Aim To investigate the neuronal basis for the effects of mirror therapy in patients with stroke.
Methods 22 patients with stroke participated in this study. The authors used functional MRI to investigate neuronal activation patterns in two experiments. In the unimanual experiment, patients moved their unaffected hand, either while observing it directly (no-mirror condition) or while observing its mirror reflection (mirror condition). In the bimanual experiment, patients moved both hands, either while observing the affected hand directly (no-mirror condition) or while observing the mirror reflection of the unaffected hand in place of the affected hand (mirror condition). A two-factorial analysis with movement (activity vs rest) and mirror (mirror vs no mirror) as main factors was performed to assess neuronal activity resultant of the mirror illusion.
Results Data on 18 participants were suitable for analysis. Results showed a significant interaction effect of movement×mirror during the bimanual experiment. Activated regions were the precuneus and the posterior cingulate cortex (p<0.05 false discovery rate).
Conclusion In this first study on the neuronal correlates of the mirror illusion in patients with stroke, the authors showed that during bimanual movement, the mirror illusion increases activity in the precuneus and the posterior cingulate cortex, areas associated with awareness of the self and spatial attention. By increasing awareness of the affected limb, the mirror illusion might reduce learnt non-use. The fact that the authors did not observe mirror-related activity in areas of the motor or mirror neuron system questions popular theories that attribute the clinical effects of mirror therapy to these systems.
- mirror therapy
- motor control
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Funding This study was supported by Hersenstichting Nederland, Fonds NutsOhra, Innovatiefonds Zorgverzekeraars, Prinses Beatrix Fonds and Wetenschappelijk College Fysiotherapie.
Competing interests None.
Patient consent Obtained.
Ethics approval Ethics approval was provided by the Medical Ethics Committee of the Erasmus University Medical Center Rotterdam.
Provenance and peer review Not commissioned; externally peer reviewed.