Role of the Brainstem in Movement More Important Than Expected Due to Newly Discovered Connection
Neuropsychological researcher Ayoub Khalil has been investigating the connection between the cerebral cortex and the cerebellum. His research has led to the discovery of a connection to the pontine nuclei, providing a new perspective on the function of these nuclei.
Role of the Pontine Nuclei
This connection, originating from the midbrain, sends inhibitory signals to the pontine nuclei, reducing local brain activity. This is definitive evidence that the pontine nuclei are not merely passive relay stations but are actively involved in processing information from the cerebral cortex.
The results suggest that not all cells in the pontine nuclei receive these inhibitory signals. It is possible that these inhibitory signals target specific information from the cerebral cortex, which follow-up research will need to confirm. Analyses indicate that these inhibitory signals are likely sent when the cerebral cortex is active, suggesting that the cortex not only sends information directly to the pontine nuclei but also indirectly inhibits them.
Coordinating Movement
The pontine nuclei are the primary source of information from the cerebral cortex to the cerebellum. Understanding their role in this system provides deeper insight into the information required by the cerebellum to coordinate movements. Movement disorders are often caused by damage to the cerebellum, but they can also result from brainstem damage, such as after a stroke. By understanding how this system processes information, we may discover ways to compensate for such damage in the future. For example, in the long term, one could imagine a smart implant that integrates with surrounding brain cells. Additionally, this knowledge may prove useful in other applications where movement coordination is crucial, such as in the development of adaptive prosthetics or robotics.
Optogenetics
The research is based on laboratory experiments. Since the brainstem is a vital part of the brain, direct measurements in this area are highly risky in living organisms. Therefore, the measurements were conducted using brain slices from mice. These slices can survive outside the brain for several hours using a special setup. With a microscope, individual cells are observed and targeted using microelectrodes. These microelectrodes record or manipulate cell activity.
This method was combined with a new technique called optogenetics, which allows brain cells to be manipulated to become sensitive to light stimulation. Using optogenetics, it becomes possible to pinpoint which cells respond to light stimulation, enabling researchers to measure activity in the pontine nuclei corresponding to specific signals from the cerebral cortex.
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