OPTICAL AND THERMAL CHANGES DURING ELECTROGENESIS

Abstract

Publisher Summary This chapter describes the optical and thermal changes during electrogenesis. Every passage of a nervous impulse in an electrogenic, excitable membrane manifests itself by an electrical spike, the action potential, accompanied by three other interrelated optical manifestations. The optical manifestations include a transient, reversible change of birefringence; a transient, reversible change of light scattering; and a dye-induced fluorescence change. In most nerves, these changes are so small that they have to be collected during hundreds of impulses with averaging computers. In the olfactory nerve of the pike, one impulse is sufficient to obtain a fine record. They show a rapid and reversible increase and decrease of birefringence or retardation during every action potential, an optical spike, which follows exactly the course of the action potential. Every change of entropy in an open system is always connected with a heat production or absorption. The rapid changes of heat production and reabsorption during the action potential in the olfactory nerve of the pike are recorded using a highly sensitive thermopile.