Tag Archives: cerebellum

Animation of cerebellum. Credit: Wikimedia Commons.

The cerebellum is much more ‘brainy’ than we thought

Animation of cerebellum. Credit: Wikimedia Commons.

Animation of the cerebellum. Credit: Wikimedia Commons.

For over a century, the scientific community thought that the cerebellum (Latin for ‘little brain’) was only responsible for motor functions. Now, a new study published by researchers at Washington University in St. Louis adds to a growing body of evidence that suggests the cerebellum is also involved in cognition — where it plays a very important role.

It wasn’t until the late 1990s that scientists started to understand the more subtle functions of the cerebellum. Thanks to the work of Jeremy Schmahmann, a professor of neurology at Harvard University and director of the ataxia unit at Massachusetts General Hospital, it was shown that the cerebellum did more than just coordinate muscle movements — it also seems to have cognitive, emotional, social, and linguistic nonmotor functions. What’s more, if it malfunctions, it not only leads to poor muscle and limb coordination but can also be responsible for mental disorders such as schizophrenia.

Scott Marek, a postdoc at Washington University, along with colleagues, performed a new study in which they confirm Schmahmann’s previous work. The team studied the brains of 10 people with a special type of MRI machine that can image fine connections between the cerebellum and other areas of the brain.

The findings suggest that just 20% of the cerebellum was dedicated to physical motion, while the rest of 80% was associated with areas of the brain involved in abstract thinking, memory, emotion, or language. The findings appeared in the journal Neuron.

“We already thought that the cerebellum was cooler than most people thought,”  Dr. Nico Dosenbach, a professor of neurology at Washington University told NPR. “But these results were way more exciting and clear than I could have ever dreamt.”

However, according to the researchers, the cerebellum isn’t involved directly in cognitive tasks. Rather, it acts as an arbiter, monitoring different brain areas and making sure the best decision is reached.

The cerebellum is found in all sorts of animals, from birds to lizards. Over hundreds of millions of years, however, it has dramatically grown in size and this extra capacity allowed the cerebellum to take on other roles. However, its main function has largely remained the same — coordination of motor, cognitive, and emotional functions.

Earlier this month, another landmark paper explored the multiple roles of the cerebellum. An international team of researchers led by senior author Nuo Li from Baylor College of Medicine in Houston, Texas studied the cerebellum activity of mice. The brains of the rodents were studied when they were motionless, but deeply entrenched in thought, planning their next move.

The team found that some specific regions of the cerebellum are active during short-term memory, even when the body is motionless.

“We knew that the frontal cortex and the cerebellum are anatomically connected with each other,” Li said in a statement. “We also knew that in humans, cerebellar damage has been known to cause memory or planning problems, so the two might be connected. We found that the output of the cerebellum targets the frontal cortex and vice versa. When we disrupt the communication between the two areas of the brain, memory activity is disrupted. Our results show that activity orchestrating a single behavior is coordinated by multiple regions of the brain.”

Today, it’s becoming clearer that the cerebellum isn’t just an ancient leftover from our reptilian past, but rather it’s an integral part of higher-order cognition. A

s we come to better grips of its many functions, scientists will be better equipped to fight a range of psychiatric diseases linked to cerebellum deficiencies, such as autism spectrum, schizophrenia, depression, or obsessive-compulsive disorder.

 

Hallucination.

Researchers identify anti-hallucination system in our brains

Our brains come equipped with a reality-check system that keeps permanently questioning past expectations and beliefs, a new study reports. When this system fails, we hallucinate.

Hallucination.

Image credits Soffie Hicks / Flickr.

It’s actually not very hard to make your brain perceive something that isn’t there. Back in the 1980s, for example, researchers at Yale University repeatedly showed volunteers and image, paired with a tone. If they did this for long enough, they found, participants would still ‘hear’ the sound when presented with the image cards — even though the scientists weren’t playing the tone back to them. And of course, there’s a kind of hallucination (both tactile and auditory) that most of us experience disturbingly often and yet simply dismiss as a nuisance — ringxiety.

“People come to expect the sound so much that the brain hears it for them,” says Albert Powers, a psychiatrist at Yale University and an author of the new study.

The fact that it can do that, frankly, is downright scary. I mean, how can I trust my brain ever again when it obviously has no qualms in making me hear what I want to hear? I use it to do my taxes, which has to be the ultimate conflict of interests ever.

Brain autocorrect

These somewhat usual examples suggest that hallucinations form when our brains rely more on beliefs and expectations than the input sensory organs supply it with, says study author and Yale psychiatrist Philip Corlett. To explore this theory, the team used a variation of the 1980s experiment, this time involving four groups: healthy people, people with psychosis who don’t hear voices, people with schizophrenia (a subtype of psychosis) who do, and people who regularly hear voices but don’t find them disturbing.– such as self-described ‘psychics’.

Participants were trained to associate a checkerboard image with a 1-kilohertz, 1-second-long tune. Its intensity could be modulated during the trial, or it may sometimes be turned off entirely, so the participants were given a button to press when they heard the tune. They were also asked to apply more or less pressure to indicate how confident they were about hearing the sound. During the trials, the team monitored participants’ brain activity using magnetic resonance imaging to see what was going on up there as they made their choices.

The team’s theory was that people who hear voices would be more inclined to trust their auditory hallucinations as genuine. And that’s exactly what happened. Both the self-described psychics and the schizophrenics were almost five times more likely to hear the tone (when there wasn’t one) than the control group. They were also around 28% more confident on average that they heard the tone, the team reports.

Both groups showed abnormal neuronal activity in several brain regions involved in monitoring “internal representations of reality”, he team notes. The more severe a person’s hallucinations were, the less activity the team saw in their cerebellum — the small bit of the brain in the back of your head. The cerebellum plays a key role in planning and carrying out future movements, a role that requires it to keep tabs on what the rest of the brain perceives of the outside world at all times.

The findings suggest that the cerebellum is a key watchdog against our brain’s potential distortion of reality, the team reports. It also goes to show how powerful our ideas or beliefs can be, having the potential to overpower our senses for the right to shape the world we perceive.

An exciting implication of this research is that future clinicians might be able to predict who’s at risk of developing schizophrenia, allowing for treatment much earlier than possible today.

The paper “Pavlovian conditioning–induced hallucinations result from overweighting of perceptual priors” has been published in the journal Science.

Chinese woman completely lacks a cerebellum

A Chinese woman has shocked doctors when it was revealed that she reached 24 years without having a cerebellum. It is not the first time a person was living fine without having a cerebellum, but she entered an extremely select group, which only features 9 other people.

A hole at the back (top) where the cerebellum should be (Top image: Feng Yu et al.; Bottom image: Zephyr/Science Photo Library )

The woman checked in at the Chinese PLA General Hospital of Jinan Military Area Command in Shandong Province, reporting a severe case of dizziness and nausea. She told doctors that she always had a problem walking straight, and she only started talking at the age of 6, but nobody was expecting this. They did a CAT scan and quickly identified the problem: her entire cerebellum was missing, being filled with cerebrospinal fluid.

The cerebellum (Latin for “little brain”) is a region of the brain that plays a crucial role in the human body. In addition to its direct role in motor control, the cerebellum also is necessary for several types of motor learning, most notably learning to adjust to changes in sensorimotor relationships – your body’s sensors. It’s different structurally from the rest of the brain, consisting of smaller and more compact folds of tissue. It amounts for only 10 percent of the brain’s volume, but has almost half of all the brain’s neurons.

The condition is so rare that there is no clear description or theory of why it happens.

“These rare cases are interesting to understand how the brain circuitry works and compensates for missing parts,” says Mario Manto, who researches cerebellar disorders at the Free University of Brussels in Belgium. The patient’s doctors suggest that normal cerebellar function may have been taken over by the cortex – brain scans should reveal the answer.

 

 

baby_brain

Baby brains grow to half the adult size in just 90 days

baby_brain

Researchers performed MRI scans on babies to see how their brains developed from birth to later stages. Their findings reveal the explosive growth of the human brain following birth: in just 90 days, the baby brain grows by 64% its initial size reaching half the adult size.

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They grow up so fast

Traditionally, brain growth is followed the old fashioned way using a measuring tape. This way, doctors casually record skull, and consequently brain growth and if any deviations from a known patterns are encountered, they then further investigate. For instance, premature babies have a smaller brain and develop slower than those delivered at term. As we all know, skulls vary in shape and size and they’re not the best metric for gauging brain size.

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Lucky for scientists, there are MRI scanners. Researchers at University of California scanned the brains of 87 babies, healthy and delivered at term, from birth until three months of age. They saw the most rapid changes immediately after birth – newborn brains grew at an average rate of 1% a day. This slowed to 0.4% per day at the end of the 90-day period. The highest growth rate among brain structures was for the cerebellum, an area of the brain involved in movement. Oppositely, the hippocampus which is responsible for memory formation and retrieval showed the least growth. Apparently, in its early stages the brain wants to concentrate resources on getting the heck out – ‘guh, guh, dadah’ is enough for now.

 

“This is the first time anyone has published accurate data about how babies’ brains grow that is not based on post-mortem studies or less effective scanning methods,” Dr Martin Ward Platt, a consultant paediatrician at the Royal Victoria Infirmary in Newcastle.

“The study should provide us with useful information as this is an important time in development.

“We know, for example, if there are difficulties around the time of birth, a baby’s growth can fall away in the first few months.”

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By closely following brain development in its early formation days, researchers hope to spot clues that might help them  identify early signs of developmental disorders such as autism.Scientists will now investigate whether alcohol and drug consumption during pregnancy alters brain size at birth. Findings appeared in JAMA Neurology.

 

You were expecting a caption with a terminator-like rat. We couldn't find any, instead have some Jean Luc Picborg.

Cyborg-rats with artificial cerebellums – first step ahead the age of borg

Remarkably enough, scientists from Tel Aviv University in Israel, have manged to implant an artificial cerebellum in a rat’s brain, which successfully restored lost brain function. This research could provide the foundations for implementing cyborg-like functions in the human brain sometime in the distant future.

You were expecting a caption with a terminator-like rat. We couldn't find any, instead have some Jean Luc Picborg.

You were expecting a caption with a terminator-like rat. We couldn't find any, instead have some Jean Luc Picborg.

Such an advancement, could possibly one day offer the prospect of a normal life to stroke victims or other patients with other brain-related injuries or traumas. It could also maybe improve learning and memory capabilities in the old. These are all still in the realm of science fiction, though, but not for too much longer, neuroscientists hope.

Modern, high-end prosthetic limbs or ear implants communicated directly to the brain, functioning based on brain impulses. They’re truly marvelous technologies, however such devices involve only one-way communication, either from the device to the brain or vice versa.

Matti Mintz of Tel Aviv University in Israel and his colleagues have created a device that is capable of much more – a synthetic cerebellum which can receive sensory inputs from the brainstem directly. The brainstem is the posterior part of the brain, adjoining and structurally continuous with the spinal cord, that provides the main motor and sensory innervation to the face and neck via the cranial nerves.

The device developed by the Israeli scientists can interpret sensory inputs from the brainstem, and send a signal to a different region of the brainstem that prompts motor neurons to execute the appropriate movement.

“It’s proof of concept that we can record information from the brain, analyse it in a way similar to the biological network, and return it to the brain,” says Mintz, who presented the work this month at the Strategies for Engineered Negligible Senescence meeting in Cambridge, UK.

Synthesizing the brain

The team analyzed brainstem signals feeding into a real rat’s cerebellum and the output it generated in response. This information, coupled with their already complete knowledge regarding the neural architecture of the cerebellum, was used to create a digital version of the cerebellum, inside a chip which was wired to a rat’s brain using electrodes.

The chip was tested and performed remarkably. An anesthetized rat had its cerebellum disabled, before the chip was attached. While still anesthetized, scientists tried to induce a conditional motor reflex – a blink. They would spray the rat’s eye with a powder while playing a tune at the same time. This was repeated until the rat would blink only at hearing the tune alone. The scientists first tried this without the chip connected, and found the rat was unable to learn the motor reflex.

“This demonstrates how far we have come towards creating circuitry that could one day replace damaged brain areas and even enhance the power of the healthy brain,” says Francesco Sepulveda of the University of Essex in Colchester, UK, who was not involved in the research. “The circuitry mimics functionality that is very basic. Nonetheless, this is an exciting step towards enormous possibilities.”

A great challenge in face of the development of genuine cyborg-brain implants someday, however, lies in modeling larger areas of the cerebellum that can learn a sequence of movements and test the chip in a conscious animal.

“It will likely take us several decades to get there, but my bet is that specific, well-organised brain parts such as the hippocampus or the visual cortex will have synthetic correlates before the end of the century,” sais Sepulveda.