The vestibular nucleus is a complex structure that is divided in several subregions which send extensive projections to other parts of the brain and spinal cord. It is involved in balance control and in the regulation of autonomic reflexes, such as modulation of blood pressure and breathing in response to posture changes, thus making it a primary candidate for the severe phenotype of Ndufs4KO mice. However, the vestibular circuitry involved the control of breathing; CO₂ sensing and cardiovascular tone is largely unknown. Currently, by combining stereotaxic viral delivery and optogenetics, the lab is defining the circuitry involved in the physiological and behavioral changes observed in Ndufs4KO mice, which will provide valuable insight in the pathophysiology of the disease.