The origin of rapid changes in birefringence, light scattering and dye absorbance associated with excitation of nerve fibers.

By comparing the time-courses of rapid optical changes in the garfish olfactory nerve evoked by electric stimulation with those of mechanical changes observed at the site of optical recording, the origin of optical changes in the nerve has been investigated. Based on the finding that the time-course of the birefringence change accurately coincides with that of swelling of the nerve, optical changes are interpreted as being brought about by invasion of water into the superficial layer of the nerve fibers. A close relationship has also been demonstrated between nerve swelling and changes in light scattering and in dye absorbance.