Vestibular and Oculomotor Laboratory
W. Michael King, Ph.D., Laboratory Director
The Vestibular and Oculomotor Laboratory at Kresge Hearing Research Institute studies the behavior and physiology of sensory-motor transformations in the vestibular and oculomotor systems. The vestibulo-collic reflex (VCR) stabilizes head position in space when the body moves (e.g., during walking). Vestibulo-ocular reflexes (VORs) stabilize eye position in space during head and body movements. As an example of what one might experience in the absence of these reflexes, imagine the jumpy images seen through a hand-held camera while walking along a busy street. To stabilize head and eye position, vestibular reflexes link diverse sensory inputs from hair cells in the inner ear, rod and cone receptors in the retina, and proprioceptive inflows from muscle to the motor systems that generate coordinated eye and head movements.
Current studies range from basic research using animal models to clinical applications and translational research in the Vestibular Testing Center. For example, we are studying how the brain transforms vestibular inputs arising from accelerations of the head into motor commands to stabilize eye (VOR) and head (VCR) position. Oscillopsia, a common symptom caused by vestibular loss, reduces visual clarity and is very disturbing. Vestibular loss may occur with age or as the result of exposure to ototoxic drugs such as aminoglycosides (e.g., streptomycin) or chemotherapy drugs such as cisplatin. In animals, we assess vestibular loss by measuring the VOR or the VCR. In mice, these studies may provide insights into the genetics of aging. In guinea pigs, we use the VCR and VOR to assess functional recovery of vestibular reflexes in collaborative studies with the Raphael lab of sensory hair cell loss and potential regenerative recovery. In cystic fibrosis patients, we are studying the incidence and severity of vestibular loss in a patient population that is repeatedly exposed to ototoxic medications.
The lab is also interested in how the brain aligns both eyes so that one perceives a single visual image. Prior studies suggested there were relatively independent motor systems devoted to moving the eyes together (the "conjugate" system) or to moving the eyes in opposite directions (the vergence system). Alternatively, the brain may construct separate motor commands for each eye ("monocular" control) and then adjust their alignment using visual information ("fusional vergence"). These studies, performed in collaboration with Hans van der Steen (Erasmus University, Rotterdam) may have particular utility for strabismus patients ("lazy-eye") who are unable to align their eyes.
In a broadest sense, we are interested in using the vestibular and oculomotor systems to study fundamental neuroscience problems related to sensory-motor transformations, the role of attention and cognition in modulating motor behavior, and sensory hair cell degeneration and regeneration.
