Key kinematic features in early training predict performance of adult female mice in a single pellet reaching and grasping task

Abstract

Detailed analyses of overly trained animal models have been long employed to decipher foundational features of skilled motor tasks and their underlying neurobiology. However, initial trial-and-error features that ultimately give rise to skilled, stereotypic movements, and the underlying neurobiological basis of flexibility in learning, to stereotypic movement in adult animals are still unclear. Knowledge obtained from addressing these questions is crucial to improve quality of life in patients affected by movement disorders. We sought to determine if known kinematic parameters of skilled movement in humans could predict learning of motor efficiency in mice during the single pellet reaching and grasping assay. Mice were food restricted to increase motivation to reach for a high reward food pellet. Their attempts to retrieve the pellet were recorded for 10 minutes a day for continuous 4 days. Individual successful and failed reaches for each mouse were manually tracked using Tracker Motion Analysis Software to extract time series data and kinematic features. We found the number of peaks and time to maximum velocity were strong predictors of individual variation in failure and success, respectively. Overall, our approach validates the use of select kinematic features to describe fine motor skill acquisition in mice and establishes peaks and time to maximum velocity as predictive measure of natural variation in motion efficiency in mice. This manually curated dataset, and kinematic parameters would be useful in comparing with pose estimation generated from deep learning approaches.

ReachingBot: an automated and scalable benchtop device for highly parallel Single Pellet Reach-and-Grasp training and assessment in mice

“…The single pellet reaching and grasping (SPRG) task was first described in 1990 by Whishaw and Pellis for use in rodents (Whishaw and Pellis, 1990). It is used to mimic reaching and grasping in humans, to study both motor learning (Mykins et al, 2021) and recovery after brain injury preclinically (Wahl et al, 2014). The SPRG task challenges animals to reach for a food reward through a thin vertical window from within a clear acrylic box.…”

“…Initially, animals first exposed to the task fail to retrieve pellets, but with training their success rate increases. The ratio of successful grasps compared to failed grasps of the food pellet reward is often used as a principle behavioural outcome measure: the rate at which this ratio increases can be used in motor learning studies, (Mykins et al, 2021, Bova et al, 2021) or in assessing deficits and recovery in animal models of stroke (Wahl et al, 2014), spinal cord injury (Fenrich et al, 2016), Huntington’s Disease (Glangetas et al, 2020) or Parkinson’s Disease (Bova et al, 2020). Other measurements can also be taken from animals executing this task, such as the kinematics of the reaching trajectory, the velocity of the reach and the number of reach attempts, for example (Bova et al, 2021, Mykins et al, 2021).…”