Control of hand movements after striatocapsular stroke: high-resolution temporal analysis of the function of ipsilateral activation.
OBJECTIVE
Hemiparesis due to infarction of the middle cerebral artery has become an increasingly important focus of research on cortical plasticity. Positron emission tomography and functional magnetic resonance imaging studies in such patients found involvement of the hemisphere ipsilateral to the affected hand related to movements of this hand. To understand the function of this ipsilateral activation, the present study investigated movement-related electroencephalogram (EEG) potentials in patients and healthy control subjects to measure timing of ipsi- and contralateral activation relative to movement onset.


METHODS
Thirteen patients were investigated in their chronic stage. Their pyramidal tracts were affected by infarctions of the middle cerebral artery at striatocapsular level. EEG potentials were recorded from 26 scalp electrodes while patients were pressing a key with their right or left index finger within a warned choice-response task.


RESULTS
Beginning 200 ms before responses of the affected hand, there was normal contralateral preponderance of EEG negativity. Briefly after response onset, however, the other unaffected hemisphere, ipsilateral to the responding hand, became additionally active. This pattern did not occur with responses made by the unaffected hand nor in healthy participants.


CONCLUSIONS
The timing of the onset of ipsilateral activity precludes its role in response initiation. Rather, this activity may indicate reflex-like activation of the unaffected motor system to compensate for possible failure of the affected hand.
Verleger
Rolf
R
Department of Neurology, Medical University of Lübeck, Ratzeburger Allee 160, D 23538 Luebeck, Germany. verleger@neuro.mu-luebeck.de
Adam
Sven
S
Rose
Michael
M
Vollmer
Clemens
C
Wauschkuhn
Bernd
B
Kömpf
Detlef
D
D000368:Aged; D000704:Analysis of Variance; D001931:Brain Mapping; D016022:Case-Control Studies; D004569:Electroencephalography / Q000379:methods; D005260:Female; D005385:Fingers / Q000502:physiology; D007839:Functional Laterality; D006225:Hand / Q000502:physiology*; D018737:Hand Strength; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009068:Movement; D010812:Physical Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D011897:Random Allocation; D011930:Reaction Time; D020521:Stroke / Q000503:physiopathology*; D013997:Time Factors