VARIATIONS OF OPTIC EVOKED POTENTIALS AS A FUNCTION OF RETICULAR ACTIVITY IN RABBITS WITH CHRONICALLY IMPLANTED ELECTRODES

Abstract

The amplitude of responses evoked by stroboscopic flash in the lateral geniculate body, the superior colliculus, and the visual cortex, was statistically studied under different conditions of brain-stem reticular activity. This activity was lowered by pentobarbital sodium (intravenous injection, 5-20 mg/kg) and increased by amphetamine sulfate (intravenous injection, 0.2-0.8 mg/kg) or by electrical stimulation of the mesencephalic reticular formation. It was found that reticular deactivation reduces the primary response (occurring between 20 and 100 msec. after the flash) of the geniculate body while increasing those of the colliculus and the cortex. The secondary response (150-300 msec. after the flash) is diminished, wherever recorded from, by reticular deactivation (barbiturate). On the other hand it is augmented, in the visual cortex only, by reticular activation (mesencephalic stimulation or amphetamine). Reticular activation procedures did not affect significantly, in the walking organism, the amplitude of primary potentials.