The inferior olive (IO) is an evolutionary conserved brain region important for motor learning. As part of the olivo-cerebellar system (OCS), the IO sends climbing fiber projections to the Purkinje neurons (PN) and generates complex spikes. Despite its significance, the mechanisms guiding IO responses to sensory inputs for complex spike generation are unclear. This project aims to uncover how IO neurons integrate sensory input, impacting cerebellar control of movement.Focusing on IO afferents from the superior colliculus (SC), crucial for orienting behavior, we identified a novel target area for SC projection in the principal olive (PO), complementing the known SC projection to the medial accessory olive (MAO). To examine if they belong to the same neuronal population we study the morphology of SC-PO and SC-MAO neurons and found that they both intermingle in the lateral SC's intermediate and deeper layers with similar gross morphology.Furthermore, we investigated whether SC axonal terminals targeted IO dendrites, where they can influence electrical coupling or target the somata to directly affect the spike generation. Putative SC-IO synaptic terminals were located on both soma and dendrites. To understand IO responses to SC input, we used optogenetic tools to stimulate the SC and IO-specific AAV9 with a calcium indicator (GCaMP6s) to monitor IO neuronal population activity in anesthetized mice. Preliminary results suggest a modulatory role of the SC-IO pathway. This study sheds light on the anatomical and functional properties of the SC-IO pathway, forming the basis for further exploration of SC-PO and SC-MAO in behavior.