QUANTUM COHERENCE IN MICROTUBULES: A NEURAL BASIS FOR EMERGENT CONSCIOUSNESS? 1

The paper begins with a general introduction to the nature of human consciousness and outlines several different philosophical approaches. A critique of traditional reductionist and dualist positions is offered and it is suggested that consciousness should be viewed as an emergent property of physical systems. However, although consciousness has its origin in distributed brain processes it has macroscopic properties — most notably the 'unitary sense of self', non-deterministic free will, and non-algorithmic 'intuitive' processing — which can best be described by quantum-mechanical principles. There have been many attempts by physicists and philosophers to apply quantum- mechanical principles to the realm of consciousness, but they have been primarily speculative and analogical as there has been little supportive evidence from the neurosciences. This paper postulates that cytoskeletal microtubules within neurons could be a possible site for quantum effects. Although the supportive evidence for such a thesis is, of necessity, highly technical, the article has been structured in such a way that the general arguments are accessible to the general reader. For those more technically minded, full supportive evidence is available in footnotes and appendices.