Dissociation between motor potential and contingent negative variation after lesions of some basal ganglia in man: electrophysiological study of torticollis

Abstract

Studied slow cortical potentials associated with voluntary movements ("readiness potential", RP and "motor potential", MP) and discrimination tasks (contingent negative variation", CNV, "expectancy wave", EW) in 11 normal subjects and 11 patients with torticollis (every person going through 2 experimental sessions). The following was found: 1. In torticollis-patients, the RP appeared as a complex, irregular wave with low--voltage, ataxic course. 2. The mean amplitude of the RP was significantly lower in the torticollis-group than in the control group. 3. The mean amplitude of the late positive component P2 of the MP was also significantly lower in torticollis-patients than in controls. 4. The CNV showed a high-voltage course in patients with torticollis. 5. The mean amplitude of the CNV was significantly higher in torticollis--patients than in controls. 6. The mean amplitude of the late positive component P2 after the resolution of the discrimination task was also higher in the torticollis--group than in the control group, but the difference did not reach the level of significance.--This marked dissociation between the adynamic RP-MP field generators and the very responsive CNV field generators is being interpreted partly as an electrophysiological symptom of impairment in programming and performance of sequential motor acts (in the case of the RP-MP), partly as a disruption of the control of emotional and affective processes, as well as non-specific (extralemniscal) afferences (in the case of the CNV) resulting from a basal ganglia lesion in torticollis.