Excitatory nucleo-olivary pathway shapes cerebellar outputs for motor control

The brain generates predictive motor commands to control the spatiotemporal precision of high-velocity movements. Yet, how the brain organizes automated internal feedback to coordinate the kinematics of such fast movements is unclear. Here we unveil a unique nucleo-olivary loop in the cerebellum and its involvement in coordinating high-velocity movements. Activating the excitatory nucleo-olivary pathway induces well-timed internal feedback complex spike signals in Purkinje cells to shape cerebellar outputs. Anatomical tracing reveals extensive axonal collaterals from the excitatory nucleo-olivary neurons to downstream motor regions, supporting integration of motor output and internal feedback signals within the cerebellum. This pathway directly drives saccades and head movements with a converging direction, while curtailing their amplitude and velocity via the powerful internal feedback mechanism. Our finding challenges the long-standing dogma that the cerebellum inhibits the inferior olivary pathway and provides a new circuit mechanism for the cerebellar control of high-velocity movements. Complex spikes (CSs) driven by inferior olivary neurons have crucial roles in motor control. Wang et al. identified an excitatory pathway from the cerebellar nuclei to the inferior olive that drives rapid feedback CSs and contributes to the fine control of ocular and body movements.

Automated summary

The brain generates predictive motor commands for high-velocity movements, but how it organizes internal feedback for coordinating these movements is unclear. This study reveals a unique nucleo-olivary loop in the cerebellum that is involved in coordinating high-velocity movements. Activation of the excitatory nucleo-olivary pathway induces well-timed internal feedback signals in Purkinje cells, shaping cerebellar outputs. This pathway directly drives saccades and head movements while curtailing their amplitude and velocity through internal feedback.