​​​​USING GENETICALLY ENCODED VOLTAGE INDICATORS TO UNCOVER GOLGI CELLS’ ACTIVITY IN VIVO

The cerebellum plays a major role in the coordination of motor actions, by continuously processing sensorimotor patterns in its cortical network. Golgi cells regulate this stream of information at the input layer, by inhibiting Granule cells at the glomeruli where they contact Mossy Fibers carrying sensorimotor patterns. Using genetically encoded voltage indicators JEDI-2P and FORCE1f, we studied Golgi cells’ activity on GlyT2-cre mice placed on a freely-moving wheel, during quiet wakefulness and spontaneous postural adjustments. The membrane potential changes in Golgi cells were recorded at several kHz in a random-access microscope with Ultra Fast Local Volume Excitation. Spikes were detected using a custom-made pipeline, from optical voltage traces denoised by template matching and wavelet filtering. Mice behavior was recorded at 200 Hz, and we performed principal component analysis and independent component analysis of differential movies. The dissection of behavior in terms of independent movements of discrete body parts allowed us to cluster pseudo-stereotyped postural adjustments using UMAP. Golgi cells’ firing rate displayed a marked increase for all the movement clusters, with a ramp-up preceding the onset of the movement. Understanding the activity of Golgi cells’ during behavior might shed light on the pattern separation at the granule layer of the cerebellum.