Summary: As rat models became proficient at learning new motor skills, they developed synchronous low-frequency oscillatory activity in two brain areas that were recorded that emerged across the cerebellum and motor cortex networks with skill consolidation.
Source: Cedars Sinai Medical Center
The findings, published in the peer-reviewed journal eNeuro, provide insight into the neural mechanisms of motor skill learning that can help lead to more effective brain-stimulation therapies for patients experiencing motor disability after a stroke.
“One of the main complaints from stroke patients is that they cannot complete the grasping action,” said Tanuj Gulati, PhD, assistant professor of Neurology and Biomedical Sciences’ Center for Neural Science and Medicine at Cedars-Sinai and senior and corresponding author of the study.
“Many patients may be able to reach for the target they want with some recovery, but they are not able to grasp it accurately. So, we are looking to understand how the brain generates movement and learns new dexterous/fine motor skills so we can potentially develop novel treatment strategies to repair these disabilities.”
To better understand changes in the brain during the course of motor learning, investigators looked at brain physiological activity in the motor cortex and the cerebellum in rats as they practiced a skilled reaching task.
The motor cortex, which is the chief driver of all movement, controls arm movement by recruiting a variety of targets in the nervous system. One fundamental projection of the motor cortex is to the cerebellum, the part of the brain that holds more than half the neurons of the entire body.
However, the activity between the motor cortex and the cerebellum that emerges as a fine motor skill is learned is not widely understood.
Using healthy rats, investigators recorded from the motor cortex and the cerebellar cortex chronically as the animals were trained for five days to perform a fine motor task where they reached for a sugar pellet placed at a distance from them. Rats had to reach for and grab the pellet and retrieve it for successful completion of the trial.
The team then compared the neural activity from the early days of training to the late days to see what changed in the brain as the rodents gained proficiency in the task.
The investigators discovered that as the rats became proficient in the task, they developed synchronous low-frequency oscillatory activity in the two areas that were recorded that emerged across the motor cortex and cerebellum networks with skill consolidation. This activity also coordinated neural spiking in both these regions for successful reach-to-grasp task execution.
Interestingly, the team did not observe the emergence of low-frequency oscillatory activity in the rats that did not gain expertise in the task within the five days.
“We were able to show this activity is a marker of skill learning,” said Gulati.
“Understanding these mechanisms in a healthy brain is an important precursor to check if similar activity is weakened in the brain after a stroke and can serve as a biomarker during recovery. This activity can then be a target for electric stimulation approaches to promote motor recovery after a stroke.”
Gulati is now working to repeat this work in stroke rats to see if this coordinated low-frequency activity in the motor cortex and cerebellum becomes weak in the animals after a stroke and resurges as the rats recover their reaching and grasping abilities.
Other Cedars-Sinai authors include Pierson Fleischer, PhD; Aamir Abbasi, PhD; Andrew Fealy; Nathan Danielsen; Ramneet Sandhu; and Philip Raj.
Funding: The research is supported by the American Heart Association, National Institutes of Health (award R00NS097620) and the National Science Foundation.
About this motor skill and neuroscience research news
Emergent low-frequency activity in cortico-cerebellar networks with motor skill learning
The motor cortex controls skilled arm movement by recruiting a variety of targets in the nervous system, and it is important to understand the emergent activity in these regions as refinement of a motor skill occurs. One fundamental projection of the motor cortex (M1) is to the cerebellum.
However, the emergent activity in the motor cortex and the cerebellum that appears as a dexterous motor skill is consolidated is incompletely understood.
Here, we report on low-frequency oscillatory (LFO) activity that emerges in cortico-cerebellar networks with learning the reach-to-grasp motor skill.
We chronically recorded the motor and the cerebellar cortices in rats which revealed the emergence of coordinated movement-related activity in the local-field potentials (LFPs) as the reaching skill consolidated. Interestingly, we found this emergent activity only in the rats that gained expertise in the task.
We found that the local and cross-area spiking activity was coordinated with LFOs in proficient rats. Finally, we also found that these neural dynamics were more prominently expressed during accurate behavior in the M1.
This work furthers our understanding on emergent dynamics in the cortico-cerebellar loop that underlie learning and execution of precise skilled movement.