http://onlinelibrary.wiley.com/doi/10.1111/dmcn.12209/abstract;jsessionid=3A43DF4626AA73D8191D1D05B94943E0.d02t01?deniedAccessCustomisedMessage=&userIsAuthenticated=false
Aim
Early
unilateral brain lesions can lead to a persistence of ipsilateral
corticospinal projections from the contralesional hemisphere, which can
enable the contralesional hemisphere to exert motor control over the
paretic hand. In contrast to the primary motor representation (M1), the
primary somatosensory representation (S1) of the paretic hand always
remains in the lesioned hemisphere. Here, we report on differences in
exercise-induced neuroplasticity between individuals with such
ipsilateral motor projections (ipsi) and individuals with early
unilateral lesions but ‘healthy’ contralateral motor projections
(contra).
Method
Sixteen children and young adults with congenital hemiparesis participated in the study (contralateral [Contra] group: n=7, four females, three males; age range 10–30y, median age 16y; ipsilateral [Ipsi] group: n=9,
four females, five males; age range 11–31y, median age 12y; Manual
Ability Classification System levels I to II in all individuals in both
groups). The participants underwent a 12-day intervention of
constraint-induced movement therapy (CIMT), consisting of individual
training (2h/d) and group training (8h/d). Before and after CIMT, hand
function was tested using the Wolf Motor Function Test (WMFT) and
diverging neuroplastic effects were observed by transcranial magnetic
stimulation (TMS), functional magnetic resonance imaging (fMRI), and
magnetoencephalography (MEG). Statistical analysis of TMS data was
performed using the non-parametric Wilcoxon signed-rank test for
pair-wise comparison; for fMRI standard statistical parametric and
non-parametric mapping (SPM5, SnPM3) procedures (first level/second
level) were carried out. Statistical analyses of MEG data involved
analyses of variance (ANOVA) and t-tests.
Results
While MEG demonstrated a significant increase in S1 activation in both groups (p=0.012), TMS showed a decrease in M1 excitability in the Ipsi group (p=0.036), but an increase in M1 excitability in the Contra group (p=0.043).
Similarly, fMRI showed a decrease in M1 activation in the Ipsi group,
but an increase in activation in the M1–S1 region in the Contra group
(for both groups p<0.001 [SnPM3] within the search volume).
Interpretation
Different
patterns of sensorimotor (re)organization in individuals with early
unilateral lesions show, on a cortical level, different patterns of
exercise-induced neuroplasticity. The findings help to improve the
understanding of the general principles of sensorimotor learning and
will help to develop more specific therapies for different pathologies
in congenital hemiparesis.
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