A quantitative framework for whole-body coordination reveals specific deficits in freely walking ataxic mice

TLDR

Movement coordination across the body is a fundamental but poorly understood motor control aspect, and cerebellar mutant mice show locomotor coordination impairments whose core features remain unclear. The study introduces LocoMouse, a system to analyze limb, head, and tail kinematics in freely walking mice. LocoMouse captures and quantifies limb, head, and tail kinematics during free walking. In pcd mice, individual paw forward motion differences are explained by speed and size, but complex 3D trajectories and inter‑limb/whole‑body coordination are specifically impaired, indicating a failure to predict and compensate for body‑wide movement consequences and revealing cerebellar contributions to coordinated locomotion.

Abstract

The coordination of movement across the body is a fundamental, yet poorly understood aspect of motor control. Mutant mice with cerebellar circuit defects exhibit characteristic impairments in locomotor coordination; however, the fundamental features of this gait ataxia have not been effectively isolated. Here we describe a novel system (LocoMouse) for analyzing limb, head, and tail kinematics of freely walking mice. Analysis of visibly ataxic Purkinje cell degeneration (pcd) mice reveals that while differences in the forward motion of individual paws are fully accounted for by changes in walking speed and body size, more complex 3D trajectories and, especially, inter-limb and whole-body coordination are specifically impaired. Moreover, the coordination deficits in pcd are consistent with a failure to predict and compensate for the consequences of movement across the body. These results isolate specific impairments in whole-body coordination in mice and provide a quantitative framework for understanding cerebellar contributions to coordinated locomotion.