TY - JOUR T1 - Evolution of gross forelimb and fine digit kinematics during skilled reaching acquisition in rats JF - eneuro JO - eNeuro DO - 10.1523/ENEURO.0153-21.2021 SP - ENEURO.0153-21.2021 AU - Alexandra Bova AU - Kenneth Ferris AU - Daniel K. Leventhal Y1 - 2021/10/08 UR - http://www.eneuro.org/content/early/2021/10/08/ENEURO.0153-21.2021.abstract N2 - The ability to learn dexterous motor skills is a fundamental aspect of human behavior. However, the underlying neural circuit mechanisms for dexterous skill learning are unclear. Advancing our understanding of motor skill learning requires the integration of modern neuroscientific techniques with a rigorously characterized dexterous task. The development of automated rodent skilled reaching with paw tracking allows detailed analysis of how reach-to-grasp kinematics evolve during learning. We assessed how both ‘gross’ forelimb and ‘fine’ digit kinematics changed as rats learned skilled reaching. Rats whose success rates increased (learners) consistently reduced the variability in their reach trajectories. Refinement of fine digit control generally continued after consistency in gross hand transport to the pellet plateaued. Interestingly, most rats whose success rates did not increase (non-learners) also converged on consistent reach kinematics. Some non-learners, however, maintained substantial variability in hand and digit trajectories throughout training. These results suggest that gross and fine motor components of dexterous skill are, on average, learned over different timescales. Nonetheless, there is significant inter-subject variability in learning rates as assessed by both reaching success and consistency of reach kinematics.SIGNIFICANCE STATEMENTHumans depend heavily on the ability to learn novel, dexterous motor skills. The rodent skilled reaching task is commonly used to study dexterous skill learning. However, how reach-to-grasp kinematics evolve as rats learn skilled reaching has not been carefully characterized. By combining an automated rodent skilled reaching task with hand and digit tracking, we found significant variability in both success rates and the evolution of hand/digit kinematics. This interindividual variability is important for interpreting skilled reaching studies. Furthermore, understanding the neurobiologic basis of this variability may yield insights into improving human motor learning and rehabilitation. ER -