Learned abilities in rats deciphered, offering insight into human mobility issues

A groundbreaking study published in Nature Neuroscience has delved into the intricate workings of the basal ganglia, a crucial part of the brain responsible for motor control, reward processing, and cognition. Led by Matthias H. Hennig and co-authors, including Bence Ölveczky, the research offers fascinating insights into the neural mechanisms underlying learned movements and natural behaviours in rats.

The study, titled "Differential kinematic coding in sensorimotor striatum across behavioral domains reflects different contributions to movement," focused on the dorsolateral striatum (DLS), a subregion of the basal ganglia that plays a key role in learned behaviours. Researchers discovered that the basal ganglia, including the DLS, use two distinct "kinematic codes," or patterns of neuronal electrical activity, during learned tasks and natural movements.

To conduct the study, the team of scientists employed rats participating in two activities: free exploration and a learned task in which they were trained to press a lever twice within a specific time interval to obtain a reward. The researchers utilized a system of six cameras around the enclosure, coupled with a software system, to categorize behaviours. They also recorded neural activity during these behaviours using electrodes implanted into the brains of rats.

Interestingly, the study found that removing the DLS did not affect free exploration but impaired learned tasks, with the impact described as a "massive change, like night and day." Rats with a lesioned DLS were unable to perform learned tasks again, indicating the DLS's importance for newly acquired skills.

These findings may be particularly informative about human movement disorders like Parkinson's disease. According to Bence Ölveczky, the pathology associated with Parkinson's disease can be understood as the diseased basal ganglia speaking "gibberish," inserting itself forcefully into behaviours it would otherwise not control. Kiah Hardcastle, another co-author, speculated that the basal ganglia may have a harmless "null code" when not directing behaviour.

The basal ganglia, including the DLS, may have remained conserved through evolutionary time. This study offers hints about neural dysfunction in human movement disorders, providing valuable insights that could potentially lead to novel therapies for these debilitating conditions.

Learned abilities in rats deciphered, offering insight into human mobility issues