CORTICAL ENDOGENOUS EVOKED-POTENTIALS IN PARKINSONISM

Averaged cortical evoked potentials (EP) to light stimuli were studied in 19 Parkinsonian patients and 12 healthy subjects under the conditi ons of passive perception (<<the background>>) and during different ps ycho-motor reactions. Differential EP waves between <<the reaction>> a nd <<the background>> were analysed, i. e. the endogenous potentials. A retardation of the psycho-motor reactions in patients was found to b e accompanied by a decrease of endogenous EP in the frontal recording. This decrease mainly concerned the potentials connected rather with t he motor acts than with the cognitive operations. The retardation of t he voluntary movements in parkinsonism is assumed to be connected with a <<deficit>> of the frontal activation due to a disfunction of the b asal ganglia.