CEREBELLAR ACTIVITY MODULATES HIPPOCAMPAL INFORMATION PROCESSING

The cerebellum is known for the integration of sensory modality inputs into precise motor activity as well as its contribution to motor learning through synaptic plasticity in the cerebellar cortex. It is also involved in higher order processes such as cognition and plays a role in spatial navigation, as demonstrated by studies of place and head direction cells in different brain structures during targeted manipulation of the cerebellar system (doi: 10.1073/pnas.2214539120; doi: 10.1007/s12311-022-01422-3). Both the cerebellum and the hippocampus engage in idiothetic information processing in support of spatial learning (DOI: 10.1016/j.brainres.2019.05.010 ; doi: 10.1016/j.cub.2025.07.050). The question arises as to whether the cerebellum can directly influence hippocampal information processing. The deep cerebellar nuclei (DCN) form the output of the cerebellum. Here, we explored whether electrophysiological activation of this structure affects synaptic strength in the hippocampus of freely behaving male mice. Patterned stimulation of the DCN during test-pulse stimulation of Schaffer collateral-CA1 synapses of the dorsal hippocampus, resulted in hippocampal long-term depression. Spatial content learning facilitated the expression of hippocampal LTD and was prevented by optogenetic modulation of the DCN, suggesting a contribution of the cerebellum to visuospatial pattern discrimination. These findings indicate that cerebellar output can modulate hippocampal synaptic plasticity related to spatial associative memory.
Acknowledgements: This study was funded by a Deutsche Forschungsgemeinschaft grant to D-M.V. (SFB 874/B10, project number: 122679504).