Mirror-induced visual illusion obtained through mirror therapy is widely used to facilitate motor recovery after stroke. Activation of primary motor cortex (M1) ipsilateral to the moving limb has been reported during mirror-induced visual illusion. However, the mechanism through which the mirror illusion elicits motor execution processes without movements observed in the mirrored limb remains unclear. This study aims to review evidence based on brain imaging studies for testing the hypothesis that neural processes associated with kinaesthetic motor imagery are attributed to ipsilateral M1 activation. Four electronic databases were searched. Studies on functional brain imaging, investigating the instant effects of mirror-induced visual illusion among stroke survivors and healthy participants were included. Thirty-five studies engaging 78 stroke survivors and 396 healthy participants were reviewed. Results of functional brain scans (n = 20) indicated that half of the studies (n = 10, 50%) reported significant changes in the activation of ipsilateral M1, which mediates motor preparation and execution. Other common neural substrates included primary somatosensory cortex (45%, kinaesthesia), precuneus (40%, image generation and self-processing operations) and cerebellum (20%, motor control). Similar patterns of ipsilateral M1 activations were observed in the two groups. These neural substrates mediated the generation, maintenance, and manipulation of motor-related images, which were the key processes in kinaesthetic motor imagery. Relationships in terms of shared neural substrates and mental processes between mirror-induced visual illusion and kinaesthetic motor imagery generate new evidence on the role of the latter in mirror therapy. Future studies should investigate the imagery processes in illusion training for post-stroke patients.

中文翻译：

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动觉运动意象在镜子诱发的视错觉中作为干预中风后康复的作用。

通过镜子疗法获得的镜子诱发的视觉错觉被广泛用于促进中风后的运动恢复。据报道，在镜子引起的视觉错觉期间，活动肢体同侧的初级运动皮层 (M1) 被激活。然而，镜像错觉在没有观察到镜像肢体运动的情况下引发运动执行过程的机制尚不清楚。本研究旨在审查基于脑成像研究的证据，以检验与动觉运动意象相关的神经过程归因于同侧 M1 激活的假设。搜索了四个电子数据库。包括对功能性脑成像的研究，调查镜子引起的视觉错觉对中风幸存者和健康参与者的即时影响。对涉及 78 名中风幸存者和 396 名健康参与者的 35 项研究进行了审查。功能性脑部扫描 (n = 20) 的结果表明，一半的研究 (n = 10, 50%) 报告了同侧 M1 激活的显着变化，其介导了运动准备和执行。其他常见的神经基质包括初级躯体感觉皮层（45%，动觉）、楔前叶（40%，图像生成和自我处理操作）和小脑（20%，运动控制）。在两组中观察到类似的同侧 M1 激活模式。这些神经基质介导了运动相关图像的生成、维护和操作，这是动觉运动图像的关键过程。镜像诱发的视觉错觉和动觉运动意象之间共享神经基础和心理过程的关系为后者在镜像治疗中的作用提供了新的证据。未来的研究应该调查中风后患者错觉训练中的意象过程。