Boosting the Motor Outcome of the Untrained Hand by Action Observation: Mirror Visual Feedback, Video Therapy, or Both Combined—What Is More Effective?

Abstract

Action observation (AO) allows access to a network that processes visuomotor and sensorimotor inputs and is believed to be involved in observational learning of motor skills. We conducted three consecutive experiments to examine the boosting effect of AO on the motor outcome of the untrained hand by either mirror visual feedback (MVF), video therapy (VT), or a combination of both. In the first experiment, healthy participants trained either with MVF or without mirror feedback while in the second experiment, participants either trained with VT or observed animal videos. In the third experiment, participants first observed video clips that were followed by either training with MVF or training without mirror feedback. The outcomes for the untrained hand were quantified by scores from five motor tasks. The results demonstrated that MVF and VT significantly increase the motor performance of the untrained hand by the use of AO. We found that MVF was the most effective approach to increase the performance of the target effector. On the contrary, the combination of MVF and VT turns out to be less effective looking from clinical perspective. The gathered results suggest that action-related motor competence with the untrained hand is acquired by both mirror-based and video-based AO.

Effects of mirror training on motor performance in healthy individuals: a systematic review and meta-analysis

“…In a short-term study in which the participants performed 20 blocks of finger sequence abduction tasks for 15 s, MTr achieved greater functional improvement in the inactive limb compared with active vision pattern 21. In three long-term studies in which participants performed comprehensive hand performance tests for 20 or 10 min daily for 4 days, there were significant improvements in motor performance in the untrained hand with MTr compared with active vision 23–25…”

“…Thus, 14 randomised controlled trials were included in the final analysis (figure 1). Nine studies were conducted in Germany18–26 (including one in collaboration with China) 19. Two studies were conducted in Australia,27 28 and the other three studies were performed in Japan,29 the Netherlands30 and the USA 31.…”

“…The studies were categorised according to their duration of experimental training. Five studies involved long-term tasks (more than 1 day, continuous training),23–26 30 while the other nine studies adopted short-term training within 1 day to evaluate immediate functional effects 18–22 27–29 31…”

“…Eight studies examined the functional performance of the untrained hand using MTr with an active vision pattern in which the participants saw their moving hand 19 21–25 27 31. Seven studies showed an unclear risk of bias and one had a low risk of bias.…”

Effects of mirror-box therapy on modulation of sensorimotor EEG oscillatory rhythms: a single-case longitudinal study

“…MT is a visual feedback training procedure in which an individual rehearses a limb movement by reflected movements of the nonparetic side in a mirror as if it were the affected side. In healthy subjects, mirror visual feedback can increase actionrelated motor competence in an untrained hand (Bähr et al 2018). In stroke patients, randomized prospective trials of MT have shown that although some recovery occurred with sham treatments, MT led to significantly greater recovery of upper extremity function (Gurbuz et al 2016;Lim et al 2016).…”