A Nano-Electro-Mechanical hydrodynamic approach to neuron function
Prof. Jörg Kotthaus (LMU München)
Alternative to the traditional Hodgkin-Huxley model of nerve conduction based on electromagnetic cable theory neurons are described as Nano-Electro-Mechanical Systems (NEMS) based on capillary forces at the neuron membrane controlled by electric field- effect. Here the soma body of a neuron acts as peristaltic pump with its volume controlled by the large local electric field of order 107 V/m across its lipid membrane. This results in a change of the capillary forces acting on the cell membrane through the reorientation of water dipoles in the adjacent only nanometer thick high-electric field region and launches capillary waves into the tubular axon. Propagating as long wavelength breathing modes with velocities comparable to measured neural signals these are accompanied by changes of the depolarization fields of the water dipoles in the high field skin. They thus can transport action potentials as neutral polarization currents with low damping and negligible distortion and act soliton-like. In analogy to sounds emitted by musical instruments they contain information about the generating soma and can be transformed into chemical signals at the synapse. Experiments are discussed that can detect the characteristic features of such an electromechanical description distinct from the Hodgkin-Huxley model. Some speculative remarks aim to understand why Nature has chosen the dendritic structure of the soma and myelination of the axons to improve neural functionalities.