On the dynamic timescale of mind-brain interaction
Danko Georgiev, Medical University of Varna
Georgiev’s presentation to the 2003 Tucson consciousness conference emphasises the onward influence of solitons (quanta propagating as solitary waves) from the microtubules to the presynaptic scaffold protein, from where, via quantum tunnelling, they are suggested to influence whether or not synapses fire in response to axon spikes. This is a Penrose-influenced theory, and the collapse of the soliton wave function is suggested as the basis of consciousness. The drawback to Georgiev’s papers is that while there is great detail in the biological theorising, the actual basis of and action of consciousness is not much more than implied, and further, it is not clear how conscious activity in individual neurons is bound together into the unified experience of consciousness.
Georgiev argues that in a theory of quantum consciousness, the physical dynamics of the system must be compatible with the time to decoherence. The system he describes involves the neuronal cytoskeleton, and particularly the pre and postsynaptic scaffold proteins. It is suggested that consciousness arises from the objective reduction of the wave function within these structures. The timescale of the system is argued to be defined by changes in tubulin conformations within the cytoskeleton and by the enzyme action in the scaffold proteins, which involves a timescale of 10-15 picoseconds, and thus implies a decoherence time on the same scale. P. Georgiev points out that it is much easier to suppose a decoherence time of this length in the brain than the 25 ms demanded by the Hameroff proposals. Georgiev accepts the neural reflexes are measured in milliseconds. However, he argues that within this time span, impulse propagation takes much longer than the picoseconds timescale needed for information processing, and it is the latter that he sees as relevant to consciousness.
Georgiev points out that it is much easier to suppose a decoherence time of this length in the brain than the 25 ms demanded by the Hameroff proposals. Georgiev accepts the neural reflexes are measured in milliseconds. However, he argues that within this time span, impulse propagation takes much longer than the picoseconds timescale needed for information processing, and it is the latter that he sees as relevant to consciousness.
The background electromagnetic field is suggested to interact with the dipoles of structured water described as sine-Gordon solitons (1. Abdalla et al, 2001). These affect both the conformational changes of the cytoskeletal proteins and the functions of the presynaptic scaffold proteins. The presynaptic scaffold proteins may affect the release of neurotransmitters at synapses via quantum tunnelling. It is implied, although not explained in any detail, that objective wave function collapse of the solitons is the basis of consciousness, which can then influence the brain via the presynaptic proteins and the synapses.
Georgiev describes two routes for the influence of the sine-Gordon solitons. One route influences the cytoskeleton and its assembly and disassembly, while a second proceeds through the presynaptic scaffold proteins to the synapses, and thence influences the postsynaptic state of other cells. Jack et al (1981) (2.)suggested an activation barrier, restricting the docking of vesicles and the release of neurotransmitters. The control of presynaptic proteins is suggested to overcome this barrier, and to regulate the vesicles that hold neurotransmitters in the axon terminals. This is suggested to be the process that decides whether a synapse will fire in response to an axon spike (a probability of only about 25%), and if it does, which of a choice of 40 or so vesicles will release its neurotransmitters. Beck and Eccles (1992) (3.) and Beck (1996) (4.) suggested that quantum tunnelling was involved in this process.
1.) Abdalla et al (2001) Information transport by sine-Gordon solitons in microtubules