Visually Evoked Responses in Man

Open Access
Publisher Website
Google Scholar
Abstract
Visual stimulation by a flash of light directed into the eyes appears particularly suitable for studying sensory input in man. The light stimulus is innocuous and controllable. With the aid of electronic averaging devices the visually evoked response (VER) can easily be distinguished from electroencephalographic background activity. In this study the technique was applied to objectively measure cerebral effects of preanesthetic drugs administered to 124 patients scheduled for surgery. Sedative and tranquilizing agents tended to alter certain components of the VER similar to natural sleep. With the substituted phenothiazines, particularly chlorpromazine, an initial state of turbulence was often observed before the characteristic depression was recorded. Morphine sulfate did not significantly affect the VER. Of the various muscarinic cholingeric blocking agents employed, scopolamine hydrobromide proved to be most effective in altering the VER while its quaternary analogue, methscopolamine, which is known to penetrate the blood-brain barrier with difficulty, had no significant effect.

This publication has 3 references indexed in Scilit: