The automatic postural adjustments maintaining human balance will be studied in freely standing subjects. The overall aim of the project is to test a concept for how the nervous system coordinates muscle contractions controlling the leg, trunk, and head components of the postural movements. Specifically, we postulate that muscle contractions are organized by a limited repertoire of discrete muscle synergies. Postural movements are then adapted to a variety of different conditions by different temporal and spatial combinations of the muscle synergies. Subjects will stand on a movable platform system. Postural adjustments to a variety of different movement perturbations will be described by analyzing the EMG activity of selected leg, lower trunk, and neck muscles and by recording the motions of the ankle, knee, hip, and neck angles. Experiments are designed to test the hypothesis that the appropriate combination of muscle synergies is selected based upon information of body segment positions, while the amplitude and timing of the movement is controlled by velocity information. Studies will include normal adult subjects and select groups of patients with peripheral vestibular deficits, Parkinson's disease, and cerebellar deficits. Patient studies will describe movement abnormalities in terms of ability to organize the individual muscle synergies, to select the appropriate combination of synergies, and to generate the appropriate amplitudes of response.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
Project #
Application #
Study Section
Orthopedics and Musculoskeletal Study Section (ORTH)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Good Samaritan Hosp & Medical Center(Prtlnd,OR)
United States
Zip Code
Horak, F B; Nashner, L M; Diener, H C (1990) Postural strategies associated with somatosensory and vestibular loss. Exp Brain Res 82:167-77
Nashner, L M; Shupert, C L; Horak, F B et al. (1989) Organization of posture controls: an analysis of sensory and mechanical constraints. Prog Brain Res 80:411-8;discussion 395-7
Horak, F B; Diener, H C; Nashner, L M (1989) Influence of central set on human postural responses. J Neurophysiol 62:841-53
Black, F O; Shupert, C L; Peterka, R J et al. (1989) Effects of unilateral loss of vestibular function on the vestibulo-ocular reflex and postural control. Ann Otol Rhinol Laryngol 98:884-9
Diener, H C; Horak, F B; Nashner, L M (1988) Influence of stimulus parameters on human postural responses. J Neurophysiol 59:1888-905
Das, P; McCollum, G (1988) Invariant structure in locomotion. Neuroscience 25:1023-34
Black, F O; Shupert, C L; Horak, F B et al. (1988) Abnormal postural control associated with peripheral vestibular disorders. Prog Brain Res 76:263-75
Moore, S P; Rushmer, D S; Windus, S L et al. (1988) Human automatic postural responses: responses to horizontal perturbations of stance in multiple directions. Exp Brain Res 73:648-58
Nashner, L M; Shupert, C L; Horak, F B (1988) Head-trunk movement coordination in the standing posture. Prog Brain Res 76:243-51
Horak, F B; Nashner, L M (1986) Central programming of postural movements: adaptation to altered support-surface configurations. J Neurophysiol 55:1369-81

Showing the most recent 10 out of 12 publications