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  • "The Search for Self"

    Posted by Diane<script language="JavaScript1.3" type="text/javascript"> document.write(timestamp(new Date(2005,11,18,12,11,0), dfrm, tfrm, 0, 0, 0, 0)); </script> (Member # 1064) on 18-12-2005 19:11<noscript>December 18, 2005 12:11 PM</noscript>:

    This excerpt is from Antonio Damasio's excellent book, The Feeling of What Happens, published in 1999. It appears on page 19, and I think sums up what is important (to me) about the whole book.

    It leaped out at me as a "deeper" investigation of the neuromatrix model laid out by Melzack. Damasio is less interested in pain as such, more interested in consciousness and emotion. But in the end it all runs together anyway, so its worth getting his take. The term "image" is used repeatedly, and I've provided Damasio's meaning at the end.

    He spends a great deal of time in the book carefully differentiating what he terms "core" consciousness/sense of self, from "extended" consciousness/ sense of self. There is discussion of "nonconsciously" operating mechanisms that are nonetheless linked to and in relationship with "consciously" operating ones (this helps Barrett's movement model take shape in my own mind). I came away from this section with a lot clearer idea of the brain as a set of nested bowls of function, each one containing a different aspect of awareness, each making its own contribution to life maintenance, each somewhat autonomous but still very interdependent with the others, like a mental ecological system.

    Note: Damasio's first language is Portugese, not English, so he will need to be read a bit slower perhaps, so that the reader's own gamma power can do a more specific translation of some of his turns of phrase.

    quote: <hr> A Search for Self
    (p 19, The Feeling of What Happens.)

    How do we ever know that we are seeing a given object? How do we become conscious in the full sense of the word? How is the sense of self in the act of knowing implanted in the mind? The way into a possible answer for the questions on self came only after I began seeing the problem of consciousness in terms of two key players, the organism and the object, and in terms of the relationships those players hold in the course of their natural interactions. The organism in question is that within which consciousness occurs; the object in question is any object that gets to be known in the consciousness process; and the relationships between organism and object are the contents of the knowledge we call consciousness. Seen in this perspective, consciousness consists of constructing knowledge about two facts: that the organism is involved in relating to some object, and that the object in the relation causes a change in the organism.

    The new perspective also makes the biological realization of consciousness a treatable problem. The process of knowledge construction requires a brain, and it requires the signaling properties with which brains can assemble neural patterns and form images. The neural patterns and images necessary for consciousness to occur are those which constitute proxies for the organism, for the object, and for the relationship between the two. Placed in this framework, understanding the biology of consciousness becomes a matter of discovering how the brain can map both the two players and the relationships they hold.

    The general problem of representing the object is not especially enigmatic. Extensive studies of perception, learning and memory, and language have given us a workable idea of how the brain processes an object, in sensory and motor terms, and an idea of how knowledge about an object can be stored in memory, categorized in conceptual or linguistic terms, and retrieved in recall or recognition modes. The neurophysiologic details of these processes have not been worked out, but the contours of these problems are understandable. From my perspective, neuroscience has been dedicating most of its efforts to understanding the neural basis of what I see as the “object proxy.” In the relationship play of consciousness, the object is exhibited in the form of neural patterns in the sensory cortices appropriate to map its characteristics. For example, in the case of the visual aspects of an object, the neural patterns are constructed in a variety of regions of the visual cortices, not just one or two, but many, working in concerted fashion to map the varied aspects of the object in visual terms. (For an account of how the visual system achieves such object representations see David Hubel’s Eye, Brain, and Vision; 1988 and Semir Zeki’s A Vision of the Brain 1993.) On the side of the organism, however, matters are quite different. To indicate how different matters are, let me suggest an exercise.

    Look up from the page, at whatever is directly in front of you, observe intently, and then return to the page. As you did so, the many stations of your visual system, from the retinas to several regions of the brain’s cerebral cortex, shifted rapidly from mapping the book’s page, to mapping the room in front of you, to mapping the page again. Now turn around 180 degrees and look at what is behind you. Again, mapping of the page vanished swiftly so that the visual system could map the new scene you were contemplating. The moral of the story: In quick succession, precisely the same brain regions constructed several entirely different maps by virtue of the different motor settings the organism assumed and of the different sensory inputs the organism gathered. The image constructed in the brain’s multiplex screens changed remarkably.

    Now consider this: While your visual system changed dutifully at the mercy of the objects it mapped, a number of regions in your brain whose job it is to regulate the life process and which contain preset maps that represent varied aspects of your body did not change at all in terms of the kind of object they represented. The body remained the “object” all along and will remain so until death ensues. But not only was the kind of object precisely the same; the degree of change occurring in the object – the body – was quite small. Why was that so? Because only a narrow range of body states is compatible with life, and the organism is genetically designed to maintain that narrow range and equipped to seek it, through thick and through thin.

    What we have in this situation, then, is an intriguing asymmetry that may be phrased in the following terms: Some parts of the brain are free to roam over the world and in so doing are free to map whatever object the organism’s design permits them to map. On the other hand, some other parts of the brain, those that represent the organism’s own state, are not free to roam at all. They are stuck. They can map nothing but the body and do so within largely preset maps. They are the body’s captive audience, and they are at the mercy of the body’s dynamic sameness.

    There are several reasons behind this asymmetry. First, the composition and general functions of the living body remain the same, in terms of their quality, across a lifetime. Second, the body changes that continuously do occur are small, in terms of their quantity. They have a narrow dynamic range because the body must operate with a limited range of parameters if it is to survive; the body’s internal state must be relatively stable by comparison to the environment surrounding it. Third, that stable state is governed from the brain by means of an elaborate neural machinery designed to detect minimal variations in the parameters of the body’s internal chemical profile and to command actions aimed at correcting the detected variations, directly or indirectly. (I will address the neuroanatomy of this system in Chapter 5. The system is made up of not one but many units, the most important of which are located in the brain stem, hypothalamus, and basal forebain sections of the brain.) In short, the organism in the relationship play of consciousness is the entire unit of our living being, our body as it were; and yet, as it turns out, the part of the organism called the brain holds within it a sort of model of the whole thing. This is a strange, overlooked and noteworthy fact, and is perhaps the single most important clue as to the possible underpinning of consciousness.

    I have come to conclude that the organism, as represented inside its own brain, is a likely biological forerunner for what eventually becomes the elusive sense of self. The deep roots for the self, including the elaborate self which encompasses identity and personhood, are to be found in the ensemble of brain devices which continuously and nonconsciously maintain the body state within the narrow range and relative stability required for survival. These devices continually represent, nonconsciously, the state of the living body, along with its many dimensions. I call the state of activity within the ensemble of such devices the proto-self, the nonconscious forerunner for the levels of self which appear in our minds as the conscious protagonists of consciousness: core self and autobiographical self.

    Should some readers get worried at this point that I am falling into the abyss of the homunculus trap, let me say immediately and vehemently that this is not the case. The “model of the body-in-the-brain” to which I am referring is nothing at all like the rigid homunculus creature of old-fashioned neurology textbooks. Nothing in it looks like a little person inside a big person; the model “perceives” nothing and “knows” nothing; it does not talk and it does not make consciousness. The model is, instead, a collection of brain devices whose main job is the automated management of the organism’s life. As we shall discuss, the management of life is achieved by a variety of innately set regulatory actions – secretion of chemical substances such as hormones as well as actual movements in viscera and in limbs. The deployment of these actions depends on the information provided by nearby neural maps which signal, moment by moment, the state of the entire organism. Most importantly, neither the life-regulating devices nor their body maps are the generators of consciousness, although their presence is indispensable for the mechanisms that do achieve core consciousness.

    This is the key issue, as argued in Chapter 5: In the relationship play of consciousness, the organism is represented in the brain, abundantly and multifariously, and that representation is tied to the maintenance of the life process. If this idea is correct, life and consciousness, specifically the self aspect of consciousness, are indelibly interwoven.
    <hr>
    All the italics are in the original. Some definitions are as follows: from p. 317 Glossary, image:
    quote: <hr> When I use the term image, I always mean mental image. A synonym for image is mental pattern. When I refer to the neural aspect of the process I use terms such as neural pattern or map. Images can be conscious or nonconscious. Nonconscious images are never accessible directly. Conscious images can be accessed only in a first-person perpective (my images, your images). Neural patterns, on the other hand, can be accessed only in a third-person perspective. If I had the chance of looking at my own neural patterns with the help of the most advanced technologies, I would still be looking at them from a third-person perspective. <hr>
    I think the following is logical: If movement such as ideomotor movement is permitted to occur, that immediately provides a more "third-person" perspective for the "conscious" and more consciously sensory parts of the brain to appreciate. It changes the "relationship" pattern (also part of the whole contribution to sense of self according to Damasio) between core and extended parts of brain function: The extended parts can note, and accept if it/they wish, a new "object relation" to map.

    Damasio continues:
    quote: <hr> Images are not just visual. By the term "images" I mean mental patterns with a structure built with the tokens of each of the sensory modalities - visual, auditory, olefactory, gustatory, and somatosensory. The somatosensory modality includes varied forms of sense: touch, muscular, temperature, pain visceral, and vestibular. The word image does not refer to "visual" image alone, and there is nothing static about images, either. The word also refers to sound images such as those caused by music or the wind, and to the somatosensory images that Einstein used in his mental problem solving - in his insightful account, he called those patterns "muscular" images. Images in all modalities "depict" processes and entities of all kinds, concrete as well as abstract. Images also "depict" the physical properties of entities and, sometimes sketchily, sometimes not, the spatial and temporal relationships among entities, as wll as their actions. In short, the process we come to know as mind when mental images become ours as a result of consciousness is a continuous flow of images many of which turn out to be logically interrelated. The flow moves forward in time, speedily or slowly, orderly or jumpily, and on occasion it moves along not just one sequence but several. Sometimes the sequences are concurrent, sometimes convergent and divergent, sometimes they are superimposed. Thought is an acceptable word to denote such a flow of images. <hr>
    Does that not sound like a kaleidoscopic perspective on brain and brain function? [IMG]smile.gif[/IMG] I love how he can describe the motion in it, but can also "thinslice" and stop parts of it to provide a more detailed examination of salient bits.

    Hope this isn't too overwhelmingly long a post to read and understand.
    <hr> Posted by Diane (Member # 1064) on <script language="JavaScript1.3" type="text/javascript"> document.write(timestamp(new Date(2005,11,18,16,47,0), dfrm, tfrm, 0, 0, 0, 0)); </script> 18-12-2005 23:47<noscript>December 18, 2005 04:47 PM</noscript>:

    More from Damasio, the end of the book this time. I left out a long tedious section that explained what an axon is, etc. I think we all know that stuff by now. What I kept is a lot more interesting and helps form a picture of what is going on in there in terms of function. Also a lot that can apply to ideomotor movement. He discusses the binding problem at the end, which links back to the gamma power thread.
    quote: <hr> Appendix
    Notes on Mind and Brain (p 317); Damasio’s The Feeling of What Happens

    A Glossary of Sorts
    Because words such as images, neural patterns, representations, and maps have unclear and various meanings, their use is fraught with difficulties. Nonetheless such words are indispensable to convey one’s ideas in any attempt to deal with the topics of this book. These notes are meant to clarify further my usage of some of those words.

    What is an Image and What is a Neural Pattern?
    When I use the term image, I always mean mental image. A synonym for image is mental pattern. I do not use the word image to refer to the pattern of neural activities that can be found, with current neuroscience methods, in activated sensory cortices – for instance, in the auditory cortices in correspondence with an auditory percept; or in the visual cortices in correspondence with a visual percept. When I refer to the neural aspect of the process I use terms such as neural pattern or map.

    Images can be conscious or nonconscious (see pages ahead). Nonconscious images are never accessible directly. Conscious images can be accessed only in a first-person perspective (my images, your images). Neural patterns, on the other hand, can be accessed only in a third-person perspective. If I had the chance of looking at my own neural patterns with the help of the most advanced technologies, I would still be looking at them from a third-person perspective.

    Images Are Not Just Visual
    By the term images I mean mental patterns with a structure built with the tokens of each of the sensory modalities – visual, auditory, olfactory, gustatory, and somatosensory. The somatosensory modality (the word comes from the Greek soma which means “body”) includes varied forms of sense: touch, muscular, temperature, pain, visceral, and vestibular. The word image does not refer to “visual” image alone, and there is nothing static about images either. The word also refers to sound images such as those caused by music or the wind, and to the somatosensory images that Einstein used in his mental problem solving – in his insightful account, he called those patterns “muscular” images (A. Einstein, cited in J. Hadamard, The Psychology of Invention in the Mathmatical Field; 1945). Images in all modalities “depict” processes and entities of all kinds, concrete as well as abstract. Images also “depict” the physical properties of entities and, sometimes sketchily, sometimes not, the spatial and temporal relationships among entities, as well as their actions. In short, the process we come to know as mind when mental images become ours as a result of consciousness is a continuous flow of images many of which turn out to be logically interrelated. The flow moves forward in time, speedily or slowly, orderly or jumpily, and on occasion it moves along not just one sequence but several. Sometimes the sequences are concurrent, sometimes convergent and divergent, sometimes they are superposed. Thought is an acceptable word to denote such a flow of images.

    Constructing Images
    Images are constructed either when we engage objects, from persons and places to toothaches, from the outside of the brain toward its inside; or when we reconstruct objects from memory, from the inside out, as it were. The business of making images never stops while we are awake and it even continues during part of our sleep, when we dream. One might argue that images are the currency of our minds. The words I am using to bring these ideas to you are first formed, however briefly and sketchily, as auditory, visual, or somatosensory images of phenomes and morphemes, before I implement them on the page in their written version. Likewise, those written words now printed before your eyes are first processed by you as verbal images before they promote the activation of yet other images, this time nonverbal, with which the “concepts” that correspond to my words can be displayed mentally. In this perspective, any symbol you can think of is an image, and there may be little leftover mental residue that is not made of images. Even the feelings that make up the backdrop of each mental instant are images, in the sense articulated above, somatosensory images, that is, which mostly signal aspects of the body state. The obsessively repeated feelings that constitute the self in the act of knowing are no exception.

    Images may be conscious or nonconscious. It should be noted, however, that not all the images the brain constructs are made conscious. There are simply too many images being generated and too much competition for the relatively small window of mind in which images can be made conscious – the window, that is, in which images are accompanied by a sense that we are apprehending them and that as a consequence, are properly attended. In other words, metaphorically speaking, there is indeed a subterranean underneath the conscious mind and there are many levels to that subterranean. One level is made of images not attended, the phenomenon to which I have just alluded. Another level is made of the neural patterns and of the relationships among neural patterns which subtend all images, whether they eventually become conscious or not. Yet another level has to do with the neural machinery required to hold records of neural patterns in memory, the kind of neural machinery which embodies innate and acquired implicit dispositions.

    Representations
    The meaning of a few other terms needs to be clarified. One is representation, a problematic but virtually inevitable term in discussions of this sort. I use representation either as a synonym of mental image or as a synonym of neural pattern. My mental image of a particular face is a representation, and so are the neural patterns that arise during the perceptual-motor processing of that face, in a variety of visual, somatosensory, and motor regions of the brain. This use of representation is conventional and transparent. It simply means “pattern that is consistently related to something,” whether with respect to a mental image or to a coherent set of neural activities within a specific brain region. The problem with the term representation is not its ambiguity, since everyone can guess what it means, but the implication that, somehow, the mental image or the neural pattern represents, in mind and in brain, with some degree of fidelity, the object to which the representation refers, as if the structure of the object were replicated in the representation. When I use the word representation, I make no such suggestion. I do not have any idea about how faithful neural patterns and mental images are, relative to the objects to which they refer. Moreover, whatever the fidelity may be, neural patterns and the corresponding mental images are as much creations of the brain as they are products of the external reality that prompts their creation. When you and I look at a object outside ourselves, we form comparable images in our respective brains. We know this well because you and I can describe the object in very similar ways, down to fine details. But that does not mean that the image we see is the copy of whatever the object is like. Whatever it is, in absolute terms, we do not know. The image we see is based on changes which occurred in our organisms – including the part of the organism called the brain – when the physical structure of the object interacts with the body. The signaling devices located throughout our body structure – in the skin, in the muscles, in the retina, and so on – help construct neural patterns which map the organism’s interaction with the object. The neural patterns are constructed according to the brain’s own conventions, and are achieved transiently in the multiple sensory and motor regions of the brain that are suitable to process signals coming from particular body sites, say, the skin, or the muscles, or the retina. The building of those neural patterns or maps is based on the momentary selection of neurons and circuits engaged by the interaction. In other words, the building blocks exist within the brain, available to be picked up and assembled. The part of the pattern that remains in memory is built according to the same principles.

    Thus the images you and I see in our minds are not facsimiles of the particular object, but rather images of the interactions between each of us and an object which engaged our organisms, constructed in a neural pattern form according to the organism’s design. The object is real, the interactions are real, and the images are as real as anything can be. And yet, the structure and properties in the image we end up seeing are brain constructions prompted by an object. There is no picture of the object being transferred from the object to the retina and from the retina to the brain. There is, rather, a set of correspondences between physical characteristics of the object and modes of reaction to the organism according to which an internally generated image is constructed. And since you and /I are similar enough biologically to construct a similar enough image of the same thing, we can accept without protest the conventional idea that we have formed the picture of some particular thing. But we did not.

    One final reason to be cautious about the term representation is that it easily conjures up the metaphor of the brain as computer. The metaphor is inadequate however. The brain does perform computations but its organization and working have little resemblance to the common notion of what a computer is.

    Maps
    Many of the same qualifications apply to the term map, a word that is almost as inevitable and irresistible as representation when it comes to discussions on the neurobiology of the mind. When the light particles known as photons strike the retina in a particular pattern related to an object, the nerve cells activated in that pattern – say, a circle or a cross – constitute a transient neural “map.” At subsequent levels of the nervous system, for instance, the visual cortices, subsequent related maps are also formed (D. Hubel, Eye, Brain, and Vision 1988; Jean-Pierre Changeux, Neuronal Man: The Biology of Mind, 1985; Gerald Edleman, Neural Darwinism: The Theory of Neuronal Group Selection, 1987). To be sure, just as with the word representation, there is a legitimate notion of pattern, and of correspondence between what is mapped and the map. But the correspondence is not point-to-point, and thus the map need not be faithful. The brain is a creative system. Rather than mirroring the environment around it, as an engineered information-processing device would, each brain constructs maps of that environment using its own parameters and internal design, and thus creates a world unique to the class of brains comparably designed.

    Mysteries and Gaps of Knowledge in the Making of Images
    There is no mystery regarding the question of where images come from. Images come from the activity of brains and those brains are part of living organisms that interact with physical, biological, and social environments. Accordingly, images arise from neural patterns, or neural maps, formed in populations of nerve cells, or neurons, that constitute circuits, or networks. There is a mystery, however, regarding how images emerge from neural patterns. How a neural pattern becomes an image is a problem that neurobiology has not yet resolved.

    Many of us in neuroscience are guided by one goal and one hope: To provide, eventually, a comprehensive explanation for how the sort of neural pattern that we can currently describe with the tools of neurobiology, from molecules to systems, even becomes the multi-dimensional, space-and-time integrated image we are experiencing this very moment. The day may come when we can explain satisfactorily all the steps that intervene from neural pattern to image but that day is not here yet. When I say that images depend on and arise from neural patterns or neural maps, rather than saying they are neural patterns or maps, I am not slipping into inadvertent dualism, i.e., neural pattern, on one side, and nonmaterial cogitum, on the other. I am simply saying that we cannot characterize yet all the biological phenomena that take place between (a) our current description of a neural pattern, at varied neural levels, and (b) our experience of the image that originated in the activity within the neural map. There is a gap between our knowledge of neural events, at molecular, cellular, and system levels, on the one hand, and the mental image whose mechanisms of appearance we wish to understand on the other. There is a gap to be filled by not yet identified but presumably identifiable physical phenomena. The size of the gap and the degree to which it is more or less likely to be bridged in the future is a matter for debate, of course. Be that as it may, I wish to make clear that I regard neural patterns as forerunners of the biological entities I call images.

    The gap I have just described is one reason why, throughout this book, I maintain two levels of description, one for the mind and one for the brain. This separation is a simple matter of intellectual hygiene and, once again, it is not the result of dualism. By keeping separate levels of description I am not suggesting that there are separate substances, one mental and the other biological. I am simply recognizing the mind as a high level of biological process, which requires and deserves its own description because of the private nature of its appearance and because that appearance is the fundamental reality we wish to explain. On the other hand, describing neural events with their proper vocabulary is part of the effort to understand how those events contribute to the creation of the mind.

    New Terms
    Several new terms are introduced in this book, e.g., core consciousness, extended consciousness (which are defined in the first chapter) and proto-self and second-order structure (which are properly introduced in chapters 5 and 6).

    Also, my use of the terms emotion and feeling is unconventional, as I explain in the beginning of chapter 2; and the term object is used in a broad and abstract sense – a person, a place, and a tool are objects, but so is a specific pain or an emotion.

    (…)

    The Brain Systems Behind the Mind
    For the purpose of investigating the relation between mental images and the brain, I have long used a framework suggested by results from experimental and clinical neuropsychology, neuroanatomy, and neurophysiology. The framework posits an image space and a dispositional space. The image space is that in which images of all sensory types occur explicitly. Some of these images constitute the manifest mental contents that consciousness lets us experience whereas some images remain nonconscious. The dispositional space is that in which dispositions contain the knowledge base and the mechanisms with which images can be constructed from recall, with which movements can be generated, and with which the processing of images can be facilitated. Unlike the contents of image space, which are explicit, the contents of the dispositional space are implicit. We can know the contents of images (once core consciousness is activated), but we never know the contents of dispositions directly. The contents of dispositions are always nonconscious and exist in dormant form. Yet dispositions can produce a large variety of actions – the release of a hormone into the bloodstream; the contraction of muscles in viscera or of muscles in a limb or in the vocal apparatus. Dispositions hold some records for an image that was actually perceived on some previous occasion and participate in the attempt to reconstruct a similar image from memory. Dispositions also assist with the processing of a currently perceived image, for instance, by influencing the degree of attention accorded to the current image. We are never aware of the knowledge necessary to perform any of these tasks, nor are we ever aware of the intermediate steps that are taken. We are only aware of results, for example, a state of well-being; the racing of the heart; the movement of a hand; the fragment of a recalled sound; the edited version of the ongoing perception of a landscape.

    All of our memory, inherited from evolution and available at birth, or acquired through learning thereafter, in short, all our memory of things, of properties of things, of persons and places, of events and relationships, of skills, of biological regulations, you name it, exists in dispositional form (a synonym for implicit, covert, nonconscious), waiting to become an explicit image or action. Note that dispositions are not words. They are abstract records of potentialities. Words or signs, which can signify any entity or event or relationship, along with the rules with which we put words and signs together also exists as dispositions and come to life as images and action, as in speech or signing. When I think of dispositions I always think of the town of Brigadoon waiting to come alive for a brief period.

    We are beginning to discern which parts of the central nervous system support the image space and which parts support the dispositional space. The areas of cerebral cortex located in and around the arrival point of visual, auditory, and other sensory signals – the so-called early sensory cortices of the varied sensory modalities – support explicit neural patterns, and so do parts of limbic areas, such as the cingulated, and noncortical structures, such as the tectum. These neural patterns of maps continuously change under the influence of internal and external inputs and are likely to be the basis for images, whose mercurial dynamics parallel the neural pattern changes over time.

    On the other hand, higher-order cortices – which make up the ocean of cerebral cortex around the islands of early sensory cortices and motor cortices – parts of limbic cortices, and numerous subcortical nuclei, from the amygdala to the brain stem, hold dispositions, that is, implicit records of knowledge. When disposition circuits are activated they signal to other circuits and cause images or actions to be generated from elsewhere in the brain.

    This bare sketch also requires the mention of other brain regions whose ostensible role is the interrelation of signals across brain areas, along with the control of their occurrence in certain brain areas. Those regions include the thalamus, the basal ganglia, the hippocampus, and the cerebellum. We would need a textbook to begin to discuss the intricacy of their respective jobs, in spite of the depth of our ignorance. For the sake of our discussion, however, I will simply say that the functions of the thalamus, e.g., interrelation of signals, control of brain activities in disparate areas, and relay of signals, are indispensable for consciousness. As far as consciousness goes, however, the role of the others is either unclear (basal ganglia, cerebellum) or negligible (hippocampus).

    I have proposed that dispositions are held in neuron ensembles called convergence zones. To the partition between an image space and a dispositional space, then, corresponds a partition in (1) explicit neural pattern maps – activated in the sensory cortices, in so-called limbic cortices, and in some subcortical nuclei; and in (2) convergence zones, located in higher-order cortices and in some subcortical nuclei.

    How this anatomical arrangement serves as a base for the sort of integrated and unified images we experience in our minds is not clear, although a number of proposals have suggested solutions to parts of this question. The question is generally known as the “binding problem.” In terms of an overall mental picture it is likely that binding requires some form of time-locking of neural activities that occur in separate but interconnected brain regions. There is little doubt that the integrated and unified scene that characterizes the conscious mind will require massive local and global signaling of populations of neurons across multiple brain regions. Gerald Edelman’s notion of reentry addresses this requirement. Rodolfo Llinás’ transcortical “binding wave” and my notion of time-locked retroactivation are other attempts to capture a mechanism capable of making the necessarily fragmented activity of our brain cohere in time and space (A. Damasio, “Time-locked multiregional retroactivation: A systems level proposal for the neural substrates of recall and recognition,” Cognition33, 1989: 25-62; “The brain binds entities and events by multiregional activation from convergence zones”, Neural Computation, 1989; G. Edelman, Neural Darwinism; R Llinás and D. Paré, “Of dreaming and wakefulness”, Neuroscience 44 1991: 521). The work of Wolf Singer has addressed the mechanisms required to generate coherence at the microstructural level (W. Singer, C. Gray, A Engel, P. Koenig, A. Artola, S. Brocher, “Formation of cortical cell assemblies”, Symposia on Quatitative Biology 55: 929-52), and Francis Crick has theorized extensively about those requirements, at cellular and microcircuit levels. (F. Crick, The Astonishing Hypothesis:The Scientific Search for the Soul, 1994; F. Crick and C Koch, “Constraints on cortical and thalamic projections: the no-strong-loops hypothesis”, Nature 391 1998: 245-50). Both Jean-Pierre Changeux and Gerald Edelman have proposed selectional frameworks for the operation of such mechanisms, and the work of Michael Merzenich shows that the brain does have the flexibility necessary to operate in this manner (J-P. Changeux, Neuronal Man; G Edelman, Neural Darwinism).
    <hr>

    <hr> Posted by Diane (Member # 1064) on <script language="JavaScript1.3" type="text/javascript"> document.write(timestamp(new Date(2005,11,19,0,33,0), dfrm, tfrm, 0, 0, 0, 0)); </script> 19-12-2005 07:33<noscript>December 19, 2005 12:33 AM</noscript>:

    quote: <hr> the term object is used in a broad and abstract sense – a person, a place, and a tool are objects, but so is a specific pain or an emotion. <hr>
    I think it is quite interesting that in Damasio's view, the extended consciousness or sense of self sees a pain as an "object." It sees an emotional state as an "object." I think that fits with how when everything feels "fine" in the body, the body is easy to ignore, but when something is not right, it's very hard to do just that. One's access to a sense of well-being is blocked by this "object." Then along comes all the need state behavior, restless seeking for solace, and willingness to suspend disbelief in quacky stuff. Anything for a wee hit of that placebo effect.
    Last edited by bernard; 29-12-2005, 06:04 PM.
    Simplicity is the ultimate sophistication. L VINCI
    We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances. I NEWTON

    Everything should be made as simple as possible, but not a bit simpler.
    If you can't explain it simply, you don't understand it well enough. Albert Einstein
    bernard
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