Pontine Functional Connectivity Gradients

The cerebellum contributes to a wide range of motor and non-motor functions through its reciprocal connections with much of the cerebral cortex. The pons is a key intermediary in these connections. It receives extensive projections from the cerebral cortex, and in turn projects to cerebellar cortex. The anatomical organization of corticopontine and pontocerebellar connectivity has a rich history of study, but the functional organization of the pons in humans remains largely unexplored. We sought to characterize the functional organization of the pons based on its functional connectivity with the cerebral and cerebellar cortices. To this end, we used diffusion map embedding to reconstruct gradients that capture the dominant patterns of its functional connectivity. Our results reveal a primary gradient in the pons that is organized along rostrocaudal and mediolateral axes. This gradient mirrors the unimodal-to-transmodal gradient previously described in the cerebral and cerebellar cortices. The observed patterns recapitulate core findings from invasive tract-tracing in non-human animals and extend them to demonstrate that pontine functional organization can be characterized by a complex pattern of segregation and integration. These findings highlight that, rather than serving as a simple relay, the pons may function as an integrative hub within the cortico-ponto-cerebellar pathway.