Lesion locations are illustrated in three axial planes (from top to bottom) and a sagittal plane for each individual participant. Right is displayed on the right (neurological convention).

Pontine lesions disrupt contralateral cerebrocerebellar circuits. (A) A schematic illustration of the relevant components of the cerebrocerebellar circuit shows a (simplified) depiction of polysynaptic efferent pathway between the cerebral cortex and the pons, which then projects to the contralateral cerebellum. The afferent pathway projects first to the deep cerebellar nuclei then to the thalamus and the cerebrum. Focal lateralized lesions to the pons preferentially disrupt the efferent pathway from the cerebrum to the cerebellum. (B) Intrinsic functional connectivity reveals the contralateral cerebrocerebellar connectivity in 11 healthy control subjects. Correlation maps based on left and right motor seed regions (top section, y =−20, MNI coordinate) were contrasted to reveal contralateral cerebellar regions in the primary and secondary somatomotor representations within the cerebellum (bottom section, y =−52). (C) Distribution of stroke lesions in left lesion (left panel) and right lesion participants (right panel). Color scale indicates number of subjects with a lesioned voxel. (D) Cerebrocerebellar functional connectivity from two individual participants with left lateralized (left panel) and right lateralized lesions (right panel). Functional connectivity strength was reduced in the lesioned circuit but remained strong in the unaffected circuit (D).

Cerebrocerebellar connectivity of the unaffected circuit (blue) is compared with the lesioned circuit (red) for each scanning session. The scanning sessions are labeled by the time following the stroke (x-axis label). Functional connectivity strength was averaged across all eleven subjects. Connectivity strength in the unaffected circuit was stronger than the lesioned circuit at all time points (see statistical analysis in the text). Vertical bars represent standard error.

Cerebral and cerebellar motor regions defined by an actual hand movement task. These apriori regions were used for all quantitative analyses.

Quantitative analysis of functional connectivity disruption in patients. (A) Cerebellar functional correlation to hand motor regions in the right lesion group, the healthy control group, and the left lesion group show reduced connectivity in the lesioned circuit. Functional connectivity in the unaffected circuit was at a level similar to that of healthy subjects. The functional connectivity maps are projected to a surface view of the cerebellum exposing the anterior lobe (where the primary somatomotor representation is visible). (B) Functional connectivity strength is illustrated for patients and controls. Each line represents an individual participant with the circles reflecting their functional connectivity strength between the left cerebral cortex and right cerebellum (LR) or right cerebral cortex and left cerebellum (RL). Bars are the mean correlation values within each subject group.

Pontine lesions also disrupt prefrontal-cerebellar circuits. Cerebellar functional correlations contrasting the right and left DLPFC regions in the left lesion group (left panel) and the right lesion group (right panel) both show reduced connectivity in the lesioned circuit. Images are transverse sections selected to contain the prefrontal seed regions (top sections, z = 36 MNI coordinate) as well as the sections capturing the cerebellar correlations (bottom sections, z = −32). Note that the cerebellar correlations fall near Crus I/Crus II, the expected location of prefrontal cerebrocerebellar circuits. The locations of cerebellar regions coupled to prefrontal cortex are anatomically distinct from the somatomotor regions displayed in Figure 3.