Sensory stimulation enhances phantom limb perception and movement decoding

Abstract

Objective. A major challenge for controlling a prosthetic arm is communication between the device and the user’s phantom limb. We show the ability to enhance phantom limb perception and improve movement decoding through targeted transcutaneous electrical nerve stimulation in individuals with an arm amputation. Approach. Transcutaneous nerve stimulation experiments were performed with four participants with arm amputation to map phantom limb perception. We measured myoelectric signals during phantom hand movements before and after participants received sensory stimulation. Using electroencephalogram (EEG) monitoring, we measured the neural activity in sensorimotor regions during phantom movements and stimulation. In one participant, we also tracked sensory mapping over 2 years and movement decoding performance over 1 year. Main results. Results show improvements in the participants’ ability to perceive and move the phantom hand as a result of sensory stimulation, which leads to improved movement decoding. In the extended study with one participant, we found that sensory mapping remains stable over 2 years. Sensory stimulation improves within-day movement decoding while performance remains stable over 1 year. From the EEG, we observed cortical correlates of sensorimotor integration and increased motor-related neural activity as a result of enhanced phantom limb perception. Significance. This work demonstrates that phantom limb perception influences prosthesis control and can benefit from targeted nerve stimulation. These findings have implications for improving prosthesis usability and function due to a heightened sense of the phantom hand.

Sensory stimulation for upper limb amputations modulates adaptability of cortical large-scale systems and combination of somatosensory and visual inputs

“…S3 B). These observations are consistent with our prior work that enhanced activation of sensorimotor regions persisted in Post-Stim 5 . Here, our findings on sustained integration suggest that sensory stimulation could have short-term influences on the large-scale systems in the brain.…”

“…Further, when such interaction was present, the task of performing a phantom hand movement showed improved outcome. Our previous work showed improved motor decoding accuracy after sensory stimulation 5 .…”

“…As an individual with upper limb amputation performs a daily task, the most common external sensory information entails somatosensory information elicited via sensory stimulation, as well as visual information present in the environment. Previous studies showed that the reintroduced sensory information helped with fulfilling task requirements such as controlling a prosthesis or identifying object compliance 5 , 12 . At the cortical level, as we carry out different daily tasks, some brain regions (or nodes, in the functional connectivity formalism) dynamically change their interaction patterns with other regions to adapt to different task demands (Fig.…”

Changes in primary somatosensory cortex following allogeneic hand transplantation or autogenic hand replantation

“…In human patients with unilateral upper extremity amputation, deafferented S1 responds to stimulation of the ipsilateral intact hand (Makin et al, 2015;Valyear et al, 2020) in addition to the contralateral phantom hand (Ding et al, 2020;Osborn et al, 2020), rather than to the corticallyadjacent lower face (which would be predicted by the classical explanation). Atypical ipsilateral responses in deafferented S1 are well-documented despite some evidence for a persistent cortical representation of the absent hand, wherein acquired amputees show a cortical representation of their intact hand, with a functional relationship between this "absent hand representation" and phantom sensation (Reilly et al, 2006;Makin and Bensmaia, 2017;Wesselink et al, 2019).…”

A multi-dimensional framework for prosthetic embodiment: a perspective for translational research

“…Body-powered prostheses are known to supply indirect proprioceptive feedback thanks to the fixed relationship between cables and joint angles [ 110 ]. This incidental sensory feedback could explain why training and adaptation might play an important role in achieving embodiment [ 73 ] and why embodiment seems achievable with various types of prostheses regardless of whether they are body-powered or myoelectric [ 8 ], functional or cosmetic [ 111 ], or when directly fixated to the bone via osseointegration with [ 112 , 113 ] or without peripheral nerve stimulation [ 114 , 115 ]. These findings reiterate the importance of having reliable means to quantify the level of embodiment that a certain prosthesis can achieve.…”