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Mind’s quality control center found in long-ignored brain area: Cerebellum checks and corrects thoughts, movement -- ScienceDaily
"The biggest surprise to me was the discovery that 80 percent of the cerebellum is devoted to the smart stuff," said senior author Nico Dosenbach, MD, PhD, an assistant professor of neurology, of occupational therapy and of pediatrics. "Everyone thought the cerebellum was about movement. If your cerebellum is damaged, you can't move smoothly -- your hand jerks around when you try to reach for something. Our research strongly suggests that just as the cerebellum serves as a quality check on movement, it also checks your thoughts as well -- smoothing them out, correcting them, perfecting things."
Dosenbach is a founding member of the Midnight Scan Club, a group of Washington University neuroscientists who have taken turns in an MRI scanner late at night, scanning their own brains for hours to generate a massive amount of high-quality data for their research. A previous analysis of Midnight Scan Club data showed that a kind of brain scan called functional connectivity MRI can reliably detect fundamental differences in how individual brains are wired.
Postdoctoral researcher and first author Scott Marek, PhD, decided to apply a similar analysis to the cerebellum. In the better-known cerebral cortex -- the crumpled outer layer of the brain -- wiring maps have been drawn that connect distant areas into networks that govern vision, attention, language and movement. But nobody knew how the cerebellum is organized in individuals, partly because a quirk of MRI technology means that data obtained from the underside of the brain tend to be low quality. In the Midnight Scan Club dataset, however, Marek had access to more than 10 hours of scans on each of 10 people, enough to take a serious look at the cerebellum.
Using the cortex's networks as a template, Marek could identify the networks in the cerebellum. Notably, the sensory networks are missing -- vision, hearing and touch -- and only 20 percent of the cerebellum is devoted to movement, roughly the same amount as in the cerebral cortex. The remaining 80 percent is occupied by networks involved in higher-order cognition: the attention network; the default network, which has to do with daydreaming, recalling memories and just idly thinking; and two networks that oversee executive functions such as decision-making and planning.
Exercise improving concentration
In research yet to be published, Maria Chiara Gallotta at the University of Rome in Italy found that twice-weekly sessions of coordinative exercises, such as basketball, volleyball or gymnastics practice, over the course of five months helped children do better on tests that required concentration and ignoring distractions.
The cerebellum — the finely wrinkled structure at the base of the brain — has been long known to be involved in coordinating movement, but is now recognised as having a role in attention as well. Practising complicated movements activates the cerebellum and, by working together with the frontal lobe, might improve attention in the process.
fMRI study of 1,246 Duke undergrads finds common brain structures in disorders
Working with colleague and coauthor, Avshalom Caspi, also a professor of psychology and neuroscience at Duke, Romer first used information from the assessments to estimate each individual's p-factor score. She then used the MRI data to test correlations between the estimated p-factor scores and grey matter volume, a measure of brain density, and the "integrity" of white matter pathways throughout the brain.
She and the team were surprised to find that higher p-factor scores were correlated with lower grey matter volume in the cerebellum, a region of the brain that has traditionally been associated more with motor function and coordination than with emotion and thinking.
She also found that students with higher p-factor scores showed less integrity of white matter pathways within the pons, which includes wiring that connects the cerebellum with higher-order reasoning centers in the prefrontal cortex. These connections are known to play a key role in providing feedback on how well our movements are in sync with our internal model of what we hope to achieve, so that we can update and change course accordingly.
These white matter pathways may also play a similar role in providing real-world feedback that helps us better regulate our thoughts and emotions, the researchers say.
What Is This Thing Called Consciousness?
Yet the cerebellum has everything you expect of neurons. It has gorgeous neurons. In fact, some of the most beautiful neurons in the brain, so-called Purkinje cells, are found in the cerebellum. Why does the cerebellum not contribute to consciousness? It has a very repetitive and monotonous circuitry. It has 69 billion neurons, but they have simple feed-forward loops. So I believe the way the cerebellum is wired up does not give rise to consciousness. Yet another part of the brain, the cerebral cortex, seems to be wired up in a much more complicated way. We know it’s really the cortex that gives rise to conscious experience.
Born without a cerebellum
We also know that consciousness does not require your entire brain. You can lose 80 percent of your neurons. You can lose the little brain at the back of your brain called the cerebellum. There was recently a 24-year-old Chinese woman who discovered, when she had to get a brain scan, that she has absolutely no cerebellum. She’s one of the extremely rare cases of people born without a cerebellum, including deep cerebellar nuclei. She never had one. She talks in a somewhat funny way and she’s a bit ataxic. It took her several years to learn how to walk and speak, but you can communicate with her. She’s married and has a child. She can talk to you about her conscious experiences. So clearly you don’t need the cerebellum.
During learning, neurons deep in brain engage in a surprising level of activity -- ScienceDaily
It's the part of the brain that makes sure you cannot tickle yourself. The cerebellum, an apple-sized region near the base of the skull, senses that your own fingers are the ones trying to tickle, and cancels your usual response.
Now an international team of researchers has learned something surprising about this region, which despite its small size contains roughly half of all the neurons in the brain. These neurons, which were thought to fire only rarely as they take in information from the senses, are in fact far more active than previously suspected. The finding, published March 20 in the journal Nature Neuroscience, may signal a major shift in our understanding of how the cerebellum encodes information.
"People used to think that the cerebellum's input layer of neurons was only sparsely active, and encoded only information collected from the external world," said Sam Wang, professor of molecular biology and the Princeton Neuroscience Institute, and a senior co-author on the study. "It turns out that they light up like a Christmas tree, and they convey information both from outside the body and from other areas within the brain."
During learning, neurons deep in brain engage in a surprising level of activity -- ScienceDaily
"People used to think that the cerebellum's input layer of neurons was only sparsely active, and encoded only information collected from the external world," said Sam Wang, professor of molecular biology and the Princeton Neuroscience Institute, and a senior co-author on the study. "It turns out that they light up like a Christmas tree, and they convey information both from outside the body and from other areas within the brain."
The study is the first to look at the activity of these neurons, known as granule cells, in the brains of living animals while they are learning a task, said Javier Medina, associate professor and the Vivian L. Smith Endowed Chair in Neuroscience at Baylor College of Medicine, and a senior co-author with Wang. "We knew very little about how these neurons in the cerebellum were firing when the brain is engaged in behavior," he said.
The cells are packed into a dense knot deep in the brain, making them difficult to study. Through advances in brain imaging techniques and computer algorithms that detangle the signals, the team was able to explore in detail the firing patterns of these neurons while mice were learning a behavior.
The researchers expected to see only a few granule cells fire at any given time, consistent with ideas that date back to the 1960s. The commonly held theory stated that the sparse firing patterns created a sort of neural code whereby each firing pattern represented a different sensory input or stimulus. The theory helped explain why there are so many granule cells: Distinct firing patterns involving just a few of the millions of granule cells would enable the brain to assign a different firing pattern to each stimulus -- for example, a different firing pattern for the touch of the fingers versus the touch of a feather duster.
