DIFFERENCES IN ELECTROPHYSIOLOGICAL PROPERTIES OF PURKINJE CELL SUBPOPULATIONS IN COMPENSATORY EYE MOVEMENT CONTROL

The cerebellum plays a key role in motor sensory integration, movement, coordination and balance. Purkinje cells (PCs) are the only output neurons of the cerebellar cortex. The cerebellum is not homogeneous; AldolaseC (AldoC) positive and negative PCs form alternating longitudinal bands across the cerebellar cortex that differ in physiology and connectivity. The flocculus is a key cerebellar hub for the control and adaptation of compensatory eye movements, including vestibular-ocular reflex (VOR) and optokinetic reflex (OKR). Here, we aim to test our working hypothesis that the 9+ and 9- subpopulations of PCs in the flocculus contribute different aspects to floccular functioning. To this end, we first tested the synaptic input and plasticity between 9+ and 9- PCs in the flocculus. Using ex vivo electrophysiological slice recordings from Kcng4-cre/Ai14-Tdtomato mice that allow us to distinguish 9- from 9+ PCs. We found that 9- PCs show a higher frequency of spontaneous excitatory and inhibitory post synaptic currents compared to 9+ PCs. Next, we examined plasticity of the parallel fiber to Purkinje cell synapse and found difference in long term potentiation (LTP) between 9+ and 9- PCs. Currently, these results are complemented with other forms of plasticity and in vivo recordings during compensatory eye movements and their adaptation. So far, our results suggest that 9- floccular PCs are more dynamic compared to 9+ PCs.