The Nature of Conscious Experience

A framework for conscious experience and its significance for perception, language, evolution, fundamental physics...

Our conscious experience of colours, shapes, movement, tunes, and abstract ideas has been considered by many people to be outside the scope of scientific study and impossible to fit into a world described by physics. This site is devoted to a different view, in which experience is central to all the sciences, as much as the humanities.

In this view, or hypothesis, a human-type experience is an event within the structural framework of an individual cell in which a complex pattern of information, presented as a field of electrical potentials, interacts with a fundamental dynamic unit linked to the ordered structure of the microtubular arrays of the cell framework (cytoskeleton).

The ramifications of this proposal spread into many branches of science but are all linked to a proposed role for experience – that of a desktop or interface that can present rich information in real time in a way that is not possible for the genetic information hidden in DNA (the read-only operating system code). Experience is where current perceptions and ideas can be compared to memories and to archetypal ideas whose blueprints are encoded in genes. It is where truth can be evaluated.

The hypothesis may prove wrong in one way or another but proposing a specific site, with well known biophysics, for conscious experience provides an opportunity to open up a whole new range of questions that might be subject to test.

A key aspect of the hypothesis is that it proposes that the conscious experiences we are familiar with are events in the internal structure of individual cells. In a sense, they belong to individual cells, not to whole organisms. There is nothing very new about this; Descartes proposed that experiences arise in the pineal. Nicholas Humphrey has suggested that as organisms become multicellular their pictures of the world become internalised and directed towards cells in the nervous system. What many people find disturbing, however, is the implication that many different cells may be hosting experiences in parallel in our brains, with there being no single overall experience. John Locke proposed that our sense of being enduring selves may just be carried over by memory. The hypothesis presented here suggests that selves as subjects may be multiple in space as well as in time.

The idea of experiences being events in cells arose originally as a way to explain how human experience could fit with neuroscience. However, the idea also makes it much easier to understand the apparently intelligent behaviour of bean plants and protozoa, neither of which have a nervous system.

A further feature of the hypothesis is the proposal that individual cells carry within their structure maps or blueprints derived from memories or archetypal (innate) patterns encoded within DNA that form a real-time accessible mirror of the organism’s relation to the world, including its outer appearance. The proposal is that as new species evolve they evolve inner representations of their relation to world in parallel, using, at least in part, the same sets of genes that determine their outer appearance. If this is the case it has major implications for diversification in evolution and perhaps in particular the Cambrian explosion. In a sense it implies that every organism is born ‘knowing what it looks like’. This of course makes it easier to find others that look the same and might even help explain how we know when we are smiling and when we are looking annoyed.

Experience as a Property of Individual Cells

The reason for suggesting that a conscious experience, of the sort we discuss, occurs in an individual cell is simple, even if the idea seems surprising. The only plausible reason why our sense organs send signals to the brain is that somewhere in the brain the signals are received and responded to. The rich patterns of sensations we experience indicate that lots of signals are received together somewhere. Individual cells in the brain receive lots of signals; they can have up to 50,000 input synapses. Nothing else in a brain receives lots of signals. All interactions are at the individual cell level – what is known as the neuron doctrine.

Descartes proposed that signals from sense organs all converged on the pineal. We now know that the pineal is not involved in the conscious experiences we talk about. It can be removed with no effect on reports of experience. Studies of nerve cell connections in the brain have shown that, at every stage of signal sending, signals diverge as much as they converge, so at every level of processing lots of cells are involved. This led to the popular and reasonable claim that ‘there is no one place in the brain where everything comes together’. Unfortunately, this seems to have been confused with ‘there is no place where everything comes together’. On the contrary there are millions of places where enough signals come together to explain a rich experience – in each of lots of cells.

The difficulty most people have with the idea that rich experiences should occur in each of lots of individual cells is that, like Descartes, they have the intuition of being ‘the only single subject in this head’. But although this intuition makes sense as a survival-adapted illusion from a co-ordination point of view it is not supported by any evidence. A key feature of conscious experience is that it is never shared. A conscious subject never has access to the consciousness of another subject.  So the fact that a subject in a human brain is completely unaware of any other subjects in the same brain tells us nothing about whether they are there or not. Similarly, subjects with the type of experience that we talk about have no way of knowing whether or not there are also subjects in a brain whose experiences are never talked about simply because their content is never relayed to the parts of the brain that control language. We have no reason to think that there are no conscious experiences in the cerebellum, for instance, just as we have no way of knowing whether there are experiences in inanimate structures.

The physical science objection to the idea of experiences occurring in individual cells is the one raised by William James: that even in a cell incoming signals are not actually together, because each reaches a different part of the cell – to be precise, a different point along the branching mass of dendrites. Physics has changed since 1890, but even in 1890 James’s objection might be open to doubt. When a radio wave photon meets a radio mast it does not interact with any particular point in the mast. It creates a voltage across the entire mast. Electromagnetic interactions are spread out, or distributed, as is now explicit in quantum field theory. This does not mean that the law of locality is broken; causes and effects are not linked faster than the speed of light.

Moreover, since the basis of neural membrane excitation was described by Hodgkin and Huxley in the 1950s the generation of an electrical ‘spike’ response by dendrites has tended to be seen as due to potentials at all the synapses acting together. In the output from a neuron, a spike takes time to propagate along the axon and is seen a chain of events each triggering the next. However, in the input dendrites triggering of a spike by synaptic potentials has been treated as a single event. Although this approach may have originally been pragmatic it may reflect a genuinely unitary interaction. 

The Biophysical basis of Experience in Cells

A specific proposal for the biophysical interaction underlying our conscious experience is explored in a paper due to be published in Journal of Consciousness Studies soon (2020-2021). A brief outline will be given here.

The assumption is made that the basis of an experience must be a causal interaction between a pattern of signals encoding information about the world and some dynamic unit influenced by those signals. In fundamental physics terms we should expect the signals to take the form of a complex pattern of field potentials. In the brain, a pattern of information about the world that might influence some single dynamic unit occurs as a field of electrical potentials generated at the synapses lying along the dendritic branches of a cell. Patterns of potentials across wider domains are not thought to co-influence any particular dynamic unit so cannot contribute to any single event of experience.

The most difficult problem has been in identifying a single dynamic unit that might be influenced by all the synaptic potentials in a dendritic tree. Craddock, Tuszynski and colleagues have recently proposed that long range collective exciton modes within the protein arrays of microtubules may be involved in experience. Specifcially, they have suggested that these modes involve oscillations between excited states of electron orbitals in aromatic amino acid at regular intervals along tubulin assemblies. Modes of excitation of this sort seem promising as ‘receivers’ of the information content in our experiences because they may be indivisibly influenced by all perturbations in electrical potentials along the length of the microtubular structure of the dendrite cytoskeleton. Influences from these potentials may alter properties of the cytoskeleton such as impedance so as to either facilitate or damp the generation of an output ‘spike’ with current flow down the dendrite.

The distributed nature of interactions in contemporary condensed matter physics, that makes use of a generalised form of quantum field theory, is counterintuitive. However, it is not perhaps as new as it might seem. Radio transmission and reception systems ha been devised before quantum theory came along. When a radio wave hits a receiver mast it influences the entire mast by generating an electrical voltage across it. The generation of radio waves by oscillating currents in transmitter masts is perhaps even more counterintuitive. An alternating movement of charges across many metres and across many cycles in time seemingly provokes the universe to ‘spit out’ photons of energy from not particular place or time. The model proposed here for an interaction between a pattern of electrical potentials along the dendrites generated at synapses and a distributed mode of excitation of a collection of electron modes is requires nothing more strange than was recognised in 1890, even if perhaps not to William James. It is more complex but it does not require things like entanglement or quantum computation or phenomena that can only occur at low temperatures.

Certain types of brain neuron can have up to 50,000 input synapses. Although it is unlikely that a cell receives more than a few hundred active synaptic signals at a time there remains the possibility of a very rich range of patterns of active and inactive synapses. Some degree of redundancy can be expected so it may be fair to suggest that inputs into dendritic trees have something like 1000 functional degrees of freedom. Popular estimates suggest that this is about right for the level of richness of information found in a conscious experience.

In this model the experiencing subject is remarkably similar to Descartes’s concept of a soul, an idea that he arrived at by very reasonable reductio ad absurdum. The subject is technically a mode of excitation of a field, or in Descartes’s terms an indivisible unit of action or spirit. As Descartes proposed, it has no ‘extension’ in the sense of excluding other things from a space but exists in association with a domain of matter that does. The key difference from Descartes is that rather than being an immortal or enduring entity a mode of excitation of an exciton field in a cell is likely to be very evanescent. Any sense of enduring self must, as Locke suggested, rely on memory.

The most difficult puzzle relating to any attempt to understand how conscious experiences are encoded in physical interactions is what sort of syntax the code might use and how it can give rise to everything from colours to abstract concepts. Finding a way to explain why signals arriving at synapses should have the meanings they do might seem impossible. On the other hand, this problem arises whatever theory of meaning of brain signals we might consider. Theories that try to relate experienced meaning to signals passing around networks must be considered just as much faced with this impossibility. They have the additional disadvantage that signals distributed around a network do not influence anything together. Nowhere are they ‘compresent’. They suffer from an insuperable ‘binding’ or ‘combination’ problem.

Part of the puzzle of internal meaning is likely to be illusory. We may wonder why the inside of a cell dendrite should appear like a sitting room. But of course the correct question is why the inside of a cell dendrite should appear like a representation of a sitting room in a cell dendrite that happens to be representing a sitting room – the answer being self-evident. We might also say that there is no particular puzzle about certain wavelengths of light being represented as what we call ‘redness’ since redness might seem to be as good as any other arbitrary choice as a symbol. What is more difficult to understand is why our experiences should include abstract ideas like value, belonging and purpose, when there do not seem to be any equivalents within physical dynamics.

Related publications

Edwards JC (2005) Is Consciousness Only a Property of Individual Cells? Journal of Consciousness Studies 12, (4-5), 60-76.

Edwards JCW (2006) How Many People Are There in My Head, and in Hers. Exeter, Imprint Academic.

Edwards JC. (2016) Distinguishing Representations as Origin and Representations as Input: Roles for Individual Neurons. Front Psychol. 7:1537. doi: 10.3389/fpsyg.2016.01537. 

Edwards JC (2018) Giving Descartes His Due. Chapter 5 in Ed. Hackett P. Mereologies, Ontologies, and Facets. Rowman and Littlefield pp87-1067.

Van Stekelenburg, T and Edwards JC (2020) Why Integrated Information Theory Must Fail on Its Own Causal Terms. J.Consciousness Studies 27, 7-8, 144-164.

Edwards JC (in press) Quantum-level experience in neural dendrites: an interpretation-neutral model J. Consciousness Studies.

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