Psychophysiological aspects of voluntary skilled movement after stroke: a follow-up study.

OBJECTIVES: The aim of the study was to follow the psychophysiological evolution of a self-paced voluntary skilled movement in hemiparetic subjects after ischemic stroke by means of a skilled performance task (SPT). The task consisted in starting a sweep of an oscilloscope trace by pushing one button with the left index finger (trigger point), and in stopping it within a central area on the oscilloscope screen, between 40 and 60 ms (correct performance) after the start of the sweep, by pushing the other button with the right index finger. A SPT yields a considerable amount of information on the electrophysiological components, which reflect pre-programming activity (Bereitschaftspotential--BP), control strategies (Skilled Performance Positivity--SPP) and behavioural response (Correct Performances). The study was also aimed at detecting any longitudinal changes in the psychophysiological pattern, as evaluated by the clinical examination and specific motility scales, that parallel motor recovery. METHODS: Movement related potentials (MRPs) were recorded in 12 control subjects and 9 patients in the acute phase, before the start of neurorehabilitation (time 0), when the patients were able to execute an index finger press with the affected hand. The patients (mean age = 62.33 years, SD = 8.17) presented a mild to moderate central arm paresis caused by a first-ever unilateral supratentorial and subcortical ischemic lesion. The subsequent recordings were carried out respectively 3, 9 and 12 months later. RESULTS: At the first recording, hemiparetic patients achieved a significantly lower percentage of correct performances and had a lower BP amplitude than controls (p < 0.001); SPP was absent. The number of correct performances did not improve significantly during the subsequent recordings. BP amplitude showed a mild increase in the second, third and fourth recordings (p < 0.05), while SPP amplitude revealed a slight improvement at the second and a marked improvement at the third and fourth recordings, when there was no longer a statistically significant difference from controls. CONCLUSIONS: Our findings point to an early recovery of pre-programming activity and a delayed improvement in control activity. The delayed development of control activity in the absence of procedural learning, i.e. skill learning through practice, forces patients to exploit attentional strategies to compensate for their procedural learning impairment. SPT shows that the efficacy of physical therapy aimed at motor ability recovery in hemiparetic patients does not keep up with the slow recovery process of an automatic motor level.

Preprogramming and control activity of bimanual self-paced motor task in Parkinson's disease.

OBJECTIVE: The authors investigated programming (Bereitschaftspotential or BP) and control activity (Skilled Performance Positivity or SPP) of a bimanual, sequential, skilled motor act in off-therapy Parkinson's disease (PD) patients. METHODS: We recorded Movement Related Potentials (MRPs) in 12, non-demented, off-therapy parkinsonian patients and in 17 control subjects who were performing a skilled, time-locked motor act, which was not routine in their everyday life but had to be learned: the Skilled Performance Task (SPT). BP, SPP and correct performances were evaluated in grand average waveforms and in sequential blocks. RESULTS: The analysis of correct performances showed that accuracy in PD patients was significantly lower than in the control group and this accuracy did not improve throughout the blocks. A significantly low level of performances was associated with an increased BP amplitude (P<0.05) and decreased SPP amplitude (P<0.05) in PD patients. CONCLUSION: Our findings suggest that skill motor learning is impaired in non-demented unmedicated PD patients. We discuss the view that PD patients may allocate more attentional resources, as suggested by the increased BP amplitude, the decreased SPP amplitude and the low correct performances, in order to perform a new skilled motor act.

L-dopa effects on preprogramming and control activity in a skilled motor act in Parkinson's disease.

OBJECTIVES: The authors investigated whether preprogramming (Bereitschaftspotential, BP) and control activity (skilled performance positivity, SPP) in a bimanual, sequential skilled performance task (SPT) is sensitive to L-dopa administration in non-demented Parkinson's disease (PD) patients. METHODS: Movement related potentials (MRPs) were recorded in 12 non-demented parkinsonian patients before and after acute L-dopa administration, and in 17 control subjects, all of whom were performing SPT for the first time. BP, SPP and correct performances were evaluated both as a grand average and in sequential blocks in order to verify the learning effect. RESULTS: After L-dopa administration the PD patients scored a significantly higher percentage of correct performances (P<0.05), linked to a decreased BP amplitude (P<0.001) and an increased SPP amplitude (P<0.005), than before therapy. Dynamic evaluation through the block analysis did not show any learning effect in off-therapy patients but showed that L-dopa intake improved learning, linked to a BP amplitude decrease (P<0.005) and a SPP amplitude increase (P<0.05). Furthermore, L-dopa minimized differences in the learning trend between off-therapy PD patients and controls. CONCLUSIONS: Our findings suggest that skilled motor learning is impaired in non-demented untreated PD patients. Dopaminergic drug administration seems to restore the ability of PD patients to use more automatic motor strategies, as demonstrated by the electrophysiological and behavioural pattern, which became more similar to that of normal subjects.

Psychophysiological approach in Parkinson's disease: L-dopa effects on preprogramming and control activity.

To investigate whether preprogramming (Bereitschaftspotential, BP) and control activity (skilled performance positivity, SPP) in a complex task are sensitive to L-dopa, movement related potentials (MRPs) were recorded in 12 non-demented Parkinson's disease (PD) patients before and after acute L-dopa administration, and in 17 control subjects. After L-dopa administration, the PD patients scored a significantly higher percentage of correct performances ( p<0.05), linked to a decreased BP amplitude ( p<0.001) and an increased SPP amplitude ( p<0.005), than before therapy. Our findings suggest that preprogramming activity is impaired in untreated PD patients. Dopaminergic drug administration seems to restore their ability to use more automatic motor strategies which become more similar to that of normal subjects.