Rethinking the Role of the Cerebellum in Mediating Human Behavior Through TMS: From Socio-Emotional Processing to Clinical Applications

Historically, the cerebellum has been primarily associated with motor control, while its contribution to higher-order cognition has only more recently been explored. The cerebellum supports a wide spectrum of functions, including emotional and social processing. Despite this growing body of evidence, relevant questions regarding its temporal and intrinsic dynamics, topographic characteristics, and clinical relevance remain unanswered. Transcranial magnetic stimulation (TMS) allows for testing causal evidence about cerebellar involvement in socioemotional processing and investigating novel therapeutic applications. In the present thesis, the involvement of the cerebellum in socio-emotional processing was investigated by employing TMS in four distinct experiments, testing for hypotheses concerning cerebellar chronometry and topography, and eventual intra-cerebellar functional dependencies. Furthermore, a systematic review was conducted to evaluate the effectiveness of multisession cerebellar TMS in treating motor and non-motor clinical conditions. Results showed that the posterior cerebellum recruits medial and lateral areas for emotional processing and social cognition (precisely, mentalizing) respectively, that medial and lateral areas are functionally independent of each other, and that it displays a specific chronometric pattern in emotional processing. Additionally, multisession cerebellar TMS was proven to be effective, safe, and tolerable in the treatment of symptoms of several motor and non-motor clinical conditions. Overall, this thesis provides causal evidence for the posterior cerebellum’s involvement in socio-emotional processing and for its central contribution to a wider social neural network, and supports the implementation of cerebellar TMS as a protocol for clinical treatment.