Automated quantification of spinal axis distortion for behavioral assessment after spinal cord injury in mice

Spinal cord injury (SCI) causes persistent locomotor deficits that are commonly evaluated in mouse SCI models using observational scoring systems such as the Basso Mouse Scale, which primarily assesses hindlimb function. Here, we established an automated behavioral analysis pipeline using DeepLabCut to quantify spinal axis distortion, a characteristic feature of locomotor impairment after SCI, during open-field locomotion in mice. By tracking multiple anatomical landmarks along the spine and tail, this approach enabled the extraction of locomotor parameters, including speed, travel distance, and segmental angular measurements of rostrocaudal spinal alignment.

SCI mice in the acute phase showed reduced locomotor speed and travel distance, and exhibited significant spinal axis distortion compared with intact controls. Furthermore, Y-27632 treatment was associated with a reduction in one segmental spinal axis angle, and spinal axis angles showed weak-to-moderate associations with BMS scores across animals. These results support spinal axis distortion as an objective quantitative metric that complements conventional locomotor scoring systems for the assessment of functional impairment and recovery after SCI.

The analysis code used in this study is publicly available at https://github.com/NCNP-MolPharm/Oe_et_al.git. Source data are publicly available in Zenodo (https://doi.org/10.5281/zenodo.22197138). Additional data are available from the corresponding author upon reasonable request.

Yoshino Yonezu for her insightful perspective on body-axis-based analysis and for her assistance with spinal cord injury surgery. Kyoka Higuchi for her assistance with animal experiments. This study was supported by AMED (Grant Number JP25gm1510009 to R.M.); JSPS KAKENHI (Grant Number JP26H02432 to R.M.); and an Intramural Research Grant for Neurological and Psychiatric Disorders of NCNP (Grant Number 8-1 to R.M.).

Department of Molecular Pharmacology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-higashi, Kodaira, Tokyo, 187-8502, Japan Natsuki Oe, Akiko Uyeda & Rieko Muramatsu Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences and Faculty of Pharmaceutical Sciences, Tokyo University of Science, Katsushika, Tokyo, Japan Department of Systems Life Engineering, Maebashi Institute of Technology, Maebashi, Gunma, Japan Department of Pharmacy and Health Sciences, Faculty of Pharmaceutical Sciences, Meiji Pharmaceutical University, Kiyose, Tokyo, Japan The authors declare no competing interests. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material.

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