Archive for the ‘Neuroscience’ Category

Rat brains provide even more evidence our brains operates near tipping point

June 7th, 2019
A real human brain suspended in liquid within a human silhouette carved into acrylic, on display at the Bristol Science Centre in England. New research finds more evidence that the brain operates near a critical point.

Enlarge / A real human brain suspended in liquid within a human silhouette carved into acrylic, on display at the Bristol Science Centre in England. New research finds more evidence that the brain operates near a critical point. (credit: Ben Birchall/PA Images/Getty Images)

The human brain doesn't seem like it would have much in common with how water freezes into ice, or heats up into a gas. But over the last decade, evidence has been mounting that the brain as a system functions much like water approaching the critical point of a phase transition. Now a team of Brazilian scientists has found additional evidence in rat brains that this might indeed be the case. The team described its findings in a recent paper in Physical Review Letters.

The notion of so-called "self-organized criticality" dates back to a landmark paper in 1987, when the late Danish physicist Per Bak concluded that nature's exquisite order was the result of a kind of phase transition. That precise moment of transition is colloquially known as the "tipping point" or "critical point."

A brain's the thing

Typically, a classical phase transition only occurs when the temperature and pressure are just right for a given system. Self-organized criticality emerges spontaneously as the result of many local interactions between the many elements of a system, like millions of grains of sand running from the top to the bottom of an hourglass. The pile grows, grain by grain, until it becomes sufficiently unstable that the next grain to drop makes the pile collapse in an avalanche. The base of the pile widens, restoring stability, and the pile-up begins anew, until the sand pile hits the critical point again. Those avalanches follow a so-called "power law," meaning smaller ones happen more often than larger ones.

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Posted in brain, brain activity, criticality, neurophysics, Neuroscience, phase transitions, Physics, science, self-organized criticality | Comments (0)

Pokémon characters have their own pea-sized region in brain, study finds

May 6th, 2019

The first Pokémon game was released in 1996 for the Nintendo Game Boy.

Detective Pikachu, the first live-action film inspired by the classic Nintendo game Pokémon, hits theaters on May 10. So it's timely that a new paper has just appeared in Nature Human Behavior, concluding that people who avidly played the game as children have developed a unique cluster of brain cells devoted to recognizing the hundreds of different Pokémon species.

It's well known that human beings are remarkably adept at visually recognizing faces, words, numbers, places, colors, and so forth thanks to a constellation of regions—small clusters of neurons about the size of a pea—in the temporal lobe, located just behind the ears. Those regions show up in the same place in most people, despite differences in age, sex, or race. There's even a so-called "Jennifer Aniston neuron," (aka the "grandmother cell") discovered by a UCLA neuroscientist in 2005, whose primary purpose seems to be to recognize images of the famous actress. Similar neurons have also been found for other celebrities like Bill Clinton, Julia Roberts, Halle Berry, and Kobe Bryant.

"This is quite remarkable, and it's still an open mystery in neuroscience why these regions appear exactly where they do in the brain," said co-author Jesse Gomez, a postdoc at the University of California, Berkeley, who conducted the experiments while a grad student at Stanford University. One way to answer this question, and determine which of several competing theories is correct, is to study people who, as children, had a unique experience with a new type of visual stimulus. If those people were shown to have developed a new brain region dedicated to recognizing that new object class, that would offer useful insight into how the brain organizes itself.

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Posted in gaming, Neuroscience, Nintendo, pokemon, science | Comments (0)

Out of bounds: Why basketball players believe they weren’t last to touch ball

April 24th, 2019
Boston Celtics' Al Horford and Indiana Pacers' Thaddeus Young chase a ball out of bounds during a March game. A new study found that a self-centered bias in time perception might affect how each perceives who touched the ball last.

Enlarge / Boston Celtics' Al Horford and Indiana Pacers' Thaddeus Young chase a ball out of bounds during a March game. A new study found that a self-centered bias in time perception might affect how each perceives who touched the ball last. (credit: Matthew J. Lee/The Boston Globe/Getty Images)

With the NBA playoffs in full swing, emotions are running high among super-fans, inevitably leading to lots of heated arguments about bad referee calls and disputed plays. For instance, when a ball goes out of bounds, it can sometimes be challenging to determine which player touched it last. Both players will undoubtedly argue their opponent touched it last, trying to give possession of the ball to their own team. The other player will just as forcefully argue the opposite.

Who is right? According to a new paper in Science Advances, both players are subject to a kind of temporal bias whereby they will perceive themselves touching the ball first. "Our brains tell us that actions generated by ourselves come before simultaneous external events," the authors write. "Briefly, we have identified what may be a principal cause of arguments in ball games, and it's about time."

According to co-author Ty Tang, a graduate student in psychology at Arizona State University, the idea for the study emerged from conversations with his advisor, Michael McBeath, about subjective perception, particularly of time. This naturally evolved into how this subjective perception plays out in sports, specifically arguments over who touched the ball last before it went out of bounds in basketball. Tang proposed a series of three experiments to determine if the players might genuinely experience hitting the ball before their opponents in such scenarios. It wasn't the chaotic environment of a live basketball game, but it allowed them to control the variables to produce a robust study.

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Posted in cognitive bias, Neuroscience, Psychology, science, temporal order bias, time perception | Comments (0)

Electrical jolts to brain restored memory of elderly to that of 20-year-old

April 9th, 2019
A patient wearing an electrical cap similar to the one used in the study.

Enlarge / A patient wearing an electrical cap similar to the one used in the study. (credit: Getty | BSIP)

Gentle jolts of alternating current to the brain restored the waning working memories of older adults (aged 60 to 76 years old) to performance levels seen in younger adults (aged 20 to 29)—at least for a little under an hour.

The scalp-delivered electrical bursts appeared to resync brain waves across areas of the noggin important for high-level thinking and memory—the prefrontal and temporal cortex—which appeared to have fallen out of step over the years. The results, published Monday in Nature Neuroscience, support the idea that out-of-sync ripples of electrical activity from neurons firing in different areas of the brain may help spark gradual declines in working memory during aging, as well as memory deterioration associated with dementias, such as Alzheimer’s. Moreover, the finding generates some early buzz that such non-invasive brain stimulation may one day, in the distant future, be used as a therapy for such memory issues.

The authors of the study, Boston University researchers Robert Reinhart and John Nguyen, concluded that “by customizing electrical stimulation to individual network dynamics it may be possible to influence putative signatures of intra- and inter-regional functional connectivity, and rapidly boost working-memory function in older adults.”

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Posted in Aging, Alzheimer's, brain, brain stimulation, memory, Neuroscience, science | Comments (0)

Hallucinating mice bring us one step closer to what’s going on in the brain

March 27th, 2019
Dumbo and Timothy Q. Mouse hallucinate pink elephants on parade in a famous animated sequence from Disney's <em>Dumbo</em> (1941). Scientists have imaged neurons of mice under the influence of a hallucinogen for a new study.

Enlarge / Dumbo and Timothy Q. Mouse hallucinate pink elephants on parade in a famous animated sequence from Disney's Dumbo (1941). Scientists have imaged neurons of mice under the influence of a hallucinogen for a new study. (credit: YouTube/Disney)

People under the influence of hallucinogenic drugs like LSD often experience vivid visual hallucinations. But exactly what is happening within the brain to induce such a state remains a mystery. According to a new paper in Cell Reports, experiments with mice under the influence of a hallucinogenic drug showed evidence that the hallucinations may be triggered by reduced signaling between neurons in the visual cortex, along with changes in the timing at which they fire.

This might seem counterintuitive, according to co-author Cris Niell, a neuroscientist at the University of Oregon. "You might expect visual hallucinations would result from neurons in the brain firing like crazy or by mismatched signals," he said. "We were surprised to find that a hallucinogenic drug instead led to a reduction of activity in the visual cortex. But in the context of visual processing, it made sense."

In short, the brain may just be over-interpreting a lack of information. When we dream, for instance, there are no visual signals entering the brain, and yet the brain still creates visual patterns.

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Posted in hallucinogenics, Neuroscience, science | Comments (0)

This is your brain on bungee jumping: Cliff divers take the leap for science

March 1st, 2019
A man bungee jumps from a metal bridge toward the village below him.

Enlarge / A study participant has his brain waves recorded as he leaps from the Europa Bridge near Innsbruck, Austria, into a 630-foot abyss. Thank goodness for that bungee cord. (credit: Soekadar/Charite)

Right before you work up the nerve to leap off a bungee-jumping platform and plummet toward the Earth, there will be a sharp, measurable increase in your brain activity—almost a full second before you make the conscious decision to jump. A new paper in Scientific Reports purports to describe the first time this effect has been measured outside the laboratory.

That telltale signal was dubbed bereitschaftspotential (BP)—or "readiness potential" in English—when it was first observed in 1964 by Luder Deecke and Hans-Helmut Kornhuber. Kornhuber and Deecke had subjects make hundreds of voluntary finger movements while otherwise sitting as still as possible in a Faraday cage. The researchers noticed a shift in the electrical voltage in the brain, as measured by electroencephalography (EEG) electrodes placed along the scalp. The effect is often cited in the ongoing, heated debate over whether or not humans truly have free will.

The German and Austrian authors of the current study opted to have their subjects go bungee jumping in hopes of recording this readiness potential. While bungee jumping has its roots in an ancient ritual on the South Pacific island-nation of Vanuatu as a way to test one's courage, prior studies have shown it results in a sharp rise in concentrations of beta-endorphins right after jumping. (This spike is despite the fact that, the authors note, bungee jumping is statistically less life-threatening than more common activities like bicycling or dancing. Our impulse reactions are not rational.)

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Posted in brain-computer interface, bungee jumping, Neuroscience, psychiatry, readiness potential, science | Comments (0)

Singing mice could offer clues about how human brains manage conversation

February 28th, 2019
This singing mouse species (<em>Scotinomys teguina</em>) thrives in the cloud forests of Costa Rica. Their songs could yield clues about how human brains accomplish the "turn-talking" that makes conversation possible.

Enlarge / This singing mouse species (Scotinomys teguina) thrives in the cloud forests of Costa Rica. Their songs could yield clues about how human brains accomplish the "turn-talking" that makes conversation possible. (credit: NYU School of Medicine)

High in the cloud forests of Costa Rica, there's a species of mouse that sings call-and-response duets, similar to the high-speed back and forth humans engage in with conversation. Now scientists have pinpointed the precise brain circuit responsible for this behavior, which may lead to fresh insights into how humans converse, according to a new paper in Science.

Co-author Michael Long of New York University's School of Medicine calls this conversational back and forth "turn talking," likening it to hitting a tennis ball back and forth over a net between two players. "If I were to summarize [the results] in one sentence, I'd say this is the first demonstration of the neural mechanisms that lead to coordinated vocal turn-talking in the mammalian brain," he said. "Our strong prediction from the mouse study is that a similar kind of vocal coordination center may exist in the human brain as well."

Long's lab specializes in the study of vocal communication, something at which human beings excel. We don't often stop to think about the intricate neural processing even a simple conversation requires. The pause time between when one speaker finishes and another begins—called "floor transfer time"—is just 200 milliseconds. But one in ten people experiences some form of communication disorder, whether due to a stroke or a developmental disorder like autism.

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Posted in Biology, Neuroscience, science, singing mice | Comments (0)

Watching brains on acid using an MRI

February 1st, 2019
LSD blotter paper

Enlarge / LSD blotter paper (credit: campusdrugprevention.gov)

What exactly happens in a brain when it is hit by a hallucinogen? Lots of drugs have effects that are obvious extensions of our normal body processes; they raise moods, dull pain, or boost our energy. But hallucinogens are notable for giving their users experiences that are anything but normal.

Now, a team of Swiss researchers have used MRI imaging to follow the brain as it's under the influence of acid. And their results support the idea that hallucinogens cause the breakdown of the system that helps the brain keep track of which information is coming from the real world and which is generated by the brain itself.

Cortex overload

The brain receives a steady flow of information, some from the outside world, some from the body, and some generated by its internal thought processes. Your brain has to essentially decide which of it to take seriously and raise to the level of consciousness, which to monitor subconsciously, and which to discard. Hallucinations, whether due to drugs or mental disorders, appear to involve a breakdown in this information processing.

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Posted in Biology, drugs, fMRI, hallucinogens, Neuroscience, science | Comments (0)

Stem cells used to trace autism back to the formation of neurons

January 8th, 2019
Microscopic closeup of human cells.

Human stem cells forming mature neurons. (credit: Dr. Ariadna Recasens, University of Sydney)

While autism is a spectrum of disorders, it's clear that the more significant cases involve physical differences in the brain's nerve cells. Several studies have reported an excess in connections among neurons in the brains of people with autism. But when does this happen? Changes in neural connections are key components of learning and memory, and they can happen at any point in life; major reorganizations in connectivity occur from before birth up to the late teens.

Anecdotal reports of autism's symptoms often suggest an onset between one and two years old. But a new study places the critical point extremely early in embryo development—at a point before there are any mature nerve cells whatsoever.

A series of challenges

Figuring out how autism starts is complicated. To begin with, it's a spectrum that might include more than one disorder. You also can't know in advance who's going to develop it, so you can only look at it retrospectively, after the problems are apparent. Finally, the human brain is simply not something you can ethically do invasive experiments on.

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Posted in autism, Biology, brain, developmental biology, Neuroscience, science | Comments (0)

Autism involves a large-scale reduction in RNA editing

December 21st, 2018
Multicolored image of the neural connections within a brain.

Enlarge (credit: Erin Hecht, Dietrich Stout)

Most genes encode proteins and are transcribed from DNA into RNA before they're translated into a protein. In complex cells, however, there are lots of added layers of complexity. The RNA typically has chunks cut out of it, has its start and end modified, and more. Collectively, these changes are called RNA processing.

Xinshu Xiao's lab at UCLA studies RNA processing in all of its many forms. RNA editing is a type of modification that involves the alteration of RNA sequences by swapping in different bases. This has the effect of increasing the number of different protein products that can be generated from a single gene.

RNA editing is known to be important in nervous system development, specifically the formation of connections between nerve cells, called synapses. Synaptic development is abnormal in autism spectrum disorders. So Xiao and her colleagues decided to look at RNA editing in the brains of people with autism. They found that RNA editing was reduced in multiple areas of the brain, and multiple genes were affected.

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Posted in autism, autism spectrum disorder, Neuroscience, RNA, science | Comments (0)