REstoring the Self with embodiable HAnd ProsthesEs

Periodic Reporting for period 4 - RESHAPE (REstoring the Self with embodiable HAnd ProsthesEs)

Période du rapport: 2021-03-01 au 2023-02-28

Amputation is a devastating event, producing functional disability and distorting the body representation, a fundamental aspect of self-awareness. Hand prostheses are designed to counteract functional impairment, not to address body alteration, a major cause of prosthesis rejection.
The objectives of RESHAPE were to: i) identify features increasing prosthesis embodiment; ii) understand the brain processes at play in embodiment, sensorimotor control, recovery plasticity and phantom limb syndrome; iii) design new neuromodulation devices and protocols to enhance prosthesis embodiment.
The lead users of RESHAPE are amputees; over 100,000 only in Europe, and increasing 2% annually. Others involved in amputee rehabilitation benefit from our strategy for increasing embodiment. Developers now have indications for producing embodiable prosthesis and scientists can use our discoveries on the neural mechanisms of embodiment, hand action perception, and related plastic phenomena.
Embodiable prostheses increase dexterity, facilitate daily-use, reduce physical and cognitive burden, improve distorted hand representations and phantom limb pain, resulting in an overall better life quality. Benefits to broader society include easier amputees’ re-employment and decreased burden upon families and caregivers.

RESHAPE pursued a multi-disciplinary, -level and -strategy approach and assembled a team of engineers, physiologists, neurologists, psychologists and one philosopher, set laboratory space in a clinical environment and the assets to develop novel technology and apply it in patients.
In healthy participants, RESHAPE studied how the sensorimotor loop builds hand representation, how this is hampered in amputees, how changes therein can be quantified, and which external interventions normalize the system.
In amputees, RESHAPE quantified the embodiment of their own commercial prostheses, to correlate it with individual profiles and device-specific features.
To rebuild the neural representation of the lost hand via somatosensory feedback, RESHAPE tested invasive electrodes implanted into the stump, advanced stump revision surgeries and non-invasive techniques.
To run these studies the team developed novel enabling technologies that were not commercially available:
• The virtual hand embodiment platform, a customizable hybrid environment to measure and induce prosthesis embodiment by modulating on-line visuotactile information (Le Jeune et al EMBC 20; D’Alonzo et al Sci Rep 19).
• Robot-aided transcranial magnetic stimulation (TMS) for neuromodulation during active tasks (Noccaro et al GNB 18, Noccaro et al BIOROB 18, Noccaro et al TBME 21).
• A MEG-compatible artificial-hand illusion platform, a metal-free instrumented platform to induce artificial hand embodiment within the MEG shielded room.
RESHAPE produced 23 scientific publications; others are submitted or in preparation. Dissemination was done via the institutional, PI’s and lab websites, and social media (LinkedIn, ResearchGate, Facebook, Twitter). RESHAPE was presented in web journals (WIRED), the 3 main Italian TV-news, TV shows, 1 TEDx and 2 TV documentaries.

RESHAPE results include:
1. Identification of pro-embodiment features. Several aspects of the prosthesis, interface and user were crucial to embodiment. For tactile sensory substitution, optimal embodiment occurred whit partly virtual vision (D’Alonzo et al Sci Rep 19) and limiting autonomous control assured prosthesis agency (Pinardi et al Cog Neurosci 20). Also, not all hand postures are equal: a posture with digits up/thumb down favored the control loop that established embodiment (Romano et al Cereb Cortex 21). In amputees, the prosthesis anthropomorphism favored sensory-oriented embodiment, but motor-oriented embodiment occurred only with training (Di Pino et al Front Neurosci 20). In 30 amputees, embodiment correlated with time of prosthesis use. Identifying these pro-embodiment features allows to develop prostheses, not currently available, specifically addressing the body image distortion.
2. Clarification of embodiment neural correlates. RESHAPE established an organized framework for the neural correlates of prosthesis embodiment, identified the MEG/EEG somatosensory activity and connectivity, and showed that the same areas supported sensory attenuation and embodiment. In amputees, RESHAPE found enhanced inhibition in the affected cortex that was independent from contralateral activity, and a reduction of somatosensory-driven plasticity. These neural correlates led to novel embodiment measures and enhancement strategies.
3. Identification of new embodiment measures. Embodiment enhanced sympathetic activation, as shown by increased variability of non-specific skin conductance (D'Alonzo et al J Cogn Neurosci 20), blood flow to the hand (Di Pino et al Open Res Eur 22), and stomach electrical activity. Since embodiment is mostly self-reported, these new, easily-to-be-collected physiological correlates can provide reliable proxies of prosthesis embodiment.
4. Embodiment enhancement via neuromodulation. Although embodiment correlates with premotor and parietal activity, facilitatory rTMS of these areas at rest had no effect on embodiment (Mioli et al Front Neurosci 18). For active-task neuromodulation, we showed the effect of white noise on plasticity (Pellegrino et al Sci Rep 22) and developed a robot-aided TMS platform. Leveraging the effect of direct current over the gamma band (Pellegrino et al Hum Brain Map 20) we developed a novel apparatus and strategy to enhance embodiment by selectively entangling connectivity between two network nodes.
5. Embodiment enhancement in neurally-interfaced prostheses. Selective sensory input relayed by invasive intraneural electrodes improved embodiment (Di Pino et al Front Neurosci 20) and reduced distorted phantom limb representation (Rognini et al J Neurol Neurosurg Psychiatry 18). Their effects included somatosensory ability to affect the motor cortex (Ranieri et al J Physiol 21) and better dexterity due to restored somatosensory-induced cortical plasticity (Zollo et al Science Rob 19).
6. Embodiment enhancement in stump surgical remodeling. Guided by the identified pro-embodiment features, we performed three more types of invasive surgical stump remodeling, which all increased embodiment: i) targeted muscle/sensory reinnervation for controlling the prosthesis with the original neural pathway from the lost hand; ii) osteointegration of the prosthesis, establishing the prosthesis user’s physical continuity and resolving socket-related issues; iii) agonist-antagonist myo-kinetic interface, restoring proprioception of the lost joint.
7. Novel platforms to investigate and induce embodiment. The Virtual hand embodiment platform and the Robot-aided TMS platform (funded by the ERC-POC) are project byproducts and technological breakthroughs, making new experiments possible. Their future application goes beyond the scope of this project, with several commercial opportunities in rehabilitation.

RESHAPE Experimental Setup

Periodic Reporting for period 4 - RESHAPE (REstoring the Self with embodiable HAnd ProsthesEs)

Partager cette page

Télécharger