Relationship between language and gesture and its impact on the rehabilitation for people with aphasia, through a telerehabilitation setting

Communication is a complex process that relies on intact language, speech, and hearing functions. After a brain lesion, some or all these functions can be affected, giving rise to a set of symptoms that fall under the term of aphasia. Aphasia is a multi-modal disorder affecting auditory comprehension, reading, oral-expressive language, writing and/or gesture. Due to the multi-modal aspects of aphasia, its recovery can rely on the recovery of different language impairments by fostering the use of alternative strategies we use to successfully communicate (i.e., writing and/or the use of gestures). During past years, the observation of the behaviour of people with aphasia suggested that they tended to use more gestures than healthy individuals. These findings have led researchers to question the possible role that gestures have on language, the possible relationship that may exist between motor and language functions, and how clinicians can take advantages from this knowledge to develop and implement treatment programs that can foster the ability to successfully communicate in people with aphasia. With this PhD project, we aimed to study the relationship between motor and language functions from different perspectives, at a neural level by a meta-analysis of functional magnetic resonance imaging studies on healthy subjects, at the behavioural level through a proof-of-concept study on stroke survivors, and from a rehabilitative point of view through a retrospective cohort study looking at the predictors of stroke recovery. Furthermore, we wanted to translate the knowledge on this relationship into clinical practice, through a telerehabilitation approach for aphasia which involves the use of gesture for lexical retrieval training and for the recovery of grammar and sentence production, compared to conversational face-to-face treatment in PWA. A first finding from secondary research investigating language and motor relationship confirmed that there is a shared activation at neural level of areas related to semantic processing and multimodal processing, suggesting for the presence of a link between co-speech gestures and spoken language during unimodal and bimodal communication. This evidence seems to be consistent with what observed during execution of experimental tasks highlighting a potential influence of semantically related action words on upper limb function. Indeed, the results from the experimental study showed a better reach-to-grasp movement execution when 11 performed combined with the presentation of a related action word, indicating that the presentation of a word with semantic movement-related information could in turn activates the related cortical motor representation facilitating upper limb movements. The case for a link between language and motor functions was also discussed through the assessment of language functions as predictors of upper limb recovery. The presence of language disorders (i.e., aphasia) seem to affect motor recovery, with reading abilities likely associated with improvements in activities of daily living. Finally, when translating evidence to clinical practice, in particular by a telerehabilitation training integrating gestures features with other strategies for successful communication for aphasia programs, we did not observe differences between telerehabilitation or in-person treatment delivery. Nevertheless, more research is needed to confirm findings from this project, with the aim to develop robust, evidence-based neurorehabilitation programs for treatment of aphasia that can take advantage from the multimodal aspects of everyday communication.