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Cortical connectivity after subcortical stroke assessed with functional magnetic resonance imaging
Author(s) -
Grefkes Christian,
Nowak Dennis A.,
Eickhoff Simon B.,
Dafotakis Manuel,
Küst Jutta,
Karbe Hans,
Fink Gereon R.
Publication year - 2008
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/ana.21228
Subject(s) - supplementary motor area , sma* , functional magnetic resonance imaging , premotor cortex , psychology , stroke (engine) , neuroscience , magnetic resonance imaging , physical medicine and rehabilitation , motor cortex , motor area , medicine , anatomy , mechanical engineering , mathematics , dorsum , radiology , combinatorics , stimulation , engineering
Objective This study aimed at identifying the impact of subcortical stroke on the interaction of cortical motor areas within and across hemispheres during the generation of voluntary hand movements. Methods Twelve subacute stroke patients with a subcortical ischemic lesion and 12 age‐matched control subjects were scanned using 3‐Tesla functional magnetic resonance imaging. Subjects performed visually paced hand movements with their left, right, or both hands. Changes of effective connectivity among a bilateral network of core motor regions comprising M1, lateral premotor cortex, and the supplementary motor area (SMA) were assessed using dynamic causal modeling. Results The data showed significant disturbances in the effective connectivity of motor areas in the patients group: Independently from hand movements, the intrinsic neural coupling between ipsilesional SMA and M1, and the interhemispheric coupling of both SMAs was significantly reduced. Furthermore, movements of the stroke‐affected hand showed additional inhibitory influences from contralesional to ipsilesional M1 that correlated with the degree of motor impairment. For bimanual movements, interhemispheric communication between ipsilesional SMA and contralesional M1 was significantly reduced, which also correlated with impaired bimanual performance. Interpretation The motor deficit of patients with a single subcortical lesion is associated with pathological interhemispheric interactions among key motor areas. The data suggest that a dysfunction between ipsilesional and contralesional M1, and between ipsilesional SMA and contralesional M1 underlies hand motor disability after stroke. Assessing effective connectivity by means of functional magnetic resonance imaging and dynamic causal modeling might be used in the future for the evaluation of interventions promoting recovery of function. Ann Neurol 2007