Article

Recent studies have shown that focal injuries can have remote effects
on network function that affect behavior, but these network-wide repercussions
are poorly understood. This study tested the hypothesis that lesions
specifically to the outflow tract of a distributed network can result in upstream
dysfunction in structurally intact portions of the network. In the somatomotor
system, this upstream dysfunction hypothesis predicted that lesions of the
corticospinal tract might be associated with functional disruption within the
system. Motor impairment might then reflect the dual contribution of
corticospinal damage and altered network functional connectivity. METHODS: A
total of 23 subacute stroke patients and 13 healthy controls participated in the
study. Corticospinal tract damage was quantified using a template of the tract
generated from diffusion tensor imaging in healthy controls. Somatomotor network
functional integrity was determined by resting state functional connectivity
magnetic resonance imaging. RESULTS: The extent of corticospinal damage was
negatively correlated with interhemispheric resting functional connectivity, in
particular with connectivity between the left and right central sulcus. Although
corticospinal damage accounted for much of the variance in motor performance, the
behavioral impact of resting connectivity was greater in subjects with mild or
moderate corticospinal damage and less in those with severe corticospinal damage.
CONCLUSIONS: Our results demonstrated that dysfunction of cortical functional
connectivity can occur after interruption of corticospinal outflow tracts and can
contribute to impaired motor performance. Recognition of these secondary effects
from a focal lesion is essential for understanding brain-behavior relationships
after injury, and they may have important implications for neurorehabilitation.

Langue : ANGLAIS