Possible role of extracellular tissue in biological neural networks

In the present paper, we analyze the role of extracellular tissue (ECT) in signal transfer and information processing in biological neural networks. Our speculative approach, which is based mainly on the facts taken from the literature, is completed by simple original models and quantitative estimates. It is shown that the presence of ECT controls some fundamental parameters of immersed biological neural network, which are traditionally treated as intrinsic to neuron membranes. We then propose that the diffusive transfer of action potential via the nervous fiber together with processes induced in the surrounding ECT, is ultimately controlled, in contrast to the standard paradigm, by the quantum diffusion of Na^+ and K^+ ions, which minimizes the heat production in nervous tissue. Furthermore the diffusion of polarization wave along the axon membrane excites in surrounding ECT temporal potential distribution, which can bias the synapses and dendrites of all vicinal neurons. We claim that just this, so-called, ephaptic coupling between neighboring neurons, completes the local neural network and in fact is responsible for information processing there. Such an idea is obviously incompatible with current models of neural networks of McCulloch–Pitts’ and Rosenblatt’s type, which assume that the information processing takes place exclusively within the neuron soma , being thus convenient merely for the description of artificial neural networks.