Article

Mirror therapy (MT) is a promising therapeutic approach in stroke
patients with severe hand paresis. 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 (SMC(left)).
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 SMC(left). 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.

Langue : ANGLAIS