Can Quantum Theory Help Us Understand Consciousness?

By Jack Tuszynski in Scientific Background on May 21st, 2007 / No Comments

Consciousness, once a topic alluded to only by philosophers and, occasionally, theologians, has – in the past 20 years or so – migrated into the domain of science and rational analysis. But this does not mean to say that conscious experience is now understood in the way that we understand other natural phenomena that were once attributed to otherworldly causes – earthquakes or solar eclipses, for example.

On the contrary, consciousness remains one of the major unsolved problems in science. But science and scientists are gradually becoming able and willing to tackle this phenomenon, to ask pertinent questions, and to use the newly available technology to carry out decisive experiments.

There are several possible definitions of consciousness, but the general consensus is that the state of being conscious is a condition in which there is awareness and knowledge of one’s surroundings and one’s own existence or self-awareness. The status quo or currently accepted substrate of consciousness emerges as a property of computational complexity among neurons. This framework depicts neurons and synapses as the fundamental units of information processing hardware in the brain, acting much like chips manipulating information bits in a computer.

Are Neurons Creating Consciousness?
It is often argued that although individual neurons are assumed to have only two different states, on when the neuron is firing and off when it is not, there is a critical level of complexity required such that when it is reached, many neurons interact with each other to form a conscious experience. While this is the currently accepted approach to explaining consciousness, it may fall short, especially in cases where the apparent randomness of neural processing is represented simply as white noise.

There are a number of theories of consciousness in existence, some of which are based on classical physics while some others require the use of quantum concepts. Although there can be no reasonable doubt that quantum events occur in the brain as elsewhere in the material world, it is the subject of controversy whether these events are in any way efficacious and relevant for those aspects of brain functioning that are correlated with mental activity and cognition.

Can Quantum Theory Help Us Understand Consciousness?
Although it requires new lines of thinking, quantum theory has invoked new perspectives of consciousness since its very beginning. It is widely accepted that consciousness or, more generally, mental activity is in some way correlated with the behavior of the material brain. Since quantum theory is the most fundamental theory of matter that is currently available, it is a legitimate question to ask whether quantum theory can help us to understand consciousness.

We will try to present the reader with a spectrum of opinions from both sides of this scientific divide letting him/her decide which of these approaches are most likely to succeed. While classical physics is easily grasped by our intuition, quantum theory often defies our common sense developed through everyday experiences. Therefore, some general introduction into quantum phenomena has been presented in this context to better understand detailed discussions presented in several chapters of the book.

The Brain Contains Both – Electrical And Chemical Synapses
The fact that neuronal assemblies are mostly described in terms of classical behavior does not rule out that the possibility that quantum effects may be significant, especially for subneuronal components such as individual proteins, or strands of DNA or RNA. The brain contains both electrical and chemical synapses, named according to the type of signal they transmit. At electrical synapses, the current generated by the action potential at the presynaptic neuron flows directly into the postsynaptic cell, which is physically connected to the presynaptic terminal by a so-called gap junction.

Chemical transmission is slower than electric transmission. At chemical synapses, there is a cleft between the pre- and postsynaptic cell. In order to propagate a signal, a chemical transmitter is released from the presynaptic terminal by a process called exocytosis. The transmitter diffuses across the synaptic cleft and binds to receptors embedded in the postsynaptic membrane, resulting in the opening of an ion channel or in the initiation of a signal transduction cascade. Although these steps operate according to classical physics, quantum processes can come into play.

For example, a physical model developed by Beck and Eccles proposes that quantum processes are relevant for exocytosis and are tightly related to states of consciousness. Another approach, developed by Flohr suggests chemical synapses using NMDA receptors are critical to perception and consciousness because of the high degree of plasticity expressed by NMDA receptors. That anesthetic agents block NMDA receptors and consequently lead to a loss of consciousness supports his theory to some extent. Nonetheless, not all synapses possess NMDA receptors.

In contrast, the neuronal cytoskeleton is the most ubiquitous and most basic subcellular level site thus far proposed for quantum processes in consciousness. The cytoskeleton consists of three types of protein networks: microfilaments, intermediate filaments and microtubules. Microtubules are essential for axoplasmic transport, signaling and neuronal plasticity, among other key cellular processes within neurons. A growing number of researchers are focusing their attention on the biophysics of the cytoskeleton in order to better understand its role in neurophysiology and consciousness.

What About Single-Celled Organism?
Another reason to look beyond classical models is that currently accepted models for consciousness are unable to explain the rather primitive consciousness in single-celled organisms. Single-celled organisms, such as the paramecium, have no neurons or synapses, but still exhibit proto-consciousness, an apparent awareness of and responsiveness to their environment. One can conclude from this that the rudiments of consciousness lie someplace other than the complex interactions between neurons and synapses, although the latter are certain to contribute to the richness of sensory experience and the resulting behavioral repertoire.

In many respects, the cytoskeleton is the control center of the cell. Microtubules control cell division and cell migration (i.e., replication and behavior). Microtubules also provide an ideal bridge between classical and quantum processing; moreover, these structures literally fill the interiors of neurons. Microtubules are composed of tubulin dimers arranged into longitudinal protofilaments. The interior milieu of tubulin can be likened to a caged qubit, capable of quantum computation, linked into a long polymer chain responsible for transmitting classical information. Substantial efforts have been made to fuse quantum theory with microtubules and consciousness, the result being one unified theory.

Most notably the work of Sir Roger Penrose and Stuart Hameroff has pointed in the direction of quantum gravity as the fundamental level at which consciousness can be best understood. Not surprisingly, their work has drawn a lot of attention, not all of it very supportive. This effort is considerably advanced from a mathematical point of view and hence inaccessible to much of the audience unfamiliar with modern physics.

According to this model, pre-conscious thought and experience exists in terms of multiple quantum states, and the conscious experience is realized when one of the many possible states prevails.

Some of the questions that are now being addressed, and which will feature in this volume are:

  • How do the feelings and sensations making up conscious experience arise from the concerted actions of nerve cells and their associated synaptic and molecular processes?
  • How do the operations of the conscious mind emerge out of the specific interactions involving billions of neurons?
  • What physical mechanisms and brain processes lie behind particular conscious experiences?
  • And how can this vital information be collected experimentally?
  • Can conscious awareness really be explained by modern science, or is an entirely different kind of explanation needed after all?

This multi-authored book seeks answers to these questions within a range of physically based frameworks. Thus, the underlying assumption is that consciousness can indeed be understood using the intellectual potential of modern physics and other sciences. There are a number of theories of consciousness in existence, some based on classical physics, whilst others require the use of quantum concepts. The latter have drawn criticism from parts of the scientific establishment, while simultaneously claiming that classical approaches are doomed to failure.

A Spectrum of Opinions
This book presents a spectrum of opinions, models and theories as well as some experimental evidence to elucidate the various approaches within this on-going scientific debate. It will enable readers to decide for themselves which hypotheses and which directions of study appear most promising. The underlying assumption made by the editor of this volume is that consciousness should be understood using the combined intellectual potential of modern physics and the life sciences.

Contributions have been gathered from a number of scientists representing a spectrum of disciplines taking a biophysics-based approach to consciousness. In their attempts to identify and understand the roots of consciousness, the authors variously exploit experimental, theoretical and even philosophical approaches.

The volume begins with a general overview written jointly by Nancy Woolf and Jack Tuszynski. This includes a detailed synopsis of the further contributions, together with a few words about the ´┐Żallegiances’ of their authors in the ongoing debate.

We believe that this book will help to set the scene for future explorations in this field by new generations of scientists and interested lay readers alike. At the least, it would be gratifying if this volume were to inspire many of its readers to think about the concept of consciousness as a journey of both scientific and personal discovery.

Available at amzon: The Emerging Physics of Consciousness

About the Author:
Professor Jack Tuszynski received his M.Sc. with distinction in Physics from the University of Poznan (Poland) in 1980. He received his Ph.D. in Condensed Matter Physics from the University of Calgary in 1983. He did a Post-Doctoral Fellowship at the University of Calgary Chemistry Department in 1983. He was an Assistant Professor at the Department of Physics of the Memorial University of Newfoundland from 1983 to 1988, and at the University of Alberta Physics Department from 1988 to 1990. He joined the University of Alberta Physics Department in 1993. He is on the editorial board of the Journal of Biological Physics.

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