"Functional polarity" of the spinal cord caused by its longitudinal electric dipole moment.
Specific reactions of the vertebrates that occur through lengthwise application of direct-current (DC) electric fields in the spinal cord and are dependent on the direction of the current (e.g., electric narcosis and electric excitation) can be explained by the existence of a longitudinal dipole moment in the spinal cord. The relationship between "functional polarity of the spinal cord" and its longitudinal dipole moment was established in two different experimental series. 1) Reactions of functional polarity were quantitatively tested on Amphioxus (lancelet) and on numerous Teleostei. On this point the findings of other researchers were confirmed and complemented. 2) Fresh, almost-live spinal cord preparations (cow) were quantitatively tested using pyroelectric (PE) methods. A longitudinal electric dipole moment was demonstrated along the entire length of the white matter. Moreover fresh spinal cord preparations showed a polar orientation on sudden temperature change in a high-voltage DC field. The PE behavior showed a pronounced electric field dependence. Because the white matter is largely composed of longitudinally arranged nerve fibers, individual axons may also have a longitudinal electric dipole moment. Consequently one might expect the following: polar orientation of the growing neurite by an applied DC field, an electric dipole field inside and outside the axon, and a transport of charge carriers along the lines of flux of this dipole field. Moreover PE and piezoelectric (PZE) properties of the neuron should be provable.