Cognitive social and affective neuroscience of patients with spinal cord injury

A successful human-environment interaction requires a continuous integration of information concerning body parts, object features and affective dynamics. Multiple neuropsychological studies show that tools can be integrated into the representation of one's own body. In particular, a tool that participates in the conscious movement of the person is added to the dynamic representation the body – often called “Body schema” – and may even affect social interaction. In light of this the wheelchair is treated as an extension of the disabled body, essentially replacing limbs that don't function properly, but it can also be a symbol of frailty and weakness. In a series of experiments, I studied plastic changes of action, tool and body representation in individuals with spinal cord injury (SCI). Due to their peripheral loss of sensorimotor functions, in the absence of brain lesions and spared higher order cognitive functions, these patients represent an excellent model to study this topic in a multi-faceted way, investigating both fundamental mechanisms and possible therapeutic interventions. In a series of experiments, I developed new behavioral methods to measure the phenomenological aspects of tool embodiment (Chapter 3), to study its functional and neural correlates (Chapter 4) and to assess the possible computational model underpinning these phenomena (Chapter 5). These tasks have been used to describe changes in tool, action and body representation following the injury (Chapter 3 and 4), but also social interactions (Chapter 7), with the aim of giving a complete portrait of change following such damage. I found that changes in the function (wheelchair use) and the structure (body brain disconnection) of the physical body, plastically modulate tool, action and body representation. Social context and social interaction are also shaped by the new configuration of bodily representations. Such a high degree of plasticity suggests that our sense of body is not given at once, but rather it is constantly constructed and adapted through experience.