[Simultaneous opposite axonal currents in neural process. Retraction hypothesis]

Bidirectional axonal current of organelles and molecules in the nerve fibers was demonstrated using radioautography, the horseradish peroxidase and in virology. However, the mechanism of this phenomenon and regulation of the currents direction in axoplasm still remain not entirely understood. In this article we used the model of living single neurons of mollusk isolated with fragment of neural process at its different levels. It was proved that the axoplasm has a mechanical tone, which is realized in the form of retraction up to complete axoplasm invagination in the neuron soma. The geometry changing of the living axon was treated as its transport neuroplasm mass. It turned out that the direction of axoplasm mass depends on the location of its adhesion sites. It is always simultaneous and bidirectional opposite, as it is the case with contractile muscle fibers.