Proprioceptive engagement of the human cerebellum studied with 7T-fMRI

Proprioception, the process of perceiving our bodies in space, is a key aspect of self-perception. The cerebellar cortex is believed to play a critical role in proprioception. However, our understanding of the functional involvement of the cerebellum in proprioception remains limited due to the intricate, thin, and highly folded structure of the human cerebellar cortex, which is more challenging to resolve using in-vivo MRI compared to the cerebral cortex. In this study, we employed high-resolution, B₁-shimmed, functional magnetic resonance imaging (fMRI) at 7T to investigate proprioceptive involvement of the cerebellum in humans. We used two tasks designed to differentially require proprioceptive information processing: midline-contralateral-finger-touch and simultaneous-unilateral-finger-flexing. We assessed responses to these tasks across three gradient directions inspired by the mesoscale cerebellar functional organisation, akin to laminar and columnar fMRI approaches in the cerebral cortex. Movements requiring higher proprioceptive engagement, in the midline-contralateral-finger-touch task, elicited stronger activations in both anterior and posterior lobe motor areas of the cerebellum (lobules V and VIIIa/b). We identified distinct activation patterns for the two tasks within these cerebellar motor regions, which may reflect differing functional roles of these motor areas. Midline-contralateral-finger-touch responses were found more medial than simultaneous-unilateral-finger-flexing responses in lobule V and deeper into the cerebellar fissures in lobule VIII. These findings contribute to a deeper understanding of cerebellar functional organisation, the cerebellar involvement in proprioception and may offer insights into addressing proprioceptive deficits associated with neurological conditions.