Control of Posture and Gait
Walking is a natural example of the intricate connection between movement and balance. In the Movement and Balance department we are interested in the underlying sensory mechanisms interacting in the control of spatial orientation and how this impinges on normal and abnormal balance control. Recently we have shown that in neurological disease considerable dissociation between the various inputs mediating verticality perception can occur, eg visually mediated verticality perception may be abnormal whereas tactile mediated perception remains normal. This finding indicates that there is no single representation of verticality but rather parallel processing of each individual sensory input.
Current interests include the role of arm movements in the control of balance. Although we tend to use our arms for balance when we are in challenging situations, such as walking on a narrow beam, very little work has addressed this question directly. There could be clinical implications in this area as some diseases with loss of postural reflexes, such as Parkinson’s disease, are notorious in that patients lose their normal arm swinging during walking.
Another area of research that is currently concentrating much of our effort relates to higher order mechanisms in balance control during walking. This is represented by the study of the so called “Broken escalator phenomenon”. Everyone is familiar with the odd sensation and slight unsteadiness experienced when mounting on an escalator that is broken and therefore stationary.
Recent work in the department has established that the broken escalator phenomenon is an after effect of gait adaptation. The work has shown that after walking on an experimental moving surface subjects cannot avoid walking too fast or becoming unsteady when climbing onto the platform when it is stationary even though subjects have been fully warned that it will not move. It is a case of “the legs not trusting the brain”. Investigation in this area will now extend to other motor aftereffects and to the study of neural structures which may be important for the release of these un-suppressible aftereffects.
References
Bronstein AM, Perennou DA, Guerraz M, Playford D, Rudge P (2003) Dissociation of visual and haptic vertical in two patients with vestibular nuclear lesions. Neurology. 61: 1260-2.
Reynolds RF, Bronstein AM (2004) The moving platform aftereffect: limited generalization of a locomotor adaptation. J Neurophysiol. 91: 92-100.
Reynolds RF, Bronstein AM (2003) The broken escalator phenomenon. Aftereffect of walking onto a moving platform. Exp Brain Res. 151: 301-8.
