1. Development and Pathophysiology of Central Vestibular System Kenna D. Peusner, PhD Professor of Anatomy and Cell Biology George Washington University Medical Center Ross Hall, 208, 209, 211, 213, & 215 994-3489, anakdp@gwumc.edu Funding from NIH “ Synaptic Transmission during Neuronal Differentiation” (R01 DC00970) “Development of Vestibular Nuclei Neurons” (R01 DC05004)

2. Vestibular system disorders The vestibular system controls posture and balance. Dizziness is a common symptom reported by patients. In 55% of patients with dizziness symptoms, the cause is due to vestibular pathology. In pediatric patients, vestibular symptoms are uncommon as a chief complaint because children (18 months to three years) rely more heavily on vision than on vestibular and proprioceptive senses. However, 50-95% of children with congenital and acquired hearing impairment have vestibular abnormalities. Developmental delays due to vestibular disorders include impaired learning, postural coordination, and motor skills. Balance disorders become very common with increasing age. About 35% of people over 75 years suffer from balance problems. Patients with unilateral peripheral vestibular lesions (acoustic neuroma) undergo recovery of function in about one week, called vestibular compensation.

3. Technical Approaches used in the laboratory -60 mV +10 mV Excitatory events Inhibitory events Spontaneous and evoked spike activity Immunolabeling of protein targets and confocal imaging of neurons During vestibular compensation, spontaneous spike firing is lost in vestibular nucleus neurons in the brain. About a week later, recovery of spike firing occurs, coincident with behavioral recovery. -80 -40 0 40 Vm (mV) 100 ms Spontaneous synaptic activity

4. Scientists presently working in the laboratory Kenna D. Peusner, PhD : PI Anastas Popratiloff, MD, PhD: Immunocytochemistry and confocal imaging Mei Shao, MD, PhD: Patch-clamp electrophysiology on brain slices John Ramcharitar, PhD: Patch-clamp electrophysiology on brain slices Adria Gottesman-Davis: Third year graduate student in IBS Xudong Cai: Research Assistant June Hirsch, PhD: Consultant in electrophysiology, Paris, France