http://nnr.sagepub.com/content/26/5/484.abstract?etoc
Abstract
Background. Mirror therapy (MT) is a promising therapeutic approach in stroke patients with severe hand paresis. Objective. The ipsilateral (contralesional) primary sensorimotor cortex (SMC) and the mirror neuron system have been suggested to play
decisive roles in the MT network. The present study investigated its underlying neural plasticity. Methods.
Two groups of healthy participants (n = 13 in each group) performed
standardized fine motor tasks moving pegs and marbles
(20 min/d for 4 days) with their right hand with
either a mirror (mirror training group, MG) or a nonreflective board
(control
training group, CG) positioned orthogonally in
front of them. The number of items moved by each hand was tested after
each
training session. Functional MRI (fMRI) was
acquired before and after the training procedure to investigate the
mirror training
(MTr)-specific network by the analysis of the
factors Time and Group. Results. The hand performance test of
the trained right hand did not differ between the 2 groups. The
untrained left hand improved
significantly more in the MG compared with the CG.
fMRI analysis of action observation and imitation of grasping tasks
demonstrated
MTr-specific activation changes within the right
dorsal and left ventral premotor cortex as well as in the left SMC (SMCleft).
Analysis of functional and effective connectivity showed a MTr-specific
increase of functional coupling between each premotor
region and the left supplementary motor area, which
in turn showed an increased functional interaction with the ipsilateral
SMCleft. Conclusions. MTr
remodels the motor system by functionally connecting hand movement to
the ipsilateral SMC. On a system level, it leads
to interference of the neural circuit related to
motor programming and observation of the trained hand with the
illusionary
movement of the untrained hand.
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