BEING ABOUT Chapter 1. Aboutness
Intrinsic aboutnessAnimate bodies are structurally adapted to the world, able to behave effectively within it. Their competency is a kind of structural aboutness. Think of the paramecium advancing on what it needs to ingest. One-celled though it is, it has the means to find it, get to it, gulp it up, incorporate parts of it and eject others. The paramecium is about bacteria, among other things, in virtue of its structure -- by being the kind of creature it is. Evolved aboutness is a diffuse characteristic of any living thing; even a plant is about many things in its environment, in this sense. What are the advantages, then, of grounding our talk about cognition and knowing in a notion as down-home and ineffable as aboutness? There are many. The first is that, just because aboutness is vague and polysemic, we have to stay aware that our founding notion is not an axiom but a stance, an unfinished setting-out to understand cognition or 'mind' as material and structural. The term acknowledges that we are not in a position to be very exact but we want to ground our thinking about cognition in the understanding that it is accomplished by spatiotemporal means, by bodies. Doing so, we can include perception and action in what we mean by knowing, because they are forms of successful contact with things in the world. We are also able to ground our sense of the cognitive moment in the whole of a scene that includes the organism (its needs as well as its capabilities), the objects it is interested in, and the background locality which is the medium of interaction. This makes it easier to notice that the environmental relatedness of an organism is not segregable in some 'symbolic' internal part. It also makes it easier to understand that an organism can be about many things at the same time, and the means by which it is so need not be analyzable into parts which are separately about different things. We are able to understand that not all cognitive structure is sentient structure, and that we need not be aware of the means by which we are aware. We can separate the notion of aboutness from the notion of representation, so that we can understand public representation as social management of structural aboutness. And we are able to extend our notion of cognitive response and capability into a complex history of structural adaptation, in which nature and nurture cannot be thought distinct. Structure and functionA living body is a configuration of biomolecules and water molecules that can be reconfigured in various ways. The configuration existing at any given moment is its physical structure. An organism builds itself, maintains itself, and sets itself tasks. These processes -- self construction, self maintenance, and transactions with other things in the world -- are its functions, what it does. When we talk about function we can mean the organism's ability to do what it does, or we can mean an actual moment of doing. There is no function in either of these senses without systematic maintenance and alteration of physical structure. Creatures are effective, capable, competent, relevant, adapted, reliable, always and only by structural means -- by being configured one way rather than another. We can think of natural selection as selection for structure, for behavior, or for self-structuring processes. These three categories are equivalent, in effect (Edelman 1988). What the organism does in a given context is what matters, but changes of function are always results of changes of structure. Similarly, changes in structure are always the result of changes in the way an organism builds itself in a context. When we are thinking of mechanisms rather than organisms, we easily think of function apart from structural change. Continuity of structure, not change of structure, is what is valued in a machine. A machine does not build or maintain itself. It is an assembly of parts formed in materials most of which are chosen for their stability. In mechanical function, parts may move in relation to each other, but we usually do not think of the parts themselves as changing. Parts that do change in a way important to successful function of the machine (toaster elements, computer switches) are usually held in frameworks that do not change in response to these changes. It is much harder to imagine a living body than it is to imagine a machine. A body functions by changing its own structure continuously and at many points at once. To imagine a functioning body, we have to imagine changes at many scales, we have to imagine many simultaneous changes at the same scale, and we have to imagine each of these changes as responses to changes in many other parts. Aboutness, cognition and knowingNot every heritable trait enhances adequacy of contact. But phyletic adaptations of contact are for obvious reasons on the front line of selective advantage: structural changes that enable an organism to respond accurately to what it meets and where it is will tend to be reproduced. There are somewhat complicated relations among the notions of structural aboutness, cognition and knowing. Structural aboutness includes everything the organism is, structurally, that fits it to live in its world. Structural aboutness is arrived at by many means and at many times. An individual organism's effective structure is partly its species structure, which includes scheduled individual development and maturation, and which is given by natural selection over evolutionary time. The individual is also constructed by 'experience', which is to say by structuring processes dependent on its contact with external occurrences within its lifetime. In some recently evolved species experience includes communicational events. The structural aboutness that results from all of these structuring events is the organism's existing structure insofar as that structure is generally adaptive. Structural aboutness includes structure that isn't immediately relevant, structure earlier organisms have found useful, or species structure that has been useful at earlier or later stages in a lifetime. Within the more encompassing category of aboutness or adapted structure there is the important subcategory of immediate aboutness, whatever structural state makes the creature able now. The processes, acts or states which are the organism's effectiveness in its present circumstance include structural changes that mediate contact with its immediate environment. Immediate aboutness includes the shaping of a fin to cope with a current, the flexing of a paw to grasp a leaf, the wriggling of an antenna, anything the organism is doing to cope with being what it is, wherever it is. Immediate aboutness also includes responsive structure that we don't think of in terms of action or perception: it would include digesting, which involves adaptive restructuring to cope with whatever has been eaten, and immune function, which is response customized to specific pathogens. We don't ascribe cognition to creatures without nervous systems and only doubtfully to the neurally simple, but it is not quite right to say cognition is coextensive with neural function, since neural function is also facilitating digestion, peripheral blood flow, and the like. We could say cognition is some undefinable subset of immediate, neurally mediated structural aboutness. In general, cognitive aboutness includes the 'ceptions (per, con, de, and apper) and 'prehesions (ap and com), and various aspects of action. Sentient cognition would be a subset of the subset of immediate structural aboutness which is cognition. Knowledge fits into this categorical frame in a number of places because the term is polysemic. In our usual sense of it, we seem to reserve knowing for effective structure that is arrived at by only some of the ways effective structure can be built. Structure we gain by experience, including communicational experience, is roughly what we have meant by this sense of knowing (knowing1). We do sometimes think of creatures as knowing by in-born means. The sorts of knowledge we have most easily thought of as built-in are dispositional: know-how, common sense, skill, moxie, maybe talent and intuition, familiarity (knowing2). Knowing has also been identified with parts of the category of sentient cognition. We tend to call various kinds of immediate conscious apprehending, recognizing, feeling, and being aware knowing when they are not mistaken (knowing3). In the larger sense of structural aboutness, an organism that has evolved in a physical world does not have knowledge, it is knowledge. In this schema, the more sophisticated sentient and linguistic aboutness we call having knowledge must be seen as floated on the implicit and inherent structural aboutness any living thing must embody to be and stay alive. Species structure that has evolved over eons of time on a planet has been intensively tested. A viable creature is more about than not. But we also have to account for not-aboutness, failure to be adequately about. Structural inadequacy can happen through deficits in any of the ways aboutness is constructed. There are mutations that don't work; some of these are developmental or maturational flaws. It can also happen through trauma to individuals that are phenotypically adequate: accidents that disrupt structure. Some of these accidents may be social and communicational. Considered structurally, maladaptive mutation, developmental error, malnourishment, disease, ignorance, and misinformation are causal variants within the one category which is failure of physical aboutness. Co-gnoscere: together to knowEvolved competence is always a competence in mutuality. Adapted structure is structural aboutness because it is differentiative. It is one way rather than another; the way it is makes it ready, able to cope. And it is the way it is because its structural state is codetermined by aspects of its environment. What an organism is doing at this moment is being done always and only by means of its physical configuration at this moment. That configuration is either just the result of structure it already has -- that structure having been determined at other times -- or it is the result of a differentiative response now, the response of what it is to what is happening around it. Although organic viability has been built always in contact with things in a surrounding niche, there are limits to how much of an organism's momentary structure can be determined by that contact in the present. Living things are only partially open systems. Even the simplest has active boundaries protecting a configuration of internal organs. An organism must be continuously building and maintaining these organs and regulating their milieu (Damasio 1999, 21, 135-39). It is in fact these internal activities that call for transactions with what is outside the boundary. The structure of the boundary must alter selectively so that it permits some materials while barring others; its operating state must vary with internal conditions. And it must, at the same time, vary with external conditions too; a root hair will grow toward a nutrient the plant needs because cell membranes are responding to indicators of its presence. The organism's immediate aboutness is constituted by its capable transactions with what is outside it -- by means of boundary states codetermined as a function of what is needed and what is there, and later by motivated coordinated action of the whole organism. In this sense of jointly determined structure, an organism is about the world even when it has largely shut down its boundary, when it is asleep or even when it is in metabolic stasis. Shutting down has itself had to pass the test of global integrated function. A theory of cognition compatible with evolutionary theory starts with perception and action understood always in the context both of the whole extant body and its niche. What a primitive organism does in this mutual context is what matters to the survival of its species form. To be effective, perception and action have to be contextual in these ways but they do not have to be sentient. They also do not have to be finely tuned to particular things in the organism's surroundings: a global take may be faster and more relevant than a registering of particulars. Primitive perception may be vaguer and more holistic than we can easily imagine: what matters is that the organism gets by. Gibson makes the point that organism effectivities -- things organisms can do -- are complements of world affordances. A coyote can hunt field mice because, among many other things, there are and have been small rodents. The seal, but not the coyote, has excellent effectivities in relation to ice crevasses under water. The seal's or coyote's aboutness is global -- the whole animal is about its niche -- and yet it is specialized. The animal is, in Gibson's phrase, attuned to the affordances its evolutionary trajectory has given it effectivities for (1966, 5). Affordances are always defined mutually. The fact that certain things in the world must be approached or avoided, and that certain other things are useable in approaching and avoiding -- and with equal significance, the fact that certain other things need not be registered at all -- is the organism's specialization, which is its particularity of aboutness. The fact that it does not respond to everything there is, and that different kinds of organisms respond to different things, does not imply deficiency of contact, but a virtue of contact. Aboutness is not representationTheories of mind and knowing that predate brain science and evolutionary biology were built on ideas about conscious knowing that could make no contact with what was known about living bodies, and that had no reach into earlier forms of life. Our inherited theories are under revision but it often isn't evident to us how deeply the old structures persist. At the core of questions about mind or cognition there has been a question about sentience. It has been hard to know how to ask it. The lingering prebiological tradition says any sentient aboutness is a property of something unusual located in parts of some living bodies. This unusual something can be about other things in the way pictures or sentences are about things other than themselves. Questions about mind and knowledge then become questions about representation: what is the relation between the representation and the thing it represents? Can we trust the representation: can we know whether it is accurate or true if we never have access to the original it represents? How do we become conscious of our representations? This manner of speaking misunderstands both representation and biological aboutness. Representation is a poor metaphor for biological aboutness, because representation is fundamentally communicational, and social uses of representing artifacts and events presuppose highly developed kinds of prior biological aboutness. An organism's aboutness is not any kind of mirroring or stating: its aboutness is the way its structure varies as a function of what it is (i.e., what it needs and what it can do) and what is there. It also is not any kind of internalization, either of an object of knowledge or of a simulacrum. The locus of aboutness is not as if some inner thing. There is no content. Nothing is contained: no images, no propositions, no symbols. (And when we come to talk about actual images, propositions and symbols we will see that nothing is contained in them either.) The world is there; the living thing moves out into it; its motion is spatially directed and its perceptual response selective, because it needs something. Its whole state of needing and going for in a world that is there around it, is its aboutness. In complex creatures, aspects of structural aboutness are means of sentient aboutness. And then, much later, the aboutness achieved by means of sentences and pictures. About aboutnessAbout < OE onbutan, <on, on + butan, outside. In contemporary English about is an adverb or preposition that can be used to evoke kinds of mutual spatial relation a living thing can have to something in its environment or to the environment in general. The water about the protozoan. To swim about, to look about. To stalk about the grass. The mouse ran about the post. Her kittens about her. The vulture hanging about. About before daylight. Going about their hunting. About to pounce. A ferocity about him. An excellence of aboutness as a term for the range of kinds of engagedness there can be between a living thing and its environment, is that contemporary uses of about already include both primary uses for active spatial relatedness, and extended and metaphorical uses for relatedness representationally mediated. Another excellence of this way of talking about organic relatedness is that the aboutness of the world -- standing (flowing) about the organism -- is there along with the organism being about it. About thus evokes at one time all three parts of the mutual event: the organism in its doing, the object it wants or wants to avoid, and the background location that supports its doing by holding them related to each other.
A cat stalking a bird is manifestly about the bird. We've seen babies when they are manifestly about the spoon. When a person or animal is intent in motivated action we can often see what they are about -- what they are directed toward, engaged with, wanting and capably going after. What if we took as our paradigm of aboutness not a moment of disaffected self consciousness but a moment of maximally effective physical engagement? It would be more apparent that whole organisms (and not just a specialized internal parts) can be, at various times, just about wholly about something outside themselves. The cat, and not just a specialized internal part of the cat, is in reference to the bird. The whole cat is in a transitive state, taking an object. The baby going after the spoon with all its little might is in a state that is visibly intentional, that is, is in a state of being about something specific. We have tended to think of organism aboutness as segregated within the organism's body -- as if most of a body is responsively inert, and only some isolated part is somehow about what there is. But there is no way to divide the organism into parts that are purely about the world and parts that are not. Inasmuch as aboutness is a relation, it cannot be localized to the organism at all. To think it adequately, we must be thinking the organism and environment at the same time. Inasmuch as it is the adapted structure of the organism, either in general or in the moment, it cannot be localized anywhere in the body. Neural states in sensory and motor cortices are indeed part of our means of being in transitive states, but we are related to objects -- referring to or 'intending' them -- also by means of the tension in our hands, the directedness of our eyes, specificity of endocrine release, shifts in heart rate, and much else. At any moment, much of our structure will be implicated in effective transactions with what is outside our boundary. For many of these structures it will not make sense to try to say whether they are primarily relevant to outside or inside conditions (Varela 1984, 219). Behaviors directed toward something outside the organism are codetermined by internal requirements; and even the organism's maintenance of homeostatic balance after effort or ingestion can be thought of as a response to external conditions. Any small mutation in the organism's structure and function will have to run the test jointly of the organism's environment and the organism's preexisting structure. In this sense the unit of selection is the entire organism in its entire developmental history (at least up to reproduction), always in a selective niche. What is selected is never the trait alone, but the fit of the new trait as a structural alteration that firstly does not significantly disturb the organism's ability to build and maintain itself internally, and then secondly may add some ability to react and to act effectively in its niche. Because the selective unit is thus the entire integrated structure of the organism over its entire developmental sequence (Edelman 1988, 45-6), and because development (even among mammals and the ovipara) requires effective contact with world conditions external to the organism, biological structure comes to be an always more complexly integrated aboutness. Species structure is the way it is, not only because the world was the way it was, but because predecessor forms were the way they were in the world the way it was. The organism is the result of a trajectory of mutuality. There are of course relative excellences of aboutness. An organism is effective in relation to something by approaching or avoiding it, or navigating it on the way to something else, always in the context of what it needs at some moment. Besides being more or less brisk and precise about the tasks of self maintenance, it can be more or less brisk and precise in going after or getting away, and in doing both at the right time relative to its system-maintenance needs. Another order of excellence of aboutness is complexity of contact (Tononi and Edelman 1998, 1851). Some organisms can be about more things at once, and in better-integrated ways. One of the things this means is that their effectivities are contextualized not only to their own internal states but also to complex affordances -- to complexes of things about the world. They are effective in relation to co-occurrences: the shape and motion of the whale's fin at this moment is about the shape of current present, as well as about the position of the fish being pursued; the sequence of tensions in the leg is about the terrain as well as about the location of the prey being stalked: this field mouse, this position of the field mouse in this terrain, as well as this state of the hunting body itself.
The whole of the body is about the world as a result of contact events occurring over three kinds of time span: species time, somatic time, and immediacy. The species structure of any viable organism is the result of successful ecosystem contact by successive approximations over evolutionary timespans. The species form, its phenotype, is thus quite generally about aspects of the world that were present in the niches of evolutionary ancestors. So an individual member of a species can be about conditions it has never met, but always within the constraints of functional integration. Embryogenesis, maturation and learning are forms of structural modification that occur in interaction with the current environment. The somatotype, the individual body form as it has been structured also by its history of contact with the world, is a tuning of the phenotype to the specific niche inhabited in somatic time. Somatic aboutness is a refinement of phenotypic aboutness: it always requires and presupposes the wider aboutness of the species. Finally, the individual is about its immediate circumstance by means of the whole of its internal reactions and external responses at that moment. It is so by means of its existing structure as modified by its interactions in the moment. At each of these time spans, aboutness is constructed interactively. Responsive structure created in the moment is jointly determined by world and existing structure. Existing structure is jointly created by world and phenotypic scheduling in development, maturation and learning. Phenotypic structure is jointly created by world and predecessor structure over evolutionary time. Thus the relatedness of a living creature in a given moment is both particular and very broad. The processes by which individual organisms construct and modify themselves in embryogenesis, maturation and learning have themselves been selected (Edelman 1988, 52) within environments some of whose physical properties go on being presupposed by and necessary to them. The replicated gene string is a set of genetic macromolecules configured in one way rather than another, forming a complex three-dimensionally self-interactive field. From that minimal beginning, everything depends on context. A genetic ordering is not so much a plan or an agent (Oyama 1993) as it is a template surrounding materials organize themselves against. The way they organize themselves is a consequence of template properties, properties of the materials themselves, and the dynamic properties resulting from their configuration into folded proteins. The self-organization of the resulting cells is also place-dependent, which is to say that differentiation into tissues and organs happens by means of chemotaxic and electromagnetic gradients that are set up step by step primarily as a result of the dynamical properties of the structure as it already exists, but also always contextually codetermined by the presence and dynamical properties of surrounding non-organism materials and states: water molecules, dissolved salts, gravitational fields. Where conditions are not enough like evolutionary conditions, there will be no, or faulty, construction. Mammals and the ovipara, which later can be viable in varying conditions, first build themselves a developmental niche, a subspace that provides them conditions more like those of evolutionary time. Living bodies continue to change all their lives. Some changes are called development and maturation, and some are called learning, but both are structural changes occurring in contact with an environment. Developmental changes tend to be thought of as genetically specified and learning is thought of as depending on particular experience, but both sorts of structural change occur in particular environments and because the organism is the kind of structure it already is. Learning is not unlike development and maturation (Edelman 1987, 3-4): it is structural change, it occurs in a structure already viable, it is evolutionarily constrained, it requires an adequate context, and it is co-determined by occurrences within that context. Not all learning is advantageous; learning may also disable an organism. But the fact that processes of structural change are selected for suggests that learning and memory (as they function at least up to the age of reproduction) will in general make the creature better able to meet whatever comes up. Nervous systemsWhat is the place of nervous systems in the global integrated aboutness of those living things that have them? A nervous system is an organ that pervades other organs and is essentially facilitative and coordinative (Jarvilehto 1998b, 337-39). The nervous system is not the locus of aboutness in a body. The entire body is about the world; the nervous system is part of the means of its aboutness.
I've said evolved living bodies are generally about their environments by being structurally adapted to them, and that they are about their immediate circumstance by means of the instantaneous responses of those structural adaptations. Animals without nervous systems can have this sort of aboutness. Even plants have limited phototaxic reactivity. What is added with the simplest nervous systems is coordinative integration. This sort of integration is essential to moving organisms: It is delightful to consider that development of a nervous system is in fact very much a property of actively moving organisms (non-sessile organisms), that is, those that do not remain fixed to a particular place, as is the case for plants. This principle is beautifully exemplified by the tunicate (a 'sea squirt') with free-swimming larvae ... In ancestral tunicates as well as in some present forms, the sessile adult form (which is rooted by its pedicle to a stable object in the sea) carries out two main functions: it feeds by filtering seawater; and it reproduces by budding. Upon reproduction, larvae are free swimming and possess a brain-like ganglion which can be informed about the environment by peripheral sensory input from a statocyst (organ for balance), a primitive eye, and a notocord (primitive spinal cord). These central nervous structures have the connections necessary to deal with the continuously changing environment, as this primitive tadpole-like larva swims through the water. Upon finding a suitable substrate, the larva proceeds to implant its head end into the selected location and becomes sessile. In doing so, it absorbs much of its brain and returns to the rather primitive condition of the adult form of the species. Llinas 1987, 341 The parts of a moving organism, internal and peripheral, must be coordinated so that activity is relevant to the organism's needs of the moment, muscles work together smoothly, and motion is well directed. To these ends, nervous system activity must be relevantly simultaneous -- correctly distributed into many cooperating regions -- and relevantly sequenced, again in such a way that simultaneous activities will be timed correctly in relation to each other and in relation to events in the world. Nerve systems coordinate complexes of organs and limbs so that many different kinds of aboutness are possible at the same time --- my hand can be about the shape of the bowl while my arm is about its position and digestive enzymes are beginning to be about its contents. Meanwhile my breathing and heart rate can be largely about stable background conditions like oxygen concentrations and temperature, as well as being keyed to internal conditions that include the states of hand, arm, mouth and gut.
Cells and tissues are watery suspensions of many kinds of chemical salt. They are, consequently, electrical fields in which positive and negative charges sum and are propagated. Every cell, non-neural as well as neural, reacts to disturbances of electrical potential that occur with changes in its chemical milieu. It restores resting potential -- its optimal electrical state -- by distributing charge across the interior of the cell. One-celled animals can make use of this electrical characteristic of biological fields. A protozoan, for instance, may have simple sensor and effector structures separated by some distance in the single cell, so that a charge instigated at a sensitive material in the cell propagates to a contractile structure that causes the creature to move toward or away from the source of chemical disturbance (Oyster 1999, 5). [1-1 Illustration of protozoan] Specialized neural cells in many-celled animals retain the propagation of electrochemical gradients that was important in one-celled creatures. All cells and tissues in a many-celled animal are electrically active, but neural cells laid down in connected series between sensors and effectors will increase the range of effect by increasing the speed and specificity of propagation. As mediational structures -- nervous systems -- evolve, larger organisms with new sorts of reactive materials become practicable. In these larger organisms, sensor and effector structures can be elaborated into receptor and motor tissues and organs.
Neural cell specializations that were necessary to build complex nervous systems on the basis of the inherent reactivity of non-neural cells include the synapse, multipolarity, myelinization, trigger zones and action potentials (Kandel 1991). Nerve tissue defines functional units by modifying the connections between cells: by growing axons and dendrites toward other cell bodies, and then by both growing and altering the synaptic junctures that allow electrical activity to propagate selectively. These connections channel activation and also modify its character. Dendrites and axons are as if the sensors and effectors of the neural cell. A dendritic synapse responds to chemical disturbance in the synaptic gap by propagating charge into the cell; an axon synapse discharges by propagating a chemical disturbance into a synaptic gap. Invertebrate neurons are predominantly unipolar; they are simple structures with dendritic and axon synapses at the same end of the cell. The multipolar neurons that are usual in the vertebrates are more differentiated, with extensive dendritic trees and sometimes very long axons. A moderate multipolar motor neuron receives 10,000 contacts from other neurons (Kandel 1991, 22). In unmyelinated axons, charge propagates slowly and dissipates with distance; in early invertebrates like the medusa, conduction occurs both ways. Myelin is an insulating substance that sheaths axon fibers and organizes rapid intense one-way discharge. One-way axon conductivity together with synaptic contact ensures that reactivity will propagate through a network. Another precondition for this sort of axonal spiking is the organization of a trigger zone within the cell body, near the top of the axon. The trigger zone, along with the cell body itself, sums or integrates all the electrical disturbances resulting from dendritic contacts, and restores membrane resting potential by propagating high amplitude spikes down the axon to junctions with other cells. The effect of axon contact with downstream cells may be excitatory or inhibitory.
Pervasive systems, like endocrine, lymphatic, blood, and nervous systems, segregate themselves but also make selective contact with surrounding tissues. Blood vessels maintain segregation and make contact through vessel walls that allow selective diffusion; nerves are similar in being able to both propagate and isolate electrochemical activation. Neural series allow sensor effect to be propagated to specific effectors without disturbing function in the sometimes long distances between the two. Like the evolution of the neuron, the evolution of the neural series required a number of innovations. Llinas (1987, 342) describes the following evolutionary sequence. A motile cell in a very early invertebrate such as a sponge contracts when stimulated. In the somewhat more complex sea anemone, receptor and motor cells are separated; the sensory cell no longer contracts, but it terminates on a muscle cell that does. In another sort of sea anemone, a motor neuron is interposed between the sensory cell and the contractile cell; the response that results is a monosynaptic reflex. In the vertebrate sensor tissues are able to propagate response to motor and other neurons by means of extensively branching networks of interneurons within the spinal cord. Three related principles are basic to everything nervous systems do. The first is the principle of integration of effect within the neural cell itself. The second is the integration of effect throughout the whole of an organism by seriation and recurrence. A third principle ensures that it will propagate in an ordered manner: it is the principle of structural potentiation. Synaptic connections between cells that discharge together are structurally modified so that they will be more likely to discharge together again when one of them is activated.
... well over a century ago a number of psychologists began to entertain the notion that the incoming afferent stimulation and the outgoing motor innervation were part of a single continuous process with no point of separation between them. Coren 1986, 408 I will wait until Chapter 2 to describe the evolution and function of neocortex, because in this chapter I want to emphasize that the extended nervous system is the embedding context of the brain, the way the environment is the embedding context of the organism. Non-cortical neural structures pre-date brains in evolution, and they provide an essential part of the brain's operating conditions, in post-natal as in pre-natal development and function. One of the implications of this emphasis is that we should in general think of nervous system structure in terms of through-lines selected when sensor-effector connections result in effective action. My use of this term is meant to emphasize the continuity rather than segregation of sensor and effector response. I am using the term in a different sense than Nauta and Feirtag (1990, 100) who use it to describe two-synapse connections into the neocortex. My emphasis would be in agreement with Llinas, who says that in considering the evolution of the brain, "the basic property implemented consists of the ability to transform given sensory responses into organized motor events" (1987, 340). Simple coelenterates, which are the earliest phylum to have nervous systems, can have as many as seven different kinds of sensor. In some of these coelenterates there are separate neural series between sensor-effector pairs of different kinds: in effect, separate nervous systems for separate perception-action functions (Bullock 1977, 394-401). To get from dedicated sensor-effector through-lines of early invertebrates to the overlaid networks that coordinate the integrated aboutness of mammals also required a series of innovations. These include interneurons, ganglia, and finally encephalization, that is, the routing of most sorts of function through structures within the head. In organisms with more than one kind of sensor it can happen that through-lines from different sensors converge on the same effector. In such cases synaptic contacts between through-lines could usefully be ampliative or inhibitive. Cross-contacts between through-lines could also act as line-splits from one set of sensors to different sets of effectors. This occurs in more developed phyla where the same interneurons make excitatory and inhibitory contact with opponent muscle groups. Higher invertebrates have plexes or ganglia of interneurons, each coordinating a different system. There are crustacea in which these ganglia are organized into three proto-lobes, which organize the behavior of eyes, antenna, and alimentary canal separately. Although the neopallium, or primitive neocortex, begins to develop over ancient olfactory cortex when early vertebrates emerge from the water, most sensory-motor behavior is still subcortical at that stage. The reptiles have well developed vision, for instance, but it is mostly organized at retinal ganglia so that reptilian cerebral visual systems "may have relatively little additional visual work to do" (Jerison 1973, 262). In the submammals motion is still locally controlled from spinal ganglia. Neural evolution from the vertebrates on up has to do with always increasing complex contextualization and integration. Mammals evolve from the point where there is encephalization of most function. The principle that seems to be present in this elaboration of encephalized structure is that early circuits are maintained but added to. The functionally primordial through-circuit that Gerald Edelman calls a sensory-motor categorization (1987) remains, but it can now act at many different levels. Something like the same response can be enacted as a reflex organized at spinal ganglia, as swift but integrated behavior organized in midbrain structures, as cortically contextualized action, or as a deliberated act extensively mediated by associative circuits. In humans many of these circuits are active at the same time, and their activity at their many levels must be coordinated. The kinds of aboutness enabled by through-circuits that are widely distributed networks whose branches are themselves networks, is a multiple simultaneous aboutness calibrated to the internal needs of the whole organism. The organism by these means is able to coordinate action relevant to many things simultaneously present in an environment, is able to be more precise in relation to particular things whose detailed differences matter, and is able to stay on top of rapid many-p-art change, all while continuously recovering internal equilibrium.
Chapter 2. Wide nets |