Quantitative evaluation of posture control in rats with inferior olive lesions

Abstract

Impairment of inferior olivary neurons (IONs) affects whole-body movements and results in abnormal gait and posture. Because IONs are activated by unpredicted motion rather than regular body movements, the postural dysfunction caused by ION lesions is expected to involve factors other than simple loss of feedback control. In this study, we measured the postural movements of rats with pharmacological ION lesions (IO rats) trained to stand on their hindlimbs. The coordination of body segments as well as the distribution and frequency characteristics of center of mass (COM) motion were analyzed. We determined that the lesion altered the peak properties of the power spectrum density of the COM, whereas changes in coordination and COM distribution were minor. To investigate how the observed properties reflected changes in the control system, we constructed a mathematical model of the standing rats and quantitatively identified the control system. We found an increase in linear proportional control and a decrease in differential and nonlinear control in IO rats compared with intact rats. The dystonia-like changes in body stiffness explain the nature of the linear proportional and differential control, and a disorder in the internal model is one possible cause of the decrease in nonlinear control.

A Model of Predictive Postural Control Against Floor Tilting in Rats

“…The mean (SD) value of the noise magnitude σ was 0.50 (± 0.23) mNm. This value was in close agreement with the previously identified noise magnitude in the quiet standing rats ( Funato et al, 2021 ).…”

“…Figure 5B shows the reaction of the conventional controller, PD controller with Peterka’s gain parameters ( Peterka, 2002 ) and a non-linear PD controller for standing rats ( Funato et al, 2021 ). Both models could stabilize the body after floor disturbances, but the behaviors were slightly different from the experiment.…”

“…(3). The control models included the PD controller based on the Peterka’s gains [ , k P = 1.46 m g h , k D =0.3 m g h ; ( Peterka, 2002 )], and the non-linear PD controller for standing rats [ , k P 2 =196 m g h , k P 0 =0.88 m g h , k D =0.11 m g h ; ( Funato et al, 2021 )]. Here, the control gains were normalized with mgh to eliminate differences in the body.…”

“…To approach the control mechanism for predictive behavior, we used a mathematical model of postural control. In previous studies, we developed a postural control model for bipedally standing rats with lesions in the olivo-cerebellar system ( Funato et al, 2021 ), and showed that the decreased non-linear control, possibly due to lesions in the internal model, caused instability. The current experiment conducted on rats is based on this study, thereby the mathematical model is also based on this study.…”

A validation study to analyze the reliability of center of pressure data in static posturography in dogs

“…Indeed, the veterinary literature documents a wide range of measurement durations and repetitions when evaluating COP data in static posturography. While the majority of these articles focus on dogs (13,15,20,25,(34)(35)(36)(37) and horses (2,39,(42)(43)(44)(45)52), others also explore species like cats (53), elephants (41), flamingos (38), and rats (54). The longest analyzed duration among these articles was 30 s in dogs (34) followed by 20 s in dogs (13,15,36) and ponies (2) and 15 s in horses (52); all these aforementioned papers used three repetitions.…”