"Stable head posture is something most people take for granted, and is essential to perform daily activities such as balancing, navigating and moving. Neck muscles generate head motion to establish a stable reference frame for the visual and vestibular (i.e. balance organ) systems, allowing the rest of our body to engage in other motor behaviours. The vestibular system provides information regarding head motion in space, and is particularly important for neck muscle control. However, for people suffering from vestibular and neck movement disorders, even the smallest head movement, whether self-generated or imposed, can induce episodes of dizziness, imbalance and fatigue. This proposal investigates how vestibular information is modulated by the nervous system to facilitate head movements, knowledge which is crucial to understand vestibular and neck movement disorders, and eventually develop therapeutic protocols.Head motion will be manipulated using novel robotic devices to study how vestibular reflexes are modulated in healthy volunteers during externally imposed and self-generated movements. A unique motion coupled electrical vestibular stimulation will provide an artificial sensation of head movement that mimics normal or conflicting relationships with the intended motion. Vestibular reflexes will be quantified using stochastic stimulation of the vestibular organ together with system identification to estimate the sensory modulation process that occurs during head movements. This project takes a multidisciplinary approach, using engineering techniques to address physiological questions, generating knowledge that is applicable to the medical field. The fundamental insight into vestibular control of neck muscles will help understand how humans achieve skilled motor performance and relate to the difficulties patients with vestibular disorders face in performing gaze change and navigation tasks."