Affiliations: [a] BrainImaging and NeuroStimulation (BINS) Laboratory, Department of Neurology, University Medical Center, Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany | [b] Clinical Stroke Imaging Laboratory, University Medical Center, Hamburg-Eppendorf, Department of Neurology, Martinistr. 52, 20246 Hamburg, Germany
Correspondence:
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Corresponding author: Christian Gerloff, MD, Department of Neurology, University Medical Center, Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany. Tel.: +49 40 7410 53770; Fax: +49 40 7410 56721; E-mail: gerloff@uke.de
Note: [1] Both authors contributed equally.
Abstract: Purpose: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. Conclusion: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.
Keywords: Stroke, hand motor deficit, task effort, EEG, FMRI, longitudinal study
