[Somatosensory evoked potentials: interference and perceptual masking of cutaneous afferents in man].
Somatosensory evoked potentials (SEP) are attenuated following double electrical stimulation of the fingers (II + III). This effect is observed at cervical (N13), parietal (N20-P27) and frontal (P22-N30) levels. We simultaneously observed in the same subjects that cutaneous perception of the test-shock is completely suppressed with interstimulus intervals (ISI) within a 0-10 msec range. With 25-30 msec ISI, the perceptive function totally recovers, but SEP inhibition remains at 50 % of the control. The SEP reduction does not result in a perception deficit as long as the cortical-test response exceeds 50% of control. These results suggest that: SEP inhibition could be a local but durable phenomenon occurring at both cervical and cortical levels. Cutaneous perception does not necessitate a maximal SEP development. The perceptive process involves other associative areas (5,7...) and is activated when the primary cortical activation exceeds a certain threshold which was found at 50% of the unconditioned response voltage.
el Kharroussi
M
M
Université Hassan II Ain Chock, faculté des sciences I, dpt de biologie, Maarif, Casablanca, Maroc.
Ibanez
V
V
Ben Jelloun
W
W
Hugon
M
M
Mauguière
F
F
D000328:Adult; D000344:Afferent Pathways / Q000502:physiology*; D000818:Animals; D004597:Electroshock; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000502:physiology; D000882:Haplorhini; D006801:Humans; D008297:Male; D008875:Middle Aged; D010296:Parietal Lobe / Q000502:physiology; D010470:Perceptual Masking / Q000502:physiology*; D011603:Psychophysiology; D012016:Reference Values; D012867:Skin / Q000294:innervation*
Potentiels évoqués somesthésiques: interférences et masquage perceptif des afférences cutanées chez l'homme.