Thesis title: Unravelling the social role of the human cerebellum: from cerebellar diseases to Autism Spectrum Disorders.
Over last decades, consensus has been reached about the role of the cerebellum in social cognition(Van Overwalle et al., 2020).The occurrence of emotional and mentalizing disturbances in patients with various types of cerebellar diseases, that impact on their social skills, has been documented (Clausi et al., 2019a; Olivito et al., 2019; Clausi et al., 202). At the same time, structural and functional cerebellar alterations have been frequently reported to be relevant for the onset of the main social and behavioural difficulties arising in Autism Spectrum Disorders (ASD), entailing both emotional and Theory of Mind dysfunctions (D’Mello et al., 2015; Olivito et al., 2017). Nevertheless, a detailed social cognition profile disentangled in its constituents, and postulations on the cerebellar specific role in each of those, have not been clearly defined in both the aforementioned conditions. From a theoretical point of view, it has been hypothesized that the typical cerebellar role in adaptive control and predictive and sequential coding of motor and cognitive functions, that culminate in the generation of internal models, could also be extended to social behavior, perhaps shaping the phenomenology of both cerebellar pathologies and ASD (Leggio and Molinari, 2015). If that’s true, some overlaps in both social cognition profiles and cerebellar structural and functional organization may be found when comparing such conditions. Thus, the general aim of the PhD project reported in the current thesis was to elucidate, by means of an integrated behavioral and neuroimaging approach, the cerebellar involvement in specific aspects of Social Cognition and to clarify the role of cerebellar-cerebral circuits in affecting the social functioning of patients with degenerative cerebellar diseases and in ASD’s pathogenesis. As reported in the results of the different studies described in the thesis, further prove on the importance of including the cerebellum in the “social brain network” was gained, corroborating the specific involvement of the cerebellar lobule Crus II in mediating ToM abilities. In addition, we provided additional hypotheses on the specific role implemented by the cerebellum in social processing, whose fluid, optimized and adaptive functioning is mediated by the constant coordination between the cerebellum and structurally and functionally connected cortical and subcortical areas. Our findings are in line with the “sequence detection theory” developed by Leggio and colleagues (2011; 2015), according to which the cerebellum produces internal models of mental processes that occur during social interactions and for which the prediction of sequential events is crucial. The cerebellar operational mode that we propose constitutes a new perspective on the role of the cerebellum in social functioning, sheding further light on the impact of social problems on the quality of life of patients with cerebellar diseases and on the pathogenesis of ASD.