TY  - JOUR
AU  - Binder, Ellen
AU  - Leimbach, Martha
AU  - Pool, Eva-Maria
AU  - Volz, Lukas J.
AU  - Eickhoff, Simon B.
AU  - Fink, Gereon R.
AU  - Grefkes, Christian
TI  - Cortical reorganization after motor stroke: A pilot study on differences between the upper and lower limbs
JO  - Human brain mapping
VL  - 42
IS  - 4
SN  - 1097-0193
CY  - New York, NY
PB  - Wiley-Liss
M1  - FZJ-2020-04516
SP  - 1013-1033
PY  - 2021
N1  - The authors would like to thank their volunteers and Dr Marc Tittgemeyer together with the MR staff for their support. E. B. was funded by the Medical Faculty, University of Cologne (3615/0129/31). L. J. V. was supported by the SAGE Center for the Study of the Mind and Brain at the University of California, Santa Barbara. C. G. was supported by grants from the Deutsche Forschungsgemeinschaft (DFG, GR 3285/2‐1; GR3285/5‐1KFO219‐TP8). The study was additionally supported by the University of Cologne Emerging Groups Initiative (CONNECT Group, C. G., G. R. F.) implemented into the Institutional Strategy of the University of Cologne and the German Excellence Initiative. S. B. E. was supported by the Deutsche Forschungsgemeinschaft (EI 816/4‐1, LA 3071/3‐1, EI 816/6‐1); the National Institute of Mental Health (R01‐MH074457); the Helmholtz Portfolio Theme “Supercomputing and Modeling for the Human Brain;” and the European Union Seventh Framework Programme (FP7/2007–2013) under grant agreement No. 604102 (Human Brain Project). G. R. F. gratefully acknowledges additional support from the Marga und Walter Boll‐Stiftung. Open access funding enabled and organized by Projekt DEAL. [Correction added on November 26, 2020 , after first online publication: Projekt Deal funding statement has been added.]
AB  - Stroke patients suffering from hemiparesis may show substantial recovery in the first months poststroke due to neural reorganization. While reorganization driving improvement of upper hand motor function has been frequently investigated, much less is known about the changes underlying recovery of lower limb function. We, therefore, investigated neural network dynamics giving rise to movements of both the hands and feet in 12 well-recovered left-hemispheric chronic stroke patients and 12 healthy participants using a functional magnetic resonance imaging sparse sampling design and dynamic causal modeling (DCM). We found that the level of neural activity underlying movements of the affected right hand and foot positively correlated with residual motor impairment, in both ipsilesional and contralesional premotor as well as left primary motor (M1) regions. Furthermore, M1 representations of the affected limb showed significantly stronger increase in BOLD activity compared to healthy controls and compared to the respective other limb. DCM revealed reduced endogenous connectivity of M1 of both limbs in patients compared to controls. However, when testing for the specific effect of movement on interregional connectivity, interhemispheric inhibition of the contralesional M1 during movements of the affected hand was not detected in patients whereas no differences in condition-dependent connectivity were found for foot movements compared to controls. In contrast, both groups featured positive interhemispheric M1 coupling, that is, facilitation of neural activity, mediating movements of the affected foot. These exploratory findings help to explain why functional recovery of the upper and lower limbs often develops differently after stroke, supporting limb-specific rehabilitative strategies.Keywords: dynamic causal modeling; effective connectivity; fMRI; interhemispheric inhibition; motor recovery; plasticity; rehabilitation.
LB  - PUB:(DE-HGF)16
C6  - 33165996
UR  - <Go to ISI:>//WOS:000587466600001
DO  - DOI:10.1002/hbm.25275
UR  - https://juser.fz-juelich.de/record/887914
ER  -