Ultimate computing

The main substance of this book deals with the scope for information processing in biological tissue and especially in the microtubules and other parts of the cytoskeleton. The question of consciousness as distinct from information processing is not given a central role, except when Hameroff discusses the effects of anaesthetics. After the book was written, Hameroff read Penrose's first consciousness book, 'The Emperor's New Mind', met Penrose and suggested to him the possibility that the microtubles might be the seat of consciousness. The Orch OR theory of quantum consciousness arose from this cooperation.

Early on in his career, when Hameroff had worked in cancer research, he had realised that cell division was orchestrated by microtubules. When they were first discovered, the cytoskeleton and its most important components, the microtubules, were seen as a support structure for the cell, but later it became apparent that they had wider functions, and were involved in cell growth and splitting and transport of molecules within the cell. They also seemed to be responsible for dynamic organisation within the cell. This implied that the cytoskeleton used some form of computing.

Hameroff suggests that sub-units of biological protein, such as the cytoskeleton and organelles could provide the basis for information processing. These sub-units undergo nanoscale conformational oscillations that may be both coherent and coupled to dipole shifts within proteins. It is suggested that this could provide a basis for information processing. Hameroff posits that neurons may not be the basic unit of consciousness or intelligence, but that this could instead lie inside the neurons. He points out that single cell organisms have no nervous system but can perform complicated tasks, which can only be achieved by means of some form of internal processing. He surmises that the same form of processing could exist in cells, including brain cells, within multi-cell organisms such as humans.

Hameroff views the functioning of protein as a form of analogue computer. Proteins oscillate between conformational states over periods varying from 10-15 seconds to minutes or longer. In the mid 20th century, the physicist Fröhlich thought that biochemical energy supplied to biomolecular assemblies could result in coherent vibrations. He suggested that a set of proteins on a common voltage gradient such as a membrane or cytoskeleton would oscillate coherently if ATP energy was supplied. This could explain long range cooperative effects, by which proteins and nucleic acids communicate.Protein conformation is a response to a complicated input of temperature, pH, ions, voltage, dipoles etc.
 
Hameroff views each neuron as a computer, and thinks that the cytoskeleton is ideally suited for information processing. Cytoplasm is neither totally regular nor totally random, and is therefore ideal for transmitting information.

There is some evidence for cytoskeletal involvement in cognitive processes. Microtubules and tubulins are increased in the brain during periods of learning, memory and experience. Tubulin production is related to learning/training etc in young chickens and rats. It is also suggested that dendritic spines change shape to alter synaptic thresholds and that this is orchestrated by microtubules.