Effects of combat sports on cerebellar function in adolescents: a resting-state fMRI study

Objectives: To evaluate the effects of combat sports on cerebellar function in adolescents based on resting-state functional MRI (rs-fMRI). Methods: Rs-fMRI data were acquired from the combat sports (CS) group (n = 32, aged 14.2 +/- 1.1 years) and nonathlete healthy control (HC) group (n = 29, aged 14.8 +/- 0.9 years). The amplitude of low-frequency fluctuation (ALFF), regional homogeneity (ReHo), and functional connectivity (FC) within the cerebellum was calculated and then compared between the two groups. Results: None of these participants displayed intracranial lesions on conventional MRI and microhemorrhages on SWI, Compared with the HC group, the CS group showed decreased ALFF and ReHo in the bilateral cerebellum, mainly located in the inferior regions of the cerebellum (Cerebellum_8, Cerebellum_9, Cerebellum_7b, and Cerebellum_Crus2). While increased was found within the cerebellar network, mainly located in the superior regions near the midline (bilateral Cerebellum_6, Cerebellum_Crus1_R, and Vermis_6). There is no internetwork FC change between the CEN and other networks. Conclusion: This study confirmed extensive effects of combat sports on cerebellar rs-fMRI in adolescents, which could enhance the understanding of cerebellar regulatory mechanism under combat conditions, and provide additional information about cerebellar protective inhibition and compensatory adaptation. Advances in knowledge: Adolescent combat participants are an ideal model to study training-induced brain plasticity and vulnerability. Relative to task-related fMRI, rs-fMRI can bring more information about cerebellar regulation and explain the Central Governor Model more comprehensively.