The Passive Iron Wire Model of Proto‐plasmic and Nervous Transmission and Its Physiological Analogues

Abstract

SummaryThe phenomena of activation and transmission in the passive iron wire model are described, and the various parallels with the irritable living system, especially nerve, are discussed. In general, the similarity of behaviour is to be referred to a single structural feature common to both systems, namely the presence of a thin, polarisable and chemically alterable interfacial layer or surface film (oxide film; plasma membrane) situated at the boundary between the metal, or the protoplasm, and the surrounding medium. This film undergoes characteristic changes of chemical composition and physical properties, e.g. of permeability and electrical polarisation, when traversed by an electric current of an intensity and duration sufficient to produce a certain critical degree of chemical decomposition. The activity of the system as a whole is controlled by the electrochemical oxidations and reductions occurring in the film under these conditions. Hence both the model and the living system are electrically sensitive and transmit local states of activity, local changes on the film being associated with local electric circuits which have electrochemical effect at regions beyond. Hence, also, the essential conditions under which electrical activation occurs are the same in both systems (polar activation, intensity‐duration relationship, etc.). Activation and transmission are similarly affected in both by changes of temperature, by variations in the composition of the medium, by electrical polarisation (analogy to electrotonus), and by surface‐active compounds (analogy to narcosis). Closely analogous processes of progressive recovery occur in both systems after the passage of an activation wave (refractory phase). Other resemblances are seen in the phenomena of automatic rhythm, the mutual interference of activation waves, the transmission of inhibitory influence, irreciprocal transmission, and distance influence, excitatory and inhibitory. Biological analogies of a more general kind, relating to mutual interdependence between processes occurring in spatially separated regions traversed by the same electric current—a possible factor in certain types of integration—are briefly discussed.

Transient and Persistent Electrochemical Bursting Induced by Halide Ions

“…The electrode−solution interface in electrochemical systems is an interfacial phase boundary serving as a membrane that is permeable to some of the chemical species comprising the phases and impervious to others. In the lower level of description, the neural cell membrane and the electrochemical interface have a phenomenological resemblance − due to several kinetic analogies between these two classes of systems. − A number of similarities have been observed also between coupled electrochemical oscillators and interacting neurons such as synchronization induced by the network morphology, propagation of external stimulus, inhibition and excitation, rapid synchronization, and coding …”

Electrical Signs of Biological Activity

“…The durations of the delayed heat given by A. V. Hilp7 correspond with our own observations of the duration of the after-potentials under comparable conditions, and in addition there is evidence of a correspondence between the rate of evolution of heat and the configuration of the potential. An analogy is found in the thickness of the oxide film formed on the surface of iron passivated in strong HNOa• Professor LiIlie 19 has called attention to the fact that after a wave associated with reduction has passed over the surface, the oxide coat is thicker at the end than it was at the beginning. The rapidly decrementing part would correspond to the early portion of the potential where the negative after-potential is visible, leaving the slowly decrementing part to cover the later period of positivity.…”