3. Electric and Magnetic Fields Inside Neurons and Their Impact upon the Cytoskeletal Microtubules

To find out whether neuronal microtubules could translate and input the information carried by electric signals entering into the brain cortex, a detailed investigation of the local electromagnetic field structure is performed. The electric and magnetic field strengths in different neuronal compartments, including dendrites, soma, and axons, are assessed from reported electrophysiological measurements. The results show that the magnetic field is too weak to input information to microtubules and cannot support quantum Hall effect. Because the magnetic flux density of individual electric spikes is 3 orders of magnitude weaker than Earth’s magnetic field, any information encoded in the magnetic signal will be suffocated by the surrounding noise. In contrast, the electric field carries biologically important information and acts upon transmembrane voltage-gated ion channels that govern the generation of neuronal action potentials. If the human mind is supported by subneuronal processing of information in the brain microtubules, then the microtubule interaction with the local electric field has to be the main source for input of sensory information. The intensity of the electric field inside the neuronal cytosol, however, is less than 500 V m^-1, which rules out any electric sensitivity of putative ferroelectric microtubules. Although the tubulin C-terminal tails are promising candidates for substrates that are both sensitive to electric signals and possess biologically useful intraneuronal functions, they lack physical means to affect back the electric output of neurons. Thus, voltage-gated ion channels incorporated into the neuronal plasma membranes appear to be best suited to support consciousness since they remain the only known biomolecular substrates that are capable of inputting, processing and outputting of electric signals.