Evolution of brain activation after stroke in a constant-effort versus constant-output motor task.
OBJECTIVE
Recovery of hand function after stroke has been associated with transient overactivation of the cerebral sensorimotor network. One open question has been as to how much this transient overactivation is related to 'true' reorganisation of the network or reflecting the fact that a simple motor task is difficult to perform for a patient with a motor deficit, i.e. reflecting 'effort'.


METHODS
To address this, we combined a constant-output (varying effort) and constant-effort (varying output) task in a longitudinal (T1 = 3-5 days, T2 = 6 weeks, T3 = 3 months after stroke) multimodal (functional magnetic resonance imaging (FMRI), electroencephalography (EEG)) study of 12 (EEG)/8 (FMRI) patients (7 male, age 67 ± 9 years) showing significant recovery from a hand motor deficit.


RESULTS
The reduction of sensorimotor activation from T1 to T3 was significant (p = 0.012). But task effort did not exhibit any significant impact on the evolution of task-related brain activation over time. This proved to be equally applicable to FMRI and EEG data.


CONCLUSIONS
We conclude that initial up-regulation of brain activity after stroke is not simply a consequence of enhanced effort early after stroke but rather reflects neural processes involved in reorganisation and recovery of function.
BrainImaging and NeuroStimulation (BINS) Laboratory, Department of Neurology, University Medical Center, Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany.
Marlene
M
Bönstrup
BrainImaging and NeuroStimulation (BINS) Laboratory, Department of Neurology, University Medical Center, Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany.
Robert
R
Schulz
Clinical Stroke Imaging Laboratory, University Medical Center, Hamburg-Eppendorf, Department of Neurology, Martinistr. 52, 20246 Hamburg, Germany.
Bastian
B
Cheng
BrainImaging and NeuroStimulation (BINS) Laboratory, Department of Neurology, University Medical Center, Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany.
Jan
J
Feldheim
BrainImaging and NeuroStimulation (BINS) Laboratory, Department of Neurology, University Medical Center, Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany.
Máximo
M
Zimerman
BrainImaging and NeuroStimulation (BINS) Laboratory, Department of Neurology, University Medical Center, Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany.
Götz
G
Thomalla
BrainImaging and NeuroStimulation (BINS) Laboratory, Department of Neurology, University Medical Center, Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany.
Friedhelm C
FC
Hummel
BrainImaging and NeuroStimulation (BINS) Laboratory, Department of Neurology, University Medical Center, Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany.
Christian
C
Gerloff
D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology / Q000503:physiopathology*; D001931:Brain Mapping; D004569:Electroencephalography; D005260:Female; D006225:Hand / Q000503:physiopathology; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D064847:Multimodal Imaging; D009434:Neural Pathways / Q000473:pathology / Q000503:physiopathology; D009473:Neuronal Plasticity / Q000502:physiology; D009483:Neuropsychological Tests; D020127:Recovery of Function / Q000502:physiology*; D020521:Stroke / Q000473:pathology / Q000503:physiopathology*
EEG; FMRI; Stroke; hand motor deficit; longitudinal study; task effort