The Home-Cage Automated Skilled Reaching Apparatus (HASRA): Individualized Training of Group-Housed Mice in a Single Pellet Reaching Task

Abstract

The single pellet reaching task is commonly used in rodents to assess the acquisition of fine motor skill and recovery of function following nervous system injury. Although this task is useful for gauging skilled forelimb use in rodents, the process of training animals is labor intensive and variable across studies and labs. To address these limitations, we developed a single pellet reaching paradigm for training and testing group housed mice within their home cage. Mice enter a training compartment attached to the outside of the cage and retrieve millet seeds presented on a motorized pedestal that can be individually positioned to present seeds to either forelimb. To identify optimal training parameters, we compared task participation and success rates between groups of animals that were presented seeds at two different heights (floor vs mouth height) and at different intervals (fixed-time vs trial-based). The mouth height/fixed interval presentation style was most effective at promoting reaching behavior as all mice reached for seeds within 5 d. Using this paradigm, we assessed stroke-induced deficits in home-cage reaching. Following three weeks of baseline training, reaching success rate was ∼40%, with most trials performed during the dark cycle. A forelimb motor cortex stroke significantly decreased interaction with presented seeds within the first 2 d and impaired reaching success rates for the first 7 d. Our data demonstrate that group-housed mice can be efficiently trained on a single pellet reaching task in the home cage and that this assay is sensitive to stroke induced motor impairments.

The Emergence of Stereotyped Kinematic Synergies when Mice Reach to Grasp Following Stroke

“…Secondly, behavioral kinematic analysis has made it feasible to complete larger sample sizes required through discovery, validation, and automation of 3D markerless tracking systems such as DeepLabCut, 47 use of synthetic animated mice to generate training data for behavioral analysis, 48 as well as creation of home-cage group housed reaching tasks. 49 Thus, preclinical studies will be able to test larger sample sizes, a variety of stroke models, and different reaching tasks, with the goal to produce targeted therapies to improve reaching impairments in stroke survivors.…”

When Spinal Neuromodulation Meets Sensorimotor Rehabilitation: Lessons Learned From Animal Models to Regain Manual Dexterity After a Spinal Cord Injury

“…Environmental enrichment is one of these ad libitum approaches, but it involves a non-task-specific training as stated above and the amount of training performed by each individual is difficult to monitor (50)(51)(52). Recently, diverse automated systems (e.g., automatic pellet dispensers) have been developed so they can be coupled to or integrated in the animal's home cage allowing for free access to forelimb task-specific training (76)(77)(78). These studies report that both intact and injured rats self-engage in reaching and grasping training more prominently during the dark (66, 79), and achieve higher amounts of rehabilitative training by self-enrolment than manual training after cervical SCI (66,76).…”

Localizing Microemboli within the Rodent Brain through Block-Face Imaging and Atlas Registration

“…Indeed, microinfarcts placed strategically within the brain can produce detectable behavioural impairments (Shih et al, 2013). To fully embrace the variability of microinfarct distribution within our model, automated behavioural paradigms (Birtalan et al, 2020;Salameh et al, 2020, Silasi et al, 2017) may be used to reveal the functional consequences of microocclusion load within sensorimotor or cognitive networks.…”