Introducing brain: new studies on our different cerebellum (Introduction)

by David Turell , Sunday, August 21, 2022, 16:04 (611 days ago) @ David Turell

Still not much known, but it seems to many controls beyond motor coordination:

https://www.the-scientist.com/features/the-multitasking-cerebellum-roles-in-cognition-e...

"For Henrietta Leiner, a neuroscientist working in the 1980s and initially trained in mathematics, physics, and computer science, it was the cerebellum’s large size in humans compared with other animals that made her question whether its role was exclusively confined to motor functions. The surface area of the human cerebellum, with its tightly wound folds, is a whopping 80 percent of that of the cerebral cortex. In 1986, before this fact was established, Leiner and her colleagues published a paper proposing that the most recently evolved parts of the cerebellum contributed to higher-level mental functions, thus enabling “mental dexterity” in addition to the “motor dexterity” the “little brain” was already known for." (my bold)

***

"Other early clues for the cerebellum’s wide-ranging functional repertoire came from studies implicating the brain region’s contributions to neuropsychiatric disorders, particularly schizophrenia and autism. For both conditions, research dating back decades has documented evidence of anatomical abnormalities within the cerebellum. These clinical observations jibed with the work of Schmahmann and others back in the 1990s, when they identified anatomical connections in the brains of monkeys that linked the cerebellum with parts of the cerebral cortex involved in memory, attention, and other high-order functions. Years later, in 2009, neuroscientists using functional magnetic resonance imaging in humans found that the cerebellum was activated during tasks involving language, memory, and emotional processing. This work also showed that in most of the cerebellum, neural activity was in sync with that of regions of the cerebral cortex responsible for these nonmotor functions.

"Together, these findings indicated that the cerebellum was potentially involved in a multitude of functions, and that pathways linked the cerebellum to the cerebral cortex, providing a putative neural infrastructure for this functionality. What was still missing was the mechanism—the details of how and when we need the cerebellum for high-order processes such as cognition, says Catherine Stoodley, professor of psychology at American University. “There’s a lot of interest from the experimental side where researchers are saying, ‘Okay, we’re buying the idea now that the cerebellum is involved in cognition—but what is it doing?’”

***

"Although the cerebellum appears small from the outside, the structure’s many coral-like branches give it a surface area that is 80 percent of the surface area of the larger cerebral cortex.

"Illustration showing how the cerebellum can be divided into specific regions linked specifically to motor, cognitive, and emotion-related functions.

"Functional MRI studies suggest that the cerebellum can be divided into specific regions linked specifically to motor, cognitive, and emotion-related functions.

"The specific mechanisms behind the cerebellum’s multitude of functions remains a mystery, but the orderly arrangement of the neurons within the structure indicate that it may carry out a single computation—or set of computations—that it applies across its many roles.

"Training a high-powered microscope on a slice of the cerebellum will reveal large, densely packed Purkinje cells arranged in an orderly, grid-like pattern. This unique architecture, which is much simpler and more uniform than that of the rest of the brain, led some researchers to propose that the cerebellum carries out a single computation—what Schmahmann calls the universal cerebellar transform—that is generally applied across its many functions, both motor and nonmotor. Jennifer Raymond, a neuroscientist at Stanford University, is one of many researchers who agree with this idea. Given how stereotyped the architecture is, she says, there must be some specific computation or set of computations that this anatomy is good for.

***

"In the case of schizophrenia, researchers have shown that stimulating a specific cerebellar circuit with TMS can alleviate the “negative” symptoms of the disorder, such as the lack of motivation or the inability to feel pleasure, in a small sample of patients. Those findings are now being explored in a larger clinical trial. Roscoe Brady, a psychiatrist at the Beth Israel Deaconess Medical Center in Boston who was involved in that research, says that he and his colleagues now have evidence that stimulating another, distinct cerebellar circuit can also reduce hallucinations. In addition, the team has pinpointed a third circuit linked specifically to cognitive deficits, Brady adds. “Our plan for the future is to try and determine if that circuit can be modulated by TMS as well.'”

Comment: our large cerebellum, compared to other organisms is finally studied. It arrived 315,000 years ago and performs its duties, and we are now trying to find out how much it does for us. Note my bold. The folding of the cerebellar surface is 80% the size of the cerebral surface. Based on this review article there is lots to learn. Read the entire article to see how much is known. To large to present here.