Thursday, September 29, 2022

Why Is The Brain Wrinkled

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Watching Baby Brains Get Wrinkly Could Flag Future Disorders

Brain Wrinkles – Why Do Our Brains Look Like That?

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A new method could lead to diagnostic tools that precisely measure the third-trimester growth and folding patterns of a babys brain in 3D.

The research could help to sound an early alarm on developmental disorders in premature infants that could affect them later in life.

We all have the same components, but our brain folds are like fingerprints: Everyone has a different pattern.

During the third trimester, a babys brain undergoes rapid development in utero. The cerebral cortex dramatically expands its surface area and begins to fold. Previous work suggests that this quick and very vital growth is an individualized process, with details varying infant to infant.

One of the things thats really interesting about peoples brains is that they are so different, yet so similar, says Philip Bayly, professor of mechanical engineering at the School of Engineering & Applied Science at Washington University in St. Louis. We all have the same components, but our brain folds are like fingerprints: Everyone has a different pattern. Understanding the mechanical process of foldingwhen it occursmight be a way to detect problems for brain development down the road.

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The researchers report their findings in PNAS. The National Institute of Health supported this work.

The Mechanics Of Brain Folding

The brain is made of two layers. The outer layer, called the cerebral cortex, is composed of folded gray matter made up of small blood vessels and the spherical cell bodies of billions of neurons. The inner layer is composed of white matter, consisting mostly of the neurons elongated tails, called myelinated axons.

In recent years, researchers have shown that mechanics, or the forces that objects exert on one another, play an important role in the growth and folding of the brain.

Among the several hypotheses that scientists have proposed to explain how brain folding works, differential tangential growth is the most commonly accepted because its well-supported by experimental observations. This theory assumes that the outer layer of the brain grows at a faster rate than the inner layer because of how neurons proliferate and migrate during development. This mismatch in growth rates puts increasing amounts of compressive forces on the outer layer, leading to overall instability of the growing brain structure. Folding these layers, however, releases this instability.

Another study using a 3D-printed hydrogel brain model also showed that a mismatch in growth rates results in folding.

Jalils research team has also found that other mechanical factors also affect the eventual shape a developing brain will take, including the brains initial outer layer thickness and how stiff the two layers are relative to each other.

Structure Of The Brain

Why human brains are folded is not known and many studies into this area focus on genetics and the cellular regulation of growth. Evidence to support models regarding the structure is limited, however, because of the ethics surrounding experiments on human brains.

In an accompanying News & Views article, Ellen Kuhl, from the the Departments of Mechanical Engineering and Bioengineering at Stanford University in California, notes that the average adult brain has a volume of 1,200 cm cubed, a surface area of 2,000 sq-cm and a cortical thickness of 2.5 mm.

The process of folding is known as ‘gyrification’, and is thought to be a mechanism by which the number of cortical neurons is maximized while the distance between them is minimized. This process begins at around 23 weeks of gestation. Our brains continue grow until adulthood.

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Your Brain Wrinkles Like A Screwed

By Aviva Rutkin

Folds up like a brain

What does your brain have in common with a scrunched-up piece of paper? Thats no riddle& colon its the latest insight into why your brain has all those folds.

It turns out that its all down to the surface area and thickness of the cerebral cortex, the outer layer of the brain that is made of grey matter.

Brains differ vastly between species. Some animals, like rats and mice, have very smooth brains, while others, like pigs and people, have ridges and furrows called gyri and sulci.

There are several theories about why the brain folds, and modelling shows that because the cortex is attached to the white matter beneath, it folds as it expands.

But how it folds is a different question. Now, a mathematical formula can predict how almost any mammals brain is folded, by comparing its wrinkles and grooves to the creases in a paper ball.

What Does A Wrinkly Brain Mean

TIL: Why Your Brain is Wrinkly

The main reason why the human brain is wrinkled is that folding in on itself allows it to gain some space. The brain folds are what are called, more appropriately, convolutions, while the furrows or fissures are the depressions between these wrinkles.

Today we wanted to continue looking for answers and the question we asked ourselves in this article is the following: Why does the brain have wrinkles? We found out why the brain looks so strange and why its folds are so important.

If you have any questions or comments please let us know!

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Why Are Our Brains Wrinkly

Brain wrinkles naturally develop as the brain gets larger in order to lend more surface area and help white matter fibers avoid long stretches

A smattering of mammalian brains. Photo: Toro et al, Evolutionary Biology

Manatee, rat and squirrel brains look more like a liver, smooth and slightly triangular, than what we think of as a brain. Dolphin brains, on the other hand, are notably crinkled, with what appears to be about twice the folds of a human brain. So what causes these differences? Is function or form to blame?

According to new research published in Evolutionary Biology its a bit of both. Carl Zimmer explains at National Geographic how the wrinkles come into play:

The more wrinkled a brain gets, the bigger the surface of the cortext becomes. The human brain is especially wrinkled. If you look at a human brain, you only see about a third of its surfacethe other two-thirds are hidden in its folds. If you could spread it out flat on a table, it would be 2500 square centimeters . A shrews brain surface would be .8 square centimeters.

Those wrinkles, Zimmer explains, provide extra surface area for our oversized brains to take advantage of.

But theres another intriguing thing about those wrinkles: they are not spread uniformly across our heads. The front of the neocortex is more wrinkly than the back. This is intriguing, because the front of the cortex handles much of the most abstract sorts of thinking. Our brains pack extra real estate there with additional folds.

The Geography Of Thought

Each cerebral hemisphere can be divided into sections, or lobes, each of which specializes in different functions. To understand each lobe and its specialty we will take a tour of the cerebral hemispheres, starting with the two frontal lobes , which lie directly behind the forehead. When you plan a schedule, imagine the future, or use reasoned arguments, these two lobes do much of the work. One of the ways the frontal lobes seem to do these things is by acting as short-term storage sites, allowing one idea to be kept in mind while other ideas are considered. In the rearmost portion of each frontal lobe is a motor area , which helps control voluntary movement. A nearby place on the left frontal lobe called Brocas area allows thoughts to be transformed into words.

When you enjoy a good mealthe taste, aroma, and texture of the foodtwo sections behind the frontal lobes called the parietal lobes are at work. The forward parts of these lobes, just behind the motor areas, are the primary sensory areas . These areas receive information about temperature, taste, touch, and movement from the rest of the body. Reading and arithmetic are also functions in the repertoire of each parietal lobe.

As you look at the words and pictures on this page, two areas at the back of the brain are at work. These lobes, called the occipital lobes , process images from the eyes and link that information with images stored in memory. Damage to the occipital lobes can cause blindness.

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Why Are Brains Wrinkly Are There Smooth Brains

Weve all heard the grey matter mass hiding in our skulls called our noodle before. Thats probably because the brain, on the outside, looks kind of like a noodle wrapped and laid over itself, since its all wrinkly like that. But, why exactly are brains wrinkly? Is a wrinkly brain better than having a smooth brain? Well get to all of that.

Brain Sizes In The Animal Kingdom

Why your brain makes you fingers wrinkle

This cortical folding is designed to make the brain more efficient thus allowing us to get smarter. If you look at the animal kingdom, then youll see that smarter animals have a denser brain in relation to their size. Elephants have far bigger brains than humans, but thats because they have much larger bodies which require far more coordination when moving around and keeping alive. If you were to compare the human brain to another animal our size like the chimpanzee you would find that our brains were much heavier which indicates more intelligence and a greater capacity for higher order thought.

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Different Areas Of The Brain

Interestingly our brains are also more wrinkled in different areas. The most wrinkled part for instance is the front of the neocortex where most of our abstract thinking takes place.

And in keeping with all this, its also true that those animals that are capable of less advanced thinking have much smoother brains. While the brain of the manatee is quite large for instance, it is completely smooth suggesting it is less capable of higher order thinking.

Interestingly though the bottleneck dolphin has a brain larger and more wrinkled than the human brain. This doesnt make dolphins necessarily more intelligent than us though as there are other factors to consider such as the fact that dolphins have a relatively thinner surface of their brain. Still though, its certainly food for thought. No pun intended

Next Steps In Brain Mechanics

Understanding the mechanisms behind brain folding and connectivity will provide researchers with the knowledge foundation to uncover their role in developmental brain disorders. In the long term, clarifying the connection between brain structure and function may lead to early diagnostic tools for brain diseases.

In the future, artificial intelligence may be able to give even more insight about the normal growth and folding of the human brain. But even with all these advancements in neuroscience, researchers like us have our work cut out for us as we continue trying to decipher the mystery of the most complex known structure in the universe.

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Why Having A Wrinkled Brain Is A Good Thing

We normally associate wrinkles with aging, such as wrinkled skin. But theres one organ that is wrinkled right from the time we are born. Its our brain. And new research shows those wrinkles are not a sign of age but are, in fact, a sign of just how large and complex our brains are.

The wrinkles, according to U.C. Santa Barbara postdoctoral scholar Eyal Karzbrun, are vital to our development because they create a greater surface area giving our neurons, or brain nerve cells, more space to create connections and deliver information.

In an article in UCSBs Daily Nexus, Karzbrun says while our knowledge of the brain is increasing there are still many things we dont understand:

The brain is a complex organ whose organization is essential to its function. Yet it is assembled by itself. How this assembly takes place and what physics come into play is fundamental to our understanding of the brain.

Eyal Karzbrun: Photo courtesy UCSB

Karzbrun used stem cells to create 3D clusters of brain cells, to better understand how they organize themselves. He said brains are like computers in the way they rely on surface area to process information.

Karzbrun says gaining a deeper understanding of how the brain is formed, and why it takes the shape it does, may help us develop new approaches to treating problems in the brain.

D Gel Model Looks Like Real Brain

Why Do Our Brains Have Folds?

Professor Mahadevan and his team used MRI scans of smooth foetus brains to build a three-dimensional gel model. They coated the surface with a thin layer of elastomer gel to represent the cortex.

To mimic brain growth, they immersed the gel brain in a solvent that was absorbed by the outer layer, causing it to swell relative to the deeper region.

Within minutes, folds started to appear that were remarkably similar in size and shape to the real thing, showing that the same process happened even though the model did not contain any living tissue.

“It looks like a real brain,” Professor Mahadevan’s colleague and fellow author Dr Jun Young Chung said.

A few other animals including chimpanzees, dolphins, elephants and pigs also have brain folds, but the human brain is the wrinkliest of them all.

The physical explanation for brain folds was first proposed by Harvard scientists 40 years ago.

Now proven by Professor Mahadevan’s team, it was considered a controversial challenge at the time to the conventional wisdom that brain folds were created by purely biological, not physical, processes.

Dr Kuhl said severe under- or over-folding could lead to seizures, motor dysfunction and developmental delay.

Knowing whether to target mechanical or biological causes should go a long way to developing better treatment.

ABC/AFP

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Some Key Neurotransmitters At Work

Neurotransmitters are chemicals that brain cells use to talk to each other. Some neurotransmitters make cells more active while others block or dampen a cell’s activity .

Acetylcholine is an excitatory neurotransmitter because it generally makes cells more excitable. It governs muscle contractions and causes glands to secrete hormones. Alzheimers disease, which initially affects memory formation, is associated with a shortage of acetylcholine.

Glutamate is a major excitatory neurotransmitter. Too much glutamate can kill or damage neurons and has been linked to disorders including Parkinson’s disease, stroke, seizures, and increased sensitivity to pain.

GABA is an inhibitory neurotransmitter that helps control muscle activity and is an important part of the visual system. Drugs that increase GABA levels in the brain are used to treat epileptic seizures and tremors in patients with Huntingtons disease.

Serotonin is a neurotransmitter that constricts blood vessels and brings on sleep. It is also involved in temperature regulation. Low levels of serotonin may cause sleep problems and depression, while too much serotonin can lead to seizures.

Dopamine is an inhibitory neurotransmitter involved in mood and the control of complex movements. The loss of dopamine activity in some portions of the brain leads to the muscular rigidity of Parkinsons disease. Many medications used to treat behavioral disorders work by modifying the action of dopamine in the brain.

Brains Slightly Wrinkled Or With Too Many Wrinkles

The wrinkles present in the human brain are balanced considering the size and thickness of the cerebral cortex, but there are certain conditions in which these grooves and gyros are not arranged as they should.

Those who suffer from polymicrogyria, a genetic condition, have a brain with excess folds given by shallow furrows. This causes psychomotor retardation, neuronal damage and epilepsy.

Another condition in Pachygyria, characterized by excessively thick folds. This congenital malformation causes delays in development, seizures and a shorter life expectancy.

Are there brains without wrinkles?

It is interesting to mention that in nature, most brains are smooth. In general, animals with large brains such as dolphins or elephants have wrinkled brain cortices, while animals with small brains such as rabbits or rats have small, smooth brains.

In humans, a smooth or lissencephalic brain is the product of a malformation caused by defects in embryonic development. This study, carried out by researchers at Harvard, is valuable in understanding how the brain develops and what happens when it does not develop properly, leading to brain disorders.

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Why Does The Brain Have Grooves

brainbrains havebrain’sbrain

. Consequently, do you really get a wrinkle in your brain when you learn something?

You Get New Brain Wrinkles When You Learn Something. As the fetus grows, its neurons also grow and migrate to different areas of the brain, creating the sulci and gyri. By the time it reaches 40 weeks, its brain is as wrinkled as yours is . So we don’t develop new wrinkles as we learn.

why is surface area important to the brain? By increasing the surface area in the brain, the brain has more room to carry out its functions within the space it has and can fit more neurons in the same amount of space.

Keeping this in view, what are the crevices in the brain called?

The wrinkles in your brain can either be crevices, known as sulci, or ridges between crevices, which are known as gyri. The folding of the cortex allows more brain area to fit into a smaller space.

What is the advantage of the cerebrum of the brain being wrinkled?

Our brains pack extra real estate there with additional folds. Wrinkles also help larger brains keep their white matter fibers that link different areas of the cortex in order. As brains grow larger, white matter fibers must stretch longer.

Power Law Relationship For Folding Applies Across Species

Episode 5 | Neuroscience | Why Do Brains Have Wrinkles?

PAPER TOSS When sheets of paper were scrunched, variations in surface area led to balls with different levels of crumpled folding. Surface area is one part of a new equation that may help describe how brains fold.

Suzana and Luiza Herculano-Houzel

By Laura Sanders

Cramming a big brain into a skull may be as easy as just wadding it up. The same physical rules that dictate how a paper ball crumples also describe how brains get their wrinkles, scientists suggest July 3 in Science.

That insight, arrived at in part by balling up sheets of standard-sized A4 office paper, offers a simple explanation for the ridges and valleys that give rise to thoughts, memories and emotions. The results also explain the shapes of a multitude of mammal brains ranging from the ultrawrinkled dolphin brain to the smooth brain of manatees, says study coauthor Suzana Herculano-Houzel. There are no outliers.

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