Dickman Lab @ WashU School of Medicine

Dickman Lab @ WashU
Vestibular Neuroscience

	The Vestibular System: A Primer
	In the Dickman lab, we study the anatomy and physiology of the vestibular system. The vestibular system not only drives gaze and body stabilizing responses to head motion in space, but also interacts in complex ways with other sensory systems to generate spatial percepts and to guide reflexive and voluntary action. Follow the links below to learn more about the vestibular system. (Vestibular primer written by Dr. J. David Dickman)

		1) Structure of the Vestibular Labyrinth		5) Vestibulo-ocular Responses
		2) Hair Cells and the Sensory Epithelium		6) Vestibulospinal Projections
		3) Function: Semicircular Canals v. Otolith Organs		7) Vestibulo-thalamo-cortical Projections
		4) Vestibular Nuclear Complex

Current Projects

	Gravity Dependence of Otolith System Function It is known that even moderate exposure to altered gravity conditions in adult animals can produce modifications in the anatomy, physiology, and neuromotor responses related to the vestibular system. In addition, more limited evidence shows that exposure to either micro- or hypergravity conditions during embryogenesis and neonatal development can produce profound alterations in vestibular system structure and function. This project will compare otolith system morphology, physiology, and behavioral responses in mice that have developed from fertilization through maturity in either Earth normal or hypergravity conditions. Aim #1: Examine and compare the distribution and type of otolith receptors and macula afferent innervation in mice raised in different gravity conditions. Aim #2: Examine the sensitivity, spatial tuning, and dynamic responses of otolith afferents in mature mice that have developed in different gravity conditions. Aim #3: Examine the effects of development in altered gravity environments on the vestibuloocular reflex and head gaze stability in mature mice during linear motion. Funded by NIH/NIDCD (R01 DC006913, 1/2006 - 12/2010) Personnel: Suhrud Rajguru
	Vestibular Lagena Structure & Function The use of Earth's magnetic field by many species for navigation has been widely documented, although the sensory mechanism for detection remains elusive. Recent evidence suggests that the lagena, the third vestibular otolith receptor found in many non-mammalian vertebrates, may provide the answer. In birds and fish, the lagena epithelium has been shown to have a high iron and zinc content, elements that could form magnetite compounds. Aim #1: Use X-ray spectroscopy and magnetic force microscopy to examine the otolith organ receptor for the presence of magnetic dipoles. Aim #2: Examine whether lagena afferents encode magnetic spatial information using extracellular neural recordings. Aim #3: Examine the effects of lagena ablation on magnetic field detection using behavioral orientation paradigms. Funded by NIH/NIDCD (R01 DC007618-01, 8/2005 - 6/2010) Personnel: Le Qing Wu
	Vestibular Regeneration following Ototoxic Damage Previous studies in our laboratory characterized the morphological and physiological regeneration and recovery of vestibular afferents following complete hair cell loss due to ototoxic damage. These studies also characterized functional recovery of the vestibuloocular and head stabilizing reflexes during regeneration, correlating recovery of behavior with recovery of the afferent population. Current studies are extending this line of inquiry by characterizing responses of central vestibular neurons in the brainstem during and following regeneration. Personnel: Zakir Mridha
	State-Dependent Vestibular Processing Previous evidence suggests that the way in which vestibular information is processed and used in sensorimotor transformations depends on the behavioral state of the animal. For example, previous studies have simulated gliding flight in pigeons in the laboratory, and have shown that head-in-space stabilizing responses to motion stimuli are enhanced when birds are in a simulated flight state. Current studies aim to characterize the neural substrate for the state-dependent enhancement of head stabilizing responses to vestibular stimulation, using behavioral and electrophysiological techniques to relate state-dependent neural responses to behavior. Personnel: Kim McArthur