The sensory process in man: its analysis by means of cortical and subcortical evoked potentials
Velasco, M.; Velasco, F.; Velasco, L.
Archivos de Investigacion Medica 18(2): 167-179
1987
ISSN/ISBN: 0066-6769 PMID: 3662726 Document Number: 298512
The sensory process in man can be analyzed by means of the somatosensory, auditory and visual evoked potentials recorded from the surface of the scalp in all patients and from the brain depth in some patients with implanted electrodes used as a diagnostic and therapeutic procedures. Sensation and perception are two consecutive stages in the sensory process, by which environmental stimuli are deteced and analyzed. Selective attention is a functional filter which facilitates perception of the relevant stimuli and blocks those that are irrelevant. Sensation is evaluated by short latency (early) evoked potentials which reveal the activation of the receptor, specific pathways and primary cortices; whereas perception is evaluated by long latency (late) evoked potentials, which reveal of a nonspecific reticulothalamic system partially mediating the attention, filtering and analyzing perceptual functions. Modulation of sensory impulses by a cortico (sensory) -reticulo- thalamo cortical (motor) loop in man, rather than in a peripheral level as in animals, allows the human brain to be continuously informed of the ongoing peripheral events and to deal with sensory motor patterns organized in time and space by the specific receptor pathways and cortices. That is, it permits the understanding and manipulation of the environment through its representation on a sensorymotor cerebral mosaic.