Mirror Visual Feedback Combining Vibrotactile Stimulation Promotes Embodiment Perception: An Electroencephalogram (EEG) Pilot Study

Abstract

As one determinant of the efficacy of mirror visual feedback (MVF) in neurorehabilitation, the embodiment perception needs to be sustainable and enhanced. This study explored integrating vibrotactile stimulation into MVF to promote the embodiment perception and provide evidence of the potential mechanism of MVF. In the experiment, the participants were instructed to keep their dominant hand still (static side), while open and close their non-dominant hand (active side) and concentrate on the image of the hand movement in the mirror. They were asked to tap the pedal with the foot of the active side once the embodiment perception is generated. A vibrotactile stimulator was attached on the hand of the active side, and three conditions were investigated: no vibration (NV), continuous vibration (CV), and intermittent vibration (IV). The effects were analyzed on both objective data, including latency time (LT) and electroencephalogram (EEG) signals, and subjective data, including embodiment questionnaire (EQ). Results of LT and EQ suggested a stronger subjective sense of embodiment under the condition of CV and IV, comparing with NV. No significant difference was found between CV and IV. EEG analysis showed that in the hemisphere of the static side, the desynchronization of CV and IV around the central-frontal region (C3 and F3) in the alpha band (8-13 Hz) was significantly prominent compared to NV, and in the hemisphere of the active side, the desynchronization of three conditions was similar. The network analysis of EEG data indicated that there was no significant difference in the efficiency of neural communication under the three conditions. These results demonstrated that MVF combined with vibrotactile stimulation could strengthen the embodiment perception with increases in motor cortical activation, which indicated an evidence-based protocol of MVF to facilitate the recovery of patients with stroke.

Synergistic Immediate Cortical Activation on Mirror Visual Feedback Combined With a Soft Robotic Bilateral Hand Rehabilitation System: A Functional Near Infrared Spectroscopy Study

“…The combination of these two strategies could lead to a synergistic gain effect. Previous studies showed that MVF induced the patient's embodiment of the feedback limb images through mirror illusion (Ding et al, 2020). Combined visual and proprioception feedback could enhance the perception of embodiment (Wittkopf et al, 2017).…”

Effectiveness of robot-assisted virtual reality mirror therapy for upper limb motor dysfunction after stroke: study protocol for a single-center randomized controlled clinical trial

“…As a new kind of mirror therapy, virtual reality mirror therapy (VRMT) can provide immersion mirror therapy for stroke patients [14]. However, mirror therapy lacks the participation of proprioception [15], which may not be able to simulate the actual scene well and activate the motor-related brain network to the greatest extent. As a clinical peripheral intervention technology, a large number of studies have proved that robot-assisted therapy (RAT) can have a positive impact on the recovery of upper limb motor dysfunction in stroke patients through programmed task training [16,17], including motor function and proprioception.…”

Enhancing Visual-Guided Motor Imagery Performance via Sensory Threshold Somatosensory Electrical Stimulation Training

“…The enhancement of ERD patterns in SES training block could be explained by the fact that the kinesthesia illusion evoked by st-SES strengthened proprioceptive afference related to MI tasks [34]. Recent evidence has shown that proprioceptive afference may play an important role in the formation of body representation and the improvement of neural activation [21].…”