Ion Channels and Consciousness
Bernroider and Roy propose a quantum information system in the brain that is driven by the entangled ion states in the voltage-gated ion channels. These ion channels, situated in the neuron’s membrane are a crucial component of the conventional neuroscience description of axon spiking leading to neural transmitter release at the synapses. The ion channels allow the influx and outflux of ions from the cell driving the fluctuation of electrical potential along the axon, which in turn provides the necessary signal to the synapse.
The authors concentrate their attention on the potassium (K+) channel and in particular the configuration of this channel when it is in the closed state. This channel is traditionally seen as having the function of resetting the membrane potential from a firing to a resting state. This is achieved by positively charged potassium (K+) ions flowing out of the neuron through the channel.
Recent progress in atomic-level spectroscopy of the membrane proteins that constitute the ion channels and the accompanying molecular dynamic simulations indicate that the organisation of the membrane proteins carries a logical coding potency, and also implies quantum entanglement within ion channels and possibly also between different ion channels. An increasing number of studies show that proteins surrounding membrane lipids are associated with the probabilistic nature of the gating of the ion channels (58. Doyle, 1998, 59. Zhou, 2001, 60. Kuyucak, 2001).
The authors draw particularly on the work of MacKinnon and his group, notably his crystallographic X-ray work. (61-64.). The study shows that ions are coordinated by carboxyl based oxygen atoms or by water molecules. An ion channel can be in either a closed or an open state, and in the closed state there are two ions in the permeation path that are confined there. The authors regard this closed gate arrangement as the essential feature with regard to their research work. The open gate presents very little resistance to the flow of potassium ions, but the closed gate is a stable ion-protein configuration.
The ion channel serves two functions, selecting K+ ions as the ones that will be given access through the membrane, and then voltage-gating the flow of the permitted K+ ions. In the authors’ view, recent studies also require a change in views both of the ion permeation and of the voltage-gating process. A charge transfer carried by amino acids is involved in the gating process. In the traditional model the charges were completely independent, whereas in the new model there is coupling with the lipids that lie next to the channel proteins. This view, which came originally from MacKinnon, is now supported by other more recent studies . The authors think that the new gating models are more likely to support computational activity, than were the traditional models.
Three potassium ions are involved in the ion channel’s closed configuration. Two of these are trapped in the permeation path of the protein, when the channel gate is closed. The filter region of the ion channel is indicated by the recent studies to have five binding pockets in the form of five sets of four carboxyl related oxygen atoms. Each of the two trapped potassium ion are bound to eight of the oxygen atoms, i.e. each of them are bound to two out of the five binding pockets. The author’s calculations predict that the trapped ions will oscillate many times before the channel re-opens, and the calculations also suggest an entangled state between the potassium ions and the binding oxygen atoms. This structure is seen as being delicately balanced and sensitive to small fluctuations in the external field. This sensitivity is viewed as possibly being able to account for the observed variations in cortical responses.
Ion Channels & Quantum Computing
The theory also relates the results of recent studies of the potassium channel and its electrical properties to the requirements for quantum computing. There have been schemes for quantum computers involving ion traps, based on electostatic interactions between ions held in microscopic traps, that have a resemblance to Bernroider’s interpretation of the possible quantum state of the K+ channel.
The authors deny that the rapid decoherence of quantum states in the brain calculated by Tegmark applies to their model. They argue that the ions are not freely moving in the ion filter area of the closed potassium channel, but are held in place by the surrounding electrical charges and the external field. The ions are particularly insulated within the carboxyl binding pockets, and it is suggested the decoherence could be avoided for the whole of the gating period of the channel, which is in the range of 10-13 seconds.
Entanglement & Ion Channels
The authors also raise the question of whether given quantum coherence in the ion channel, it is possible for the channel states to be communicated to the rest of the cell membrane. This could include connections to other ion channels in the same membrane, possibly by means of quantum entanglement.
Bernroider’s work might not be considered to be a fully fledged separate quantum consciousness theory. In the early part of the decade, Bernroider seemed to associate himself with David Bohm’s implicate order, but the lack of much specific neuroscience in Bohm’s version makes it hard to make any definite connection between it and the type of detailed neuroscientific argument offered by Bernroider.
Bernroider can be seen to differ from the various quantum brain dynamics theories that derive from Umezawa, in concentrating on quantum mechanics rather than quantum field theory, and in not giving a major role to water. It also varies from Orch OR in focusing on the cell membrane rather than the cytoskeleton and on the axons rather than the dendrites, and by dealing with simple ions rather than Bose condensates. However, it is possible to speculate that wave function collapse under the Bernroider proposals could still result in objective reduction, and thus provide a link to Penrose’s fundamental spacetime geometry.
Bernroider’s theory might be seen to represent even more of a challenge to conventional neuroscience than the other quantum consciousness theories. This is because its recruits as its basis the axon membrane and ion channels which form a crucial part of the conventional neuroscience model, and then tries to remodel these core structures on a quantum-driven basis. It is hard to deny that if this theory were to become better substantiated, it would produce in neuroscience a revolution of the most profound kind.