Evidence for Subcortical Regulation of the Afferent Discharge to the Somatic Sensory Cortex in Man

Abstract

PREVIOUS experiments^1,2 have shown that, in curarized cats, electrical stimulation of certain central structures (for example, the brain stem reticular formation) depresses a postsynaptic evoked response in various primary sensory relays. On the other hand, barbiturate anæsthesia or certain central lesions (involving, for example, the reticular formation) may enhance these afferent responses. These results were interpreted as a manifestation of descending inhibitory influences capable of preventing afferent signals from the sense organs from reaching the cerebral cortex. A possible clue to the physiological significance of this mechanism is provided by the interesting observation² that in unrestrained animals a postsynaptic auditory response in the cochlear nucleus can be blocked by turning the animal's attention toward visual or olfactory stimuli. In a similar way, a postsynaptic visual response could be depressed by turning the animal's attention toward auditory stimuli.