Biology subjects

Agger, S.

Publications and source records attributed to Agger, S..

2 recordsLinked to original sources

bioRxiv2021

Refinement of corticospinal neuron activity during skilled motor learning

The learning of motor skills relies on plasticity of the primary motor cortex as task acquisition drives the remodeling of cortical motor networks1,2. Large scale cortical remodeling of evoked motor outputs occurs in response to the learning of skilled, corticospinal-dependent behavior, but not simple, unskilled tasks1. Here we determine the response of corticospinal neurons to both skilled and unskilled motor training and assess the role of corticospinal neuron activity in the execution of the trained behaviors. Using in vivo calcium imaging, we found temporal coding of corticospinal activity coincided with the development of skilled, but not unskilled, motor expertise. Animals that failed to learn our skilled, precision isometric pull task exhibited a limited repertoire of dynamic movements and reduced network modulation. Transection of the corticospinal tract and optogenetic regulation of corticospinal activity show the necessity for patterned corticospinal network activity in the execution of skilled, but not unskilled, movement. We reveal a critical role for corticospinal network modulation in the learning and execution of skilled motor movements. The integrity of the corticospinal tract is essential to the recovery of dexterous movement after central nervous system injuries and these findings should help to shape translational approaches to motor recovery.

neuroscience↗

bioRxiv2020

Temporal regulation of motor behavior on a modified forelimb dexterity test in mice

Hand and arm manual dexterity is a hallmark of humans and non-human primates. While rodents are less dexterous than primates, they provide powerful models for testing neural circuit function in behavioral output, including dexterous behaviors. In rodents, the single pellet reach task has been used extensively to study both dexterous forelimb motor learning as well as recovery from injury; however, mice exhibit high variability in task acquisition in comparison to rats and a significant percentage fail to learn the task. We have created a recessed version of the task that requires greater dexterity. This subtle modification increases both task difficulty as well as the proportion of mice that show an improvement with training. Furthermore, motor cortex inactivation shows a greater effect on the execution of the recessed forelimb reach task, with distinct effects on reach targeting vs grasping components depending on the timing of inhibitory activation. Kinematic analysis revealed differences in reach targeting upon transient cortical inhibition prior to reach onset. In summary, the recessed single pellet reach task provides a robust assessment of forelimb dexterity in mice and a tool for studying skilled motor acquisition and execution.

neuroscience↗