Cross-Modal Functional Connectivity of the Premotor Cortex Reflects Residual Motor Output after Stroke
Brain Connectivity. 2020-06-01; 10(5): 236-249
DOI: 10.1089/brain.2020.0750
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Brihmat N(1), Tarri M(1), Gasq D(1)(2), Marque P(1)(3), Castel-Lacanal E(1)(3), Loubinoux I(1).
Author information:
(1)ToNIC, Toulouse NeuroImaging Center, Université de Toulouse, Inserm, UPS,
France.
(2)Department of Functional and Physiological Explorations, University Hospital
of Toulouse, Toulouse, France.
(3)Department of Rehabilitation and Physical Medicine, University Hospital of
Toulouse, Toulouse, France.
Stroke is known to cause widespread activation and connectivity changes
resulting in different levels of functional impairment. Recovery of motor
functions is thought to rely mainly on reorganizations within the sensorimotor
cortex, but increasing attention is being paid to other cerebral regions. To
investigate the motor task-related functional connectivity (FC) of the
ipsilesional premotor cortex (PMC) and its relation to residual motor output
after stroke in a population of mostly poorly recoverd patients. Twenty-four
stroke patients (23 right handed, mean age = 52.4 ± 12.6 years) with varying
levels of motor deficits underwent functional magnetic resonance imaging while
performing different motor tasks (passive mobilization, motor execution, and
motor imagery of an extension movement of the unaffected hand [UH] or affected
hand [AH]). For the different motor tasks, analyses of cerebral activation and
task-related FC of the ipsilesional lateral sensorimotor network (SMN), and
particularly the premotor cortex (PMC), were performed. Compared with UH data,
FC of the ipsilesional lateral SMN during the passive or active motor tasks
involving the AH was decreased with regions of the ipsilesional SMN and was
increased with regions of the bilateral frontal and the ipsilesional posterior
parietal cortices such as the precuneus (Pcu). During passive wrist
mobilization, FC between the ipsilesional PMC and the contralesional SMN was
negatively correlated with residual motor function, whereas that with nonmotor
regions such as the bilateral Pcu and the contralesional dorsolateral prefrontal
cortex was positively correlated with the residual motor function. Cross-modal
FC of the ipsilesional PMC may reflect compensation strategies after stroke. The
results emphasize the importance of the PMC and other nonmotor regions as
prominent nodes involved in reorganization processes after a stroke.