Consciousness, Self, and the Prefrontal Cortex

cartesian-theater

There is a basic question that must be addressed when pondering the nature of consciousness, and that is: why have consciousness at all? The brain processes a great deal of information below the level of conscious awareness, from visual to auditory to tactile, and then the integration of all of these before they can be brought into conscious awareness. Yet conscious awareness itself seems much more limited in the amount of information that it can handle at a time—5 to 9 “chunks” of information, at a time, it would seem. So why rely on conscious awareness as heavily as we do? It certainly seems, at least from this angle, much less able than non-conscious processing—yet, given its apparent efficacy in raising humanity to the heights of culture and insight that we enjoy today, it surely has something essential to offer us.

The prefrontal cortex is the latest structure to appear in the evolution of the brain, and is the structure that shows the greatest development between humans and our closest biological relatives. Furthermore, it is known to mediate a great deal of the abilities considered distinctly human, such as planning, reflection, and empathy, all of which apparently require conscious awareness. Surprisingly, however, a vast abundance of the projections that the prefrontal cortex sends back to more primitive, sub-cortical structures are inhibitory—they function largely to suppress activity in these regions. In fact, this has led several researchers to rethink the concept of free will and, somewhat amusingly, refer to it rather as “free won’t,” in that we are mainly choosing what not to do, of all of the responses recommended by sub-cortical structures. And this is where we might find a reason for conscious awareness.

Consciousness relies on a crucial ingredient for dealing with the world in the way that the prefrontal cortex specializes in doing: it removes behavior from the moment-to-moment sensory perceptions incessantly presenting themselves to sub-cortical brain regions. Instead of constantly responding to each and every stimulus as it comes in, consciousness introduces a disconnect that allows reality apart from oneself to be treated as perceived, and thus distinct from the self and manipulable. Non-conscious responses don’t require perception in the same way that conscious processes do. In order to consciously ponder a course of action while planning, you need a virtual representation to work with, and in order to do that, you need some distance between yourself and the object being represented. Every day perceptions such as the visual field in front of you may function in a very similar manner: a stimulus presents itself, is processed by sub-cortical structures, and then a course of action is offered up to conscious awareness to be chosen or discarded by conscious reflection. There is a whiff of “opponent processing” going on in this narrative, something that comes up a lot in systems biology: two structures working in opposite directions in order to better center around a single desired outcome. Non-conscious, sub-cortical processing is largely reactive, leading to sometimes extreme, reflexive responses; conscious prefrontal processing, on the other hand, divorced from the constant demands of the environment, is more receptive to multiple courses of action, but can sometimes leave us unable to settle on an alternative. With the two of these working with opposing aims, however, behavior that is reactive enough to survive, but receptive enough to be a functioning member of society, can be attained.

This is far from a coherent theory or hypothesis, but the parallels between the roles of sub-cortical and non-conscious processes on the one hand, and prefrontal and conscious processes on the other, along with the connections between the two, are surely going to be important in mapping human consciousness.

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Conversations on Consciousness

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Since the spring semester is now in full swing, it has been increasingly difficult for me to devote the necessary time to a full-length treatment of consciousness as I would like. This in mind, I picked up a copy of Susan Blackmore’s Conversations on Consciousness the other day, and I have not regretted it. It serves as an informal introduction to several competing theories and views on the scientific study of the brain and conscious experience. The set-up of the book is simple: interviews with the researchers/philosophers themselves explaining their theories in their own, colloquial way. Add to this a few questions on free will and the fate of consciousness after death, and you get twenty of the most interesting conversations that I’ve ever had the pleasure to read. They allow, among other things, the chance to see these researchers as actual people, and not simply as objective reporters of experimental results as happens far too often.

I have only one complaint about the book, which you may have guessed given the author, Susan Blackmore. Put simply, Blackmore endorses a few very fringe (and some, myself included, would say absurd) ideas about the nature of consciousness. Normally, this would not be an issue—everyone is entitled to their own opinions, and I often disagree with the authors that I read. The complaint comes, however, in the questions that Blackmore chooses to ask her interviewees. The book is accompanied by the sub-script, “What the Best Minds Think about the Brain, Free Will, and What it Means to be Human.” At times, though, it seems like it would read more accurately as, “What the Best Minds Think about My Ideas about the Brain, Free Will, and What it Means to be Human.” This is not over-riding, and most of the time the book stays true to its stated purpose (I thank the interviewees for most of this, they do a good job sticking to what they believe are the real issues), but it is, at times, distracting. It is not enough to knock this down as a great book, well worth reading, but it is something that should be noted, nonetheless.

I would like to give this five out of five stars—it was great fun to read—but the above complaint makes me unable to do so. That said, I would give the interviewees five out of five stars and Blackmore four out of five stars, so let’s say that the book as a whole gets four and a half out of five stars.

Brief Thoughts on the Analogy with Vitalism

It is sometimes asserted that consciousness and many of its aspects are illusory. Some of this, I believe, may turn out to be true. For example, our naive conception of conscious will seems to be at least partially illusory (see here and here for my views on that). Some, however, claim that even such fundamental notions as our sense of self are illusory, finally claiming that consciousness as a whole will one day be explained away as an illusion. I, as you may have guessed, take serious issue with this claim.

A common line of argument taken to support the claim draws an analogy between the present situation and the endeavor to explain life some hundred years ago. There were, in those days, the vitalists. These were the theorists who could not imagine that dead matter and its interactions could account for all that there is to complex life—there had to be something extra, some elan vital, or life force, underlying all of this. Even if we explain heredity, reproduction, growth, etc., we will still be missing something—namely life itself. We now know that they were wrong, dead wrong, and that, in fact, there is simply dead matter interacting in specific ways that leads to the formation of complex, living organisms.

Now take the assertion made by many contemporary philosophers of mind: even if we explain vision, intelligence, emotion, etc. (i.e., the so-called “easy problems” of consciousness), then we will still be missing something—namely consciousness itself. If we explain all of those things that can be worked out computationally, then we will be missing the very thing that we sought to explain in the first place: subjective, conscious minds. But is this necessarily the case? Might consciousness simply fade away the more and more we know about these other processes? Maybe consciousness is simply the elan vital of philosophy of mind, say proponents of this analogy.

This could not be further from the truth. When it came to explaining life, a higher-level property such as the elan vital was postulated to account for something that we did not know the cause of: the difference between living and dead objects. When it comes to consciousness, we are not postulating something above and beyond what we already know. In the words of Descartes, “I think, therefore I am.” His dualism may have been misguided, but he was spot on in stating that there is nothing that we know with more certainty than that we are conscious, that we are our own self. In this way, the analogy is deeply flawed. Something can only be explained away if it was postulated to explain something that we know to be true. Consciousness, however, was never postulated. Instead, it was the very phenomenon that we set out to explain. We may be wrong about the details, and in all likelihood we are, but we are not, as a matter of fact, wrong when we state that we are conscious beings, that consciousness is a real, existing phenomenon that begs explanation in its own right.

The Rediscovery of the Mind

I finished reading Searle’s The Rediscovery of the Mind last week, and it was quite an exciting read, to say the least. In a field full of confusing, frustrating, and downright baffling theories and assertions, a little bit of no-nonsense pseudo-polemic writing can be a breath of fresh air, and this book is just that.

At it’s heart, this book is an argument for Searle’s own theory of mind: Biological Naturalism, which can be summed up as saying that the brain, under the right conditions, gives rise to conscious experience in the same way that water, under the right conditions, gives rise to liquidity. Even more fundamentally, however, Searle uses this book to remind us all of what we are really doing when we propose theories of mind, hopefully in a way that helps us realize the obvious mistakes we make all too often.

Searle closes the book with a near perfect set of guidelines, which I have re-printed below, because, even if you aren’t able to read the book in its entirety, I think that you should consider them:

In spite of our modern arrogance about how much we know, in spite of the assurance and universality of our science, where the mind is concerned we are characteristically confused and in disagreement. Like the proverbial blind men and the elephant, we grasp onto some alleged feature and pronounce it the essence of the mental. ‘There are invisible sentences in there!’ (the language of thought). ‘There is a computer program in there!’ (cognitivism). ‘There are only causal relations in there!’ (functionalism). ‘There is nothing in there!’ (eliminativism). And so, depressingly, on.

Just as bad, we let our research methods dictate the subject matter, rather than the converse. Like the drunk who loses his car keys in the dark bushes but looks for them under the streetlight, ‘because the light is better here,’ we try to find out how humans might resemble our computational models rather than trying to figure out how the conscious human mind actually works. I am frequently asked, ‘But how could you study consciousness scientifically? How could there be a theory?”

I do not believe there is any simple or single path to the rediscovery of the mind. Some rough guidelines are:

First, we ought to stop saying things that are obviously false. The serious acceptance of this maxim might revolutionize the study of the mind.

Second, we ought to keep reminding ourselves of what we know for sure. For example, we know for sue that inside our skulls there is a brain, sometimes it is conscious, and brain processes cause consciousness in all its forms.

Third, we ought to keep asking ourselves what actual facts in the world are supposed to correspond to the claims we make about the mind. It does not mater whether ‘true’ means corresponds to the facts, because ‘corresponds to the facts’ does mean corresponds to the facts, and any discipline that aims to describe the world is aims for this correspondence. If you keep asking yourself this question in the light of the knowledge that the brain is the only thing in there, and the brain causes consciousness, I believe you will come up with the results I have reached in this chapter, and indeed many of the results I have come up with in this book.

But that is only to take a first step on the road back to the mind. A fourth and final guideline is that we need to rediscover the social character of the mind.

If this closing passage appeals to you, I would recommend that you read this book in its entirety. I certainly found it well worth the effort (and it is an effort). Five out of five stars—I’ll be revisiting this many times.

Minds, Brains and Science

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John Searle’s Minds, Brains and Science is a collection of the six Reith Lectures that he gave in 1984 on the relation between our conscious, meaningful, phenomenal experiences and the backdrop of nonconscious, meaningless, objective physical reality against which all of the former inevitably play out. Essentially, the problem is this: We experience things, but everywhere else we look in the universe, we do not see experiences. How do we explain this seemingly trivial fact and make consciousness fit in with everything else we know?

This is inevitably a question that he is unable to provide a clear answer for, but, nonetheless, this was a successful, and worthwhile, work. The lectures were intended for a lay audience, so they are largely non-technical, but as far as I can tell, none of the necessary content was lost. Searle is still able to explicate each of the sub-problems and arguments very well. He manages to minimize caricaturing his opponents while simultaneously keeping the focus on what, he thinks, are the real issues. All the while, he manages to introduce several new ideas. His remarks on the social sciences and the freedom of the will are especially noteworthy.

In its entirety, the read comes down to less than a hundred pages, making it a perfect introduction to the problem at large. At the same time, it retains enough depth to catch the eye of even the most weathered philosopher-scientist—and for that, I give it five out of five stars.

Consciousness: Confessions of a Romantic Reductionist

Consciousness: Confessions of a Romantic Reductionist

Christof Koch’s autobiographical work Consciousness: Confessions of a Romantic Reductionist is just that: his confessions relating to his career, and why he does what he does. I’m going to keep this review short, since this book is not primarily about his own theories. Instead, he takes this book as a chance for him to drop his professional guise and explain why, deep down, he believes certain facts about the universe to be the way that they are. He does not pretend to have pristine motives, or that he only ever disagrees with other researchers based purely on an objective, reflective foundation. He states very clearly his most fundamental beliefs about the topic at hand. He talks, quite honestly, about his lifelong struggle with religion, about his relationship with Francis Crick, about his love of dogs—about anything and everything that he thinks is relevant to, as before, why he does what he does.

For anyone fed up with the sterility and impersonal nature of research on consciousness, this will be a long-needed breath of fresh air. It will be especially useful, I think, for those partaking, or aspiring to partake, in the great quest for consciousness themselves. In particular for those still aspiring, it may be nice to see, explicitly, that a larger-than-life researcher, decades into his own quest, still has some of the same doubts and moments of personal struggle that you may be faced with ever too frequently. Of note, this same researcher who spent 30 some years of life searching for a truly “reductive” explanation of consciousness endorses in this book, quite clearly, property dualism. Take that as you will.

Five out of five stars, one of my new personal favorites. Be sure to check out the cover art, it’s quite impressive.

The Problem, continued

John Tyndall, 1868:

The passage from the physics of the brain to the corresponding facts of consciousness is unthinkable as a result of mechanics. Granted that a definite thought, and a definite molecular action in the brain, occur simultaneously; we do not possess the intellectual organ, nor apparently any rudiment of the organ, which would enable us to pass, by a process of reasoning, from the one phenomenon to the other. They appear together, but we do not know why. Were our minds and senses so expanded, strengthened, and illuminated, as to enable us to see and feel the very molecules of the brain; were we capable of following all their motions, all their groupings, all their electric discharges, if such there be; and were we intimately acquainted  with the corresponding states of thought and feeling, we should be as far as ever from the solution of the problem, “How are these physical processes connected with the facts of consciousness?” The chasm between the two classes of phenomena would still remain intellectually impassable. Let the consciousness for love, for example, be associated with a right-handed spiral motion of the molecules of the brain, and the consciousness of hate with a left-handed spiral motion. We should then know, when we love, that the motion is in one direction, and, when we hate, that the motion is in the other; but the “WHY?” would remain as unanswerable as before.

An Introduction to the Problem

The problems of consciousness are many, and equally varied, but I think it would prove useful to put forth a rough description, nonetheless.

What it comes down to is the following: there is something that it is like to be a conscious being. You can describe the brain as much as you like and abstract away from the details, but all of these purely physical, third-person accounts seem to inevitably miss some crucial element, namely consciousness itself. Brains can instantiate causal relations, we know that. Brains can control behaviour, we know that, too. But how do physical brains give rise to subjective, mental contents? This is the most fundamental problem that all of the remaining issues derive from.

Everywhere else we look in the universe, we see physical entities and nothing more, we see objectivity. In a way, the entirety of scientific discovery, in crude form, is dependent on this, so how are we even to approach the problem at hand? All of our traditional tools of measurement, of explanation, of prediction rely on roughly deterministic, objective natures. Consciousness alone stands in the face of this, or at least it appears to. We would like to find a theory that accounts for this, but how is not at all clear. In fact, it could be said that conscious existence is one of the few remaining problems in science for which we do not even know how to ask the question. This should help to explain all of the contradictory accounts that are thrown around on a day to day basis. It helps explain why so many resorted, in desperation, to dualism. Life would be a lot simpler if there were some mysterious substance just out of reach that could do exactly what we need it to. But this is probably not the case, and most modern theorists understand this. Equally, it helps explain a great deal of the contemporary resistance to the downfall of materialism (or physicalism, if you prefer). Materialism is all that we know, it seems, are we not lost if we give up on it? From a more reflective point of view, though, and with time, I think these perspectives can be overcome.

To the cry of desperation of the materialist, think of this: physicalism is not all that you know—you know of your own conscious mind much more soundly, even if in an irritatingly limited manner. To the dualist, not all avenues of inquiry have been exhausted. In fact, we likely have barely scratched the surface of this enormously complex phenomenon. Where we go from here, I do not know, and it is probably anyone’s guess, but we at least have some idea of what we need to think about, and the work of others before us will allow us to avoid their pitfalls and misfortunes. This is, I think, the greatest question that lays before us as a species, and I think we may—finally—be prepared to tackle it head on.

via An Introduction to the Problem.

The Argument from Fading Qualia

In studies of consciousness, it is often maintained that purely artificial systems—say, those made of silicon chips—could never implement a conscious state. Consciousness is purely the realm of biological systems. In response to this, David Chalmers constructed the following thought experiment:

Suppose that there are two functionally identical systems: one (brain) made of neurons, and another made of silicon chips in place of those neurons, each residing inside a skull and properly connected to peripheral systems. All of the causal relations instantiated by the neuronal version are also instantiated by the silicon version. From the outside, then, the functional role of each in controlling behaviour would be effectively identical. The question lies in what it would be like to be each of these systems. Naturally, we accept that the neuronal construction would have a fully rich conscious experience. If it were me right now, then it would be seeing and feeling my fingers pressing each black key as I type this post. What of the silicon version? Relying on intuition, it seems natural to say that it isn’t “experiencing” anything. It might look like it’s experiencing something. It might even say that it is if we asked it. Still, we would cling to the notion that it is not.

Now, imagine an intermediate state between a fully neuronal brain and this fully silicon “brain.” In this system, half of the functional units in the “brain” are neurons, and the other half silicon. All of the causal relations from the original neuronal version, however, are still in place. (We can imagine a complex system of interfaces between neuron and silicon involving all kinds of sensors and effectors to accomplish this, but these details of practicality are irrelevant here. All that matters is that there is nothing contradictory in this picture.) Now comes the crucial question of the thought experiment: what is it to be like this neuron-silicon hybrid? All of the actions that would be accomplished by a neuronal brain are still being accomplished—the only difference is the physical substrate that is realizing them. Would it be conscious, but only slightly so? If so, this system might see gray where I see black; however, it would still say that it is seeing black due to the functional connections underlying its behaviour. We are left with a system that maintains some aspects of consciousness, but that is systematically wrong about its own conscious state.

The conclusion that Chalmers would like us to draw here is that there is no room in a functionally identical system to produce changes in conscious states. This would produce a “strong dissociation between consciousness and cognition” that we have never seen outside of certain neuropathological conditions. The difference here, though, is that neuropathology causes these problems by disrupting function. In the case of the intermediate, all functional aspects are upheld, so we have no reason to believe that there is any possibility of altered experience.

Explicitly, Chalmers uses this conclusion to support his psychophysical law of Organizational Invariance, which states that any functionally identical copy of a conscious brain, regardless of physical substrate, will have qualitatively identical experiences as the original system. This has strong implications for many areas. Specifically, it opens the door for the construction of “Strong AI,” or artificial intelligence that possesses a conscious mind, which is a very exciting possibility for humanity.

(The relevant supporting text can be found in David Chalmers’ The Conscious Mind, pages 253 to 263)