Embodied neurofeedback with an anthropomorphic robotic hand

Abstract

Neurofeedback-guided motor imagery training (NF-MIT) has been suggested as a promising therapy for stroke-induced motor impairment. Whereas much NF-MIT research has aimed at signal processing optimization, the type of sensory feedback given to the participant has received less attention. Often the feedback signal is highly abstract and not inherently coupled to the mental act performed. In this study, we asked whether an embodied feedback signal is more efficient for neurofeedback operation than a non-embodiable feedback signal. Inspired by the rubber hand illusion, demonstrating that an artificial hand can be incorporated into one’s own body scheme, we used an anthropomorphic robotic hand to visually guide the participants’ motor imagery act and to deliver neurofeedback. Using two experimental manipulations, we investigated how a participant’s neurofeedback performance and subjective experience were influenced by the embodiability of the robotic hand, and by the neurofeedback signal’s validity. As pertains to embodiment, we found a promoting effect of robotic-hand embodiment in subjective, behavioral, electrophysiological and electrodermal measures. Regarding neurofeedback signal validity, we found some differences between real and sham neurofeedback in terms of subjective and electrodermal measures, but not in terms of behavioral and electrophysiological measures. This study motivates the further development of embodied feedback signals for NF-MIT.

What if I had a third arm? An EEG study of a supernumerary BCI system

“…Furthermore, for this approach, the influence of embodiment feedback ( Hands ) was compared with the standard Graz training in VR. In line with the previous works [34, 35, 26], both the classification rates and the modulation of ERD/ERS signals were enhanced by the realistic feedback, evidencing its importance inside the BCI loop. Also, our work goes further than the one done by Skola and Liarnokapis [34] because they compared an embodied VR scenario against a monitor-based Graz, creating a bias in the users who started with VR.…”

“…The authors report improvements in both ERD/ERS modulation and classification rates by the neurofeedback-guided motor imagery training. Likewise, Braun et al [35] report the same sort of results using an anthropomorphic robotic hand as a visual guide. Also, they found differences between the two conditions in the electrodermal activity and subjective measures.…”

Exploring Self-Paced Embodiable Neurofeedback for Post-stroke Motor Rehabilitation

“…A few studies have developed an EFS Alimardani et al, 2013;Ono et al, 2013;Pichiorri et al, 2015;Braun et al, 2016). Most of these studies were inspired by the active rubber hand illusion (aRHI; Ehrsson, 2012, 2014;Braun et al, 2014) or its VR-based derivatives (Slater et al, 2008Sanchez-Vives et al, 2010;Kilteni et al, 2012;Ma and Hommel, 2013;Pichiorri et al, 2015;Ma et al, 2017).…”

“…The aRHI is a special variant of the classical rubber hand illusion, in which a movable artificial robotic hand (RH), rather than a static rubber hand, is placed visibly, and in an anatomically-plausible position, in front of the individual, while the individual's own hand is hidden from view. If the RH is repeatedly moved in synchrony with the individual's real or imagined hand movements, an illusory sense of ownership (SoO) and sense of agency (SoA) for the artificial hand can typically be induced Ehrsson, 2012, 2014;Braun et al, 2014Braun et al, , 2016. That is, individuals may then experience the RH as part of their own body (SoO) and its movements as under their voluntary movement control (SoA).…”

“…In order to provide real-time feedback for the MI within an aRHI paradigm, imagined hand movements are decoded from electrical brain activity and the corresponding commands are issued to the RH. Ideally, the RH then executes the imagined movements with little temporal delay (Braun et al, 2016).…”