#  Basal ganglia research offers possible clues into human movement disorders 

 





August 11, 2025

 

 

     ![Postdoc Kiah Hardcastle working in the lab](/sites/g/files/omnuum6811/files/styles/hwp_16_9__480x270/public/2025-08/Kiah%20Hardcastle_credit%20Staphanie%20Mitchell-Harvard%20Staff%20Photographer.jpeg?h=cbd5af35&itok=_0zD2L5T) 

Lead author, Kiah Hardcastle, working in the lab. Credit: Stephanie Mitchell-Harvard Staff Photographer



 



 

Neuroscientists have long known that movements of the body are controlled by the basal ganglia area of the brain. But a new study published in [Nature Neuroscience](https://www.nature.com/articles/s41593-025-02026-w) discovered that this system uses two distinct codes to guide behavior: one for recently acquired learned movements and another for innate "natural" behaviors.

“When we compared the codes across these two behavioral domains, we found that they were very different,” said senior author Professor Bence Ölveczky. “They had nothing to do with each other. They were both faithfully reflecting the animal’s movements, but the language was profoundly different.”

The study, led by postdoctoral researcher Kiah Hardcastle, examined one part of the basal ganglia in rats — the dorsolateral striatum (DLS), which plays a role in learned behaviors. Using implanted electrodes and motion-tracking technology, the researchers monitored rats during both free exploration and a learned lever-pressing task. They found that the DLS showed distinct patterns of electrical activity for each type of movement.

[In earlier studies](https://www.nature.com/articles/s41593-021-00889-3) the team removed the DLS in the rats which left natural behaviors intact, but wiped out the rats' ability to perform the learned task, underscoring its role in practiced skills.

“There was a massive change, like night and day,” said Hardcastle. “The animal could do a task super well, performing a stereotyped movement repeatedly, like 30,000 times. Then you lesion the DLS, and they never do that movement again.”

In this study the team discovered that the basal ganglia used two distinct patterns of neuronal electrical activity: one during a learned task and another during a natural movement.

"The basal ganglia appears to switch back and forth between being an essential actor and a mere observer," said Hardcastle, who further speculated that the basal ganglia may be unable to fully shut down an electrical signal when not directing a behavior.

Hardcastle speculated that the basal ganglia may be unable to completely turn off electrical signaling when not directing behavior, so it shifts to a harmless “null code.”

The surprise findings combined with the location of the basal ganglia in the midbrain below the cerebral cortex, may offer clues into some of the most troubling movement disorders: Huntington’s disease, Tourette’s syndrome, and Parkinson’s all arise from different defects of the basal ganglia.



 

 

 



 

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