Automated Forelimb Tasks for Rodents: Current Advantages and Limitations, and Future Promise

Abstract

Rodent tests of function have advanced our understanding of movement, largely through the human training and testing and manual assessment. Tools such as reaching and grasping of a food pellet have been widely adopted because they are effective and simple to use. However, these tools are time-consuming, subjective, and often qualitative. Automation of training, testing, and assessment has the potential to increase efficiency while ensuring tasks are objective and quantitative. We detail new methods for automating rodent forelimb tests, including the use of pellet dispensers, sensors, computer vision, and home cage systems. We argue that limitations in existing forelimb tasks are driving the innovations in automated systems. We further argue that automated tasks partially address these limitations, and we outline necessary precautions and remaining challenges when adopting these types of tasks. Finally, we suggest attributes of future automated rodent assessment tools that can enable widespread adoption and help us better understand forelimb function in health and disease.

N-Acetylcysteine Treatment May Compensate Motor Impairments through Dopaminergic Transmission Modulation in a Striatal 6-Hydroxydopamine Parkinson’s Disease Rat Model

“…Regarding the manual foot task, the absence of foot-faults score differences observed in the left side of both fore- and hindlimbs ( Figure 5 ) could be justified by the scoring system applied. This method cannot track movements, with the high resolution being largely qualitative [ 87 ]. Among hindlimbs, results clearly reflect an increase in basic locomotor function during walking ( Figure 5 ), which could likely be related to anatomical differences in limbs or to the fact that the hindlimb may not be essential for locomotor control under these conditions [ 88 ].…”

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

“…Clinicians assess motor efficiency by using scoring systems combined with kinematic parameters such as peaks, mean squared jerk, and time to maximum velocity (Bosecker et al, 2010;Carr et al, 1985;Fugl-Meyer et al, 1975). Scoring systems in rodents are not ideal as these systems rely on the presence or absence of motor deficits and cannot discern more subtle changes in movements in rodents (Sindhurakar et al, 2019). Growing evidence from qualitative and quantitative analyses of reach kinematics supports the notion that motions utilized by rodents and humans in reach-tograsp task are homologous (Becker et al, 2020;Buitrago et al, 2004;Karl & Whishaw, 2013;Klein et al, 2012;Sacrey et al, 2009;Whishaw et al, 1992).…”

AutoRG: An automatized reach-to-grasp platform technology for assessing forelimb motor function, neural circuit activation, and cognition in rodents

“…Moreover, while rodents assessed with the single-pellet SRT often display no functional impairment by week 6 post-injury, there is evidence that the pull task is more sensitive to long-term impairment as task ability persists at a reduced capacity in this same time frame ( Sloan, 2015 ). Though these automated systems are able to reduce the amount of experimenter intervention and the time necessary to train the rats to consistent task performance, the hardware required to execute these manipulandum assays like the knob supination task and the isometric pull task are expensive and cost around $3500 per device commercially ( Sindhurakar et al, 2019 ), which significantly limits simultaneous functional assessment of animal cohorts. Further, the cortical motor circuitry evoked by this emerging isometric pull task has not yet been histologically evaluated in comparison to the conventional single pellet SRT.…”