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CHARACTERIZATION OF STATES OF CONSCIOUSNESS BASED ON GLOBAL DESCRIPTORS OF BRAIN ELECTRICAL DYNAMICS.

ABSTRACT: The spatiotemporal dynamics of the electrical field of the brain reflects variations in the global functional state of the brain. Functional states of the brain are related to states of consciousness. A quantitative assessment of the electrical activity of the brain (EEG) as a whole is thus a prerequisite for an objective characterization of states of consciousness. The traditional methods of EEG analysis focused on the frequency representation of local activities. The spatial approach, which takes snapshots of entire brain's field topographies for units of analysis, is better suited for a global assessment of the brain's state. Extending the spatial approach, multi-channel EEG may be represented as a trajectory in the so-called state space: functional states of the brain are reflected by the geometry of the trajectories. A system of three global descriptors was proposed to characterize the trajectories: [sigma], [phi] and [omega] These descriptors provide for a global, macroscopic, "holistic" descr iption and 3-dimensional visualization of the varieties of brain functional states. The importance of the global approach is illustrated on some experimental results, and its applicability to the psi research and to the altered states of consciousness is briefly discussed.

There is no doubt that states of consciousness (SC) and functional states of the brain (FSB) are somehow interrelated. Whatever our philosophical position regarding the so-called psychophysical ("mind-brain") problem, the empirical fact of this correlation is there, given as a hard datum. [1] The evidence for correlations between the varieties of SCs and FSBs has been established by findings in clinical and experimental neurophysiology and particularly by the empirical base on electroencephalography (EEG) studies in electrical fields of the human brain.

In the present article, I wish to approach the problem of characterization of states of consciousness by employing of quantitative assessment of the brain's functional states.

FUNDAMENTALS OF SC/FSB CORRELATION

Phenomenology of SC/FSB Variety

The variety of SCs is, first of all, experienced; we know from our own subjective experience that the ways in which our awareness of the external world and of ourselves is organized and articulated may strongly differ between subjects at the same time, and within a subject at different times. We recognize the fact that there are more or less smooth transitions between these states (e.g., wakefulness and drowsiness). We also realize that there are discontinuities or incompatibilities between some special states, for example, between the "standard" awake consciousness of the outer world and the "dream consciousness" of the inner world, the hallucinatory consciousness of a psychotic experience, or the ecstatic consciousness of a mystic experience. The variety of possible states of consciousness is systematized and objectivized in the language and, in this way, made communicable between subjects as (meta) experience.

The variety of FSBs is an observed fact; we know from our objective (that is, intersubjectively agreed-upon) experience (above all, from our physiological or physical measurements) that patterns of manifestations of the brain's functioning also differ to a considerable extent--again, between and within subjects. Particularly, the differences in the frequency content of the electrical activity of the brain (EEG), that is, presence of various rhythmical activities at different intensities, were recognized very early as signatures of various FSBs, and gave rise to empirical correspondence rules: alpha (8-12 Hz) [approximately equals] relaxed wakefulness, beta ([greater than] 12 Hz) = focused attention or anxiety, etc. In fact, most frequency-domain-based methods of signal analysis (spectral representation via Fast Fourier Transform algorithm) were utilized to characterize the electrical manifestations of brain states. The variety of observable functional brain states was then systematized in formal systems of d escription and thus available to quantitative studies, hypotheses testing, etc.

Confrontation of these two parallel areas of experience leads directly to the following question: What means do we have to characterize and systematize these two varieties of data, and what is the role played by the correlation between the states of consciousness and functional states of the brain?

Three Levels of Characterization

We now want to focus on the hierarchy of levels of conceptualization or characterization of both SCs and FSBs. For the sake of clarity I will specify the three levels in a somewhat schematic way, avoiding repeated examples.

At the very basic, taxonomic, level we operate with verbal, categorial descriptions rooted in informal (experiential) or formal (observational) languages (verbal labels).

The next level takes into account the topology of the varieties of states in question: the topology may be defined by (a) similarities in terms of their characteristic features, (b) by available transitions between states, or (c) by operational means applicable for an intentional induction of these states. Thus the topological level involves a variety of states as well as a relational structure of similarity/dissimilarity.

Finally, the highest level of characterization defines a metric of the variety of states, thus translating the notions of similarity or dissimilarity into those of proximity or distance. In this way, the qualitative, taxonomical, or topological description is expanded into a strictly quantitative assessment. Briefly, we could speak about a transition from taxonomy to metronomy.

From Assignments to Morphisms

The correlations between SCs and FSBs are given empirically as a set of bidirectional assignments between the two domains (Figure 1, a).

In an ideal case, such a correspondence system should consist of unique (one-to-one) assignments. In practice, such a requirement may be too strong; in many applications, uniqueness can be required only over a defined subdomain of SCs, while many-to-one correspondences are allowed outside of the area of interest. However, a universally valid system of unique correspondences is the ultimate requirement.

At the taxonomic level, no more requirements are imposed onto the system of SC/FSB correspondences. As we move to topological or metrical levels of assessment, additional requirements play a role: those of continuity (topological level) and smoothness (metrical level). An additional requirement of linearity can be fulfilled on the metrical level by a proper scale transformation; these rather technical points will be omitted here.

Generally speaking, we require that the correspondence system between SC and FSB domains is not only unique, but also has to preserve topological or metrical structures defined in both domains; in other words, we are looking for isomorphisms between the two domains (Figure 1, b). The requirement of isomorphy applies, in fact, to any task of quantification of observable phenomena. However, in our special case, the requirement implies some nontrivial problems: (a) examining the topological structure of the SC variety, (b) constructing a topological or metrical structure on the FSB variety, and (c) matching dimensionality of correlated domains.

Dimensionality of Description

As argued here previously, the states of consciousness are given directly by the subjective experience and, in a mediated form, by intersubjective language constructs; this is the material from which the search for order will start. The dominating dimensions revealed are, no doubt, the dimension of vigilance, because the entire life is embedded in the cycle of wakefulness and sleep, and the dimension of activation, which is closely related to the waking sector of the vigilance continuum. Additional dimensions may be required for emotional tuning or mood, etc. Still, the dimensionality of SC variety seems to be relatively low, while the variety of possible combination of states may be very rich.

However, the dimensionality of a variety of SCs accessible to a subjective experience or to an intersubjective discourse may be restricted due to many factors such as inadequate conceptualization, lack or loss of the ability to enter some (generally available) states, sociohistorical and cultural norms, including political restrictions. (The increasing interest in altered states of consciousness seems to support this assumption.)

On the other hand, FSBs are given in form of data aggregates obtained by our measurements--and here the dimensionality of the data spaces may be increased deliberately. Techniques of multivariate statistics, factor analysis, or multidimensional scaling are typically used to reduce the dimensionality of the data space and to provide a model of FSBs' variety which would, at least roughly, match the dimensionality of the SCs' domain. The difficulty with these strategies is that the relations between the domains are given by "specification equations" containing many terms, without any comprehensive link to the correlate. Later in this article, I will attempt to show that this need not necessarily be the case if proper methods of parametrization of FSB variety are chosen.

THE HOLISTIC ARGUMENT

Unity of Consciousness

There is only one consciousness, that is, one frame of reference of all perceptions, emotions, volitional acts, etc., of a conscious individuum. Even if, under special conditions, the world is experienced in such a way that an expression in terms of multiple consciousness (from ego dissociation down to ego splitting) may seem appropriate, there is still one ultimate frame of reference relative to which the multiplicity is recognized. Even those who argue that the evidence for the unity of the consciousness may well be an illusion (e.g., Farthing, 1992, p. 42) have no better arguments than references to cerebral substructures--arguments located outside of the experiential evidence.

It is the current state of consciousness that determines the strategies of integration of all conscious contents into a whole, into a conscious experience of the (external and internal) world (apperception, in terms of a more traditional language).

It follows, then, that the notion of a state of consciousness is inherently holistic: the whole determines the meaning of all involved constituents.

Unity of Brain Functioning

While the arguments for a fundamental unity of consciousness are anchored in our continuous subjective experience and thus justified by it, it is much harder to argue for a corresponding unity of brain functioning. A fleeting look into a textbook on neuroanatomy provides a picture of the brain as a highly complex and hierarchically structured system, and even this initial picture of structural complexity fades out when compared to the functional complexity of each sensory or motor subsystem. The complexity of the brain as a whole, then, exceeds any imaginable representation. What do we mean when we speak about a unity of the brain functioning?

To start the argument, we first reword the previous statements on the unity of consciousness to its equivalent brain-related form. Then we can look for an additional support for the argument.

There is one brain, that is, one common place where the physiological processes conditioning or correlating with the conscious experience take place. Even if the brain is a highly structured organ system with specialized subsystems, it still makes sense--indeed, it is inevitable--to conceptualize a global functional state of the brain as a whole. [2] This global state is a kind of Gestalt that determines the functional significance of the activation pattern of each subsystem. As we will argue below, the "via regia" to an operational assessment of the global functional states of the brain (GFSB) is to study its electrical "signatures," as manifested by the spatial distribution of the brain's electrical field. And, according to the arguments presented above, the spatiotemporal dynamics of the brain's electrical activity should be assessed by means of few global quantitative descriptors that are capable of characterizing the variety of GFSBs on the topological or metrical level.

More Data = More Knowledge?

This stated objective seems to be contrary to the current trends of methodology in the neurosciences. What sense does it make to study electrical fields of the brain recorded from the scalp surface if we can go to the depth and perform intracranial electrical measurements on dense electrode grids applied directly to the brain structures in question? And, in addition, modern imaging methods provide direct access to activation patterns within the entire brain volume, with still higher spatial resolution. Thus, the claim raised in the previous section may appear an overly reactionary approach based on obsolete methodology.

The answer to the objection is that the concept of the global state of the brain implies integration of data from the entire active brain; in the case of scalp field measurements, the very nature of the measurement process provides a natural integration of activation patterns of neural structures generating the observable field. As we will show below, it is the "landscape," the spatial distribution of this summarized field, that carries information about the global brain state (at least as far as it is manifested by electrical phenomena).

Finally, to qualify the notion that more data is equal to more knowledge, I will reproduce two pictures. The first (Figure 2, a) one is taken from Descartes' treatise L'Homme and is often reproduced in popular introductions to neurobiology or brain physiology; indeed, in my source book (Robin, 1992, p. 71), the picture stands for an epitome of a crude understanding of human anatomy and physiology. I found the picture reproduced again in a review article on the human visual system (Singer, 1997, p. 40), accompanied by a modern view of the structure of the visual system (Figure 2, b). The purpose is obvious: the marked contrast between Descartes' rough, mechanical concept of the sensory mechanism, and our modern, detailed, refined (nonetheless, still mechanical!) view of the "wired paths" of visual information processing should illustrate the progress achieved by modern experimental brain research. There is no doubt that progress of technology over the last decades made it possible to perform detailed investig ations of various brain subsystems, their functioning and "wiring" schemes, etc. Yet--does this really imply progress in terms of understanding the variety of brain states, their intrinsic functional significance, and their importance for the dynamics of states of consciousness?

Orchestra Metaphor

I would like to illustrate my point by a simple metaphor (and will refer to my personal conscious experience for a while). I belong to those people who prefer to listen to music with closed eyes and to perceive it in an abstract space. Actually, if I happen to listen to a musical performance given on TV, I am too easily distracted and very disturbed by the TV images that continually change from one visual detail to the other, to single players, the conductor, or the whole of the concert hall.

Now, an orchestra performing a musical opus may serve as an excellent metaphor for the brain's functioning (surely better than the old-fashioned mechanical or computer models). The sound is produced by a synchronized action of specialized structures (players with their instruments); nonetheless, it is the Gestalt of the musical composition that determines the actions of the sound-generating structures.

These are trivial facts, at least from the point of view of a music lover; however, a modern neuroscientist might have a different opinion. The music is, no doubt, the sound of music; thus, according to his methodology, he has to examine how and where the sound is generated. Consequently, the scientist would want to have a closer look at the details of the orchestra's operations. Even by a superficial visual inspection he would discover various sections of instruments characterized by different sound frequencies, intensities, etc. Then, refining his methods of observation and data analysis, he might increase the spatiotemporal resolution and get into more and more details of the functioning of the orchestra. [3] Finally, he would learn more about the motor skills of a violin player, about mechanics of flutes, about resonance properties of drum membranes, etc., etc.

This is what neurosciences are doing nowadays in the effort to understand the brain's functioning. And yet, I maintain that in doing so, we might easily--well, we surely will--miss the meaning of the musical piece that is being played. Beethoven, Haydn, Orff--what will remain from the intrinsic structure of the musical opus?

Thus, even if we understand very well the mechanics of the orchestra, we need a different approach to assess the meaning of the musical piece being played. Perhaps we should stay behind the concert hall doors and listen to what we can hear, and not be distracted by what we can see.

BRAIN FIELD TOPOGRAPHY AS A HOLISTIC ASSESSMENT OF FSBs

From the Time Domain to the Space Domain

The quantitative EEG analysis in its traditional form is a product of clinical empirism and engineering approaches to the signal processing. The hypothesis of a unique functional significance of the different rhythms was realized in a straightforward way, using the transformation of the EEG signals from the time domain into the frequency domain, and computing integral power for the various frequency bands. This is not the proper place to discuss the virtues and pitfalls of this ubiquitous strategy. From our point of view, the major disadvantage of this approach is that it completely neglects the holistic aspect of the brain's electrical field: Spatially sampled recordings are treated as one-dimensional time series, processed by methods of frequency analysis, and only post hoc a topographical synopsis of the results is constructed (the so-called "brain mapping").

The complementary approach, based in the space domain (Lehmann, 1987, 1990), takes a vector of simultaneous measurements at all N electrode sites (where N is at least 19, according to the International 10/20 Standard System, but may be many dozens) as a unit of analysis. Thus, the primary data consist of a stream of N-dimensional measurement vectors that can be transformed to a series of field maps, or snapshots of field topographies. This strategy turned out to be extremely fruitful since Lehmann's pioneering work on the topography of alpha EEG fields (Lehmann, 1970).

Analyses of multichannel EEG map series showed that the repetitive patterns of brain fields display periods of relatively stable configurations; the duration of these segments is in the order of magnitude of hundreds of milliseconds. Lehmann and the Zurich school (Lehmann, 1984) hypothesized that during each of those stationary segments the brain is in one global functional "microstate," and that the sequence of microstates reflects sequential information processing performed by the brain. Thus, the microstates are tentatively identified as putative building blocks of the brain's operations (Lehmann 1984, 1990; Wackermann et al., 1993).

Whatever the functional meaning of brain microstates, their very existence provides strong support to the notion of a global FSB. We can conceptualize the microstates as global states of the first order, from which the functional microstates (GFSB in our sense) are built up. While the microstate analysis operates on a time scale of milliseconds, we need an effective method that condenses extremely large amounts of information from multi-channel recordings, lasting seconds or minutes, into a relatively low number of quantitative descriptors.

Low-dimensional Description of GISBs: [sigma][phi][omega] System

The following presents such a low-dimensional system of description of GFSB, known as the [sigma][phi][omega]system (Wackermann, 1996). I will sketch, in rough contours, the logic of its design, and then refer to some empirical results achieved with this method. (Even if the underlying mathematics is quite simple, we will omit any mathematical formalism to make the idea accessible to a general reader.)

A segment of the brain's electrical activity recorded from multiple electrode sites may be represented either as an array of curves (time domain representation) or as a series of field maps (space domain representation). A synthesis of these two (essentially equivalent) representations is provided by the notion of state space: momentary measurements of the electric field of the brain, "voltage vectors," are interpreted as points in an N-dimensional space. In this way, the evolution of the field dynamics over a time epoch is translated to a sequence of points, or a trajectory in state space. (In spite of the fact that the trajectory is embedded in an N-dimensional space, it can be projected into a space of lower dimensionality without much distortion.) Figure 3 illustrates the diversity of state space trajectories of a multi-channel EEG recorded in different functional states. The geometry of the trajectory reflects essential characteristics of the dynamics of the brain's electrical field: its diameter corres ponds to maximal amplitudes of the so-called Global Field Power (Lehmann, 1987); the density of points along the trajectory is inversely related to the speed of change of the field's configuration; and the overall shape of the trajectory, with its extension along its principal axes, corresponds to the magnitude of spatial synchronization between activities recorded from different loci on the scalp.

Following the reasoning above, a system of three quantitative descriptors has been proposed (Wackermann, 1996): [sigma] (the integral global power, measured in [micro]V) [phi] (a generalized measure of frequency, measured in Hz), and [omega] (a dimensionless indicator of spatial complexity or inverse of spatial synchronization, which attains values from 1 [maximal synchronization] through N [no synchronization]) [4] Thus, a putative GFSB, represented by an epoch of few seconds of multichannel EEG data, is characterized by a triplet of three global descriptors. These three values can be taken as coordinates of a 3-dimensional "macrostate" space. (In a sense we "collapse" the brain geometry from a spatial extension to a pointwise representation in the macrostate space.) Consequently, we expect that similar GFSBs will project to similar locations in the macrostate space. The limitation to only three global descriptors is rather arbitrary, but has an additional advantage : varieties of GFSBs in a 3-dimensional m acrostate space can easily be visualized.

Selected Applications of the [sigma][phi][omega] System

The following few examples shall illustrate the applicability of the [sigma][phi][omega] system to selected research areas in neuro- or psychophysiology. We will pay attention only to those examples related directly to studies of consciousness. In addition, the descriptor of spatial complexity ([omega]) itself has proven to be a quite sensitive indicator of GFSBs "shifts" caused by psychotropic or nootropic drugs (Kondakor et al., 1997b; Yagyu et al, 1996) or by manifest psychopathology (Saito et al., 1998).

Discrimination of sleep stages. The sleep/wakefulness cycle represents the most impressive natural variation of states of consciousness; whole-night sleep EEG recordings were studied by means of the [sigma][phi][omega] descriptors by Szelenberger et al. (1996). The analyses showed a significant difference in all three descriptors between sleep stages scored by the standard methodology (Rechtschaffen & Kales, 1968), and a significant contribution of [omega] complexity to discrimination between sleep stages.

From the point of view of this paper, the relationships between macrostate variables are more pertinent. In the [sigma][phi][omega] space, the variety of sleeping brain states is typically restricted to a curved, thin, elongated area along which the sleep stages are distributed; because of its curved shape and translucent, fragile appearance in 3D displays, the term "sleep shell" was coined for the object (Wackermann & Szelenberger, 1996). The occurrence and hyperboloid shape of the sleep shell is universal; on the other hand, the absolute position of the shell in the [sigma][phi][omega] space as well as the distribution of sleep stages within the shell show a considerable interindividual variance.

Sleep onset and scale of vigilance Macrostate space representation also enables study of the process of transition from wakefulness to sleep. For a subset of subjects, EEG data from Multiple Sleep Latency Tests (MSLT) were available with the sleep EEG. An example of daytime sleep onset data merged with the night-sleep EEG data is shown in Figure 4. The waking states appear as a more or less condensed cloud separated from the sleep shell (Wackermann & Szelenberger, 1996). During the sleep onset process, the [sigma][phi][omega]representations of the global brain state approach the inner curvature of the sleep shell.

This qualitative observation is of crucial importance for the theory of sleep/wakefulness because it suggests that at least two dimensions are necessary for an adequate assessment of GFSB transitions at the sleep onset. A question of possible objective quantification of the process arises immediately. It was shown that a simple logarithmic transformation of the original state variables, [sigma] and [phi]is able to separate cleanly two dimensions of the process and to identify one of those dimensions as an electrophysiological measure of vigilance (Wackermann, in press).

The major conclusions from these findings are: (a) SCs and their correlates, GFSBs, can be "mapped" into the macrostate space and distinguished by their position, and (b) the assignment of SCs to regions or locations in the macrostate space may show individual features (cf. Tart's 1977 discussion on individual definition of discrete SCs).

EEG changes under varying visual input. The reactivity of the EEG to opening/closing of the eyes has been well-known since the dawn of electroencephalography ("alpha attenuation," "desynchronization"). The traditional picture of the reaction has focused on changes in the frequency spectrum. Recently, changes in spatial distribution of the populations of electric generators in the brain volume, and also changes in global state descriptors were studied under varying visual input (Kondakor et al., 1997). As expected, the [sigma] and [phi] decreased and increased, respectively, thus reproducing the established picture of "desynchronization"; furthermore, [sigma] complexity increased significantly, thus reflecting the reorganization of activation patterns in the brain.

Again, the joint representation in the 3-dimensional macrostate space is of more interest and provides more insight than separate univariate statistics. The change of the GFSB caused by eyes opening (i.e., enabling the visual input) is expressed in a simultaneous shift of state towards lower power, higher general frequency, and higher complexity; the magnitude of the change depends on the resting values ("no input" condition). The shifts are constrained to a narrow area which circumscribes the limits of reactivity of the brain to the enabled input. Consequently, a description of the reaction in terms of a "directional" field in the [sigma][phi][omega]space seems to be more adequate to the phenomenon than a mere statement of "alpha attenuation."

Combining the outcomes of aforementioned studies, we can easily see that two application areas are of particular relevance to the psi research: the changes induced by varying sensory input, and the spontaneous changes at the sleep onset. Since pioneering studies on information transfer in Ganzfeld (Braud, Wood, & Braud, 1975; Honorton & Harper, 1974; Parker, 1975), the ganzfeld procedure has become a widely used procedure to induce an internal attentional state. The state shift caused by the homogenized visual field should have an objective correlate in the [sigma][phi][omega]space, as was the case with eyes open/closed conditions. What the ganzfeld condition has in common with the hypnagogic stage (Mavromatis, 1987; Sherwood, 1998) of the sleep-onset process is the occurrence of internal imagery. It seems reasonable that the macrostate space portraits of brain states in the ganzfeld and sleep-onset conditions, respectively, should make it possible to identify subregions of imagery-producing states, and also allow for objective comparisons between the two conditions. [5] What remains open is the question of whether the global description strategy could provide additional insight into the objective definition of psi-conducive states in general; such a possibility cannot be a priori excluded.

CONCLUDING REMARRS

Towards a Quantitative Phenomenology of Consciousness

In contrast to current trends of brain research methodologies that tend to refinement of spatial and temporal resolution, the approach presented in this article is based on the classical multichannel scalp electroencephalography, and intends a holistic, macroscopic description of the brain's functioning as a whole. Instead of collecting masses of data that would later have to be collapsed by methods of multivariate statistics, the approach presented here aims to data reduction as the earliest possible stage of the data processing and analysis, thus condensing the useful information on the global spatiotemporal electrical dynamics of the brain to a few quantitative parameters. This procedure allows recognition of the correlations between SCs and GFSBs as they are apparent in synoptic portraits of GFSBs and their shifts or transitions in the macrostate space. Simple mathematical transformations of the macrostate variables then make it possible to construct dimensions of GFSB varieties corresponding to subjecti vely given dimensions of SCs. These features justify the term "quantitative phenomenology" of brain functional states or, correspondingly, of consciousness.

There is a striking parallel to the approach in the realm of physics, where properties of material objects can be studied either at the microscopic level, as the fine structure of matter, using methods of statistical physics, or at the macroscopic level, using phenomenological description. I believe that the latter approach is better suited to establish links and to investigate correlations between the consciousness and brain physiology.

A Remark on Altered States of Consciousness

Let me conclude with a simple question: What makes altered states of consciousness (ASCs) so extraordinary that they deserve special attention and also require intensive effort to be reinstated as legitimate objects of scientific exploration? In my opinion, the core problem is the difficulty in finding a proper place for ASCs in the one-dimensional topology of "normal," everyday psychophysiology, reduced to the "activation continuum" ranging from sleep through relaxed waking up to alert, focused attention. [6] A classical study of EEG changes during Zen meditation (Kasamatsu & Hirai, 1990) may serve as an example for my point; the observed effects initially follow the wakefulness-sleep dimension, but at later stages of meditation show a significant departure from the well-known pattern.

Because the taxonomy of patterns of brain electrical activity was constructed to match the "activation continuum" (Lindsley, 1952) given directly to subjective experience and fixed in the public language expression, the resulting topology of FSBs could only blindly follow the impoverished conceptual scheme of SCs' variety, and apparently confirm its validity. In other words, the FSBs corresponding to ASCs probably cannot be characterized properly unless the dimensionality of the embedding space is increased. [7]

However, as we have seen previously, a careful study of the topology of waking and sleeping brain states have led to an at least two-dimensional variety. Consequently, we can expect that a similar strategy applied to the exploration of ASCs would yield a "natural" extension of dimensionality of our description of FSBs, and that, going in the reverse direction, an improved understanding of the topology or metrics of FSBs might contribute to an advanced conceptualization of ASCs.

This article is based on the text of the invited lecture given by the author at the 41st Annual Convention of the Parapsychological Association, August 6-9, 1998. Halifax, New Scotia, Canada. The author thanks Prof. Dietrich Lehmann (The KEY Institute for Brain-Mind Research, Zurich, Switzerland) for stimulating and helpful discussions at the later stages of manuscript.

(1.) The fact that I avoid a discussion of the psychophysical problem does not imply that I consider the problem irrelevant--in fact, die opposite is true--but even a marginal discussion of the basic issues related to the brain-mind problem would lead us too far from the central topic. To be less nonspecific about my personal position: I definitely decline the mainstream physicalist paradigm and accept phenomenal experience as the primary reality. However, I would not like to have this position labeled as "mentalism." As for the criticism of physicalism, the position taken by A.J. Rudd (1998) is very similar to mine.

(2.) Experiments with split-brain patients do not contradict our thesis; on the contrary, these experiments reveal that even after massive destruction of commissural connections, the correlative unity of brain and consciousness is still preserved. If this were not the case, there would be no frame of reference to which the peculiar phenomena observed in those subjects could be related.

(3.) It is tempting to extend this metaphor, taking into account the orchestra conductor. From the neuroscientist's point of view, the presence of a conductor "explains" the musical performance, while from the holistic point of view advocated here, the role of conductor is just to transmit the Gestalt of the musical composition to distributed processing and to synchronize the players. These contrasting views could perhaps be of relevance for a discussion of the "40 Hz oscillations" and consciousness (Crick & Koch, 1990).

(4.) To avoid misunderstanding, we note that the terms "synchronization" and "synchronized" are traditionally used in a different sense in classical EEG literature. Time-domain-oriented EEG specialists used to call a curve with a narrow frequency spectrum (i.e., well-formed rhythmical pattern) a "synchronized" activity. Technical terms like "synchronized alpha" and "desynchronization reaction" are based on this usage and refer always to local (single-channel) recordings. In our usage, the term "synchronization" refers to the covariance between two spatially distinct recording sites.

(5.) As of writing this, an EEG study aimed at electrophysiological correlates of the ganzfeld and hypnagogic state has been actually started in the Laboratory of Psychophysiology of the IGPP in Freiburg. In this first study, ganzfeld is applied as a purely sensory manipulation, without any psi communication.

(6.) It might be interesting to introduce a sociocultural perspective to attempt to elucidate Use predominance of the "activation continuum" in the characterization of SCs and, consequently, the reduction of the topology of SCs to a single dimension. This may be related to the appearance of the modern Western life pattern oscillating between maximum activation, induced to pursue distant goals in a concentrated effort, and a relaxed idling or sleep (or surrogate activities), justifiable only as means of recovery in order to continue the effort later. With progressive secularization, the alternative (orthogonal) dimensions of experience were suppressed or largely marginalized, and so were conceptual dimensions of the corresponding states of consciousness, respectively. This may explain why the alternative ways of the conscious experience have to be rediscovered as the altered states of consciousness. Before Use (re) discovery of ASCs, only private "minor ecstasies" like intense love experience or drug-induced states could perhaps enforce conceptual extension of dimensionality of the SC variety.

(7.) This translation of the notion of "altered" states as those "requiring extra dimension" roughly corresponds to the rather informal definition of ASCs given by Ludwig (1990, p. 18): "any mental state(s) ... which can be recognized subjectively by the individual himself (or by an objective observer of the individual) as representing a sufficient deviation in subjective experience or psychological functioning from certain general norms for that individual during alert, waking consciousness." We may add that, due to the normative potential of the socially accepted one-dimensional conceptualization of the variety of SCs, any attempt to add extra dimensions could he avoided only at the costs of labeling ASCs as pathological departures from the "normal" variety.

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Author:Wackermann, Jiri
Publication:The Journal of Parapsychology
Date:Jun 1, 1999
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