, transient, stereotyped, and unconscious. They can be thought of as cortical reflexes and are sometimes called zombie behaviors. A slower, all-purpose conscious mode deals with broader, less stereotyped, and more complex aspects of the sensory input (or a reflection of these, as in imagery) and takes time to decide on appropriate responses. A consciousness mode is needed because otherwise a vast number of different zombie modes would be required to react to unusual events. The conscious system may interfere somewhat with the concurrent zombie systems: focusing consciousness onto the smooth execution of a complex, multi-component, and highly trained sensorimotor task -- dribbling a soccer ball, to give one example -- can interfere with its smooth execution, something well known to athletes and their trainers. Having both a zombie mode that responds in a well-rehearsed and stereotyped manner and a slower system that allows time for planning more complex behavior is a great evolutionary discovery. This latter aspect, planning, may be one of the principal functions of consciousness.

It seems possible that visual zombie modes in the cortex mainly use the dorsal stream in the parietal region. However, parietal activity can affect consciousness by producing attentional effects on the ventral stream, at least under some circumstances. The basis of this inference is clinical case studies and fMRI experiments in normal subjects. The conscious mode for vision depends largely on the ventral "what" stream.

Seemingly complex visual processing (such as detecting animals in natural, cluttered images) can be accomplished by cortex within 130-150 ms, too fast for consciousness to occur. It is plausible that such behaviors are mediated by a purely feedforward moving wave of spiking activity that passes from the retina through V1, into V4, IT, and prefrontal cortex, until it affects motor neurons in the spinal cord that control the finger press (as in a typical laboratory experiment). The hypothesis that the basic processing of information is feedforward is supported most directly by the short times required for a selective response to appear in IT cells. Indeed, Hung and colleagues were able to decode from the spiking activity 100 ms after image onset from a couple of hundred neurons in monkey IT the identity of a single image flashed onto the retina of the fixating animal. Coupled with a suitable motor output, such a feedforward network implements a zombie behavior -- rapidly and efficiently subserving a binary categorization task in the absence of any conscious experience.

Conscious perception is believed to require more sustained, reverberatory neural activty, most likely by way of cortico-cortical feedback from other neocorical regions. These feedback loops would explain why in backward masking a second stimulus, flashed 80-100 ms after onset of a first image, can still interfere (mask) with the percept of the first image. The reverberatory activity builds up over time until it exceeds a critical threshold. At this point, the sustained neural activity rapidly propagates to parietal, prefrontal, and anterior cingulate cortical regions, thalamus, claustrum, and related structures that support short-term memory, multimodality integration, planning, speech, and other processes intimately related to consciousness. Competition prevents more than one or a very small number of percepts to be simultaneously and actively represented. This is the hypothesis at the heart of the global workspace model of consciousness.

Just in case there are any lurkers who don't have the time or inclination to learn textbook jargon, this is basically saying that it's possible for people to do things that we normally would think would have to involve conscious awareness -- like clicking a button when you recognize an animal hiding in a forest in a picture -- much more quickly than would be possible if consciousness were actually involved.

This is because there are "feedforward" (i.e. one-way) pathways through our brains that allow us to respond to recognition of certain kinds of things. Basically, from eyes straight through the brain and out to our muscles.

You'll notice that the study that was mentioned involved recognizing animals in landscapes. We're pretty good at that, having evolved to do it. There's a reason they didn't choose, say, picking out 3-digit numbers that are multiples of seven from among random arrays of 2-4 digit numbers.

So our "zombie" modules in the brain are limited. They deal with things we're evolved to know how to do, and things we're very well trained how to do, such as dribble a soccer ball.

So if that's feedforward mode, what about consciousness?

Koch describes a feedback system within the neocortex (our most recently evolved brain tissue) which reaches a threshold before "rapidly [propagating] to parietal, prefrontal, and anterior cingulate cortical regions, thalamus, claustrum, and related structures that support short-term memory, multimodality integration, planning, speech, and other processes intimately related to consciousness".

That would explain why a "masking" image flashed after exposure to a previous image can prevent you from ever being aware of the first image -- the first image didn't have time to reach the feedback threshold that would make it perceptible to consciousness, even though it's perceptible to certain zombie modules.

So here we have a framework for understanding how one attentional system can serve those brain structures and processes responsible for generating conscious experience and at the same time serve those brain structures and processes that do other things.

Gazzaniga has some very interesting things to say about Jeff Hawkins' view of those feedback systems, but I'm not convinced that those comments belong on this thread. Perhaps I can pare them down....

 

[yy2bggggs]

...you're starting from an untestable theory and trying to find observational gaps where the theory can be shoehorned in.

What is that theory?

 

[Piggy]

Piggy,

So the Claustrum has connections to the Centromedian Nucleus.

BTW: What exactly is the ILN?

I'm going to try to answer that last question in a way that will no doubt repeat much of what you already know, because I'm hoping this thread will eventually attract lurkers, even if it doesn't now... on the gamble that others will eventually join in who know much more than I do.

The spine runs up into the brain stem, which is very old in evolutionary terms. Very basic essential stuff goes on there.

The core tissue is symmetrical but not divided, like the pons and the pituitary gland, which sit right on top of the spinal nerves.

The thalamus is a bit higher up, and it's split into a left and right lobe, kind of like the headlights of your car, which do the same thing, and are connected to the same basic circuits, but which service two different sides of the vehicle and can each continue to function even if the other one is damaged, although the impaired functionality might result in undesirable consequences.

Beelzebuddy linked earlier to some information about the brain stem, so you might want to go back and look at those links.

But at this point, we've got to describe the brain in terms of nuclei, which are clusters of neurons that operate in coordination to accomplish certain tasks.

If you think about it, your muscles are a kind of nuclei, and so are your bones.

Anyway, Carter describes the thalamus as "a relay station between the sense organs and the brain".

Each side... contains more than 20 nuclei consisting of "gray matter" -- that is, collections of nerve-cell bodies. These nuclei... are in groups separated by sheets of white matter (myelinated nerve fibers) known as laminae.

The thalamus is wired up to a whole bunch of different areas, like the inner ear (medial genticulate nuclei), retina (lateral genticulate nuclei), visual cortex (lateral nuclei), face and mouth (trigeminothalamic tract), premotor cortex (lateral anterior nuclei), prefrontal cortex (medial dorsal nuclei), etc.

Way down deep in the core, surrounded by the internal lamina, are the ILN, intralaminar nuclei, including the centromedian nucleus. Proper functioning of an ILN is required for core consciousness.

 

[Beelzebuddy]

I'd rather you had answered my question. I am interested in hearing the answer. Do you also deny the phenomenon of sleep? After all, if consciousness doesn't exist, why should being asleep be considered something different from being awake?

Sleep, no, but I'll deny consciousness until the cock crows thrice.

Sleep can be measured. It can be defined. Given knowledge of your brain, we can tell you if you're asleep.

Consciousness cannot be measured. It isn't defined. It's entirely subjective. Like the soul and the id, it's just a convenient explanation for subjective experience.

Actually, we're starting from an observation and trying to understand what produces that observation. Are you saying that you don't think that science can study the human process that we term consciousness? After all, the scientific study of sleep is fairly well underway.

No, you're starting from an experience, deriving a theory, and searching for observations that fit the theory. And no, science can't study something that you can't define at all, except in terms of "oh c'mon it's totally there what you gonna deny oceans too?" Without a definition, there's nothing to test. Without empirical tests, there's no science.

Also, to drag you into the current argument, was Terry Schiavo conscious? She was certainly awake, and earlier you did define consciousness as being awake.

However, "consciousness" is certainly not "meaningless drivel". As I said, it refers to something we all observe, about which there is no serious doubt. If you're experiencing something -- a regular waking moment, a dream, an acid trip -- you're in some way conscious. If you're not -- e.g. you're under general anesthesia or you're in deep sleep or you're in TS's situation -- then you're not conscious.

End of story.

That's the phenomenon being studied, and to assert that no such phenomenon exists is simply ridiculous.

So consciousness == waking state & REM sleep? Is that what consciousness is? Was Terry Schiavo conscious? If not, which specific mechanisms was she lacking that are required for consciousness?

this is basically saying that it's possible for people to do things that we normally would think would have to involve conscious awareness -- like clicking a button when you recognize an animal hiding in a forest in a picture -- much more quickly than would be possible if consciousness were actually involved.

But this is an attentional mechanism. Does consciousness == attention instead?

What is that theory?

Well, you'd have to ask piggy, I've been trying to get that out of him for pages. He'll insist that the theory is true, and is apparently the world's foremost expert on what it is and isn't, but damned if he can actually lay it out for you.

IMO basically, that consciousness is some kind of abstract homunculus operating as an organizing agent in our brain, which for instance determines the difference between brain activity composing a thought and brain activity just being brain activity.

 

[Beth]

Sleep, no, but I'll deny consciousness until the cock crows thrice.

This makes no sense. If you agree that sleep exists, and consciousness is the term we apply to people and animals that are not asleep, how can deny that consciousness exists? It would be like acknowledging the existence of night, but claiming that day doesn't exist.

Sleep can be measured. It can be defined. Given knowledge of your brain, we can tell you if you're asleep.

Then we can also tell if you're not asleep - i.e. conscious.

Consciousness cannot be measured. It isn't defined. It's entirely subjective. Like the soul and the id, it's just a convenient explanation for subjective experience.

It's not an explanation but a label for an observation. There's a difference. Lacking an explanation or a precise definition for an observation does not preclude recognizing it.

No, you're starting from an experience, deriving a theory, and searching for observations that fit the theory.

What theory is that? That consciousness exists?

This is like claiming that our experience of sunlight on a regular basis has led to developing a theory of 'day' and now we are searching for observations to fit our theory that 'day' exists.

And no, science can't study something that you can't define at all, except in terms of "oh c'mon it's totally there what you gonna deny oceans too?" Without a definition, there's nothing to test. Without empirical tests, there's no science.

A precise definition is not necessary to scientifically study something. Instead precise definitions are developed as scientific study proceeds and we learn more about the phenomena of interest. At any rate, we can clearly study consciousness and even manipulate it. Scientists are already doing so. Piggy has been posting excerpts from books and papers about it. Anesthesiology has been around for even longer.

Also, to drag you into the current argument, was Terry Schiavo conscious? She was certainly awake, and earlier you did define consciousness as being awake.

Yes, I defined consciousness as being awake in the same way you defined oceans as being salt water between continental shelves. Such definitions sacrifice precision for ease of understanding. As far as TS goes, I don't know enough to make or accept any claims about her state of consciousness.

 

[Piggy]

Consciousness cannot be measured.

Sure it can.

We know, for example, where the temporal threshold is for visual stimulus to make it into conscious awareness, which is what allows researchers to set up experiments that expose people to subliminal and non-subliminal stimuli.

The set-up with the image pairs in binocular competition allow us to measure the duration of the conscious percepts and to compare them with the continual activity in V1.

And so on and so forth.

I'm reading a paper right now that's making quite an ambitious argument for measuring the quantity and strength of consciousness, but so far it's disappointing, I have to say.

But anyway, yes, consciousness is observable and, in many ways, measurable. I'm sure as more work is done, it will become increasingly amenable to various types of measurement.

 

[Piggy]

So consciousness == waking state & REM sleep? Is that what consciousness is? Was Terry Schiavo conscious? If not, which specific mechanisms was she lacking that are required for consciousness?

Let me again clarify.... Consciousness is not the same as "being awake" since "being awake" includes a lot of brain activity other than the brain activity which is generating conscious experience.

As I've said before, if you're having some sort of experience -- whether that's during waking activity, or while dreaming, or while experiencing the effects of a hallucinogenic drug -- then you're in some sort of conscious state; if you're not having any kind of experience at all -- such as when you're under general anesthesia or when you're asleep and not dreaming -- then you're not in a conscious state.

I hope that's the last time I have to repeat that.

That's what "consciousness" refers to, and that's the phenomenon (or phenomena) that's being studied.

Terry Shiavo was not conscious, according to neurologists, because her brain damage was too severe and widespread to allow conscious awareness. Here's one interview. And if the global workspace theory turns out to be correct, then the absence of neocortical tissue would indeed prevent conscious awareness in a human.

That said, here's a report on the autopsy which contends that TS's mental state could not be determined, but that her brain damage was irreversible.

 

[Piggy]

Does consciousness == attention instead?

That's already been answered. Consciousness and attention are not equivalent. It's like asking if running == muscle contraction.

 

[Piggy]

Well, you'd have to ask piggy, I've been trying to get that out of him for pages. He'll insist that the theory is true, and is apparently the world's foremost expert on what it is and isn't, but damned if he can actually lay it out for you.

I'm with yy2bggggs on this one... what theory are you talking about?

 

[Piggy]

This is like claiming that our experience of sunlight on a regular basis has led to developing a theory of 'day' and now we are searching for observations to fit our theory that 'day' exists.

Perfect.

 

[Piggy]

Btw, Beelzebuddy, if you had open heart surgery, would you save a few bucks by telling them not to use an anesthesiologist, on the grounds that consciousness doesn't exist, therefore there's no point paying good money to turn it off during the operation?

If not... if you would insist on anesthesia... then you're agreeing with me and Beth and every neurobiologist cited on this thread regarding the reality of consciousness.

If you say that you would refuse anesthesia, then I have to conclude that either you're not being honest, or you're crazy.

From what I can gather, there are 2 things being discussed here... consciousness, which is what's being investigated in the cited studies and discussed on this thread, and b-consciousness, which is some other thing entirely and which you say does not exist and I won't argue with you on that point.

 

[Beelzebuddy]

This makes no sense. If you agree that sleep exists, and consciousness is the term we apply to people and animals that are not asleep, how can deny that consciousness exists? It would be like acknowledging the existence of night, but claiming that day doesn't exist.

Wait, let's back up a sec. If we're defining consciousness as wakefulness, i.e. "being conscious," that's fine. It's a bit redundant, but w/e, that's a definition we can use. Terry Schiavo was then conscious, as she was clearly awake.

Piggy does not define consciousness as wakefulness, but as wakefulness+. It's the plus that's troublesome, because he uses it to equivocate, using wakefulness to define consciousness when it suits him and denying that awake==conscious when other people try to use that. Terry Schiavo, for instance, was NOT conscious despite being awake. Consciousness for him is also attention+, and episodic memory+. It's an uphill battle just to narrow down consciousness in any specific instance.

For my part, I don't particularly care. The brain just does stuff, without any apparent overarching control program. If you wanna call that consciousness or the soul in action, go ahead, it'll keep working regardless. However, piggy spent the first half of the thread telling people to GTFO because their definition of consciousness didn't match his unstated one, which I gotta say slightly riled me. If you want to have a scientific discussion, you have to have proper definitions and allow others to use them too, otherwise we're just pissing past each other.

We know, for example, where the temporal threshold is for visual stimulus to make it into conscious awareness, which is what allows researchers to set up experiments that expose people to subliminal and non-subliminal stimuli.

Is this what consciousness is? Activity is consciousness iff it reaches this threshold? And your perceptual illusion stuff from last page was just that - perceptual illusion?

Let me again clarify.... Consciousness is not the same as "being awake" since "being awake" includes a lot of brain activity other than the brain activity which is generating conscious experience.

Which brain activity is this? You surely must know, because you seem to have a firm grasp of what it isn't.

As I've said before, if you're having some sort of experience [then you're conscious]

That's just moving the goalposts, shifting the ambiguity to "experience." What IS an experience, in your definition?

 

[Beelzebuddy]

Btw, Beelzebuddy, if you had open heart surgery, would you save a few bucks by telling them not to use an anesthesiologist, on the grounds that consciousness doesn't exist, therefore there's no point paying good money to turn it off during the operation?

If not... if you would insist on anesthesia... then you're agreeing with me and Beth and every neurobiologist cited on this thread regarding the reality of consciousness.

False dichotomy. Consciousness doesn't have to exist for pain to exist, and when it comes to pain, I am an inveterate coward. Honestly, given some way of disabling pain receptors entirely I'd prefer to remain awake during the procedure, as the other sensations would surely be fascinating. Sadly, functionally decoupling the peripheral nervous system through induced sleep is still the best way we have to go about it.

And I'd hold off on the ad populum for now, seeing as how you and Beth still aren't using the same definition of consciousness. Beth's is much closer to your OP, but less similar to your fully equivocated p-theory of consciousness.

 

[Paul C. Anagnostopoulos]

Wouldn't it be cool if we knew how much of consciousness is innate and how much is a learned social construct?

After all, how much time do we spend marveling at the evolution of the ability to do calculus? What we have is the ability to count and maybe add and maybe compare and the rest is a social construct.

Exactly how conscious is that 3-week old baby?

~~ Paul

 

[Piggy]

Exactly how conscious is that 3-week old baby?

Core consciousness is up and running.

The various components of extended consciousness will take many months to become active.

 

[Piggy]

Piggy does not define consciousness as wakefulness, but as wakefulness+.

Sorry, it's wakefulness-, not wakefulness+.

Only part of what your brain is doing when you're awake is involved in conscious awareness. This is extremely well established experimentally.

 

[Piggy]

The brain just does stuff, without any apparent overarching control program. If you wanna call that consciousness or the soul in action, go ahead, it'll keep working regardless. However, piggy spent the first half of the thread telling people to GTFO because their definition of consciousness didn't match his unstated one, which I gotta say slightly riled me.

The stipulative definition for this thread is right there in the OP. It is not unstated.

And you agree with the research when you say that there is no "overarching control program" (see the citation from the interview with Koch).