FIBER GROUPS IN THE OPTIC NERVE

Abstract

Three distinguishable groups of fibers are found in the optic nerves of frogs and rabbits, resembling in the configuration of their action potentials and other physiological properties the A, B and C groups of peripheral nerves. The first 2 are sensory components whose stimulation gives rise to the 2 different potential responses recorded from the optic cortex when the rabbit optic nerve is stimulated at different thresholds. The 3rd group is inferred to be efferent, without definite evidence as to its function. The rabbit''s optic nerve becomes non-functional immediately upon cessation of blood supply and must be studied in situ; the frog nerve can be excised and studied in the thermostat. Action potentials were recorded by means of the cathode ray oscillograph and amplifier. The data consist of measurements of conduction rates, areas of potentials and refractory periods, at various strengths of stimulation.