Neuroscientists

When Do Brains Grow Up? New Findings Shock Neuroscientists

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Recent research has revealed that mice and primates, despite their differing lifespans, develop brain synapses at the same rate. This surprising discovery challenges previous assumptions in neuroscience about aging and disease, and it opens new avenues for understanding human brain development and improving neurological disorder treatments.

Recent research indicates that mouse and primate brains mature at a similar rate.

A study by Argonne National Laboratory finds that both short-lived mice and longer-living primates develop brain synapses on the exact same timeline, challenging assumptions about disease and aging. But what does this mean for humans — and past research?

Mice typically live two years and monkeys live 25 years, but the brains of both appear to develop their synapses at the same time. This finding, published in a recent study led by neuroscientist Bobby Kasthuri of the U.S. Department of Energy’s (DOE) Argonne National Laboratory and his colleagues at the University of Chicago, is a shock for neuroscientists.

Shattering Previous Assumptions in Neuroscience

Until now, brain development was understood as happening faster in mice than in other, longer-living mammals such as primates and humans. Those studying the brain of a 2-month-old mouse, for example, assumed the brain was already finished developing because it had a shorter overall lifespan in which to develop. In contrast, the brain of a 2-month-old primate was still considered going through developmental changes. Accordingly, the 2-month-old mouse brain was not considered a good comparison model to that of a 2-month-old primate.

That assumption appears to be completely wrong, which the authors think will call into question many results using young mouse brain data as the basis for research into various human conditions, including autism and other neurodevelopmental disorders.

“A fundamental question in neuroscience, especially in mammalian brains, is how do brains grow up?” said Kasthuri. ​“It turns out that mammalian brains mature at the same rate, at every absolute stage. We are going to have to rethink aging and development now that we find it’s the same clock.”

Study Methodology and Astonishing Findings

Gregg Wildenberg is a staff scientist at The University of Chicago and the lead author of the study along with Kasthuri and graduate students Hanyu Li, Vandana Sampathkumar, and Anastasia Sorokina. He looked closely at the neurons and synapses firing in the brains of very young mice. He marveled that the baby mouse crawled, ate, and behaved just as one would expect despite having next to no measurable connections in its brain circuitry.

“I think I found one synapse along an entire neuron, and that is shocking,” said Wildenberg. ​“This living baby animal existed outside of the womb six days after birth, behaving and experiencing the world without any of its brain’s neurons actually connected to each other. We have to be careful about overinterpreting our results, but it’s fascinating.”

Brain neurons are different than every other organ’s cells’ neurons because brain cells are post-mitotic, meaning they never divide. All other cells in the body — liver, stomach, heart, skin, and so on — divide, get replaced, and deteriorate over the course of a lifetime. This process begins at development and ultimately transitions into aging. The brain, however, is the only mammalian organ that has essentially the same cells on the first and the last day of life.

Exploring Developmental Mysteries and Technological Advances

Complicating matters, early embryonic cells of every species appear identical. If fish, mouse, primate, and human embryos were all together in a petri dish, it would be virtually impossible to figure out which embryo would develop into what species. At some mysterious point, a developmental programming change happens within an embryo and only one specific species emerges. Scientists would like to understand the role of brain cells in brain development as well as in the physical development within species.

Kasthuri and his team were able to advance their recent discovery thanks to the Argonne Leadership Computing Facility (ALCF), a DOE Office of Science user facility. The ALCF is able to handle enormous datasets — ​“terabytes, terabytes and more terabytes of data,” said Kasthuri — to look at brain cells at the nanoscale. The researchers used the supercomputer facility to look at every neuron and count every synapse across multiple brain samples at multiple ages of the two species. Collecting and analyzing that level of data would have been impossible, said Kasthuri, without the ALCF.

Reevaluating Past Research and Looking Forward

Kasthuri knows many scientists will want more data to confirm the findings of the recent study. He himself is reconsidering past research results in the context of the new information.

“One of the previous studies we did was comparing an adult mouse brain to an adult primate brain. We thought primates are smarter than mice so every neuron should have more connections, be more flexible, have more routes, and so on,” he explained. ​“We found that the exact opposite is true. Primate neurons have way fewer connections than mouse neurons. Now, looking back, we thought we were comparing similar species but we were not. We were comparing a 3-month-old mouse to a 5-year-old primate.”

The research’s implications for humans is blurry. For one thing, behaviorally, humans develop more slowly than other species. For example, many four-legged mammals can walk within the first hour of life whereas humans frequently take more than a year before walking first steps. Are the rules and pace of synaptic development different in human brains compared to other mammalian brains?

“We believe something remarkable, something magical, will be revealed when we are able to look at human tissues,” said Kasthuri, who suspects humans may be on a different schedule altogether. ​“That’s where the clock that is the same for all these other mammalian species may get broken.”

Wildenberg hopes the information gathered during the study will lead to the development of pharmaceuticals that better target human neurological disorders and diseases.

“Mouse models may be great for developing cardiovascular medicines because hearts, which are basically pumps, work similarly across species,” he said. ​“However, developing drugs for neurological conditions is extremely hard. It’s important to understand how different species’ brains evolve so that scientists can tailor approaches based on the brain’s innovations and adaptations.”

Neuroscientists identify ‘chemical imprint of desire’

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Hop in the car to meet your lover for dinner and a flood of dopamine— the same hormone underlying cravings for sugar, nicotine and cocaine—likely infuses your brain’s reward center, motivating you to brave the traffic to keep that unique bond alive. But if that dinner is with a mere work acquaintance, that flood might look more like a trickle, suggests new research by University of Colorado Boulder neuroscientists.

“What we have found, essentially, is a biological signature of desire that helps us explain why we want to be with some people more than other people,” said senior author Zoe Donaldson, associate professor of behavioral neuroscience at CU Boulder.

The study, published Jan. 12 in the journal Current Biology, centers around prairie voles, which have the distinction of being among the 3% to 5% of mammals that form monogamous pair bonds.

Like humans, these fuzzy, wide-eyed rodents tend to couple up long-term, share a home, raise offspring together, and experience something akin to grief when they lose their partner.

By studying them, Donaldson seeks to gain new insight into what goes on inside the human brain to make intimate relationships possible and how we get over it, neurochemically speaking, when those bonds are severed.

The new study gets at both questions, showing for the first time that the neurotransmitter dopamine plays a critical role in keeping love alive.

“As humans, our entire social world is basically defined by different degrees of selective desire to interact with different people, whether it’s your romantic partner or your close friends,” said Donaldson. “This research suggests that certain people leave a unique chemical imprint on our brain that drives us to maintain these bonds over time.”

How love lights up the brain

For the study, Donaldson and her colleagues used state-of-the art neuroimaging technology to measure, in real time, what happens in the brain as a vole tries to get to its partner. In one scenario, the vole had to press a lever to open a door to the room where her partner was. In another, she had to climb over a fence for that reunion.

Meanwhile a tiny fiber-optic sensor tracked activity, millisecond by millisecond, in the animal’s nucleus accumbens, a brain region responsible for motivating humans to seek rewarding things, from water and food to drugs of abuse. (Human neuroimaging studies have shown it is the nucleus accumbens that lights up when we hold our partner’s hand).

Each time the sensor detects a spurt of dopamine, it “lights up like a glow stick,” explained first-author Anne Pierce, who worked on the study as a graduate student in Donaldson’s lab. When the voles pushed the lever or climbed over the wall to see their life partner, the fiber “lit up like a rave,” she said. And the party continued as they snuggled and sniffed one another.

In contrast, when a random vole is on the other side of that door or wall, the glow stick dims.

“This suggests that not only is dopamine really important for motivating us to seek out our partner, but there’s actually more dopamine coursing through our reward center when we are with our partner than when we are with a stranger,” said Pierce.

Hope for the heartbroken

In another experiment, the vole couple was kept apart for four weeks—an eternity in the life of a rodent—and long enough for voles in the wild to find another partner.

When reunited, they remembered one another, but their signature dopamine surge had almost vanished. In essence, that fingerprint of desire was gone. As far as their brains were concerned, their former partner was indistinguishable from any other vole.

“We think of this as sort of a reset within the brain that allows the animal to now go on and potentially form a new bond,” Donaldson said.

This could be good news for humans who have undergone a painful break-up, or even lost a spouse, suggesting that the brain has an inherent mechanism to protect us from endless unrequited love.

The authors stress that more research is necessary to determine how well results in voles translate to their bigger-brained, two-legged counterparts. But they believe their work could ultimately have important implications for people who either have trouble forming close relationships or those who struggle to get over loss—a condition known as Prolonged Grief Disorder.

“The hope is that by understanding what healthy bonds look like within the brain, we can begin to identify new therapies to help the many people with mental illnesses that affect their social world,” said Donaldson.

Best Friends Really do Share Brain Patterns, Neuroscientists Reveal

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Whenever my best friends and I say the same thing in a group chat, we send the wavy dash emoji, 〰️, shorthand for we’re on the same wavelength! The concept gets tossed around in pop culture, though its meaning has always been more symbolic than scientific. Until Wednesday, there wasn’t much proof that friends who think the same thing shared anything but a set of references and some dumb inside jokes.

brainwaves friends

But in the journal Nature Communications, a team of Dartmouth College scientists provided evidence of what best friends have imagined all along:

“Neural responses to dynamic, naturalistic stimuli, like videos, can give us a window into people’s unconstrained, spontaneous thought processes as they unfold. Our results suggest that friends process the world around them in exceptionally similar ways,” said lead author Carolyn Parkinson in a statement on Wednesday. At the time of the study, Parkinson was at Dartmouth, and she’s currently an assistant professor of psychology and director of the Computational Social Neuroscience Lab at the University of California, Los Angeles.

fMRI of 'me'
fMRI machines are used to measure changes in brain activity in real time.

Taking 280 graduate students of varying degrees of friendship, which participants self-reported, Parkinson and her team wondered whether they could predict which individuals were closer friends based solely on their brain activity while watching the same set of videos. Their hypothesis, a slightly more refined version of pop psychology’s 〰️ theory, was that people who had closer social ties would respond to the videos in more similar ways, which in turn would be reflected in their patterns of brain activity. Plotting the self-reported relationships on a map, the researchers then got to work on finding the links between individuals’ brain activity.

In solitude, 42 of the participants watched the same series of politics, science, comedy, and music videos as the researchers observed their brain activity using an fMRI scanner, a device that tracks changes in blood flow in the brain. The idea is that certain regions of the brain surge with blood — that is, become more active — depending on how the individual responds to the video.

Across the participants, the parts of the brain linked to emotional responses, attention, and high-level reasoning became active, in varying degrees. The analysis revealed that, as the researchers predicted, the people with the most similar brain activity patterns were the closest friends. The strength of the correlation was directly related to the social closeness of the individuals, even when the researchers considered variables like handedness, age, gender, ethnicity, and nationality.

“We are a social species and live our lives connected to everybody else. If we want to understand how the human brain works, then we need to understand how brains work in combination— how minds shape each other,” explained senior author Thalia Wheatley, Ph.D., a study co-author and psychologist at Dartmouth, in a statement.

Mapping the experimental data produced a social network that the researchers could use to predict how close individuals were, solely on the basis of their brain activity. As many of us have already intuited, it seems clear that the experiences we share with our closest friends do cause us to think and respond to things in similar ways, but the exact mechanisms that lead to synchronicity — is it a function of time spent together or laughter shared? — remain to be discovered.

Yale Neuroscientists Can Now Determine Human Intelligence Through Brain Scans.

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Article Image
The human connectome. By Andreashorn – Own work, CC BY-SA 4.0.

Do you feel like you were born to do something? There is just a certain skill like playing an instrument or sport, or a certain subject, like math, which you naturally excel in? It might have to do with the way your brain is wired. Different people have different aptitudes. The repositories for these lie in different parts of the brain and, as scientists are learning more and more, in the connectome or the connections between regions.

Today, neuroscientists can determine one’s intelligence through a brain scan, as sci-fi as that sounds. Not only that, it’s only a matter of time before they are able to tell each individual’s set of aptitudes and shortcomings, simply from scanning their brain. Researchers at Yale led the study. They interpreted intelligence in this case as abstract reasoning, also known as fluid intelligence. This is the ability to recognize patterns, solve problems, and identify relationships. Fluid intelligence is known to be a consistent predictor of academic performance. Yet, abstract reasoning is difficult to teach, and standardized tests often miss it.

Researchers in this study could accurately predict how a participant would do on a certain test by scanning their brain with an fMRI. 126 participants, all a part of the Human Connectome Project, were recruited. The Human Connectome Project is the mapping of all the connections inside the brain, to get a better understanding of how the wiring works and what it means for things like intellect, the emotions, and more. For this study, researchers at Yale put participants through a series of different tests to assess memory, intelligence, motor skills, and abstract thinking.

They were able to map the connectivity in 268 individual brain regions. Investigators could tell how strong the connections were, how active, and how activity was coordinated between regions. Each person’s connectome was as unique as their fingerprint, scientists found. They could identify one participant from another with 99% accuracy, from their brain scan. Yale researchers could also tell whether the person was engaged in the assessment they were taking or if they were aloof about it.

Emily Finn was a grad student and co-author of this study. She said, “The more certain regions are talking to one another, the better you’re able to process information quickly and make inferences.” Mostly, fluid intelligence had to do with the connections between the frontal and parietal lobes. The stronger and swifter the communication between these two regions, the better one’s score in the abstract thinking test. These are some of the latest regions to have evolved in the brain. They house the higher level functions, such as memory and language, which are essentially what make us human.

Axonal nerve fibers in the real brain, by jgmarcelino from Newcastle upon Tyne, UK

Yale researchers believe that by learning more about the human connectome, they might find novel treatments for psychiatric disorders. Things like schizophrenia vary widely from one patient to the next. By finding what’s unique to a particular patient, a psychiatrist can tailor treatment to suit their needs. Understanding one’s connectome could give insight into how the disease progresses, and if and how the patient might respond to certain therapies or medications. But there are other uses which we may or may not feel comfortable with.

For instance, your child could have their brain scanned to track them at school, according to study author Todd Constable. It might be used to say whether or not a candidate is qualified for a job or should pursue a certain career. Brain scans could tell who might be prone to addiction, or what sort of learning environment a student might flourish in. School curriculum could even be changed on a day-to-day basis to fit student’s needs. And the dreaded SAT might even be shelved too, in favor of a simple brain scan.

Peter Bandettini is the chief of functional imaging methods at the National Institute of Mental Health (NIMH). He told PBS that barring ethical issues, brain scans could someday be used by employers to tell which potential candidate possesses desirable aptitudes or personality traits, be they diligent, hardworking, or what-have-you. Richard Haier, an intelligence researcher at UC Irvine, foresees prison officials using such scans on inmates to tell who might be prone to violence.

We may even someday learn how to augment human intelligence from studies such as this. It’s important to remember that intelligence research is still in its infancy. Yet, according to Yale scientists, we are moving in this direction.

Some fear a Minority Report-like misuse of said technology. Neuroethicist Laura Cabrera at Michigan State University enumerated for WIRED her concerns. What if insurance companies denied coverage based on such a scan, due to a tendency toward addiction or some other predisposition. Of course, just because someone has a higher risk of something, doesn’t mean they will develop it. Without proper guidelines in place and oversight, we could quickly see banks, schools, universities, and other institutions taking part in “neuro-discrimination.” Strong laws will have to be put in place to defend against misuse.

There are limits to what we now know about the human connectome that have yet to be overcome. For instance, we can only look at the connections as they are now. We don’t know how they form or develop over time. And fluid intelligence is merely one type out of several different kinds. We are still far from applying such technology in the real world. But the potential is there.

To learn more about the Human Connectome Project, click here:

Watch the video.URL:

Source:http://bigthink.com

 

Why Brain-to-Brain Communication Is No Longer Unthinkable

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Exploring uncharted territory, neuroscientists are making strides with human subjects who can “talk” directly by using their minds.

MAY2015_L01_MindtoMind.jpg

Telepathy, circa 23rd century: The Vulcan mind meld, accomplished by touching the temples with the fingertips, is an accepted technique for advancing the plot of a “Star Trek” episode with a minimum of dialogue, by sharing sensory impressions, memories and thoughts between nonhuman characters.

For nearly all of human history, only the five natural senses were known to serve as a way into the brain, and language and gesture as the channels out. Now researchers are breaching those boundaries of the mind, moving information in and out and across space and time, manipulating it and potentially enhancing it. This experiment and others have been a “demonstration to get the conversation started,” says researcher Rajesh Rao, who conducted it along with his colleague Andrea Stocco. The conversation, which will likely dominate neuroscience for much of this century, holds the promise of new technology that will dramatically affect how we treat dementia, stroke and spinal cord injuries. But it will also be about the ethics of powerful new tools to enhance thinking, and, ultimately, the very nature of consciousness and identity.

That new study grew out of Rao’s work in “brain-computer interfaces,” which process neural impulses into signals that can control external devices. Using an EEG to control a robot that can navigate a room and pick up objects—which Rao and his colleagues demonstrated as far back as 2008—may be commonplace someday for quadriplegics.

 

Neuroscientists Confirm That Our Loved Ones Become Ourselves

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Self-identity is entwined with the people you empathize with at a neural level.

A new study has confirmed that humankind’s capacity for love and friendship sets us apart from all other species. Researchers at University of Virginia have found that humans are hardwired to empathize with those close to them at a neural level.

Interestingly, the ability to put yourselves in another person’s shoes depends drastically on whether the person is a stranger or someone you know. The study titled “Familiarity Promotes the Blurring of Self and Other in the Neural Representation of Threat” appears in the August issue of the journal Social Cognitive and Affective Neuroscience.

According to researchers, the human brain puts strangers in one bin and the people we know in another compartment. People in your social network literally become entwined with your sense of self at a neural level. “With familiarity, other people become part of ourselves,” said James Coan, a psychology professor in University of Virginia’s College of Arts & Sciences who used functional magnetic resonance imaging brain (fMRI) scans to find that people closely correlate people to whom they are attached to themselves.

Humans have evolved to have our self-identity become woven into a neural tapestry with our loved ones. James Coan said, “Our self comes to include the people we feel close to. This likely is because humans need to have friends and allies who they can side with and see as being the same as themselves. And as people spend more time together, they become more similar.”

To test this hypothesis, Coan and his colleagues conducted a study with 22 young adult participants who underwent fMRI scans of their brains during experiments to monitor brain activity while under threat of receiving mild electrical shocks to themselves versus a shock to a friend or a stranger.

The researchers found that regions of the brain responsible for threat response – the anterior insula, putamen and supramarginal gyrus – became active under threat of shock to the self and to the threat to a friend. However, when the threat of shock was to a stranger, these brain areas showed minimal activity. When the threat of shock was to a friend, the brain activity of the participant was basically identical to the activity displayed under threat to the self.

“The correlation between self and friend was remarkably similar,” Coan said. “The finding shows the brain’s remarkable capacity to model self to others; that people close to us become a part of ourselves, and that is not just metaphor or poetry, it’s very real. Literally we are under threat when a friend is under threat. But not so when a stranger is under threat.”

“It’s essentially a breakdown of self and other; our self comes to include the people we become close to,” Coan said. “If a friend is under threat, it becomes the same as if we ourselves are under threat. We can understand the pain or difficulty they may be going through in the same way we understand our own pain.”

Why do some people hurt the ones they love?

Have you ever had someone that you consider to be a close friend, ally or loved one turn on you and become cold or cruel? Usually the outbursts of anger and blind rage are short and episodic but they give a window into the underbelly of someone’s psyche. One’s implusive response is to detach and unravel this person from your neural tapestry. This is a natural response of self-protection at a neural level but isn’t always the best response.

A solution for breaking this pattern of behavior is to take a two-pronged approach of both bolstering self-love and taking the high road of remaining empathetic towards loved ones who are hateful by recognizing that mean-spirtedness is a manifestation of self-hate. For more on this please check out my Psychology Today blog “The Guts Enough Not to Fight Back.” As a caveat, this is in no way implying that you should stay in a seriously harmful or abusive relationship.

Patterns of behavior are often learned and repeated within families and passed on through generations. A promising aspect of this new study is that it offers clues on ways to break the cycle.

By not fighting back – but instead practicing loving-kindness – you can keep loved ones in your life and over time you will remain an integral part of one another’s neural tapestry. This will fortify both people’s sense of being worthy of love and belonging and make everyone feel safe and sound over the long run. As Martin Luther King, Jr. said famously, “Darkness cannot drive out darkness; only light can do that. Hate cannot drive out hate; only love can do that.”

Conclusion: Come in From the Cold

We need friends and family more than anything else. One of the most fascinating aspects of this study is the insight that someone being non-empathetic to a loved one is a reflection of lacking self-love. The realization that self-hate is neurobiologically at the root of a loved one being cruel makes it easy to feel sorry for them and empathize, instead of perpetuating a cycle of anger and disconnection.

One of my favorite Joni Mitchell lines is from a song called “Come in From the Cold.” In the song she says, “We get hurt and we just panic. And we strike out. Out of fear.” We all know the classic three-step cycle of: 1) Hurt 2) Panic 3) Lashing out because of fear.

When someone you love is mean to you, the knee-jerk reaction to the threat is to strike back in self-defense. Unfortunately, doing so perpetuates the vicious cycle of mistrust, anger, and loneliness. When the empathetic response is unplugged at a neural level on both sides disconnection occurs. This is tragic because human connection matters more than anything in our lives. Luckily, through loving-kindness meditation and compassion training you can break this cycle. Empathy can be learned and fortified with mindfulness training.

If you hate yourself on some level – and friends and loved ones are embedded into your sense of self at a neural level – it would make sense that your empathetic response would short-circuit and falter if you were filled with self-loathing.

But how do you build self-love? That’s a big question, I know. One way to start is to focus on the importance of fortifying your sense of being worthy of love and belonging. And to make lifestyle choices everyday that break the cycle of self-loathing by taking care of yourself through regular physical activity, eating foods that nourish your body, filling your mind with ideas that educate/enlighten, and practicing mindfulness and loving-kindness.

“A threat to ourselves is a threat to our resources,” he said. “Threats can take things away from us. But when we develop friendships, people we can trust and rely on who in essence become we, then our resources are expanded, we gain. Your goal becomes my goal. It’s a part of our survivability.” Coan concludes, “People need friends, like one hand needs another to clap.”

How the brain processes emotions: Neuroscientists identify circuits that could play a role in mental illnesses, including depression.

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A new study reveals how two populations of neurons in the brain contribute to the brain’s inability to correctly assign emotional associations to events. Learning how this information is routed and misrouted could shed light on mental illnesses including depression, addiction, anxiety, and posttraumatic stress disorder.
Two neurons of the basolateral amygdala. MIT neuroscientists have found that these neurons play a key role in separating information about positive and negative experiences.

Some mental illnesses may stem, in part, from the brain’s inability to correctly assign emotional associations to events. For example, people who are depressed often do not feel happy even when experiencing something that they normally enjoy.

A new study from MIT reveals how two populations of neurons in the brain contribute to this process. The researchers found that these neurons, located in an almond-sized region known as the amygdala, form parallel channels that carry information about pleasant or unpleasant events.

Learning more about how this information is routed and misrouted could shed light on mental illnesses including depression, addiction, anxiety, and posttraumatic stress disorder, says Kay Tye, the Whitehead Career Development Assistant Professor of Brain and Cognitive Sciences and a member of MIT’s Picower Institute for Learning and Memory.

“I think this project really cuts across specific categorizations of diseases and could be applicable to almost any mental illness,” says Tye, the senior author of the study, which appears in the March 31 online issue of Neuron.

The paper’s lead authors are postdoc Anna Beyeler and graduate student Praneeth Namburi.

Emotional circuits

In a previous study, Tye’s lab identified two populations of neurons involved in processing positive and negative emotions. One of these populations relays information to the nucleus accumbens, which plays a role in learning to seek rewarding experiences, while the other sends input to the centromedial amygdala.

In the new study, the researchers wanted to find out what those neurons actually do as an animal reacts to a frightening or pleasurable stimulus. To do that, they first tagged each population with a light-sensitive protein called channelrhodopsin. In three groups of mice, they labeled cells projecting to the nucleus accumbens, the centromedial amygdala, and a third population that connects to the ventral hippocampus. Tye’s lab has previously shown that the connection to the ventral hippocampus is involved in anxiety.

Tagging the neurons is necessary because the populations that project to different targets are otherwise indistinguishable. “As far as we can tell they’re heavily intermingled,” Tye says. “Unlike some other regions of the brain, there is no topographical separation based on where they go.”

After labeling each cell population, the researchers trained the mice to discriminate between two different sounds, one associated with a reward (sugar water) and the other associated with a bitter taste (quinine). They then recorded electrical activity from each group of neurons as the mice encountered the two stimuli. This technique allows scientists to compare the brain’s anatomy (which neurons are connected to each other) and its physiology (how those neurons respond to environmental input).

The researchers were surprised to find that neurons within each subpopulation did not all respond the same way. Some responded to one cue and some responded to the other, and some responded to both. Some neurons were excited by the cue while others were inhibited.

“The neurons within each projection are very heterogeneous. They don’t all do the same thing,” Tye says.

However, despite these differences, the researchers did find overall patterns for each population. Among the neurons that project to the nucleus accumbens, most were excited by the rewarding stimulus and did not respond to the aversive one. Among neurons that project to the central amygdala, most were excited by the aversive cue but not the rewarding cue. Among neurons that project to the ventral hippocampus, the neurons appeared to be more balanced between responding to the positive and negative cues.

“This is consistent with the previous paper, but we added the actual neural dynamics of the firing and the heterogeneity that was masked by the previous approach of optogenetic manipulation,” Tye says. “The missing piece of that story was what are these neurons actually doing, in real time, when the animal is being presented with stimuli.”

Digging deep

The findings suggest that to fully understand how the brain processes emotions, neuroscientists will have to delve deeper into more specific populations, Tye says.

“Five or 10 years ago, everything was all about specific brain regions. And then in the past four or five years there’s been more focus on specific projections. And now, this study presents a window into the next era, when even specific projections are not specific enough. There’s still heterogeneity even when you subdivide at this level,” she says. “We’ve still got a long way to go in terms of appreciating the full complexities of the brain.”

Another question still remaining is why these different populations are intermingled in the amygdala. One hypothesis is that the cells responding to different inputs need to be able to quickly interact with each other, coordinating responses to an urgent signal, such as an alert that danger is present. “We are exploring the interactions between these different projections, and we think that could be a key to how we so quickly select an appropriate action when we’re presented with a stimulus,” Tye says.

In the long term, the researchers hope their work will lead to new therapies for mental illnesses. “The first step is to define the circuits and then try to go in animal models of these pathologies and see how these circuits are functioning differently. Then we can try to develop strategies to restore them and try to translate that to human patients,” says Beyeler, who is soon starting her own lab at the University of Lausanne to further pursue this line of research.

Neuroscientists ‘rediscover’ entire brain region linked to reading.

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Neuroscientists have ‘rediscovered’ a large part of the brain that disappeared from the scientific literature during the early 1900s. Now that it’s been properly analysed, it’s thought to be involved in crucial mental processes such as reading and recognising faces.
Neuroscientists in the US have accidentally rediscovered a forgotten region of the brain while investigating how reading skills develop over time in children.

“We couldn’t find it in any atlas,” one of the team, Jason Yeatman from the University of Washington’s Institute for Learning and Brain Sciences, told Laura Geggel at LiveScience. “We’d thought we had discovered a new pathway that no one else had noticed before.”

What they’d found was a region that, for reasons unknown, dropped out of the scientific literature describing human brains about a century ago, but continued to have a known prescence in the brains of other primates.

First discovered in 1881 by German neurologist Carl Wernicke, region is called the vertical occipital fasciculus (VOF). This flat, 5.5-centimetre cluster of long nerve fibres running vertically along the rear of the brain was found by Wenicke during a monkey brain dissection, and while it was later found in human brains, it remained conspicuously absent from anatomical drawings called ‘brain atlases’ throughout history.

This is something of a major oversight, as the VOF is now thought to play a unique and crucial role in how we’re able to process visual information. It maintains several connections between the nearby ‘vision sub-regions’ of the brain, which work together with visual cortex – also in the rear section of the brain – to process what we’re seeing at any given moment.

“I stumbled upon it while studying the visual word form area,” Yeatman told Mo Costandi at The Guardian. “In every subject, I found this large, vertically-oriented fibre bundle terminating in that region of the brain.”

After poring through both contemporary and historic literature for mentions of the region, Yeatman says a colleague remembered having seen something like it in an old medical textbook. So he dipped into the brain atlases of the late 1800s and early 1900s to discover a bizarre squabble between some of the world’s most imminent neuroscientists at the time.

It seems that Wenicke’s superior, German-Austrian neuroanatomist, Theodor Meynert, more or less ignored his student’s discovery, perhaps because it clashed with his own conclusions about the human brain. Meynert, who also taught none other than Sigmund Freud, had proposed a theory that said the neural pathways of the brain ran horizontally from the front of the brain to the back, not vertically, as Wenicke’s new discovery appeared to do.

Or perhaps Wenicke’s discovery was so removed from what Meynert was working on at the time that he ignored the discovery simply because he was focussing on something else. “Meynert’s apparent non-discussion of these fibre systems may simply have reflected his interest and focus,” Jeremy Schmahmann, a neurologist  from the Massachusetts General Hospital and Harvard Medical School who was not involved in the study, told Geggel at LiveScience.

Add the oversight of one of the world’s most respected neuroanatomists to the fact that in many of the brain atlases the VOF did turn up in, it had all kinds of different names, and that it can be very easily missed when you’re dissecting a human brain, and it makes sense how Wenicke’s discovery could have disappeared into obscurity.

Now that they’ve found it, Yeatman’s team has scanned over 70 people to locate and map the VOF properly, and the findings have been published today in the Proceedings of the National Academy of Sciences.

According to Costandi at The Guardian, the team describe the VOF as connecting the ‘upper’ and ‘lower’ streams of the brain’s visual pathway. “The lower stream connects brain regions involved in processes such as object recognition, including the fusiform gyrus, and the upper stream connects the angular gyrus to other areas involved in attention, motion detection, and visually-guided behaviour,” she says.

Yeatman and his team are continuing their research into how learning to read impacts a young person’s brain structure, and he says he thinks there’s a good chance that the newly rediscovered VOF will play a crucial role in that work.

What do you want to know about sleep? Neuroscientists answer your questions

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Sleep is vital for our mental and physical health, yet an increasing number of people are getting less than they need. Do you have problems sleeping? Neuroscientists from the University of Oxford answered your questions

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Do you get enough sleep? Ask your question in the comment thread 

Do you have difficulty getting enough sleep? Sleep problems affect one in three of us at any one time, and about 10% of the population on a chronic basis. Of Guardian readers who responded to a recent poll, 23% reported that they sleep between four and six hours a night.

With continued lack of sufficient sleep, the part of the brain that controls language and memory is severely impaired, and 17 hours of sustained wakefulness is equivalent to performing on a blood alcohol level of 0.05% – the UK’s legal drink driving limit.

In 2002, American researchers analysed data from more than one million people, and found that getting less than six hours’ sleep a night was associated with an early demise – as was getting over eight hours.

Studies have found that blood pressure is more than three times greater among those who sleep for less than six hours a night, and women who have less than four hours of sleep are twice as likely to die from heart disease. Other research suggests that a lack of sleep is also related to the onset of diabetes, obesity, and cancer.

Are you worried about how much sleep you get?