Mirror Movements are Linked to Executive Control in Healthy and Brain-injured Adults

It has been shown that brain-injured patients (BIP) have exacerbated mirror movements (MM). MM are involuntary contractions occurring in homologous muscles contralateral to voluntary movements, particularly in distal upper limb muscles. Attentional and inhibitory processes have been proposed as key factors to explain the level of MM. However, the link between MM and attentional/inhibitory processes has never been formally tested. The present study aims to test this link in 24 right-handed healthy adults and eight chronic BIP. We investigated the link between the amount/intensity of MM and attentional/inhibitory functions. For each participant, MM produced on each limb were assessed with two tasks, and the attentional and inhibitory functions were assessed with six neuropsychological tests. Our results showed (1) a greater amount and intensity of MM and (2) a selective deficit in sustained attention in BIP compared to healthy adults. Moreover, (3) in all participants - independent of the type of task used to evaluate MM - the amount and intensity of MM was predicted by the level of executive control, assessed by the Trail Making Test. High level of MM was associated with weak executive control abilities. This study is the first to highlight the link between MM and executive functioning, which may have implications for rehabilitation in BIP.