A Key Role for the Thalamus in Adult Brain Plasticity
The thalamus, which is often only thought of as a relay station, is being highlighted by researchers as a crucial component of adult brain plasticity.
Contrary to popular opinion, which places most of the emphasis on the cortex, mouse models in vision research have revealed that the thalamus plays a substantial role in adjusting sensory and motor input.
While visual data does travel through the thalamus on its way from the retina to the visual cortex, this study emphasizes that the thalamus is not just a passive conduit for information but also an active participant in adaptation processes.
By expanding the focus from the brain to include the thalamus, new therapeutic strategies for disorders like lazy eye may be made possible.
Key Facts:
Critical Component: The thalamus’s function in brain plasticity is highlighted by the ablation of the GABA-alpha 1 subunit during the crucial stage of mice’s visual development, which drastically changed the traditional visual cortex response.
Adaptability Insights: Experiments showed that adult thalamic plasticity took place and was crucial for changes in the cortex, demonstrating its significant presence beyond merely sensory relay.
Potential treatment Applications: The findings point to the thalamus as a potential treatment target for conditions that have previously been assigned to the brain, such as lazy eye.
Author: KNAW
The cortex is usually thought to have a major role in the adult brain’s ability to adapt. A recent study from the Netherlands Institute for Neuroscience reveals that the thalamus, which serves as a relay station for incoming sensory and motor information, really plays a surprising function in this process.
Christiaan Levelt says, “This could be an interesting starting point for different therapies.”
Our brains must have a significant amount of processing power to learn new things. The adaptation of our brain as a result of new experiences is called plasticity. Critical periods are times in human development when brain networks exhibit a high level of flexibility. The adult brain can also adapt, though. It is unclear exactly where in the adult brain this plasticity occurs.
Under the direction of Christiaan Levelt, Yi Qin and his associates investigated the mouse visual system to learn more about this issue. Due to its simplicity of manipulation, this model is a favorite for research on plasticity. The retina sends visual information to the thalamus. The visual cortex receives processed information from this brain region and vice versa. An experiment on mice can plainly show how adaptable the adult brain is.
“The visual cortex of the mouse begins to respond less effectively to the closed eye and more efficiently to the open eye after several days of occlusion of one eye. For a very long time, it has been unclear how exactly this is governed. But these new findings highlight a crucial player: the thalamus.
New Viewpoint
“Five years ago, we found that the thalamus plays a critical role in the plasticity of the visual cortex during critical periods of development,” says Christiaan Levelt. Our understanding of how this entire system operates has changed as a result.
“We all believed that the visual cortex controlled this process, but it wasn’t the complete picture. We learned this by eliminating a very specific component from mice’s thalamus during a crucial moment for vision, the GABA-alpha 1 subunit. Removal of this element decreased inhibition because it is in charge of inhibiting the thalamus.
“In these mice, the shift in behavior vanished when we shut one eye. Was the thalamus involved in adaptation in the adult visual system? This was a crucial topic since the adult brain uses different plasticity processes than the developing brain.
“In the current study, we carried out the same experiment on adult mice and noticed similar outcomes,” says Yi Qin. When the alpha-1 subunit was eliminated, we found that plasticity no longer existed in the adult thalamus. There was consequently no longer a shift in the cortex.
We wondered if the visual cortex also contributes to the thalamus’ plasticity because we are aware that the visual cortex communicates with the thalamus through a feedback mechanism.
“We looked into this by conducting the experiment backwards and turning off the visual cortex. What happens to the thalamic shift in responses then? We saw no difference in the shift in mature animals.
But when we turned off the visual cortex in rats during their critical phase, the shift went back to the thalamus. Therefore, in the developing brain, thalamic and cortical plasticity interact significantly more, whereas in the adult brain, the thalamus is crucial for cortical plasticity but not the other way around.
a number of processes
“Plasticity is important in many processes,” Levelt explains. Although vision is the sensory modality on which we are now concentrating, plasticity is equally essential for memory and other cognitive processes. These fresh perceptions might help us comprehend learning difficulties, for instance.
It’s probable that the thalamus, rather than the brain, is where these issues originated. Consequently, a different strategy is required. When it comes to treatments and the pathophysiology of these problems, we should take the thalamus into account as well as the cortex. This new interpretation is significant.
Even while a lazy eye is thought to be a cortex-related issue, the thalamus may also be involved, according to Qin. In Europe, we start testing children early to see if they have sluggish eyes. By covering the “good eye” for a short time at the crucial time, this problem can be treated while strengthening the connections to the weaker eye.
pertaining to this news on neuroplasticity
Eline Feenstra, author
Author: KNAW
You can reach Eline Feenstra at KNAW.
Image: Neuroscience News is given credit for this one.