Chaotic state transitions in brains

as a basis for the formation of social groups

Walter J Freeman

Department of Molecular & Cell Biology

University of California, Berkeley

Tel: 1 (510)642-4220 FAX: 1 (510)643-6791

e-mail: wfreeman@socrates.berkeley.edu

Chapter 20 in: "CHAOS AND SOCIETY" Albert A (ed.), 1995

Presse de l'Université du Québec

Hull, Québec, CANADA J8X 3X7

pp. 119-132

 

Hector: "'Tis mad idolatry

To make the service greater than the god.

And the will dotes that is attributive

To what infectiously itself affects,

Without some image of the affected merit."

Act II, Scene ii

Troilus: "I am giddy, expectation whirls me round.

The imaginary relish is so sweet

That it enchants my sense."

Act III, Scene ii, Troilus and Cressida, Wm. Shakespeare

 

ABSTRACT

Experimental observations on the brain activity that ensues on sensory stimulation of animals show that sensory cortex engages in the construction of activity patterns in response to stimuli. The operation is not that of a filter or correlation mechanism. It is a state transition by which the cortex switches abruptly from one basin of attraction to another, thereby to jump from one spatial pattern to another as do frames in a cinema film. Each transition involves learning, so that cumulatively a trajectory is formed by each brain over its lifetime. Each spatial pattern as it occurs reflects the entire content of the trajectory. Subjectively, the several patterns of the sensory cortexes combined in the limbic system constitute the biological basis of consciousness, for which the role is to make available to the subject the entire body of experience as the basis for each new step, word, or decision. This constitutes also a new meaning for the concept of intentionality.

It follows that each brain creates its own trajectory and its own frames of reference, which are not directly accessible by any other brain. How, then, can two or more brains be shaped by learning so as to form cooperative pairs for reproduction and groups for survival? Evolution has provided a biological mechanism that first came under scientific scrutiny in the form of Pavlovian 'brain washing'. Under now well known conditions of stress in the internal and external environments of the brain, a global discharge takes place, following which the brain sustains a remarkable period of malleability and adaptiveness. Examples of the process include hazing by fraternities, indoctrination of recruits in military 'boot camps', tribal dance ceremonies, evangelical religious conversions, and, most importantly, sexual orgasm as the basis for pair bonding and cooperation for the nurture of the young. The subjective and objective manifestations of the madness (folie á deux) that accompanies the dissolution of intentionality in humans is wonderfully described in "Troilus and Cressida". An excessive concern for computational algorithms currently leads many scientists to neglect these noncomputational processes as the bases for pair bonding and group behavior. Nonlinear dynamics and the theory of chaos offer new approaches to understanding these neurobiological mechanisms by which societies are formed and maintained.

1. INTRODUCTION

The gap between neurobiology and sociology may seem wide and even unbridgeable except by analogy, metonymy and metaphor. Yet there exist short pathways by which to travel from one to the other and back again, and the study of chaos offers one such path. Brains are composed of elementary parts called neurons, and societies are made of individuals each with a brain. The organization of function by large numbers of neurons is governed by chaotic dynamics and is expressed in global state transitions, such as from sleep to waking, walking to running, and breathing to speaking. One class of state transitions in brains provides for the formation of social groups such as marriages, tribes, and fraternities. My purpose here is not to analogize between neurons and individuals, as Minsky (1985) did, but to describe the biology of this class of state transitions, its role in the coalescence of rapport between individuals, and its importance for human welfare.

It is essential in this approach to deal explicitly with the biological phenomenon of consciousness. Its physical basis can be explored with two assumptions, that animals are conscious albeit in ways less complex than those of humans, and that neural mechanisms operate pari passu with mental processes. We make these two assumptions in our dealings with our fellow humans, and the extension to animals makes it possible to explore the neural operations during normal behavior with techniques that are essential for understanding the biology but inadmissible for use on our fellow humans. My main concern here is with a salient property of consciousness, namely the inviolable isolation between different brains, which is experienced subjectively as the inexchangeability of qualia. How is it that we cannot be certain, by direct experience, what any other entity has in the content of its consciousness, whether it is an animal, a machine, or a fellow human being? Research on the electroencephalogram (brain wave, EEG) offers a mechanistic answer to this fundamental epistemological question. By direct measurement of the signs of neural activity in the brain we can follow the flow of sensory input from the receptors into the cerebral cortex and identify the neural mechanisms by which that input is transformed into spatial patterns of neural activity. We observe these EEG patterns and correlate then with overt behavior during sensory discrimination. It becomes clear that these patterns are constructed by brains to replace raw sensory input. They are not computed by the brain from sensory traces. Hence no two brains are alike, and no brain can directly access any other brain. This property of isolation has been inferred from introspection, but always with the tantalizing supposition that one might be able to peer beyond one's senses into the real world. We cannot. The question to be asked is, what are the implications of these experimental findings and interpretations for our understanding of social constructs as the basis for shared social action?

2. EVIDENCE REQUIRED FOR DYNAMIC MODELS OF THE BRAIN

As a dynamical system seen from the outside, the brain takes inputs in the form of stimuli and gives outputs in the form of responses. We should not begin with the whole but with the smallest part that will suffice. For many purposes that is the neuron. We measure its input, such as a volley of afferent action potentials, and its output, such as the electric currents of the dendrites seen as a 'postsynaptic potential', and we use the ratio of output to input to specify the relationship of an input-output pair. We repeat this test ad nauseam under varying conditions, until there are no more surprises. The collection of input-output pairs and their ratios constitutes our experimental data base.

We examine these pairs and devise a model, which consists of a differential equation that, when solved for the input and the initial conditions at the start of the input, yields a curve that can be fitted to the observed output. We can call this equation an operator that transforms the input into the output. For example, a nerve impulse is transformed by a synapse into an exponentially decaying postsynaptic potential, and a model consisting of a differential equation suffices to describe this operation. From this simple beginning, which forms a main foundation of modern cellular neurophysiology and more recently of the new field of neural networks, we generalize to arrays of interconnected neurons and to trains of impulses in an unlimited variety of network configurations.

My own work has been focused on the olfactory system in small laboratory animals, because this is the simplest and phylogenetically oldest sensory system, and because it is the most important of the senses for cats, rabbits and rats. The crucial experiments were simple in conception. Rabbits were implanted with an array of 64 electrodes in an 8 x 8 grid placed onto the surface of the olfactory bulb. They were trained to respond by licking to one odorant, such as amyl acetate that was accompanied by a reward (water), and merely to sniff in response to another odorant (such as butyric acid) as an unrewarded stimulus. On each trial a set of 64 EEG traces was recorded for 6 sec, that included a control period and a test period (Figure 1). Brief EEG segments lasting 75 msec were selected during the times of inhalation of the background, control air or either of the two odorants presented on randomly interspersed trials. Sets of several hundred of these EEG segments were analyzed for each animal. We knew which of the 3 states each segment came from. The crucial question was, what aspect or aspects of the segments would enable us to classify the segments correctly in respect to the antecedent odorant conditions?

The hypotheses were that, between the time of inhalation and the performance of a correct response, odorant information existed in the bulb as a pattern of neural activity, on the basis of which the animal made the discrimination, and that this information would be detectable in some as yet to be determined properties of the EEGs. Our results showed that the information we sought was indeed manifested in the EEGs. It was identified as a spatial pattern of oscillation between 40 Hz to 80 Hz that we termed the "gamma" range, in analogy to the high end of the x-ray spectrum (Bressler and Freeman, 1980). A common wave form was found in each segment (Figure 2), and the spatial pattern of its amplitude tended to converge toward a reproducible shape each time that the background or an odorant was present. In principle this form of display is quite simple. It is like a frame in a black-and-white movie or a page in a book, in which the carrier wave is the light, and the shape is formed by the highs and lows of the amplitude or intensity of the light.

3. INTERPRETATION OF THE EXPERIMENTAL DATA

The finding that the central "code" for olfaction is spatial is not surprising. This was predicted by Adrian (1950) on the basis of his pioneering studies in the hedgehog. The role of the receptors forming a sheet of neurons in the nasal cavity is to transform an incident chemical species into a spatial pattern of action potentials, much as a retinal pattern of light is transformed to a pattern of ganglion cell activity. This spatial pattern of receptor activity is transmitted to the bulb by unbranched axons that have some degree of topographic order, so that a new spatial pattern can be predicted to be generated in the bulb for each new odorant. And it is not surprising that the information should exist in the induced burst of activity accompanying each inhalation, which rises above the background activity during inhalation, because it is well known that detection of odors takes place on inhalation. But there are three aspects that are very surprising.

 

 

Figure 1. An EEG is illustrated from the olfactory bulb. Each inhalation excites the receptors, which send action potentials to the bulb and destabilize it. This results in a 'burst' of oscillation that controls the transmission of action potentials to the cortex.

Figure 2. The oscillation is recorded with 8 x 8 electrodes in a square array, and the incident odorant is expressed as a spatial pattern of amplitude of the burst. The pattern changes with each new odorant in serial generalization and does not go back to the original pattern when the original stimulus is re-introduced.

First, the information is uniformly distributed over the entire olfactory bulb for every odorant. By inference every neuron participates in every discrimination, even if and perhaps especially if it does not fire, because a spatial pattern requires both black and white. This fact has been demonstrated by repeating the classification test while deleting randomly selected groups of channels. No channel is any more or less important than any other channel in effecting correct classifications. Furthermore, we and many other investigators have attempted to demonstrate odorant specificity in the discharge rates of action potentials from single neurons. These attempts have never succeeded. In view of the facts that the minimal number of channels for correct classification of EEG segments is 8 to 16, and that each segment reflects the activity of many thousands of neurons, we have concluded that the information relating to odorants is carried by the millions of neurons in the entire bulb, and it is not detectable in the activity of any handful of neurons that can be simultaneously accessed by multiple microelectrode recording.

This finding establishes the significance of the EEGs as experimental variables. These electrical potentials result from the dendritic currents of neurons that flow between the cells, where they sum over the contributions of large numbers of neurons (Freeman 1975, 1991). Thereby the EEGs give direct access to the amplitudes of synaptic activity of populations of neurons. This is the hierarchical level, I believe, at which the goal-oriented behavior is being elaborated.

Second, we find that the bulbar information does not relate to the stimulus directly but instead to the meaning of the stimulus. This has been shown in several ways. The simplest way is to switch a reward between two odorants, so that the previously rewarded stimulus is no longer reinforced and vice versa. This is called reinforcement contingency reversal (Figure 3). Both spatial patterns change, though the two odorants do not. So also does the spatial pattern for the control segments in background air. So also do all pre-existing patterns change when a new odorant is added to the repertoire. We infer that the patterns for all odorants that can be discriminated by a subject change whenever there is a change in the odorant environment. Furthermore, we trained rabbits serially to generalize to odorants A, B, C, D, and then back to A, and found that the original pattern did not recur (Figure 2), but a new one appeared (Freeman 1991). These properties are to be expected in associative memories, because the context changes with each addition to the store.

The point here is that the brain does not process "information" in the commonly used sense of the word. It processes meaning. When we scan a photograph or an abstract, we take in its import, not its number of pixels or bits. The regularities that we should seek and find in patterns of central neural activity have no immediate or direct relations to the patterns of sensory stimuli that induce the cortical activity but instead to the perceptions and goals of the subjects.

Third, the carrier wave is aperiodic. That is, it does not show oscillations at single frequencies, but instead has wave forms that are erratic and unpredictable in each segment, nor is it ever the same in any two segments, irrespective of odorant condition. Yet the same wave form appears on all the channels, although of course at different amplitudes. Moreover, during exhalation and prior to each inhalation there is persisting background activity, which is highly irregular, with its energy uniformly distributed over the gamma range of the spectrum. The odorant segments in many instances show no increase or even a decrease in overall EEG amplitude from this basal state, yet always display a remarkable commonality of wave form across channels.

The possibility that this seemingly random wave form could occur by chance almost simultaneously on all channels is vanishingly small. We sought a mechanism by which a common activity might be imposed in this gamma spectral range onto the whole bulb, either by receptors or by centrifugal pathways from the forebrain and brainstem. We found firm evidence that no external driving can produce the observed commonality of wave form. A substantial aperiodic basal activity persists after the bulb and olfactory cortex are surgically isolated as a unit from the rest of the brain.

 

Figure 3. The lack of invariance of EEG patterns in respect to stimuli shows that changes in the meaning of the stimuli are critical determinants of the patterns.

Figure 4. A circuit diagram of the limbic system illustrates some of the neural feedback loops that support voluntary behavior. Behavioral actions are initiated in the limbic system, here simplified to the entorhinal-hippocampal components. Each motor command is accompanied by reafferent messages to all sensory systems that incorporate expectancy particularly of the consequences for sensory input of the forthcoming action. The activated receptors transmit to the sensory systems in which chaotic constructive processes are maintained by sensory feedback loops. All sensory systems convey their resultant by serial stages to the entorhinal cortex, which combines them and engages the hippocampus in short term memory. This dynamical system recursively provides for the next purposive behavioral output. We speculate that the process of reafference provides a physiological basis for consciousness.

 

These findings have led to the insight, already reached independently by other investigators (e.g. Babloyantz and Destexhe 1986), that the brain activity is characteristically chaotic. More specifically, many parts of the physicochemical brain are capable of generating controlled but locally unpredictable activity that looks like noise but is not. This is significant in two respects. The lesser is that it directs us to search for carrier wave forms that are aperiodic and not for oscillations at specific frequencies such as the alpha or the "40 Hz". The greater significance attaches to the property of chaotic systems in their ability to jump suddenly and completely from one global activity pattern to another, just as, for example, we jump from one word to the next in the rapid flow of speech and from one gait to another in walking, jogging and running. Our EEGs are showing us sequences of patterns, each of which is carried by a chaotic wave form and not by a wave at a single frequency, as previous EEG studies had led us to expect.

The chaotic activity that is produced by the bulb and the olfactory cortex is a global property of the entire central system. The irregular activity is not the local sum of the noise of idle neurons. It is the controlled and directed product of the whole. Further, the background state is not a silent equilibrium that is perturbed by noise. It is a chaotic state that keeps the system in constant readiness to jump to any desired perceptual state at any time.

4. MODELING OLFACTORY DYNAMICS FROM ACTION POTENTIALS AND EEGs.

These surprising results give us several key insights into the dynamical processes to be modeled. First, we are assured that the proper element for our model is the local population and not the single neuron. Perhaps paradoxically this provides an enormous simplification, because the dendrites of neurons in a local neighborhood can be modeled as a simple integrator. The amplitude of output is transformed to the frequency of pulses, but the relationship is not shown by a straight line (linear) as it is for single neurons (reviewed by Freeman 1975). Instead it has the form of a sigmoid (S-shaped) curve between the axonal thresholds and maximal firing frequencies for the population. Most of the complexities of the single neuron remain at the hierarchical level of the neuron, and the population is described with a linear second order differential equation and a static sigmoid curve (Freeman, 1975).

Oscillations arise when an excitatory population is coupled into a loop with an inhibitory population to form a negative feedback loop. The oscillations are periodic in a model of the bulb, as we find to be the case in the experimentally isolated bulb. Chaos in the model arises when the bulbar loop is interconnected with the olfactory cortical loop, so that each excites the other. Each oscillator has its own characteristic period, but they differ and cannot agree. Neither can escape the other, so that perennial aperiodic oscillation results. If the two parts are disconnected, the chaos in the model disappears, as it does in the experimental animals, when the bulb and cortex are disconnected from each other.

The bulb and the cortex are each simulated by an array of local oscillators, that are interconnected between the excitatory elements by simulated synapses, so that they excite each other. These connections couple the oscillators into a layer, and they ensure that the whole array oscillates with a common wave form. The chaotic waveforms are simulated with the solutions of a network of coupled nonlinear differential equations (Freeman, 1987, 1992). There are large numbers of input an output connections, essentially one pair for each local oscillator. The mutually excitatory synapses between the oscillators are selectively strengthened during classical conditioning to classify a simulated odorant by presentation of examples of a class of stimuli, leading to the formation of a Hebbian nerve cell assembly (Hebb 1949) consisting of groups of local oscillators that are co-excited by the stimuli. A global command is required in the model to "form an assembly", which is equivalent to the release of chemical modulators such as norepinephrine into the bulb by the brain in response to reinforcement by an unconditioned stimulus. Multiple assemblies are formed corresponding to classes of inputs in sequential 'training' sessions, leading to formation of multiple 'nerve cell assemblies' that are separated by simulated 'habituation'.

The end result is that the array of coupled oscillators generates a recognizable spatial pattern of amplitude of a common chaotic wave form whenever an example of a learned class of stimuli is presented to the model. That pattern serves to identify and classify the stimulus presented. In dynamical parlance we say that the system, whether the brain or a model, has a global chaotic attractor with multiple wings, one for each learned class of stimuli with its attendant basin of attraction. The global attractor is like a house, and each wing is like a room to which the system is sent by a stimulus, such as the kitchen with hunger, the bedroom with fatigue, and so on. This means that the olfactory system (and its model) has certain preferred patterns of activity, any one of which it naturally falls into if given the opportunity. That opportunity is provided by the presence of any stimulus in a class that it has learned to respond to, whether or not the example was included in the original training set. A stimulus of this class provides the input and starting conditions that are needed to place the system into the basin of attraction, so named in analogy to a bowl in which a ball will roll to the bottom. Its basin defines the range of generalization for identification of a stimulus of that class.

Some caution should be exercised not to take too literally the mathematical concepts of attractor and basin, any more so than Fourier components and Gaussian distributions. These concepts are derived by theorists to describe systems which are autonomous and stationary, that is, which are left to themselves and settle into an unchanging routine. Brains are in continuous interaction with the environment and are continually undergoing state transitions, which are not stationary, linear or Gaussian. Though all of these are powerful tools within their limits, a better descriptor for brain function is 'chaotic itinerancy' (Tsuda, 1991), which is metaphorical from the peddler who moves from one village to another, often recursively with the seasons, not necessarily in the same sequence, and with never quite the same episode on each return. The journey is described as a trajectory in the space of travel, and the stops are states in the state space. Neural states and thoughts similarly flicker in sequence, often recurring, but never twice the same. A compelling example of chaotic itinerancy has been developed by Greeley (1994) from analyses of philosophical discourse.

5. SOME IMPLICATIONS OF THESE FINDINGS FOR PSYCHOLOGY

These experimental data and descriptive dynamic models have profound consequences for understanding how sensory cortexes work at the interface between the brain and the outside world. The crucial point is made by tracing the course of a stimulus into the receptor layer, where it is transduced into a pattern of action potentials, and then into the cerebral cortex, through the thalamus for other systems but directly for olfactory input. What happens in the bulb is a sudden destabilization of the bulbar system, so that it makes an explosive jump from a pre-existing state, expressed in a spatial pattern of activity, to a new state that is expressed in a different spatial pattern. The pattern is selected by the stimulus, and, if reinforcement is provided, there is further slight modification of the pattern, but in the main the pattern is determined by prior experience with this class of stimulus. The pattern expresses the nature of the class and the meaning for the subject rather than the eidetic details of the particular stimulus. The identity of the receptors that are activated is irrelevant and is not retained, because the activated receptors belong in a class of equivalent receptors. The output does not express the identity of a chemical material but a collection of experiences that the subject has had with the material. The sensory data serve to trigger the formation of the action pattern that then replaces them.

The need for this process can be comprehended by noting that the olfactory environment is indefinitely rich in odorant substances, only a small portion of which ever come to the attention of a subject or form the basis for action. That portion is different for every subject, because it depends in part on genetic determinants of the system but mostly on previous experience with selected odorants and the contexts of reinforcement. In a word, the rate flow of information from the environment is infinite. Any system for coping with the environment must reduce such a flow to a finite rate, lest it become confused or overwhelmed. Man-made systems do this by means of filters, which are designed by observers to accept the portions that are desired by the observers. Brains have no 'homunculus' to specify their goals and desired inputs, and they rely instead on chaotic processes to generate activity patterns that are finite in dimension. The commonly used sobriquet 'self-organizing' connotes the feature that chaotic systems can create information as well as destroy it. Chaotic neurodynamics of the kind we have modeled can serve to explain the origin of novel behavior as diverse as learning by insight or trial and error, invention, recollection both accurate and faulty, and outright confabulation. In brief, perception and recollection are a unitary dynamical process by which meaning is created.

Because each chaotic pattern is created from within and not imposed from outside, there would appear to be no instance in which raw sense data are incorporated and stored in the cortex as episodic representations. There is only the modification of synaptic weights among populations of neurons, such that after some train of experience there is an appurtenant pattern of neural activity and of behavior in follow up to the presentation, by stimulation or recall, of an example of a learned class of stimuli. The perceptual process that I have sketched here allows the brain to 'know' only its own experience of the odorant and not the 'reality'.

This conclusion is not new, and it is perhaps not even surprising to many philosophers and psychologists, who are already aware that perception is in the mind of the beholder, and that memory is a creative process rather than a look-up table of imprinted data (e.g. Bartlett, 1932). But the critical question I am addressing here is: what new evidence can experimental brain science bring to drive home this conclusion? The discovery of meaningful spatial patterns in EEGs is not in itself convincing, because two kinds of spatially patterned activity co-exist in the bulb with each inhalation concurrently. One consists of the global spatial pattern of cooperative bulbar activity that expresses the meaning of a stimulus. The other kind is stimulus-evoked activity, which has the differing form of spatial patterns of pulse firings in sparse networks of interconnected neurons, and which expresses the properties of the stimulus. Both kinds of patterns can be observed and measured only in part, but they can be inferred to exist in their entirety, the global pattern by spatial ensemble averaging and the pulse pattern by time ensemble averaging (Freeman 1987). How can we know which of these patterns is accepted and acted upon by the olfactory cortex to which the bulb transmits?

It is immediately clear that the global pattern that is transmitted from the bulb is accepted by the cortex, because the EEGs of the olfactory cortex are usually highly correlated with those of the bulb in the gamma range of frequencies at which the bulb is driving the cortex (Bressler 1987). But what happens to the stimulus-evoked activity pattern after it is transmitted from the bulb? An answer is based on the structure of the transmission pathway and the functional properties of the cortical neurons that receive the bulbar output. Each bulbar axon branches and distributes its output broadly over the cortex. Conversely each cortical neuron receives input from many thousands of widely distributed bulbar neurons, and its dendrites sum that input continually over time. I have demonstrated both experimentally and mathematically that the only portion of the input from the bulb to the cortex that survives this operation of space-time integration is the common wave form, which is the product of the global cooperativity between the bulb and cortex. The stimulus-evoked pulse pattern is localized spatially, and it is poorly coordinated temporally, so that even though it is transmitted from the bulb, as recordings from the pathway have demonstrated, it is expunged by the smoothing process of integration in the receiving neurons. Hence experimental evidence from contemporary electrophysiology conjoins the insight of Immanuel Kant (1781) from pure reason that objects are unknowable and cannot be represented in their full complexity. The model asserts that their traces are abated by a 'laundering' operation in the second stage of the synthesizing processes of perception. Yet the model also asserts that the traces continue to exist in the bulbar messages, and that if some aspect of an object is made significant by further reinforcement, the cortical neurons modify their sensitivities and by accepting that aspect in turn transmit it to higher centers, although not by any sequence of steps the infinitely complex 'whole object'. This appears to be how more complex discriminations are achieved, particularly by humans using language (Cain and Gent, 1986).

6. CONSCIOUSNESS

We now have substantial experimental evidence from EEG recordings that these same processes occur in all other sensory systems (Freeman and van Dijk, 1987; Freeman and Barrie, 1994). When an animal is trained to discriminate and respond to a visual, auditory or somatic stimulus, the appropriate sensory cortex constructs a rapid sequence lasting half a second of spatial patterns on receipt of the learned stimulus. Each pattern has the form of a distributed aperiodic oscillation that is modulated in amplitude and that lasts about a tenth of a second. These patterns also lack invariance with respect to the physical inputs under conditions involving changes in their significance, such as contingency reversal of the conditioned stimuli, implying that these cortical areas also code for meaning and not for information. We infer that each sensory cortex maintains a global chaotic attractor with multiple wings, one for each discriminable class of stimuli, and that when it is accessed, a wing determines the spatial pattern that is to be transmitted by that cortex to other areas of the brain.

The most important target of transmission for each sensory cortex is the entorhinal cortex, which receives transmissions from all sensory systems, combines them, and sends them to the hippocampus. Because the 'code' of the operation is common to all of the transmitting cortices and the receiving cortex as well, it is clear in principle that the convergence of perceptual flow in the entorhinal cortex can explain the unity of perceptual experience. It is also clear that the hippocampus is required to combine meanings over short periods of time, the "psychological now" of William James, although the neural mechanism for the temporal integration is still unknown (O'Keefe and Nadel, 1978). The hippocampus sends its output into the motor systems of the brain and also back to the entorhinal cortex, which in turn distributes the resultant back to the sensory cortexes. Putatively these pathways provide the anatomical basis for reafference (Freeman, 1990), which is the mechanism by which the brain adjusts the sensory cortexes to compensate for the changes in sensory input that results from motor actions that it has itself initiated (Figure 4). How else would one know that when the world appears to move, it is really the eyes that have done so?

These neurobiological properties of the sensory and limbic systems correspond in detail to verbal reports on the subjective experience of the dynamics of consciousness: the fusion of modalities, the rapid sequence of frames, the limited span of a few heartbeats, and the causal sense of an impending action and its sensory consequences. Further, the fact that each addition of a new discriminandum changes the patterns for all of previously learned discriminanda implies that the memory store in each area of cortex is a seamless web with no compartments, and that the whole store of learning participates in each act of perceptual experience. If this property can be shown to hold for the entorhinal cortex and the hippocampus as well, then it will follow that the limbic mechanism for consciousness makes available to an individual the entire body of past experience, which serves to guide each new step, breath, and word. Then this biological process can be seen to have immense power and survival value for the individual. It corresponds to the concept of intentionality in the dynamical sense of Dreyfus (1993) and earlier Dewey (1912), who in his critique of the conditioned reflex concluded that subjects initiate action "into the stimulus" to "incorporate it for the guidance of future action", but not in the representational sense of Husserl and Searle (1983), by which "According to the phenomenologist (Husserl), [psychological knowledge] is a "material a priori'. ... When pushed to the limit, eidetic psychology becomes analytic-existential" (Merleau-Ponty, 1964, p.95).

7. BRAIN WASHING

This intentional mechanism has its price, which is the isolation of each brain. With respect to energy and information each brain is an open system with continual throughput, but with respect to meaning it is a closed system. This is because meaning is constructed afresh by each brain in the context of its individual genetic, experiential, and cultural history (Bartlett, 1932). Geometrically, intentionality can be conceived as a structure, and the meaning of an event is a place in that structure. Because the patterns of neural activity are self-organized by chaotic dynamics, so also are the frames of reference of each intentional structure. Hence there is no way by which to cross reference meanings between these individual structures. One may construe that language has evolved among higher primates as a device to overcome this communication barrier between individuals, though deconstructionists recently have exposed some of the limitations of speech and writing as means for communication, and teachers have for centuries been frustrated by the ineffectiveness of exhortation and homily in shaping the behavior of rebellious youth. Nature, however, has evolved a much more powerful method for the re-shaping of intentional structure. This is a learning process which complements the Hebbian synaptic modification described heretofore, and which enables individual brains to approach each other in their forms of intentional structure as the basis for social cooperation and lessen the tendency to solipsism and autism.

An approach to the scientific study of this process was discovered by Ivan Pavlov (1955) following a laboratory accident in which some of his trained dogs were rescued from nearly drowning. The River Neva in St. Petersburg was flooded by an ice jam in a spring thaw, and the dogs were found swimming with their noses at the tops of the wire cages in the basement. Afterward Pavlov found that these dogs had to be re-trained, because they had forgotten their prior training, as though their memories had been wiped clean. Systematic exploration of the phenomenon revealed the biological conditions by which the modification of an individual brain could be induced. These included fatigue induced by severe muscular exercise, sensory overload by continuous bombardment at high intensity, lack of sleep, isolation from the accustomed sensory environment, chemical insults to the brain such as by starvation, toxics such as alcohol, emetics, and purgatives, and especially assaults by intense emotions such as rage, shame, and, most easily, fear. The utility of these techniques was quickly recognized by the sponsors of Pavlov's research and put to use in a program for the perfectibility of the model Soviet citizen, and their effectiveness was recognized in the astonishing changes in values and behavior of individuals that were displayed in the Moscow show trials of the 1930's. The methods of interrogation were described by several writers such as Koestler (1950), and they became known colloquially in the West as 'brain washing.'

The pejorative connotation of the phrase and the political context in which it emerged have concealed from social scientists and the general public the ubiquity of the biological process and the crucial role that it plays in many forms of social organization. Anyone who has undergone hazing in preparation for joining a sorority or fraternity, or who has experienced military indoctrination in a boot camp, or has participated in meetings of Alcoholics Anonymous, will recognize the manipulations by which conformity is internalized, and by which 'old grads' form unthinking life-long allegiances to Alma Mater or to 'old boy' networks. Some subjective correlates of the explosive process have been reported by reformed alcoholics (Sargant, 1957) and epileptics during the aura preceding an attack. But the most powerful form of modification is the most basic to the survival of society and the human race. The sexual orgasm is best known in terms of its hedonistic aspect and motivational impact. Less well understood is the malleability that follows orgasm in the belief structures of the participant individuals, especially in late adolescents on the threshold of breaking away from family and undertaking child rearing, though it also occurs in middle age on the threshold for second childhood. Subjectively the process is experienced as falling in love. Bourgeois societies have traditionally recognized the importance of first sexual experience for imprinting character, and under the ideals of chastity and purity have shielded their nubile daughters from contacts with males not of acceptable social race or class. Pluralistic societies in modern industrial nations have relaxed these behavioral controls by tolerating 'free sex' and random matings across cultural and racial lines, thereby gaining greater cohesiveness in the nation state, but at the cost of diminished familial allegiance manifested in the higher incidences of divorce and single parenthood. A failure to understand the biological role of sexual initiation rites to weaken existing belief structures in preparation for their replacement has also led to widespread efforts to curb or stamp out teenage gangs instead of comprehending and re-directing the underlying natural processes toward more constructive social goals.

The process then is the abrupt dissolution of the structure of intentionality by an electrochemical discharge in the brain, leaving the brain in a state of malleability for the construction of a new belief structure by which to guide behavior. Fisher (1994) has described the residues of this primordial mechanism for pair bonding in the statistics of contemporary mating and divorce in American and Finnish cultures. The discovery of the techniques by which this class of electrochemical discharge can be induced for purposes of establishing and maintaining tribal allegiance must have occurred early in the social history of mankind. Sargant (1957) has described the use of rhythmic singing and dancing in pre-industrial societies and modern evangelical churches to induce religious transports and conversions. Fischer (1971, 1992) has described the use of hallucinogens and other psychoactive compounds to induce altered states of consciousness that form a spectrum from "normal" awareness to deep meditation in one direction and in the other to ecstasy. At either extreme the individual may experience subjectively the transcendence of the barrier of isolation of the self-organized brain and sense a union with some other form of consciousness. That union is not, of course, accessible by an observer who may witness the behavior of the individual during the religious transport.

CONCLUSION

My intent in this essay has been to bring to the attention of sociologists a form of learning that transcends logic and rhetorical appeal, which can best be understood as a chaotic state transition in brain dynamics, and which may be required for the rapid adaptation of young adults for their altered roles in state transitions from child to parent. The discovery of the means for inducing this form of learning by physical and chemical manipulations may have profoundly influenced the early social development of tribal groups, and there is good evidence for the pervasive use of these techniques throughout contemporary societies. The physiology of the process is still poorly understood, in part owing to the diversity and complexity of the electrophysiology and neurochemistry of the process, and in part owing to the social taboos that surround it. We do not have a name for the class of process or an agreed-upon taxonomy of the neurobiological forms it may take. The term 'brain washing' is useful only to describe its deliberate induction for purposes of behavioral control with which we do not agree. We might otherwise call it an effective method of education, but that would hardly suffice to bring it to the attention of scientists who should be aware of it, if they propose to understand the biological mechanisms by which societies are formed, maintained, and modified.

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ACKNOWLEDGEMENT

My research was supported by a MERIT Award from National Institute of Mental Health, MH 06686.