Body representations and tool embodiment following body-brain disconnection

Body and mind affect each other reciprocally at multiple levels. One condition required to produce any successful, voluntary, and aimed action for the brain is to own sufficiently refined body representations. Moreover, these representations must be constantly updated to meet environmental changes and body needs. Tools are an answer to these requests and may become, at least partially, extensions of our bodies via a process of embodiment. But what happens when the body itself changes or its communication pathways with the brain are severely damaged or completely severed? In this work, I try to offer an overview starting with a review of the literature regarding embodiment, body representations, and the ability to incorporate different tools or devices. The next step will be to comprehend, consistently with actual knowledge, what happens when the body is disconnected from the brain. The two clinical conditions of brachial plexus injury and spinal cord injuries (SCI) will be presented to achieve this goal. The first of the three experimental experiments will highlight how, following the sensorimotor deafferentation of an arm, the body representation of the same limb undergoes an autonomous process of reorganization but contextually can be modulated through targeted external interventions such as body illusions. Subsequently, the relationship between lesion level, body ownership, and interoceptive ability will be evaluated in a group of participants with spinal lesions. The third and final study will provide insights into how using an exoskeleton by patients with spinal cord injury may impact global body representation.