The mirror paradigm and mirror therapy: does the "virtual hand" have a beneficial impact on motor behavior?

Abstract

The mirror paradigm can be used to investigate the role of visual afferents in motor control as well as in position perception and kinesthesia. The paradigm has also been evaluated as tool (i.e. mirror therapy) for restoring brain functions in general and promoting recovery from hemiparesis in particular. However, recent reviews have cast doubt on the mirror paradigm's beneficial impact on motor behavior. In this Research Highlight, we briefly review recently published results (including our own work) on the impact of the mirror paradigm and mirror therapy on motor functions in stroke patients and in healthy participants with or without simulated motor dysfunctions. Overall, our assessment failed to evidence clear or systematic mirror facilitation of motor behavior (i.e. bimanual coupling) in either voluntary or involuntary upper limb activity in healthy participants. Our findings thus "mirror" those of recent reviews questioning the benefit of mirror therapy over mental imagery or bimanual coupling in recovery from motor dysfunction following stroke.