Postural Control in the Rabbit Maintaining Balance on the Tilting Platform

• Published in: Journal of neurophysiology Vol. 90; no. 6; pp. 3783 - 3793
• Main Authors: Beloozerova, I. N, Zelenin, P. V, Popova, L. B, Orlovsky, G. N, Grillner, S, Deliagina, T. G
• Format: Journal Article
• Language: English
• Published: United States Am Phys Soc 01-12-2003
• Subjects: Animals; Biomechanical Phenomena; Ear, Inner - physiology; Electric Stimulation; Electromyography; Forelimb - physiology; Head-Down Tilt; Hindlimb - physiology; Medicin och hälsovetenskap; Movement - physiology; Muscle, Skeletal - physiology; Photic Stimulation; Physical Stimulation; Postural Balance - physiology; Rabbits; Sensory Thresholds - physiology; Vestibule, Labyrinth - physiology
• ISSN: 0022-3077; 1522-1598
• DOI: 10.1152/jn.00590.2003

1 The Nobel Institute for Neurophysiology, Department of Neuroscience, Karolinska Institute, SE-17177 Stockholm, Sweden; 2 Barrow Neurological Institute, St. Joseph Hospital and Medical Center, Phoenix, Arizona 85013; and 3 A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia
Submitted 18 June 2003;
accepted in final form 18 August 2003
A deviation from the dorsal-side-up body posture in quadrupeds activates the mechanisms for postural corrections. Operation of these mechanisms was studied in the rabbit maintaining balance on a platform periodically tilted in the frontal plane. First, we characterized the kinematics and electromyographic (EMG) patterns of postural responses to tilts. It was found that a reaction to tilt includes an extension of the limbs on the side moving down and flexion on the opposite side. These limb movements are primarily due to a modulation of the activity of extensor muscles. Second, it was found that rabbits can effectively maintain the dorsal-side-up body posture when complex postural stimuli are applied, i.e., asynchronous tilts of the platforms supporting the anterior and posterior parts of the body. These data suggest that the nervous mechanisms controlling positions of these parts of the body can operate independently of each other. Third, we found that normally the somatosensory input plays a predominant role for the generation of postural responses. However, when the postural response appears insufficient to maintain balance, the vestibular input contributes considerably to activation of postural mechanisms. We also found that an asymmetry in the tonic vestibular input, caused by galvanic stimulation of the labyrinths, can affect the stabilized body orientation while the magnitude of postural responses to tilts remains unchanged. Fourth, we found that the mechanisms for postural corrections respond only to tilts that exceed a certain (threshold) value.
Address for reprint requests and other correspondence: T. G. Deliagina, The Nobel Institute for Neurophysiology, Dept. of Neuroscience, Karolinska Institute, SE-17177 Stockholm (E-mail: Tatiana.Deliagina{at}neuro.ki.se ).