Postural control during quiet bipedal standing in rats

Abstract

The control of bipedal posture in humans is subject to non-ideal conditions such as delayed sensation and heartbeat noise. However, the controller achieves a high level of functionality by utilizing body dynamics dexterously. In order to elucidate the neural mechanism responsible for postural control, the present study made use of an experimental setup involving rats because they have more accessible neural structures. The experimental design requires rats to stand bipedally in order to obtain a water reward placed in a water supplier above them. Their motions can be measured in detail using a motion capture system and a force plate. Rats have the ability to stand bipedally for long durations (over 200 s), allowing for the construction of an experimental environment in which the steady standing motion of rats could be measured. The characteristics of the measured motion were evaluated based on aspects of the rats’ intersegmental coordination and power spectrum density (PSD). These characteristics were compared with those of the human bipedal posture. The intersegmental coordination of the standing rats included two components that were similar to that of standing humans: center of mass and trunk motion. The rats’ PSD showed a peak at approximately 1.8 Hz and the pattern of the PSD under the peak frequency was similar to that of the human PSD. However, the frequencies were five times higher in rats than in humans. Based on the analysis of the rats’ bipedal standing motion, there were some common characteristics between rat and human standing motions. Thus, using standing rats is expected to be a powerful tool to reveal the neural basis of postural control.

Quantitative evaluation of posture control in rats with inferior olive lesions

“…The PC of the body segments represents a motion element with a fixed ratio among body segments, and this motion element represents the coordination among segments. Previous studies of standing in both humans 15 and intact rats 13 showed that mainly just two PCs contribute to bipedal standing. The study that assessed the coordination of intact rats 13 also indicated that PC 1 was strongly correlated with COM movements, whereas PC 2 was correlated mainly with trunk movements.…”

“…Previous studies of standing in both humans 15 and intact rats 13 showed that mainly just two PCs contribute to bipedal standing. The study that assessed the coordination of intact rats 13 also indicated that PC 1 was strongly correlated with COM movements, whereas PC 2 was correlated mainly with trunk movements. Figure 2 shows the contribution ratio (Fig.…”

“…To reveal the contribution of olivo-cerebellar system lesions to the destabilized posture, it would be useful to quantitatively evaluate the control system through the measurement of the movement of animals with olivo-cerebellar system lesions and a comparison with a mathematical model of the control system. In previous work, we constructed an experimental system for measuring the movement of rats with bipedal standing 13 . Because bipedal standing is unstable, rats must move for stabilization.…”

Identification of New Biomarkers of Posturo-Locomotor Instability in a Rodent Model of Vestibular Pathology

“…This used in human clinical practice for the diagnosis and evaluation of postural disorders and for the assessment of instability. Statokinesiograms are shown here for the first time in rats under ecological conditions, without any restraint, unlike in other studies (23,43). In this study, postural parameters are automatically studied when an animal voluntarily immobilizes itself, which reduces the need to retrain animals subjected to a stressful model of pathology (25).…”

Automated home cage training of mice in a hold-still center-out reach task

“…Due to the joystick's low stiffness, the hold-in-center requirement approximates an inverted pendulum or stick balancing problem, in which a control policy is required to produce corrective micromovements to counter deviations from the center position (Anderson 1989;Bhounsule et al 2015;Cabrera and Milton 2002;Funato et al 2017). Consistent with this, whereas early in training trajectories exhibited rapid displacements from the center position, later in training all mice produced a clearly resolved sequence of "micromovements" that maintained the joystick within the inner radius for longer periods of time (Fig.…”