Climbing fiber multi-innervation of mouse Purkinje dendrites with arborization common to human

Canonically, each Purkinje cell in the adult cerebellum receives only one
climbing fiber from the inferior olive. Underlying current theories of
cerebellar function is the notion that this highly conserved one-to-one
relationship renders Purkinje dendrites into a single computational
compartment. However, we show that multiple primary dendrites are a
near-universal morphological feature in humans. Using tract-tracing,
immunolabeling, and in vitro electrophysiology, we demonstrate in mice
that ~25% of mature polydendritic cells receive more than one climbing
fiber input. Two-photon calcium imaging in vivo reveals that separate
dendrites can exhibit distinct response properties to sensory stimulation,
indicating some polydendritic cells integrate functionally independent
climbing fiber receptive fields. These findings reveal that Purkinje cells
are morphologically and functionally more diverse than previously thought.