van Hoogstraten, W. S. | Search bioRxiv

bioRxiv2026

Open- and Closed-Loop Microcomplexes in Neocerebellum

Neocerebellum facilitates motor and cognitive behavior via olivocerebellar modules, in which Purkinje cells (PCs), cerebellar nuclei (CN) neurons and olivary cells are supposed to form exclusively closed-loops. Here, we provide evidence that parts of the modules may be organized in an open-loop feedforward fashion where PCs do not contact the CN neurons that provide feedback to the olive. The PCs in the open-loop microcomplexes exclusively target projection CN neurons, through which cerebellum modulates downstream brainstem regions controlling behavior. This novel cerebellar architecture, containing open- and closed-loop microcomplexes within single modules, offers a mechanism by which mossy fiber information can be differentially used either as feedforward control of behavior and/or as feedback to the olivary subnuclei that regulates activity and plasticity within the module involved. This potential for both integrated and segregated regulation of behavior and feedback within single modules enriches the computational repertoire of the olivocerebellar system.

neuroscience↗

bioRxiv2024

Encoding of cerebellar dentate neuronal activity during visual attention in rhesus macaques

The role of cerebellum in controlling eye movements is well established, but its contribution to more complex forms of visual behavior has remained elusive. To study cerebellar activity during visual attention we recorded extracellular activity of dentate nucleus (DN) neurons in two non-human primates (NHPs). NHPs were trained to read the direction indicated by a peripheral visual stimulus while maintaining fixation at the center, and report the direction of the cue by performing a saccadic eye movement into the same direction following a delay. We found that single unit DN neurons modulated spiking activity over the entire time-course of the task, and that their activity often bridged temporally separated intra-trial events, yet in a heterogeneous manner. To better understand the heterogeneous relationship between task structure, behavioral performance and neural dynamics, we constructed a behavioral, an encoding and a decoding model. Both NHPs showed different behavioral strategies, which influenced the performance. Activity of the DN neurons reflected the unique strategies, with the direction of the visual stimulus frequently being encoded long before an upcoming saccade. Moreover, the latency of the ramping activity of DN neurons following presentation of the visual stimulus was shorter in the better performing NHP. Labeling with the retrograde tracer CTB in the recording location in the DN indicated that these neurons predominantly receive inputs from Purkinje cells in the D1 and D2 zones of the lateral cerebellum as well as neurons of the principal olive and medial pons, all regions known to connect with neurons in the prefrontal cortex contributing to planning of saccades. Together, our results highlight that DN neurons can dynamically modulate their activity during a visual attention task, comprising not only sensorimotor but also cognitive attentional components.

neuroscience↗