SAN DIEGO (KGTV) — Scientists from UC San Diego have published a study in the journal Nature detailing how brain wiring changes while learning. The study's findings are supported by the National Institutes of Health and U.S. National Science Foundation, and UCSD scientists say this discovery could help offer a path to new therapies and technologies that aid those with neurological disorders.
For many years, neuroscientists have identified the brain’s primary motor cortex (M1), which lies in the frontal lobe region, as a hub for sending out signals related to complex movements as animals are learning, researchers say. More recently, the motor thalamus, located in the center of the brain, is an area that influences M1 during motor learning functions.
Despite these advancements, researchers lacked evidence on how the learning process happens, mainly because it is difficult to monitor how cells interact with one another from different areas of the brain.
For this study, a research team led by Professor Takaki Komiyama’s laboratory used high-tech imaging and a novel data analysis method on mice to identify the thalamocortical pathway, a communication bridge between the thalamus and the cortex, as the key area that is molded during learning.
Researchers also found that links between brain regions change physically as learning happens. The study states that motor learning does much more than adjust brain activity levels; it also forms the circuit's wiring, which refines cellular communication between the thalamus and cortex.
“Our findings show that learning goes beyond local changes — it reshapes the communication between brain regions, making it faster, stronger, and more precise,” said Assaf Ramot, the study’s lead author and a postdoctoral scholar in the Komiyama Lab. “Learning doesn’t just change what the brain does — it changes how the brain is wired to do it.”
As mice learned specific movements during the study, researchers found out that learning caused a focused reorganization of the interaction between the cortex and thalamus. As learning happens, researchers noticed that the thalamus managed to activate M1 neurons to "encode the learned movement and to halt the activation of neurons not involved with the movement being learned."
“During learning, these parallel and precise changes are generated by the thalamus activating a specific subset of M1 neurons, which then activate other M1 neurons to generate a learned activity pattern,” said Komiyama, a professor in the departments of Neurobiology and Neurosciences.
A key insight from this study was bringing the activity of specific neurons into focus. UCSD credits Neurobiology Assistant Professor Marcus Benna and graduate student Felix Tashbach with creating the Shared Representation Discovery, or ShaReD, analytical method.
See the diagram below:
According to Taschbach, who spearheaded this part of the project, identifying behaviors that are commonly encoded across different subjects presents "a significant challenge because behaviors and their neural representations can vary substantially between animals."
Using ShaReD, the researchers were able to identify one instance of a "shared behavioral representation" that correlates with brain activity across different animals, allowing them to map "subtle behavioral features" to the neural activity in each subject.
According to the study, previous methods usually enforced artificial alignment to reduce individual variability — similar to requiring everyone to follow exactly the same route to a destination. In contrast, ShaReD functions more like identifying which landmarks consistently help travelers navigate, regardless of their specific route choices. The ShaReD method was critical to the study’s findings.
“This new method allows us to combine data from multiple experiments to make detailed discoveries that would not have been possible using only the limited number of relevant neurons recorded in an individual brain,” said Marcus K. Benna, a computational neuroscientist and co-corresponding author of this study.
