Patient-therapist INTERaction During RObotic GAIT Rehabilitation After Spinal Cord Injury: Clinical, Instrumental and Hyperscanning Study.

Gait recovery is a main goal in the rehabilitation of individuals with in incomplete SCI (i-SCI). Modern approaches favor task specific repetitive rehabilitation, with high intensity and early multisensorial stimulation such as the robot assisted gait training (RAGT). The growing interest in robotic therapy has attracted attention to human-robot interactions in the rehabilitation framework, and a consensus is forming on the importance of top-down approaches in rehabilitation, particularly when dealing with robotic devices. The critical aspects of top-down approaches are multifarious and include motivation, active participation, learning skills and error-driven-learning, evidencing the key aspects of feedback (FB) information to guide and improve HRI interactions. These evidences highlight the crucial function of active patient (Pt) involvement and the importance of information that is provided by the physiotherapist (PhT) to the Pt for supporting recovery. Further, Pts who feel engaged in the treatment and receive FB are more adherent to rehabilitation and the Pht can provide reinforcement, giving positive attention, praise, and encouragement for the Pt's effort. PhT-Pt interaction is a key aspect for success in rehabilitation: physical, verbal, and technical exchanges between the PhT and Pt highly influence the outcome. In robotic gait rehabilitation Pht-Pt interaction depends on various aspects which include the amount and quality of information exchanged between Pt and robot and Pht and robot, in a threefold relationship.

Recent data on human-to-human interactions and neural correlates of interpersonally coordinated motor behavior have indicated that cooperative motor behavior engages specific cortical and subcortical areas of the motor system compared with execution of the task alone, promoting the learning of motor strategies to support recovery. Recently, a new conceptual and methodological framework has been proposed to investigate the neural basis of human social interaction: the two-person neuroscience. It focuses on studying the dual exchange rather than only on the individual behavior, by using simultaneous neurophysiological recordings from two or more subjects, commonly referred to as hyperscanning or dual scanning. An approach that can provide a viable way to untangle the social interaction from two-persons data is multiple-brain connectivity (also referred to, in some studies, as hyperconnectivity). Thereby temporal correlations between signals derived from the brain regions of different subjects during their interaction are studied to understand how the brain activity of each subject is correlated to the activity in the brain of the other subject. Inter-subject connectivity was described by fMRI, MEG and EEG studies, the latter allowing for an ecological setting. Furthermore, the use of indices derived from graph theory allows to characterize the multiple brain system by means of its properties. The literature is vast on the effects of RAGT on i-SCI gait performances, particularly on speed parameters. However the impact of Pht-Pt interaction on gait outcome has never been investigated in this context at the time of this proposal. The combination of EEG hyperscanning and multiple-brain connectivity could be a powerful tool to objectively measure the Pht-Pt interaction and put it in relation with the rehabilitation outcomes. INTERROGAIT will explore such context by modulating Pht-Pt interaction during gait rehabilitation with the Lokomat device in iSCI patients.

The main hypothesis is that RAGT performed using the FB provided the Lokomat device with an high level of Pht-Pt interaction can lead to a better functional outcome for Pts, in comparison to a minimum interaction. Moreover, we will provide quantitative assessment of Pht-Pt interaction (EEG hyperscanning study) and seek for correlations between neurophysiological descriptors and clinical outcome, supporting our main hypothesis.

The main aim of this study is to test the effects of maximum and minimum PhT-Pt interaction in RAGT on clinical and functional performences in iSCI subjects, through a single blind longitudinal randomized controlled clinical trial.

Furthermore, the study will be aimed to identify neurophysiological indices derived from hyperscanning EEG data monitoring the establishment and development of Pht-Pt interaction during RAGT and to investigate the correlation between the establishment of a successful Pht-Pt interaction as assessed via neurophysiological indices and psychological variables and the rehabilitation outcome. Aspects related to acceptability and usability of the approaches will be evaluated. In detail for the Pt mood, motivation and satisfaction will be evaluated before (mood, motivation) and after (satisfaction) RAGT sessions by means of Visual Analogue Scales; workload will be evaluated at the end of the training sessions by means of the Nasa-Task Load Index. For both Pht and Pt the empathy and the ability to recognize or express emotion will be assesses before and after the training according to Emotional Response Scale, Impression Scale, Interpersonal Reactivity Index,Empathy Quotient, Assertion Inventory, Responsibility Attitude Scale.