Differential Behavioral and Neural Effects of Regional Cerebellar tDCS.

The human cerebellum contributes to both motor and non-motor processes. Within the cerebellum, different subregions support sensorimotor and broader cognitive functions, due to regional patterns in anatomical connectivity with the cerebral cortex and spinal and vestibular systems. We evaluated the effects of transcranial direct current stimulation (tDCS) targeting different cerebellar regions on language task performance and whole-brain functional activation patterns. Functional MRI data were acquired while 43 healthy young adults (15 males, 28 females; 23.3 ± 3.0 years) performed a sentence completion task before and after 20 min of 1.5 mA anodal tDCS. Participants received tDCS targeting either the anterior sensorimotor cerebellum (n = 11; 3 cm right of inion, over lobule V); the right posterolateral cerebellum (n = 18; 1 cm down and 4 cm right of inion, over lobule VII); or sham tDCS (n = 14). TDCS targeting the right posterolateral cerebellum improved task accuracy relative to the sham condition (p = 0.04) and increased activation in left frontal and temporal cortices relevant to task performance (post-tDCS > pre-tDCS; T 3.17, FDR p < 0.05 cluster correction). The regions of increased BOLD signal after right posterolateral cerebellar tDCS fell within the network showing functional connectivity with right cerebellar lobule VII, suggesting specific modulation of this network. In contrast, tDCS targeting the sensorimotor cerebellum did not impact task performance and increased BOLD signal only in one cluster extending into the precentral gyrus. These findings indicate that sensorimotor and cognitive functional cerebellar subregions differentially impact behavioral task performance and task-relevant activation patterns, further contributing to our understanding of the cerebellar modulation of motor and non-motor functions.