Oscillating electrical signal propagation along microtubules

Microtubules (MTs) are tubular cytoskeletal polymers with a regular longitudinal arrangement of nanopores connecting the outer and inner surfaces. A compact and tiny "skin-like" ionic aqueous layer formed between the surrounding fluid and each surface of the filament gives these MTs an extraordinary ability to sustain ionic conductance to transmit and amplify oscillatory electric signals, the frequency of which is similar to the one measured in electrical activities of the brain. This study introduces a novel coupled electrical circuit transmission line model for isolated MTs to investigate the molecular mechanisms underlying the axial transmission and amplification of the oscillating signals. Each transmission line represents the ionic current flowing on the outer and inner surfaces of the MT. At the same time, ionic nanopore currents cause the transmission lines to be coupled through nanopores. Our preliminary results revealed axial oscillating ionic currents as traveling localized ionic waves. Meanwhile, the energetic interchange between the outer and inner ionic currents produces oscillations controlled by the nanopore conducting properties. These features provide the cytoskeletal matrix with a novel mechanism for neuron information processing.