The findings, published in the peer-reviewed journal eNeuro, provide insights into the neural mechanisms of motor skill learning that may help lead to more effective brain stimulation therapies for patients who experience motor impairment after stroke.
Tanuj Gulati, PhD, assistant professor of Neurology and Biomedical Sciences Center for Neural Science and Medicine at Cedars-Sinai and lead and corresponding author of the study’s paper said “One of the chief complaints of stroke patients is that they can’t complete a grasping action, many patients may be able to reach the goal they want with some recovery, but not be able to grasp it precisely. So we’re trying to understand how the brain generates movement and learns new dexterous/fine motor skills to potentially develop new treatment strategies to correct these disabilities”.
To better understand the changes in the brain during motor learning, the investigators monitored physiological brain activity in the motor cortex and cerebellum of rats as they practiced a skilled reaching task.
The motor cortex, which is the prime mover of all movement, controls arm movement by receiving various targets in the nervous system. One of the basic projections of the motor cortex is the cerebellum, the part of the brain that holds more than half of the neurons in the entire body.
However, the activity between the motor cortex and the cerebellum that occurs during fine motor learning is not widely understood.
Using healthy rats, the investigators recorded chronically from the motor cortex and cerebellar cortex as the animals were trained for five days to perform a fine motor task in which they reached for a sugar pellet placed some distance away. Rats had to reach for the pellet, grasp it, and retrieve it to successfully complete the trial.
The team then compared neural activity from the early days of training to late days to see what changed in the brain as the rodents gained expertise in the task.
The investigators found that as the rats became proficient at the task, they developed synchronous low-frequency oscillatory activity in the two recorded regions that appeared across the skill consolidation network of the motor cortex and cerebellum. This activity also coordinated neural spiking in both of these regions for successful performance of the reach-to-grasp task.
Interestingly, the team did not observe the emergence of low-frequency oscillatory activity in rats that did not gain expertise in the task within five days. “We were able to show that this activity is an indicator of skill learning,” Gulati said. “Understanding these mechanisms in the healthy brain is an important prerequisite for checking whether similar activity is attenuated in the post-stroke brain and can serve as a biomarker during recovery. This activity can then be a target for electrical stimulation approaches to support motor regeneration after stroke.”
