In the late 80s and early 90s Francis Crick (of Double Helix fame) and neuroscientist, Cristoff Koch began what what would become a partnership in neuroscience that lasted until Crick's death in 2004. Their work was focused on an issue that at the time seemed very new and strange-- a neurobiological explanation of that notoriously elusive and mysterious thing we call 'consciousness.' Their 1990 paper, "Toward a Neurobiological Theory of Consciousness" began by stating that "It is remarkable that most of the work in both cognitive science and neuroscience makes no reference to consciousness." It is hard to remember now how true those words were then.
In 1994, Francis Crick of DNA double helix fame published the game-changing book, The Astonishing Hypothesis. In The Astonishing Hypothesis is, Crick explained, that
“'You,' your joys and your sorrows, your memories and your ambitions, your sense of identity and free will, are in fact no more than the behaviour of a vast assembly of nerve cells and their associated molecules. As Lewis Carroll’s Alice might have phrased it: You’re nothing but a pack of neurons.This idea was still "astonishing"at the time, but the framework that Crick and Koch established has remained influential among many neuroscientists today. There are several assumptions that were made in setting out this new science of consciousness. One assumption is that consciousness is not an exclusively human phenomenon but one that arises in other animals --especially higher mammals. Thus they did not assume, as some theorists have, that consciousness as experienced by human beings required the acquisition of language. Cognitive properties exist across a large swathe of the animal kingdom. Although they didn't speculate on how far down the evolutionary ladder this went, it was clear that this open question would allow extrapolation from results of animal experiments to the formulation of hypotheses about human consciousness since there was an undefined element of continuity across at least a great many species up to humans. This proved to be an important assumption, as it has allowed for extrapolations from relatively simple neural systems to the staggeringly complex circuits and networks of the human brain. For example, Eric Kendall's Nobel Prize winning research on memory storage in the late 90s was based on observations of sea slugs whose neurons are so few and large as to be visible to the naked eye.
Nevertheless, with the guiding principle of consciousness as a continuum across species, he was able to extrapolate from the slugs to human beings in order to hypothesize mechanisms that are the alleged basis for human memory storage. Just how much these snails can really tell us about our own qualitatively different memory processes is a matter of controversy.
Additionally, certain questions were left unanswered deliberately at the outset. These included a) the very definition of consciousness or "C" b) speculation on the function of consciousness and c) the vexing "problem of qualia" (i.e.how and why a "pack of neurons" can manifest itself as subjective experience that is qualitative, including what it feels like to be, to breathe, to eat, think, move, struggle through pain or feel happy etc.). David Chalmers has called this problem The Hard Problem(he discusses it in the short video below). The putting aside of these 3 issues led to criticisms that we still hear today. If subjective experience is not explained (i.e. if "qualia" are put aside), then can we even call Crick and Koch's "C" 'consciousness' in any recognizable sense? If we can't define it and don't know what its function is then how can it be an object of scientific inquiry? Clearly these issues that were put to the side were of great significance.
Nevertheless, they made it clear that they were setting up a preliminary framework for working out a theory of consciousness. What was important was a) to identify what they called neural or neuronal correlates of consciousness (NCCs) and b) to try to solve what they called "the binding problem." NCCs are defined on Koch's website thus:
Neuronal correlates of consciousness (NCCs): The minimal set of neuronal mechanisms or events jointly sufficient for any one specific conscious percept or experience. Discovering and characterizing them in normal human subjects as well as in in patients, newborns, animals, and other non-linguistic competent individuals would represent great progress toward an scientific theory of consciousness.The "Binding Problem" is defined in the same online glossary as follows:
The binding problem, by many other names, is a longstanding metaphysical issue that has been addressed by thinkers ranging from Ancient India and Greece to David Hume and Kant. Usually it is raised not at the neuronal level but the subjective level which is where binding as defined above is experienced.How is it that we experience diverse and unrelated percepts as seemingly unified "selves." Various theories have been proposed, and some have been revisited by neuroscientists. But what sets Crick and Koch's approach apart is that they focused exclusively on brain states which were assumed to be correlates of the mental experience of unitary consciousness. At the subjective level of qualia I am currently aware of the feeling of the cool air from the a/c unit, the thoughts that I am thinking, the sensations in my arm muscles and fingers as I type some of these thoughts, the contact of my posterior on the chair, my spacial orientation in a vertical sitting position (proprioception) and any incidental percepts in the flux of experience such as passing cars, overhead planes etc. The traditional question is how so many logically, spatially and temporally separate experiences can be perceived as a unified field of continuous experience which feels unitary, continuous and orderly. Crick compared it to the difference between an orchestra playing together led by a conductor as opposed to the chaos of that same orchestra without a conductor where each player goes his or her own way resulting in a cacophony and not 'music.' This analogy also indicates his and Koch's proposed hypothesis: If the conductor is the "binding" force that harmonizes the musicians to make sure each plays the proper parts simultaneously, then there must be some equivalent or at least analogous principle of unification in humans. Binding must be temporal. Just as the critical difference between cacophony and organized sound is that the musicians are in sync with one another, so the neural firing in the brain must be "synchronous" for binding to occur.
Binding problem: How distinct attributes of one or several objects in the world, represented by neural activity at many distributed sites, are combined into unitary percepts is known as the binding problem. For instance, how are the color, motion, and sounds of a red Ferrari, zooming past at high speed,
combined into a single percept when their underlying neural activity is distributed at many sites? And how is this kept apart from the neural representation of a simultaneously perceived motorcycle?
Thus the first theory of binding was based on the idea of "temporal binding". Their hypothesis is that binding occurs through the synchronization in the oscillation patterns of neuron firing we usually call brainwaves. EEG recordings show particular firing patterns in particular areas of the brain. Sometimes these are slow-- alpha waves at 8-12 cycles per second or hertz. Sometimes they are fast-- gamma waves at 40-70 hertz. Crick and Koch cite experimental data on cats showing that when they move a bar in experiments, neurons some distance apart in their brains oscillate in a synchronized fashion. This synchronous firing is what binding is, they speculated. Boldly going even further, they hypothesized that this synchronous firing is ultimately what consciousness itself is. They wrote:
“We suggest that one of the functions of consciousness is to present the result of various underlying computations and this involves an attentional mechanism that temporarily binds the relevant neurons together by synchronizing their spikes in 40Hz oscillation.”This initial hypothesis didn't fare very well as there was disconfirming evidence. In 2004 it was later replaced by an anatomical theory of binding which attributed the coordination and unification of percepts to a small part of the brain deep in its interior called the Claustrum. Crick's final paper (written with Koch and published in 2005, https://www.ncbi.nlm.nih.go... hypothesized that if the Claustrum was removed from an organism, the binding process could not occur. If so there would be indicators of the now disorganized experiences of the animal. Could there be such a simple explanation for such an elusive property as the unity of consciousness itself; a property which they now claimed is the same thing as consciousness? It was recently shown that stimulation of the Claustrum was correlated with an epileptic patient going from a state of wakefulness to being unconscious. However the implications of that event are far from straightforwardly clear. There are also now competing paradigms and hypotheses regarding the nature and mechanisms of consciousness. We simply don't know which, if any, are true.
Crick died in 2004 (that final paper was published posthumously) and Koch abandoned the Neurobiological paradigm in 2014 (when he also left Cal Tech).In a surprising change of perspective, he now favors a metaphysical theory of consciousness known as Panpsychism, which states that many complex forms of matter possess varying degrees of consciousness and not just living beings.
https://www.scientificameri... and https://en.wikipedia.org/wi.... He is now Chief Scientific Officer at The Allen Institute for Brain Science.
The Implications of "The Astonishing Hypothesis" for subsequent neuroscience:
Though he is now working outside the neurobiological paradigm he co-created with Crick, the basic features of the NCC-based approach are now fairly standard. Sure, there are other models such as Gerald Edelman's "Neural Darwinism," Bernard Baars' "Global Workspace Theory," various (highly speculative) Quantum based theories associated with the work of such theorists as Henry Stapp and Roger Penrose, Enactivist theories of embodied cognition, David Chalmers' theory of The Extended Mind-- the first scientific version of pan-psychism proposed in 1998, and there are various non-biological computational models of consciousness in which inorganic material can realize. consciousness (as in some strong AI models). But much of the research in neuroscience today is predicated on the assumptions set out in the early 90s by Crick and Koch. Consciousness including "You, all your joys and sorrows, memories and ambitions..." emerges from lower order (less complex) neuronal events in the brain "somehow"-- be it synchronous brainwaves, the Claustrum or any other as yet unknown brain processes. What counts is with that assumption, scientists can infer that upward causation (from neuronal events to complex experiences of the conscious subject) occurs all the time.
Rather than trying to establish the cause of consciousness itself in one fell swoop, most research today takes a piecemeal approach as per the NCC program reviewed above. Researchers look for neural correlates for a wide range of conscious processes and experiences such as emotions (Affective Neuroscience) learning (cognitive science) processing of music (neuroaesthetics) and even the property of religiosity in Andrew Newberg's "neurotheology." All such work involves the postulation of brain regions and/or neural networking patterns that, when they are active, coincide with the experiences which they are said to cause. Work on emotions by Joseph Ledoux in the 90s and early 21st century, for example, focused on the role of the Amygdala in producing states of fear. When oxygenated blood flow increases in the amygdala (detected via fMRI neuroimaging), subjects report feeling fear. Further, significantly correlated events such as increase in heart rate, skin resistance and observed facial expressions correlated with fear et al. tend to arise along with the observed changes in blood flow in the brain region of the amygdala. All of this lends support to the idea that fear is caused by neuronal events in the limbic system, particularly the amygdala we have just discussed.
One problem with this approach is that we have found that, in this example, the amygdala is also active when we process positive events, and more generally whenever we consolidate emotionally significant memories of any kind, positive or negative (damage to the amygdala is correlated with decreased memory of strong emotional episodes). The "function" of the amygdala seems to be not singular but rather multiple. It is best viewed as part of the brain involved in various functions including motivation, potentiation of learning, sexual arousal, formation of long term memories (i.e. consolidation) and who knows what else. Buddhists meditating on compassion undergo blood flow changes in the amygdala detected in fMRI brains scans-- a long way off from fear or panic! Damage to the amygdala also reduces motivation to a significant degree. To read more about this fascinating brain region read here https://en.wikipedia.org/wi... For purposes of this overview of neurobiological theories of consciousness, the point I'm making is that Neuronal Correlates can be misleading since any one region of the brain or neural pathway may function in a variety of different ways, having different functions in different situations. This is, I believe, a serious problem which may explain, in part, the significant problems encountered when attempting to replicate NCC studies and indeed neurimaging based studies generally. The "crisis of reproducibility" in neuroscience has caused such alarm that Stanford University now offers an award to those who do solid replication studies. http://reproducibility.stan... For further discussion of these issues https://disqus.com/home/dis...
Ultimately, any theory of consciousness must rely on first person reports, as when a test subject is asked how they feel or what they see during an experiment. Their report is compared to some specified changes in the brain hypothesized to be causes of the phenomena experienced by the subject. It may also be compared to animal studies that are taken to signify related conscious events assumed to occur in lower animals. Gradually, as with a jigsaw puzzle, the hope is that we will find "neural substrates" or neurobiological causes of more and more diverse and complex aspects of consciousness. But note, all the piecemeal work on locating NCCs of emotions, cognition, perception etc. presupposes that the "Astonishing Hypothesis" we began with is really true in some generic sense. The brain, on this view, is a sufficient cause of consciousness, therefore neuronal correlates are sufficient conditions of feelings, thoughts, beliefs and so on. Somehow, on this view, a virtual infinity of complex quantitative neural events-- bits of matter in motion-- become "You" with all the attendant emotional, perceptual and cognitive properties that entails. What we don't know is what really causes consciousness (whether it be the Claustrum, synchronous brainwaves, or any other faculty X that has been or will be hypothesized). More important, we don't know how such a neurobiological faculty can literally also BE "You and all your joys and sorrows..." etc. as per the quote with which we began from Crick. This leads to one last topic.
Dualism or Monism?
It has become very "unfashionable" and even a bit of a stigma to admit to being a dualist in neuroscience, and increasingly in all science including psychiatry and general medicine. It's no surprise then, that most consciousness theorists whether Crick, Koch, Michael Gazzangia, Dan Dennett, Gerald Edalman, et al. tend to explicitly disavow dualism in favor of some form of materialism or physicalism. That means there simply is nothing over and above the physical events in the brain, and that when seen scientifically these events ARE consciousness. This has long been called "The Identity Thesis." Yet although papers frequently begin with the dismissal of all dualist accounts, yet quickly slip into talk of physical processes that "generate" consciousness, or "cause," or "give rise to" consciousness. This way of talking only makes sense within a dualist framework. For example, if consciousness turns out to be nothing more than the state a person is in when the Claustrum (aka "the consciousness switch") is active, then the Claustrum does not cause consciousness, but as Crick and Koch insisted, it IS consciousness. It IS the site of binding, and therefore of consciousness itself. That's the non-dualist version. But sworn non-dualists often go on to to talk about how a neuronal process like that "enables" or "causes" C (= conscicousness), which logically implies that the "neural substrate" and C are not one and the same thing. To say C causes/enables/leads to C is tautological. It is like saying "Talking causes talking " or "Ideas cause ideas." It is understandable that this way of talking arises.
Deep down most of us think of ourselves as "Persons" with capacities that are not reducible to the complex machinations of matter in motion. If I am enjoying a good meal (qualia) I don't imagine that to be the same thing as whatever my brain happens to be doing at that time. In the case of significant activities getting married or deciding to move I certainly don't think that what is happening is simply a manifestation of the behavior of "a pack of neurons." No, persons act for reasons rather than from mechanical causation. If I decide to move 2000 miles away and take a new job, it would never occur to me that this is just a subjective manifestation of dancing brain cells. So, the threat of eclipsing personhood and agency is something that needs to be considered when interpreting the neuroscience of consciousness.
There are at least 3 ways to respond to this. We can bite the bullet and admit we are end-products of dancing neurons and that qualia (the feeling of being a person with agency and qualia) is really just an illusion. Dan Dennett is probably the most famous proponent of this approach as captured in the mini-doc video below). The second approach is to embrace a qualified dualism such as "Property Dualism" which asserts that although everything is ultimately physical, some physical events have mental properties. Sometimes this is explained in terms of "emergence" whereby complex interactions at the neuronal level lead to new properties or systems bearing properties that are distinctly mental and cannot in turn be reduced to the lower level events from which they emerged.. Then we can say, for example, thinking is a property of a high-order system whose causes are all ultimately lower-order neural substrates. How this works is an utter mystery, and for that reason some would argue it solves nothing that dualism can't solve and tries to have it both ways by saying we can "talk like dualists but not be dualists." I will leave you to ponder that conundrum if such it is. Finally there is a position exemplified most forcefully by Colin McGuinn which is called "mysterianism." Thankfully this position is very simple. In a nutshell, we do not, cannot and never will understand what consciousness is. It is an intractable "mystery." A less dramatic response is weak agnosticism which holds that we DO NOT know what consciousness is at this time, but that we may learn much more about it in the future. I'll end there since that is my own position.
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Recommended Reading:
Consciousness: A Very Short Introduction, Blackmore, Susan: Oxford: The book is well written and informative but the author is not shy about revealing her own positions.
Introducing Consciousness: Papineau, David; Icon books: This is a very good way for the newbie to get a reliable overview of the topic because it is presented in the form of cartoons with very "user-friendly" dialogue that makes learning the material both entertaining and relatively easy. The book is balanced and does not promote any theory over any other one.
The Philosophy of Mind: The Metaphysics of Consciousness: Jacquette Dale, Continuum Books: Excellent 300 page text book which is both thorough and (for a text book) concise. Good for those who are not new to the phil of mind and neuroscience, but want to fill in a few blanks. Organized by topic, one can easily zoom in on a given area simply by using the TOC or index.
For a quick, accessible overview of some themes in this OP... https://en.wikipedia.org/wi...
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Possible Question:.
Are 'you,' as a conscious person, nothing other than a manifestation of neruonal events
in the brain and nervous system? If so does that lessen the significance of your experience or not? If so why? If not, why not?
This 12 minute video may help to better understand some of the issues discussed above. It features some of the "major players" in the field such as Francis Crick, Cristoff Koch, David Chalmers, Daniel Dennett, and others. Concepts such as qualia, neural correlates of consciousness, dualism, physicalism, and others are introduced. I hope it helps.
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