Design and optimisation of OpenStride an open-source inexpensive force plate actometer

Abstract

Quantitative assessment of rodent motor behaviour is central to preclinical neuroscience, and evaluation of naturalistic movement is of particular interest. In the early 2000s, force plate actometry (FPA) was developed to track rodent subject centre-of-mass (COM) with high temporal and spatial precision, enabling varied quantifications relevant to motor performance and behaviour. While FPA was commercialised, these systems cost ~$15,000 AUD and are no longer produced. Thus, despite clear utility, particularly in movement disorders and neuropsychiatric research, FPA adoption has remained limited. In this work, we sought to develop an open-source, low-cost FPA system called OpenStride, and to characterise how its performance is shaped by hardware and signal processing choices, providing users with information needed to use it effectively across varied experimental contexts.

We designed OpenStride to be able to be fabricated for ~$800 AUD using standard 3D printing and laser cutting. OpenStride achieves minimal static drift during long recordings and minimal signal displacement in response to environmental perturbation; further, it reliably tracks position and distance and can separate groups of rodents with established motor phenotypes. We characterised the influence of five key variables on measurement quality: applied load, load cell excitation voltage, mechanical damping, platform mass, and signal filtering, providing suggestions on how to optimise setup in a context-dependent manner.

Our findings support the interpretation that OpenStride is capable of meaningful motor and behavioural quantification across rodent species and experimental paradigms. Its performance is influenced by modifiable parameters, and understanding these relationships allows users to configure the system to suit their specific needs. All hardware and software files have been distributed freely via GitHub, with the intent of making force plate actometry accessible to the research community.