The role of the cerebellum in facial expression processing and mentalizing in autism: a systematic literature review

Abstract

Deficits in social cognition, including facial expression processing and theory of mind, is one of the main symptoms of autism spectrum disorder (ASD) and is also a predictor for several functional problems. In the past, the cerebellum was only known for its role in controlling and coordinating complex movements. Recently, the cerebellum has been associated with its contribution to emotional processing and mentalizing. Research indicated that the cerebellum has functional and structural impairments in individuals with ASD. The purpose of the current systematic literature review was to examine the role of the cerebellum in facial expression processing and theory of mind in ASD by reviewing published functional and structural brain imaging studies. We used PubMed and Web of Science to find all functional- and structural neuroimaging studies reporting on cerebellar activity in individuals with ASD regarding facial expression processing and/or theory of mind, published up to April 2023. In total, 18 functional and structural neuroimaging studies were selected for reviewing. Results Most facial expression processing studies reported reduced left and/or right posterior cerebellar activity in ASD compared to typical developing controls. In line with this, most functional connectivity (FC) studies indicated decreased FC in ASD between the (left) cerebellum and certain temporal, and parietal brain areas involved in mentalizing in the right hemisphere. The reviewed theory of mind studies reported conflicting and mixed results. Our findings suggest that reduced cerebellar activity in facial expression processing might contribute to the reduced ability to recognize facial expressions in other individuals. The results also suggest that reduced FC of the cerebellum with brain areas involved in mentalizing might contribute to mentalizing deficits in ASD. However, the results should be interpreted with caution due to small samples, different age groups, medication use and comorbidities in the included studies. In future studies, it might be interesting to focus on FC in ASD relative to healthy controls during emotion processing and theory of mind tasks. It might also be interesting to establish the role of distinct cerebellar regions in emotion- and mentalizing processes in ASD.