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Mind and Brain: A Catalytic Theory of Embodiment

Patricia A. Carpenter1

Department of Psychology

Carnegie Mellon University

and

Christopher J. Davia

Centre for Research in Cognitive Science

University of Sussex

Manuscript: October, 2005 Patricia A. Carpenter, PhD Department of Psychology Carnegie Mellon University Pittsburgh PA 15217 Phone: 412-268-2792 e-mail: carpent@andrew.cmu.edu

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Abstract

This paper describes a catalytic theory that grounds cognition in biology. An enzyme

is a biological catalyst that increases the speed of a molecular reaction; the reaction is thought

to occur via a traveling wave, a soliton, whose formation and persistence depend on the

structure or invariance of the catalytic environment. Generalizing to cognition, the invariance

of perceptual events plays the role of the environmental structure necessary for catalysis

(Davia, in press). Synchronized traveling waves of activity in the nervous system and in

motor behavior resemble catalytic solitons. The waves are the way an organism mediates or

catalyzes its environment and constitute the organism’s experience. This proposal builds on

insights of Gestaltists and neuroscientists about the importance of synchronized traveling

waves and suggests that cognition is embodied, not representational.

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In this paper, we will consider the relation of ‘mind and brain,’ a phrase that expresses a problematic duality at the heart of our field. In one attempt to bridge it, some scientists assume that the ‘mind’ eventually will be understood in terms of the neurology or biochemistry of the brain and body, a reductionist stance (see Gold & Stoljar, 1999). Gestalt psychologists and connectionists have linked the two constructs metaphorically, exploring how features of the mind are analogous to features of the brain. But any simple reduction of ‘mind’ to brain or body is challenged by the persistent divergences in the results from various methodologies, such as neuroimaging, electrophysiology, and patient studies, even with similar tasks and even within a methodology, when the same ‘function’ is situated in a slightly different context (Cabeza & Nyberg, 1997, 2000; Carpenter, Just & Reichle, 2000; Koshino, Carpenter, Keller & Just, 2005). Many other researchers, inspired by the computer metaphor, study the ‘mind’ as though it were independent of its biological ‘implementation,’ but that approach is challenged by the overlap of data from those same neuroscience methodologies.

To relate ‘mind’ and ‘brain,’ we will challenge two assumptions that lay the foundation for most of the current attempts to bridge them. One assumption, representationalism, is that information about the world is taken in, represented and processed by the perceiver. It is hard to see that this is an assumption; after all, when we open our eyes each morning, we see our world as ‘out there.’ But it is an assumption and a powerful one. It suggests that the job of the nervous system is to transmit information about the world, and the job of the neuroscientist is to determine its codes. Our scientific debates focus on the nature of internal representations, not whether there are internal representations. Of course, humans and at least some primates can represent aspects of the world through concepts in language, but this is not evidence of symbolic processes per se (Elman et al., 1996). We will suggest that experience arises as a more basic, non-representational process (see also Edelman & Tononi, 2000; Roy, Petitot, Pachoud, & Varela, 2000).

A second assumption, functionalism, considers the mind as a set of information-processing functions, such as perceiving, encoding, remembering, responding, and so forth. Debates in cognitive science often concern the relations among proposed functions (for example, whether “verbal working memory” is the same as “spatial working memory”). But the functionalist approach has not converged on a shared vocabulary. For example, different operationalizations of a construct result in differences in the associated behavioral and neural correlates. The lack of convergence might be expected. Functions are descriptions of how a process fits into a context from the perspective of an observer, not from the perspective of an organism (Maturana & Varela, 1987). We will delay the topic of functions until the final discussion.

Paper’s outline. This paper describes an alternative theory of the relation of mind and brain/body. We begin by considering how living processes relate to cognition by describing two proposals from biology and biophysics, Autopoiesis and enzyme catalysis. We summarize a proposal by Davia (in press) that ‘catalysis’ is the general process by which living systems mediate their environments. In a second section, we describe two sets of phenomena that support and illuminate the proposed alternative approach: sensory substitution and ‘illusions’ of our sense of body location. Both classes of phenomena also challenge representationalism. In a final section, we situate the theory in relation to other approaches and consider the role of life in relation to consciousness.

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I. Background: Waves, Autopoiesis and Enzyme Catalysis A. Traveling waves Tracing back at least to the Gestalt psychologists and up to the present, a minority of researchers have suggested that neural and psychological processes are characterized by wave-like activity. One of the best known proposals is Hebb’s (1949) ‘reverberatory cell assemblies,’ and others include Ashby’s ‘reverberatory circuits,’ Lashley’s ‘cortical standing waves’ and ‘resonance’ (see Lehar, 2004; Shepard, 1984). Recently, neuroscientists have related sensory consciousness to the wide-spread, synchronized, neural traveling waves in the cortex and thalamus (e.g., Crick & Koch, 2003; Edelman & Tononi, 2000; Llinas, 2001, pp. 123-124; Singer, 1993; Thompson & Varela, 2001; Varela, 1995, p. 83). Also, dynamic systems approaches have demonstrated that complex, wave-like patterns emerge when behaviors at many different levels are traced over time (Thelen, 1993; van Gelder & Port, 1995). These ‘wave-like’ patterns of metabolic and behavioral activities are non-linear and ‘active’ or anticipatory. The main thesis of this paper is that these ideas and observations reflect a single, unifying principle; namely, the wave-like processes, whether viewed as metabolic activity or behavior, are a general form of catalysis, the process by which living organisms mediate their environment. (We use ‘metabolic activity’ to denote neural activity as well as biochemical and electrical events; however, we suggest that the same analysis applies to behavior, and that the duality is one of perspective, not principle.) Such processes are the dynamic solution to the problem that is posed by the apparent separation of an animal, or any living entity, from its environment. A traveling wave is a disturbance that propagates through a medium that is capable of replenishing its energy, called an excitable medium. An apt example is the action potential of a neuron. If a threshold is reached, a patch of the axon fires and the current causes a nearby patch to exceed threshold; so, the traveling wave of voltage change propagates along the axon, followed by decay and a refractory period until the energy is restored (Aslanidi & Mornev, 1999; Filippov, 1999). Going up in scale, the entire cortex is an excitable medium with traveling waves of excitation and inhibition (Sole & Goodwin, 2000). Although these ideas may broaden our understanding of non-linear traveling waves, it does not yet clarify their relation to ‘mind.’ To support that step, we first will describe a non-representational theory that reframes the ‘mind’ by anchoring it in living systems. B. Autopoiesis

Autopoiesis, meaning ‘self-making,’ is the name of the theory developed by two brilliant biologists/neuroscientists, Maturana and Varela (1980, 1987), who were dissatisfied with the assumption that we represent an independent environment. Autopoiesis is a non-representational theory that makes living processes the ground of mind. To get an intuitive feel for how to ‘drop’ the representational assumption, first consider a type of experience that is often not felt to be a representation of the world ‘out there,’ namely, emotion. We often experience our joys and sorrows as inside us, and the same point might be made about our experience of pain or the awareness of our body, our foot or knee. To move from this starting point to other types of phenomena, recall your experiences as a novice in some area, such as music. When a novice first hears notes from unfamiliar instruments in a foreign musical tradition, such as the Carnatic music of India, it is not experienced as a melody. The experience of ‘melody’ only arises after repeatedly hearing that sequence of notes, as well as others in that tradition. Conversely, familiarity with a musical tradition affects the perception

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of the individual notes (Rumelhart & McClelland, 1986). The organization of the listener anticipates and organizes the sounds. Further support for this point comes from individuals with long-standing peripheral (not cortical) damage, such as cataracts that developed in childhood and left the person blind. When the condition is reversed in adulthood, the individuals still are unable to perceive shapes and distances because they lack the metabolic (including neural) structures and corresponding behavioral routines that would organize those possible experiences (Sacks, 1995; Fine et al., 2003).

Color also illustrates the dependence of experience on the organism’s organization. The color vision of primates and bees has three dimensions (hue, saturation and brightness); but other animals are dichromats (two dimensions) or tetrachromats (four), and diurnal birds may be pentachromats (five) (Varela, Thompson & Rosch, 1991, pp.157-184). But we cannot conceive of the color experiences of these other species. Electromagnetic energy potentially varies along many dimensions, but our color experiences arise from its interaction with our own organization. In sum, even though we experience events, shapes, colors and music as ‘out there,’ Autopoiesis suggests that experience arises from the interaction of energy with our own metabolic organizations, rather than being the representation of an independent environment.

Maturana and Varela explored how the organization of a living system may give rise to cognition by considering a cell. Each cell has a boundary that establishes its autonomy. What crosses that boundary and subsequent processing depend on the cell’s metabolic organization. Maturana and Varela argued that a cell is organizationally closed. The organization of the cell determines which environmental events trigger changes in the cell, as well as what the changes are, and this may also be true of organisms. To link cells and their environments, Autopoiesis proposes that they are ‘structurally coupled,’ as diagrammed in Fig. 1; changes in both are correlational, not causally related. Instead of representing or coding an independent environment, Autopoiesis proposes that the organism brings forth its environment. This radical reframing is difficult for some researchers to understand. Still, it has strongly influenced researchers in embodiment (Varela, Thompson & Rosch, 1991), AI (Brooks, Note 1), and situated cognition (e.g., Winograd & Flores, 1986). By rooting ‘cognition’ in a living cell, Autopoiesis shifts its definition from the conventional meaning, like ‘perception, action, and (human) thought,’ to something like ‘experience,’ pointing to something so basic that it is associated with life itself.

Fig. 1. A diagram of the ‘structural coupling’ between an organism and its environment at Time 1 and at a later time, 1+n, depicting correlated changes in both the organism and environment, in which each changes according to its own internal organization. (Adapted from Maturana & Varela, 1998, p. 74.)

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Although the non-representational approach of Autopoiesis is a starting point, we are

looking for a biophysical mechanism to relate organisms and their environments. We adopt the insight of Autopoiesis, looking at the arising of ‘experience’ in an entity and viewing ‘mind’ or experience as a process (see also Bateson, 1999; Edelman & Tononi, 2000). In addition, the mechanism we seek must apply across many scales, from the cell, to an organ and organism; it must scale up to the massively parallel, intercorrelated processes that co-occur in a complex organism and its environment. Finally, we view the key issue as one that arises by virtue of the organism’s apparent separation from its environment. In contrast to a cell’s autonomy, which is the focus of Autopoiesis, we will argue that a cell, or any organism, is intimately related to its environment. At any particular moment, a cell or an organism must survive an environment whose conditions are changing, and we examine how this is done. In order to ground the proposed solution in biophysics, we will turn to a basic thermodynamic process – enzyme catalysis.

C. Enzyme Catalysis

Our look at this seemingly obscure topic is partly motivated by its importance to living processes; most chemical reactions in living organisms are thought to be catalyzed. But the main rationale is to lay the ground work for generalizing catalysis beyond the molecular level and considering it to be the mechanism by which a living system mediates its environment (Davia, in press). Moreover, we will argue that the ‘standing waves’ of cortical neural activity, the focus of Gestalt psychologists and current neuroscientists, are instances of this general process of catalysis.

A catalyst increases the speed by which molecular reactant(s) form a thermodynamically more stable product(s). The catalyst is called an enzyme if it is a protein or protein complex2. In enzyme catalysis, most reactions involve the transfer of a hydrogen nucleus, a proton. The enzyme emerges from the reaction, able to catalyze another such reaction. All catalyzed reactions run in the same direction as they would without a catalyst. An analogy can be made to a ball rolling down a hill, as opposed to up a hill; catalysis is analogous to removing a rock that is stopping the ball. The reaction would occur eventually even without the catalyst, but the speed increase can be enormous, a factor of 106 to 1012 times (Note 2).

Catalytic loops. Theories of how enzymes work in the metabolism of a cell or organism increasingly resemble networks of intercorrelated relations. For example, a common, earlier model of metabolism in biology was that several enzymes worked in a specific order to create and control metabolic pathways. Even the word ‘pathway’ suggested a linear series of steps, with an enzyme controlling each step. An example of a pathway model for the fermentation process is depicted in Fig. 2. But pathway models are giving way to a more subtle understanding of metabolic activity in terms of self-reinforcing cycles of enzyme-catalyzed reactions (Weber & Depew, 2001). This change has been described by a cognitive scientist, Bechtel (1998), who contrasted the stepwise pathway model of fermentation with the same process, now conceptualized as a dynamic system, a self-reinforcing set of catalytic-loops, depicted on the right of Fig. 2. Such massively parallel, self-reinforcing, catalytic loops may provide an excellent model of living systems. Finally, enzyme catalysis is relevant to the fact that living systems require energy and dissipate energy; their metabolism keeps them far from thermodynamic equilibrium, and catalysis itself is a far-from-equilibrium

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process. These observations are consistent with the proposal that we can understand an organism’s metabolism as a unitary process of catalysis.

Fig. 2. A pathway representation (on the left) with a series of co-enzymes shown as side loops; and an integrated loop representation (on the right) of the fermentation process (adapted from Bechtel, 1998, p. 310).

Life may have evolved as sets of multiply embedded, catalytic loops. Eigen, a Nobel Laureate, and Schuster modeled the far-from-equilibrium conditions of early Earth and argued that with sufficient time, such systems give rise to loops of catalytic cycles (Eigen, 1992; Eigen & Schuster, 1979; also Capra, 1966, pp. 92-94; Kauffman, 1995). A second needed component is some type of barrier that restricts the entry of possible reactants. Then catalysts will tend to persist because a catalyst emerges from a reaction, able to mediate it again. Consequently, substances that act as catalysts in those environments would be favored over non-catalysts by a type of Darwinian-selection bias. These catalytic loops then form larger loops (hypercycles), in which each link may be an ‘embedded’ catalytic cycle. Examples include the symbiogenesis of eukaryotic cells from the embedding of organelles in nucleated host cells some 2.2 billion years ago (Margulis & Sagan, 1986) and also DNA recombination

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which, for example, results in bacterial drug resistance (Capra, 1996, pp. 227-263). Such ‘embeddings’ are relative because all ‘barriers’ are only relatively impermeable. Eigen also proposed an evolutionary path from single macromolecules to integrated cells.

Perception. To bring this cyclic model of catalysis back to the more familiar topic of sensory perception, we will describe the processes associated with rods, a visual receptor-cell in the retina, depicted in Fig. 3. The main point of Fig. 3 is that the individual enzymatic processes, when considered as a whole, constitute a massively parallel, unitary process of catalysis. Rods contain a complex protein molecule, rhodopsin, whose shape changes when light energy is absorbed, in a fast (200 femtosec) wave process, a quantum process. An intermediate enzyme, Metarhodopsin II, activates an enzyme called transducin, a type of ‘G-protein’ that correlates with the rod’s neural action potential. G-protein initiated neural activity also occurs in smell and taste perception, and throughout the body in response to hormones and neurotransmitters (Hall, Premont & Lefkowitz, 1999; Smith & Margolskee, 2001). Rhodopsin is also regenerated by way of enzyme catalysis, as shown on the left of Fig. 3. We suggest that the entire rhodopsin cycle acts like an enzyme, mediating the transition between incident light and neural activity. More complex cycles mediate ‘high-level’ transitions, such as that between a rotating cube and the metabolic activity that is experienced as the rotating cube. This proposal grounds experience in a biophysical process.

Fig. 3. The enzyme cycle of the decomposition and regeneration of rhodopsin, beginning with the trigger of light energy and showing the enzyme cascade involving a G-protein, Transducin, that correlates with the neural action potential of the rod. (Adapted from http://education.vetmed.vt.edu/Curriculum/VM8054/EYE/RHODOPSN.HTM).

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The molecular process. It has been theorized that enzyme catalysis involves a type of localized, non-linear traveling wave called a soliton that may help to connect mind and brain because some neural processes and behavioral waves are soliton-like. The action potentials of neurons are soliton-like (Aslanidi & Mornev, 1999; Filippov, 2000), and the motor movements made by moving fish, snakes and millipedes are solitons (Petoukhov, 1999). This section describes enzyme catalysis by drawing on Davia (in press), which is published in a volume edited by a biophysicist, Tuszynski, who has done research on solitons and enzyme catalysis (see Sataric, Zakula, Ivic & Tuszynski, 1991; Tuszynski, Bolterauer & Sataric, 1992).

The emerging model of enzyme catalysis is worth considering because its characteristics will be generalized to other scales, including the brain. Initially during molecular catalysis, the reactants bind with the enzyme, forming an enzyme-reactant complex. It was believed that the enzyme facilitated the reactants going to an intermediate configuration, called the transition state, through a classical (non-quantum mechanical) process. More recently, the transition is thought to be promoted by a vibrational mode of the enzyme/substrate complex, a soliton wave (Sataric, Zakula, Ivic & Tuszynski, 1991; also Georgiev, Papaioanou & Glazebrook, 2004). The soliton is a wave, a deformation that progresses along the protein chain that comprises the enzyme. The wave changes the conformation of the enzyme/reactant complex, lessening the distance between specific parts of the molecular chains and thereby lessening the distance between the molecular reagents that are bound to it. This shorter distance increases the rate of the reaction because it increases the possibility of ‘quantum tunneling’ of the proton. The quantum perspective describes a particle in terms of a probability wave function. If a particle is near a barrier, its wave function extends into the barrier. If the barrier is narrow enough, the wave function may extend through the barrier entirely. Thus, there is a chance that the particle will ‘disappear’ from one side of the barrier and ‘appear’ on the other side, which is quantum tunneling. There is a growing consensus that quantum tunneling is a major mechanism of enzyme catalysis at physiological temperatures (Knapp & Klinman, 2002; Sutcliffe & Scrutton, 2000, 2002).

Solitons. Although solitons in enzyme catalysis may be quantum-coherent processes, solitons also occur in classical processes (Scott, 1999) and have similar properties, which may assist any transitions between quantum and classical processes. Pragmatically, this observation helps us to circumvent the debate about how widespread quantum processes are in neural and biological systems (Tegmark, 2000; Xie, van der Meer, Hoff & Austin, 2000).

A soliton was first identified in water in the mid-1800’s by J. Russell Scott when a boat stopped suddenly in a canal, and a solitary wave formed and moved, maintaining its structure for two miles (Remoissenet, 1999, pp. 1-10). Solitons are localized and can be very robust. A soliton can be a solitary wave, an envelope (group soliton), or a complex, multidimensional pattern. Under some circumstances solitons are particle-like and obey the laws of classical physics (Filippov, 2000, p. 188-189). Although an initial impetus may start a soliton, as with the neuron’s action potential, the soliton’s characteristics and duration depend on the structural regularities and symmetries of its environment. There are a variety of phenomena and mathematical entities that are members of the ‘soliton club’ (Filippov, 2000, pp. 188-191). Also, a variety of names have been used for closely related phenomena – scroll waves, spiral waves, conformons, and instantons. The important characteristics for the current argument are that the waves are robust, localized (they do not dissipate or spread out to infinity), and nonlinear solutions to the boundary conditions that constitute their

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environments. Also, their formation and persistence are related to the structure (invariance or symmetries) of the environment.

D. Generalizing enzyme catalysis

The key characteristics of enzyme catalysis include reagent(s) that is/are in a far-from-equilibrium state. The structures of the molecules constitute the structural constraint that keeps the reaction from proceeding spontaneously. To overcome this constraint, the proposed mechanism, the soliton, requires environmental regularity or symmetry in order to form and persist, regularity that is provided by the protein’s structure. Enzyme catalysis requires the precise application of energy along what is termed a reaction coordinate, although how the soliton achieves this is still a matter of research. The formation of solitons is related to the structural properties of their environments in other biological, catalytic-like processes (see Davia, in press). For example, solitons may use the regularity of the alpha-helices in proteins for energy transfer to assist in muscle movement (Cruzeiro-Hansson, 1994; Davydov, 1980; Xie, van der Meer, Hoff & Austin, 2000). Of direct relevance to the current theory, simulation models of the action potential show that it exhibits soliton-like characteristics (Aslanidi & Mornev, 1999; Filippov, 2000, pp 194-9). More generally, the cortex is an excitable medium with traveling waves of excitation and inhibition.

If the essential theme of catalysis involves overcoming structural constraints to dissipate energy, then the term ‘catalysis’ may apply to macro-level processes that facilitate such transitions. Davia (in press) examined the properties and pervasiveness of soliton-like traveling waves in physiology and macro-level living systems. He suggested that all biological processes mediate transitions by channeling energy via structure. This general principle applies at many scales, from enzymes, to cells, organs and organisms; a living entity can be understood as a unitary process of catalysis, mediating its environment.

The key proposal, applied to animals, is that the metabolic traveling waves of the brain and body constitute a unitary process of catalysis that relates directly to the organism’s experience. In enzyme catalysis, a soliton can mediate a set of ordered transitions that constitutes its environment by removing the discontinuity between energy and structure. The theory proposes a similar understanding of how soliton-like traveling waves operate in neural systems. The complex non-linear waves unite the boundary conditions arising from the organism’s interaction in its ‘world.’ Instead of imagining that the traveling waves are like the water waves that move through a canal, a more appropriate image reverses the two components. Imagine a standing wave that maintains its organization while the canal moves past. We can use this alternative, but equally valid, perspective to analyze neural traveling waves. The brain is an excitable medium as a consequence of the metabolism of glucose and other essential nutrients. This energy gradient is dissipated by the activity that depends on the organism’s history and its on-going interaction with its environment. Thus, the non-linear traveling wave is a self-maintaining and self-sustaining dynamic, an autopoietic process and a solution to the environmental boundary conditions. The neural processes are studied by neuroscientists; the same solution, viewed from another perspective and at another scale by the cognitive scientist, is the organism’s behavior.

In enzyme catalysis, a reaction ultimately occurs because the product(s) is/are more thermodynamically stable than the individual reactants; the catalytic process facilitates the transition by overcoming the structural constraints of the reactants’ structure and dynamics. Bringing this insight into the cognitive domain, the brain and body can be understood as the

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medium of catalysis. The objects and events of the environment are not unified entities in themselves, in spite of their appearance. Rather, they are unitized by virtue of the organism’s experience, by neural traveling waves. A rotating cube does not constitute a continuous, unified dynamic. However, if we perceive a rotating cube, the traveling wave associated with that perception is a unified dynamic, a solution to the boundary conditions imposed on the eyes. Thus, the perception/action of the organism makes explicit what is only implicit around it (Davia, in press).

II. Research Phenomena

To make this proposal relevant to cognitive science and neuroscience, we will examine the relation between experience and traveling waves from three perspectives: the nervous system, motor behavior and phenomenology. We suggest that these are three aspects or perspectives of the same process. Second, we will discuss sensory substitution and illusions in self perception, showing how implicit order influences how the organism experiences the environment and itself. A. Traveling waves and experience

Many studies support correlations between experience, or states of consciousness, and traveling waves in the cortical and peripheral nervous systems (Edelman & Tononi, 2000; Thompson & Varela, 2001). Moreover, properties of these waves map onto characteristics of enzyme catalysis that were described in the previous section. We suggest that these traveling waves are instances of Davia’s generalized definition of catalysis and that is why they correlate with experience.

Neural systems. Different experiences (states of consciousness) correlate with different patterns of cortical neural activity, as roughly indexed by the dominant frequency of the cortical electroencephalograms (EEG): Gamma (greater than 30 Hz, sensory consciousness), Beta (13-30 Hz, can also include sensory consciousness), Alpha (8-12 Hz, relaxed wakefulness, eyes closed), Theta (4-8 Hz), and Delta (less than 4 Hz, stages 3, 4 of sleep). Because EEGs are more complex than a single dominant frequency, the mathematical tools of non-linear dynamics have been used to describe them (Babloyantz & Destexhe, 1986, cited in Sole & Goodwin, 2000, p. 135; Tsuda, 2001). One EEG study of over 100 patients during the administration of surgical anesthesia found that the loss of sensory awareness correlated with changes in the EEG waves: an increase in slower waveforms, an increase in EEG power, an increase in synchrony over the front of the brain, and a loss of coordination between the major regions of the cortex and with the thalamus, and the changes reversed as the patient regained sensory awareness (John, 2001). Micro-electrode studies also have recorded synchronized traveling waves of neural excitation; for example, in one study, they were associated with mental rotation (Georgopoulous, Kettner & Schwartz, 1988).

Many researchers have speculated that wide-spread, synchronized traveling waves are the mechanism of perceptual binding, the coherence of experience (Crick & Koch, 2003; Edelman & Tononi, 2000; Llinas, 2001, pp. 123-124; Singer, 1993; Thompson & Varela, 2001; Varela, 1995, p. 83). The synchronized traveling waves are facilitated by extensive reciprocal projections among cortical regions and with subcortical regions (Fuster, 1995, pp. 70-71; Constantinidis, Franowicz & Goldman-Rakic, 2001). Research on the rabbit’s olfactory bulb and cortex provides more detailed evidence that patterns of neural activity

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(EEGs) correlate with the rabbit’s experience of familiar odors; Freeman (1999) described their main conclusions:

…(When an) Expected stimulus arrives, the activated receptors transmit pulses to the sensory cortex where they elicit the construction by nonlinear dynamics of macroscopic, spatially coherent oscillatory patterns that cover the entire cortex (Freeman 1975, 1991)…. The emergent pattern is not a representation of a stimulus, nor a ringing as when a bell is struck, nor a resonance as when one string of a guitar vibrates when another does so at its natural frequency. It is a phase transition that is induced by a stimulus, followed by a construction of a pattern that is shaped by the synaptic modulation among cortical neurons from prior learning. It is also dependent on the brain stem nuclei that bathe the forebrain in neuromodulatory chemicals. It is a dynamic action pattern that creates and carries the meaning of the stimulus for the subject. It reflects the individual history, present context, and expectancy, corresponding to the unity and wholeness of intentionality (Freeman, 1999, p 151).

‘Phase transition’ in physics refers to a sudden change of a thermodynamic system from one state to another, signaled by a change in a physical property; Freeman says that the phase transition, followed by a coherent oscillatory pattern, is the animal’s experience.

A second important point to emerge from Freeman’s research is that similar EEG parameters are found at multiple spatial and temporal scales; they exhibit ‘scale invariance.’ This phrase, in Mandlebrot’s fractal geometry (1982), refers to structural characteristics that are similar across various magnifications, as in ferns, the cortical vasculature, or mathematically generated fractals. In the present context, scale invariance describes self-similar processes rather than structures. But if, as traditional neuroscience approaches assume, neural processes reflect local, contingent solutions to functional challenges, why should there be self similarity across scales? Self-similar processes may arise from a solution that integrates constraints at multiple scales and instantiates the same principle at multiple scales: mediation of the organism’s environment.

Traveling waves in the auditory system illustrate the active, anticipatory aspect of these processes. As sound waves occur, the eardrum vibrates, as do the bundles of hair cells on the surface of the basilar membrane of the cochlea (Von Bekesy, 1960; Duke & Jülicher, 2003). The wave responses of the hair-cell bundles are highly nonlinear and active (Rhode & Recio, 2001), increasing the sensitivity of the basilar membrane to particular frequencies by slightly anticipating the sound. This is similar to how a child on a swing can make it go higher by timing her pulling of the ropes with the upward motion of the swing. Gestaltists also noted the anticipatory nature of perception. The neuroanatomist and clinician, Kurt Goldstein, noted that “we have the ‘feel’ of a familiar object even before we grasp it” (1995, p. 91). In visual perception, this aspect is demonstrated by the phenomenon of ‘inattention blindness.’ Participants who have judged some feature of a series of visual displays frequently do not perceive the first presentation of an unexpected, unrelated display, even though it is also above threshold (Braun, 2001; Mack & Rock, 1998). The expectation may help structure the experience of the organism; the flip side is that everyday perceptions are projective.

Motor behavior. Many theorists have argued that perception and action are two aspects of a unitary construct. The interrelation of perception and action was articulated in 1950 by von Weizsacker, a neurologist, who referred to it as a ‘gestalt cycle’ (see Fuster, 1995, p. 275). There are extensive reciprocal connections among perception systems and action systems in multiple cortical regions, enabling reinterant activity (Fuster, 1995; Goldman-

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Rakic, 1988, p. 153). The interrelation of perception and action also has been demonstrated developmentally with behavioral paradigms (Held & Hein, 1963; Piaget, 1954), as well as in the design of robots (Brooks, 1987, cited in Varela, Thompson & Rosch, 1991, pp. 208-211). O’Regan and Noe (2001) collapsed the distinction by hypothesizing that visual perception is exploratory activity. The philosopher Merleau-Ponty made a similar argument (1962, pp. 152-3): “In the gaze, we have at our disposal an instrument analogous to the blind man’s stick.” and “Learning to find one’s way among things with a stick, …an example of a motor habit, is equally an example of a perceptual habit.” Visual experience ceases if a visual display is stabilized on the lens so that it moves with the eyes and no new pattern is presented as a consequence of eye movements (O’Regan & Noe, 2001; Edelman & Tononi, 2000, p. 73). These analyses argue against the assumption that we perceive a world that is independent of our actions. We will point to their interdependence by using the phrase ‘perception/action’ in place of ‘perception.’

Motor research also reveals waves of behavioral activity. After analyzing of the locomotion of many species, such as fish, snakes and millipedes, Petroukhov (1999) identified the waves, such as the side-to-side waves that travel down a swimming fish, as solitons. This analysis is important evidence for mapping from behavior to the process of catalysis, and supports catalysis as a biological mechanism. Although waves of behavior may be more obvious to us when we observe eels, fish and so forth, centipedes, insects and similar creatures walk via coordinated waves of leg activity. Cockroaches walk with a posterior-to-anterior wave of movements of their legs relative to the body; no leg protracts until the one behind is placed in a supporting position and contra-lateral legs of the same segment alternate in phase (Wilson, 1966). Human bipedal walking can be described with two out-of-phase oscillators (Strogatz & Stewart, 1993). Non-linear waves at multiple temporal scales also are found in the finger movements of adults (Kelso, 1995) and in the development of reaching and grasping by infants (Thelen, 1993). Voluntary muscle contraction in reaching and walking by adults show undulations in the 8-12 Hz range; these also occur in maintained posture and supported limbs at rest, and the rhythm correlates with the initiation of large movements (Llinas, 2002, pp. 29-51). Traveling waves manifest at multiple levels in the motor activities of developing organisms, including embryos (Llinas, 2002). These waves are metabolic activity, but viewed from a different perspective -- as the organism’s behavior. Thus, soliton-like waves are found in both the behavioral and neural or metabolic domains. Moreover, we suggest that behavioral waves and neural waves are two perspectives of the same phenomenon.

Phenomenology. Another entry into the relation between traveling waves and experience is the study of phenomenology. This approach has been taken by a few eminent researchers, such as Shepard and Gestalt psychologists who pointed to the wave-like or resonance-like quality of experience itself. Shepard (1984, p. 433) claimed that “the organism is, at any given moment, tuned to resonate to the incoming patterns that correspond to the invariants that are significant for it,” and he enumerated several analogies between mechanical resonance and visual phenomenology. That resonant systems can be excited from within, Shepard proposed, is analogous to the overlap of perception with dreaming, hallucination and imagery. Shepard also thought that the ability to excite resonant systems in multiple ways was analogous to context effects, such as the alternative interpretations of the ambiguous ‘old woman/ young woman’ picture, which interpretation is influenced by the preceding unambiguous picture. Context effects, which occur throughout cognitive science

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and neuroscience, demonstrate that phenomena cannot be separated from their spatial and temporal environment.

In sum, non-linear traveling waves that correlate with experience are pervasive in the nervous system, in behavior and phenomenological experience. The evidence of traveling waves in motor activity and perceptual processes makes it less compelling to assume that the nervous system is translating between ‘input’ and ‘output.’ If perceptual systems, motor systems, and the nervous systems use the same vocabulary, namely, traveling waves, then what need is there for translation? The current proposal is that there is no translation because the neural activity is not a code. The waves are not a representation of the environment, but rather, the unfolding of the organism’s experience.

B. Implicit Order

A second key concept in the present theory is that of ‘implicit order,’ which refers to patterns, symmetries, and relations that are invariant under transformations of time or space. The importance of invariant relations in perception has been emphasized by Gibson (1966, 1979) and other theorists. An example is ‘visual looming’ or the uniform expansion of a visual pattern when an object looms toward a viewer. Everyday words, like ‘object’ and ‘environment,’ are problematic for the current explanation because typically they refer to independently existing objects and events. However, we suggest that the organism plays a crucial role in making explicit an order that is only implicit. Consider the apparent motion of an arrow that is shown in several spatially and temporally discontinuous displays; we propose that these discontinuous events and the arrow itself are only unified and made explicit in our experience. To point to this alternative understanding of invariant, we will use the phrase implicit order. The role of implicit order in perception/action is that of the structural constraint of the enzyme-reactant substrate that is overcome and unified by virtue of the traveling wave of energy dissipation. Using our earlier example, as a person listens to a new type of music, she assimilates aspects of its implicit order. If the same music is played again, a traveling wave now constitutes a neural pattern, both anticipating and unifying the notes and giving rise to the organism’s experience of music.

We illustrate the concept of implicit order by briefly reviewing some sensory-substitution research: After practice with a sensory-substitution device, a blind individual can see without eyes. A second point is that even the perceiver’s experience of herself, as well as the ‘external’ environment, may co-arise in perception. This point is supported by ‘illusions’ in which the experience of one’s body does not coincide with its physical location. If catalysis requires order or structure, and an organism’s experience arises by virtue of catalysis, then experience may make explicit, the implicit order of the interaction of the perceiver and environment. Sensory-substitution research. The concept of implicit order is illustrated by research on tactile-visual substitution systems, in which the input from a camera is fed to a vibro-tactile array that is either on the person’s back or tongue (Bach-y-Rita, Kaczmarek, Tyler & Garcia-Lara, 1998; Bach-y-Rita, Tyler & Kaczmarek, 2003; White et al., 1970). Roughly analogous to reading a word as another person writes it on one’s back, the results of practice with such devices are illuminating. The perceiver, and not some other individual, must control the camera, which is evidence for the interdependence of perception and action. After practice with a vibro-tactile array on the tongue, even congenitally blind individuals can catch and throw balls and report seeing the flicker of candle flame (Bach-y-Rita, Note 3).

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Participants initially report sensing the stimulation as coming from the location of the vibro-tactile device on their back or tongue. Only with practice do they locate the source as outside themselves, at which time, the stimulation at the location of the device is perceived but it is less salient. Practice with such a system can be understood as a dynamic structuring process that enables the formation and persistence of traveling waves in the organism’s physiology and behavior. A more dramatic demonstration of sensory substitution comes from an auditory-visual system called vOICe (Oh-I-See). Grey-scale images from a video camera are mapped into sounds via a left-to-right scan, with pitch indicating elevation and loudness indicating brightness (Meijer, 1992, Note 4). For instance, a bright speck of light would give a loud, short beep coming from the side on which it occurs. Considerable practice with the device is needed to experience sight. One individual, who had lost her sight as an adult through an industrial accident, spent two years practicing with the vOICe system in her bedroom, and she reported gradually acquiring spatial navigation and object recognition in that context (Fletcher, Note 5). Then she acquired sensitivity to visual texture, depth, and the ability to see objects and navigate in new environments. It is important, but not entirely uncontroversial, that the individuals who use these systems report “seeing,” a report that is consistent with their ability to describe events and navigate in new environments3. Although sensory substitution is unusual, it is a robust phenomenon, and it strikingly dissociates the quality of the experience (‘seeing’) from its typical sensory modality (eyes). This dissociation indicates the need for an explanatory framework other than the standard one that we represent the external world by means of particular senses. The technique of sensory-substitution has been extended to study how individuals may develop sensitivity to electromagnetic spectra that typically are imperceptible (to humans). For example, a subject practiced wearing a belt with vibrators that were connected to sensors that detected the magnetic north. Along with becoming aware of the ‘north’ direction, the user could detect the large-scale electromagnetic fields surrounding a commuter train and associated power lines (Krueger, 2004). The phenomenon also is explicable by the proposed mechanism of catalysis. These unusual cases motivate our examination of catalysis as a non-representational process; but importantly, catalysis is offered to account also for the common, everyday examples of perceptual learning and development.

Self perception. In perceiving the environment ‘out there,’ we simultaneously may perceive our body, feelings, and so forth. The perception of ourselves is not a ‘given’ and also may be understood in terms of making explicit an implicit order. This point is supported by illusions that alter where individuals experience their hands to be located (Ramachandran & Blakeslee, 1998). A participant sits near a table with her/his hands hidden beneath it; a glove, a plastic hand, or nothing at all is on the table top. One of the experimenter’s hands is visible to the subject, on top of the glove or table top. Her other hand, under the table, is not visible to the subject. The experimenter touches the glove/table top and the subject’s one hand, using a synchronized, quasi-random pattern of taps and short strokes. Ramachandran reports that in 1-2 min., over half of his subjects experience the glove or table as their own hand or the two as merged. The visually perceived tapping overrides the subject’s knowledge of his hand’s physical location, an experience that naïve participants report to be disconcerting. The illusion recedes if the participant shifts his attention away from experimenter’s visible, tapping hand. In another variant, the participant perceives his nose as displaced out in front of his face by a foot! As Ramachandran’s research with the phantom limbs of amputees has shown, some

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illusory bodily experiences are resilient, although they too can change (Ramachandran & Hirstein, 1998).

The malleability of our sense of body also is illustrated by more commonplace experiences. Gibson (1979) observed that even ordinary visual perception may give rise to the experience of both the world ‘out there’ and the perceiver, “When a man sees the world, he sees his nose at the same time; or rather, the world and his nose are both specified and his awareness can shift.…Self perception and environment perception go together” (Gibson, 1979, p. 116). But our sense of our body, and hence, our ‘boundary’ from our environment, can change when we use well-engineered athletic equipment, tools and remote sensing devices. A skilled rower can feel the water through an oar, and analogous experiences are reported by horse riders, and so forth. With skilled use, the equipment is so transparent to our experience that some researchers in the tradition of Gibson, argue that perception is constrained by the environment rather than dependent on sensations (Carello & Turvey, 2000). Flexibility of the implicit order is evident in the successful use of an artificial prosthesis, which requires merging it with one’s (now illusory) sense of body, and even the loss of prosthesis can result in a ‘phantom prosthesis’ (Ramachandran & Blakeslee, 1998, pp. 56-57). In the current theory, the organism’s experience of itself and its environment arises from catalysis, a process that makes explicit what is implicit in the organism’s current circumstances and history. A life-time of experience with limbs of a certain length and our nose at a certain position makes those implicit relations a powerful influence on current experience. But as the ‘hand illusion’ illustrates, even that experience can change. The inference we may make of a constant ‘self’ may not accord with the experiences of a variety of ‘selves’ that vary with the situation (see also Varela, Thompson & Rosch, 1991, pp. 66-72). Our experience need not entail awareness of a separate self, even for awake humans. When individuals are in a ‘flow’ state, skillfully performing a task that is at the cusp of their competence, they may not experience themselves as separate from the event (Csikszentmihalyi, 1993, pp. 173-187). The philosopher Heidegger argued that everyday cognition is fundamentally this type of embodied know-how, which is awareness without separating oneself out from the activity (Wheeler, 2005, pp. 130-132). The term ‘consciousness’ typically entails the awareness of a self and something other than the self (Nagarjuna, 1995). Such a separation does not occur in flow experiences, indeed, the lack of separation is one of the defining characteristics of flow. This suggests that the separation of self and environment is an implicit order that need not be made explicit. Our ability to use language and other symbolic systems also can be understood within this framework, as making explicit the implicit orders or patterns of many levels. For example, connectionist models have successfully simulated aspects of language performance by mirroring the statistical distribution of language patterns at various levels (e.g., phonological, morphological, syntactic, semantic) (Elman et al., 1996). To use language, these patterns are associated with experiences of events and objects, types of implicit order we have already considered. Successful conversations, for example, depend on the shared experience of the participants (Wilkes-Gibbs & Clark, 1992). But even words that have apparently concrete referents can be associated with different patterns of experience for different individuals. During language acquisition, the child acquires sensitivity both to the patterns of spoken language and their association with perceptual events and perspectives (MacWhinney, 1998). Thus, the current approach can accommodate the acquisition of conceptual skills and language.

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Although we focused on sensory substitution and self-perception to illuminate and support the current proposal, these phenomena also challenge representational approaches to consciousness. Sensory substitution breaks the typical correlation between phenomenological data (sight) and modality (eyes) that has been a mainstay of representational approaches. These approaches account for the quality of our experience in terms of specific senses; they propose that we can see because we had eyes or hear because we have ears. This assumption is called ‘Muller’s doctrine of specific nerve energy.’ Clearly, the ability to see via the tactile or auditory modality disproves this doctrine (see O’Regan & Noe, 2001, pp. 956-959). It also raises the question of how it is that we do see. The current proposal is that the person’s practice with a sensory-substitution device entails implicit order. Movements of the head and body and the related responses of the technology imply a three-dimensional, textured field that is subsequently made explicit as ‘vision.’ Thus, practice with the technology helps to structure the person herself, so that she is able to catalyze the impinging energy; this makes the implicit visuo-spatial order explicit in her experience. This order overlaps with, but is not identical to, that which arises when seeing by eye. If an individual practices with devices that are sensitive to electromagnetic variation that is normally outside of human sensitivity, new dimensions of experience can develop. But importantly, the same mechanism is proposed to account for ordinary perception/action. By contrast, approaches that assume the nervous system is representing a world that is independent of the organism have the additional challenge of accounting for these unusual phenomena.

A somewhat different difficulty with representational approaches is highlighted by phenomena related to self perception, including the Ramachandran-type ‘illusions’ and the more routine ability to experience the ‘environment’ directly through tools and equipment. By and large, current representational theories lack a causal conception of bodily experience. This is a rather remarkable blind spot and perhaps reflects the powerful influence of the computer metaphor in shaping the field’s methods and questions. Computers are largely appreciated for their functionality, not for their implementations, and even the proposed division between functionality and implementation is challenged by the current proposal. By contrast, much of the computer inspired research avoids the physicality that is basic to organic life. But we apprehend our body as something that we are, not as an object among other objects, although that, too, can occur. Then too, the absence of a clear articulation of self perception may relate to the bias in favor of ‘objective,’ behavioral measures over experiential data, a long and complex debate in the field (see Varela & Shear, eds., 1999). The catalytic theory takes ‘experience’ as a fundamental phenomenon, so its account extends to experience that includes the self as well as the other than self.

The two concepts, sensory substitution and implicit order, are highly related. The sensory-substitution research showed that practice with the device is necessary to experience sight by touch or sound. Practice is understood as a structuring process that enables the formation and persistence of traveling waves that embody the implicit order of the organism’s interaction with the ‘world.’ (Again, we face a limitation of vocabulary because the current proposal is that the ‘world’ is brought forth in the organism’s experience.) It is also important that the ‘implicit order’ can simultaneously give rise to the sense of self; the role of ‘implicit order’ in the sense of self is highlighted by the unusual cases of ‘a self’ who extends to the tip of an oar, a cane, or a real or phantom prosthesis. These examples illustrate the way in which experience may make explicit an implicit order that is not defined by the organism’s physical boundaries, but varies with the organism’s history and current situation.

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III. Discussion: Consciousness and Implications

The key proposal is that the metabolic traveling waves of the brain and body constitute a unitary process of catalysis, dissipating energy by way of paths that arise by virtue of the structure that is implicit in the organism’s history and on-going interactions with its ‘environment.’ This perspective suggests that the metabolic processes are essentially processes of mediation. The organism’s behavior is the same process, albeit from another perspective. For the organism, catalysis is its experience. This is the proposed relation between mind and brain, or more precisely, between experience and life. Although our presentation has focused specifically on ‘the brain,’ the catalytic principle applies to the entire organism. Indeed, it is proposed to be scale invariant, applicable to cells, organs, and organisms. Even a simple form of life, we propose, exists by virtue of catalyzing or mediating its environment, and hence, has experience. One of the implications of the current approach is that ‘experience’ is not an evolutionary accomplishment associated with higher animals, but rather, it is associated with all of life. The current proposal challenges the dualism that is reflected in the usual concepts of ‘mind’ and ‘brain,’ a Cartesian split that has greatly influenced cognitive neuroscience and the scientific enterprise in general. We typically assume that an entity, its energy, and any conscious state associated with it, are all different things. The current proposal is that the distinctions break down in situations where structure and energy come together. At the quantum level, Einstein’s famous equation, E = MC2, showed that energy and mass are the same thing. But such unified states of matter and energy do not make up much of the classical world. For example, a cardboard box is comprised of many discontinuous particles that may be unified individually, but which do not add-up to a unified state of energy and form at the macroscopic scale of the box. However, enabling unified states at macroscopic scales may be what life does in the classical world. The wide-spread, complex oscillatory patterns observed in the nervous system of animals, for example, constitute large-scale, unified states. These states may be understood as generalizations of enzyme catalysis, a process that removes the discontinuity between energy and biological structure. The proposal is that everything that exists as a unified state of energy and matter is also a conscious state; so, even a single living cell is conscious. A logical follow-up question to this proposal is, “If a particle, or even a single cell, is conscious, then what is it conscious of?” The answer relates to the cell’s ontology, a word that refers to being or existence. A bacterium is a solution to a set of boundary conditions that are imposed by its structure and interaction with its environment. Its experience may be the simple, metabolic hum corresponding to its harmony with its environment. To gain insight into the conscious state of an organism, we may ask what the boundary conditions are for which the organism is a solution. As one goes up the evolutionary scale, entities are capable of mediating more complex environments. In spite of the additional levels of complexity in a primate’s repertoire compared to that of a bacterium, the proposed generalization of enzyme catalysis is scale invariant and applies to both. A. Other approaches The catalytic theory builds on the theoretical insights of Gestalt psychology, as well as neuroscience, which have focused on the role of wide-spread coherent neural activity in

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sensory awareness (see the references in Sections I and II). The present theory also builds on the general insight from cognitive science to abandon the homunculus, the ‘little person’ that we may imagine in our heads, decoding the signals from the world. The current proposal makes experience (or phenomenological data) a key theoretical construct, instead of ignoring it or treating it as an epiphenomenon or causally impotent. But having argued that the activity of the nervous system is not a representation or a code, we can ask what it is and how it is adaptive. The current proposal is that the significance of a neural event is that it occurs at a certain place and time within an overall context of neural events taking place in space and time. The correspondence between the relative position and timing of events in the brain and the body in the ‘environmental field’ enables perception/action that is favorable to the organism. Dynamic Systems and Connectionism. The current approach builds on insights from both Dynamic Systems Theories (DST) and connectionist models, particularly their focus on time-varying, massively parallel processes. Both express the nonlinear, nonstationary and contingent nature of living systems, and the ability of such systems to self-organize and manifest emergent properties. Connectionist models formally instantiate certain aspects of neurophysiology, although the mapping is limited (Wheeler, 2005, p. 85-88). One connectionist proposal equates conscious experience with a stable pattern of activation across a network (O’Brien & Opie, 1999). However, these models typically are representational, albeit involving ‘wide-spread and distributed representations.’ Consequently, they face the difficulties of more classical representational approaches. Perhaps the patterns of activity could be better understood as abstract models of aspects of a catalytic process.4 Some dynamic systems theorists have argued that their approach is non-representational (van Gelder & Port, 1995)5. Examples include the dynamic systems approach to motor development (Thelen, 1993; Thelen & Smith, 1993) and motor behavior (Kelso, 1995). These theories, like the current one, acknowledge the importance of organism-environment interaction. Also, the method of explanation used by dynamic system theories may differ from the typical methods of current cognitive science and neuroscience, which explain performance through decomposition into various functions and localization (Bechtel, 1998). By contrast, Bechtel suggests that dynamic system theories appeal to general relations, a ‘covering law’ type of explanation; this characterization applies to the current theory. The ‘law’ proposed here is that all living processes exist and persist by virtue of catalyzing (mediating) their environments, and the scale-invariant aspect of the theory enables its application from the level of enzymes and cells up to organisms. Representations and conscious. Most representational theories assume a series of causal links resulting in perception: the event, the ambient energy propagated to the receptors, the receptors and neural system, and finally, the experience. A key problem is explaining how a physical causal process gives rise to nonphysical (mental) experience (Shaw & Bransford, 1977, pp. 12-13). Some theorists try to side-step this difficulty by assuming that conscious experience is a correlate of physical events, but itself is not causally in the chain. For example, in their recent theory of consciousness, Edelman and Tononi (2000) suggested a causal role for synchronized neural activity, supported by the reentrant connections among cortical areas and with subcortical areas. However, this proposal makes phenomenal experience only a correlate of neural activity, an epiphenomenon. By contrast, in the current account, metabolic activity, and behavioral activity, is interpreted as the process of catalysis. Edelman and Tononi further identify two characteristics of consciousness as key: the unity of

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consciousness and the ability to differentiate among experiences. In the current perspective, the traveling wave unites structure and energy, and so it is a unitary experience. For example, a patient does not experience the ‘blind spot’ that arises in the condition of neglect, after a debilitating parietal stroke. Also, because the environment and organism change, the catalytic process changes, accounting for the differentiation in an organism’s experience. The catalytic theory suggests an explanation of the property of ‘intentionality,’ which is that consciousness is consciousness of something, such as our awareness of the green trees outside the window or the computer on the desk. This property may be one of the hidden reasons why representationalism is an implicit or explicit assumption of most current scientific approaches to consciousness. We may assume that we are representing green trees, for example, because that is the content of our awareness. But the current proposal suggests an alternative understanding of intentionality. In enzyme catalysis, the catalyst only speeds a reaction, but it has nothing to do with the direction and likelihood of it. The direction of the reaction depends on the relative thermodynamic stability of the reagents and the product. So, too, an organism’s experience is about the world it embodies, which may include the organism. Also, an organism, like a type of enzyme, facilitates only certain reactions that depend on its past and its on-going perception and actions. As we quoted earlier (Freeman, 1999), the emergent pattern of neural activity, coincident on a stimulus, is “a phase transition …that creates and carries the meaning of the stimulus for the subject. It reflects the individual history, present context, and expectancy, corresponding to the unity and wholeness of intentionality.” Although we have not given explicit consideration to emotions, those also fit with the current theoretical framework. An emotion is a unified and dynamic pattern of energy and structure that we typically experience as within ourselves and to which we often give a label, such as joy, sadness or grief.

Functionalism. This current approach raises the issue of how we should understand ‘functions’ (such as encoding, memory retrieval, recognition, etc.) that are invoked in most standard accounts of cognition. Functionalism assumes that there are abstract functions that can be described separately from their metabolism. This assumption may be based on a misleading analogy to computers because a computer’s function depends on the program’s logic, which is separate from the circuit boards and so forth that make up its metabolism. However, for living processes, the concept of function may only make sense from the perspective of an observer who is situating some process in a larger context (Maturana & Varela, 1998). A proposed function, such as ‘object recognition’ or ‘retrieval,’ is an act of categorization by an observer that ignores the biophysical context. By contrast, from the organism’s perspective, metabolism is function and there is no distinction (Davia, in press). The proposed identity of metabolism and function is more apparent with simple organisms. If a bacterium is removed from its environment, it dies. After a cerebral stroke, secondary damage that not near the original site can occur if the stroke destroyed cells that resonated with the ‘secondary’ cells, and hence, constituted their neural environment (Witte, 1998). Proposed functions may appear to be distinct from metabolism because humans catalyze a variety of environments. Finally, the field’s inability to converge on a set of basic functions is also evidence against the functionalist approach. The current theory’s emphasis on ‘experience’ and phenomenology fits more smoothly with some embodied approaches (Varela, Thompson & Rosch, 1991), although even that phrase refers to a diverse family of ideas. At least the current proposal is part of a

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renewed dialogue among cognitive scientists, neuroscientists, and philosophers (see the edited volumes of Petitot, Varela, Pachoud, & Roy, 2000; Varela & Shear, 1999). The intention is to deepen our understanding of consciousness by considering ‘phenomenological experience’ as a critical construct in cognitive science and neuroscience, while simultaneously taking into account the data of these fields. B. Implications for life and the environment Having now discussed a theory that begins with ‘living processes,’ we can look at the implications for anchoring experience in life. The current account claims that the organism brings forth its environment, and proposes a biophysical mechanism for realizing it. The catalytic theory suggests an intimate relation between an organism and its environment; by contrast representational approaches assume that an organism codes and responds to a separate environment. In the perspective of catalysis, life cannot be separated from its environment; it is a process of the environment. If the environment changes so drastically that it cannot be mediated, then the processes become incoherent and the entity dies. If we truly separate a living entity from its environment, it dies.

Our emphasis on life may suggest a sharper discontinuity between living and non-living systems than is warranted. As we pointed out in the introduction, Eigen and others have argued that pre-biotic evolution involved catalysis. Continuity is also supported by the mutual support of living and non-living planetary processes that are thought to maintain the dynamic range of oxygen, methane, water, and other constituents on Earth that are needed for life (Lovelock’s Gaia hypothesis, 1979). In addition, our division between living and non-living processes may depend on where the boundary is drawn for an ‘entity’ and ‘its environment.’ A division can be made, but it varies from situation to situation, limited by the purposes of the observer. For example, the boundary of the process we call a ‘tree’ will change depending on whether we are thinking about its grossly visible form, or how it breathes in CO2 and breathes out O2, or how its seeds are dispersed by the birds that feed on its fruit, and so forth. On the other hand, if we just take at face value that there is a distinction between living and non-living processes, the current proposal leads to some interesting conjectures with respect to some of the proposed characteristics of life. For instance, water has been suggested as a necessary constituent of living processes; seeds remain dormant without it. It is also known that water molecules in living systems are not positioned haphazardly, as they are in ‘free water’ (Ling, 1984); and this property might help support long distance, non-linear metabolic waves in living organisms (Mesquita, Vasconcellos, Luzzi, & Mascarenhas, 2004, p. 462). A second speculation concerns the finding that living cells emit weak electromagnetic radiation in the infrared to ultraviolet range (Ho, 1995). This process, proposed by some to be a source of communication among living cells (Ho & Popp, Note 6), might relate to catalytic processes. The general suggestion of the current theory is that life catalyzes its environment, implying some sort of literal harmony between life and environment.

Thermodynamics and energy dissipation are not typical topics in cognitive science and neuroscience, but they are central to ecology, the relation of life and its environment. Ecological psychologists, for example, point out that that the perception-action cycles of more complex animals increase the available paths for energy dissipation compared to those of less complex organisms (Swenson, 2000; Swenson & Turvey, 1991). Data from ecosystems show that their development correlates with an increasing number of paths for energy dissipation (Schneider & Kay, 1994). Theories of ‘self organization’ and ‘complexity’ also use the basic

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laws of thermodynamics to anchor their speculations about how life develops order, in spite of the tendency of non-living systems to go toward disorder (Prigogine & Stengers, 1984; Rosen, 1991). As we discussed in the introduction, Eigen and Schuster’s theory of catalytic hypercycles gives both a rationale and a possible path for pre-biotic Earth to have developed into complex, embedded, catalytic systems (see also Kauffman, 1995; Waldrop, 1992). Contrary to earlier ideas that life is a fragile process and its development an unlikely event, the laws of thermodynamics favor its evolution, although they do not specify its form (Cockrell, 2003). The robustness of life also is generally consistent with intuition that life mediates or catalyzes its environment (Davia, in press). Because the current theory also is anchored in thermodynamics, it may help us to articulate the relation between cognitive science and neuroscience and these broad ideas about the relation between life and the universe.

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Footnotes

1. Please address comments to: Patricia Carpenter: Carpent@andrew.cmu.edu

We thank Drs. Brian MacWhinney, Walter Freeman, Joseph Goguen, Hideya Koshina, Anat

Prior-Unger, and especially Dwight Kravitz for their comments on the paper.

2. Although enzymes used to be considered exclusively proteins, in the 1990’s it was

discovered that some RNA (ribozymes) are enzymes and single-stranded DNA is an enzyme

(Sen & Geyer, 1998); these findings illustrate the rapid changes in research on molecular-

level enzyme catalysis. However, our primary focus is on generalizing the concept of catalysis

to higher levels.

3. The phenomenology of ‘seeing’ via the vOICe system is not identical to that via the eyes.

For example, Fletcher reported experiencing the scene as though ‘sketched’ in black and

white, as well as enhanced sensitivity to visual texture. The enhanced sensitivity to visual

texture agrees with the reports of congenitally color-blind individuals described in Sacks

(1997).

4. We thank Dwight Kravitz for pointing out to us the reconciliation of connectionist models

with the current approach.

5. Dynamic systems theories include connectionist models with both feedforward and

feedback relations, which as we pointed out, typically are interpreted as representational.

Consequently, we are focusing on non-connectionist dynamic systems theories.

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Reference Notes

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2. http://encyclopedia.lockergnome.com/s/b/Enzyme May, 2005.

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Figure Captions

Fig. 1. A diagram of the ‘structural coupling’ between an organism and its environment at

Time 1 and at a later time, 1+n, depicting correlated changes in both the organism and

environment, in which each changes according to its own internal organization. (Adapted

from Maturana & Varela, 1998, p. 74.)

Fig. 2. A pathway representation (on the left) with a series of co-enzymes shown as side

loops; and an integrated loop representation (on the right) of the fermentation process

(adapted from Bechtel, 1998, p. 310).

Fig. 3. The enzyme cycle of the decomposition and regeneration of rhodopsin, beginning

with the trigger of light energy and showing the enzyme cascade involving a G-protein,

Transducin, that correlates with the neural action potential of the rod. (Adapted from

http://education.vetmed.vt.edu/Curriculum/VM8054/EYE/RHODOPSN.HTM).