Conrad Wall, III, Ph.D.

Harvard Medical School

Professor of Otolaryngology

Massachusetts Eye and Ear

Senior Scientist

Research Summary

Research Area Affiliations

Research Summary

Dr. Wall’s research interests include: interactions of motion with vision, vestibular diagnostic testing, and balance prostheses. Select projects are outlined below:

Sensory interaction of motion with vision: Motion sickness may be caused by sensory conflict. Does the central nervous system use correlation between the senses to detect such conflict? Dr. Wall and colleagues characterized the eye movement response to linear body motion paired with wide field visual motion. Applying stimuli of two different frequencies (one for motion, one for vision), they produced responses predicted by a correlation process. This provided further support for a motion conflict detector that can help explain the mechanisms causing motion sickness.

Tests of posture and gait: Early on, Dr. Wall, along with colleagues Drs. Nashner and Black, showed that vestibulopathic subjects were unable to maintain their postural stability under conditions that rendered sensory inputs to vision and proprioception unreliable. This paved the way for clinical posture testing. More recently, NASA charged Dr. Wall to lead a multi-project effort of five prominent investigators. His contribution was a perturbation technique to evaluate astronauts’ gait upon return from microgravity.

Application of multivariate analysis to diagnostic testing: The objective of this research was to increase the "resolving power" of existing vestibular tests. The sensitivity of these tests has been significantly increased (e.g., from 86% to 97%) with no increased testing.

Prostheses for balance: Dr. Wall first-authored the paper that defines the challenges for vestibular/balance prostheses. With collaborators in Geneva, he showed for the first time the ability to acutely generate in humans the robust, controllable compensatory eye movements needed for clear vision during self-movement – a vestibular implant goal. He designed and tested the first device that used body-mounted motion sensors to let subjects control their body sway using vibrotactile feedback. Results showed a significantly reduced chance of falling in balance-deficient subjects, enhanced effectiveness for balance rehabilitation, and reduced fall risk indicators in fall-prone elders during walking.

Select Publications

Human eye movement response to z-axis linear acceleration: The effect of varying the phase relationships between visual and vestibular inputs. Lathan CE, Wall III C, Harris LR, Exp. Brain Res.1995; 103(2):256-66.

Application of multivariate statistics to vestibular testing: discriminating between Meniere's disease and migraine associated dizziness. Dimitri, P.S., Wall, C, Oas JG, Rauch SD, J Vestib Res. 2001;11(1):53-65.

Eye movements in response to electric stimulation of the human posterior ampullary nerve. Wall C, Kos MI, Guyot JP. Ann Otol Rhinol Laryngol. 2007;116(5):369-74.

Balance prosthesis based on micromechanical sensors using vibrotactile feedback of tilt. Wall C., Weinberg MS, Schmidt PB, Krebs DE, IEEE Trans Biomed Eng. 2001;48(10):1153-61.

Vibrotactile tilt feedback improves dynamic gait index: a fall risk indicator in older adults. Wall C, Wrisley DM, Statler KD. Gait and Posture. 2009; 30(1): 16-21.

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