neurosciencestuff:

For combat veterans suffering from post-traumatic stress disorder, ‘fear circuitry’ in the brain never rests

Chronic trauma can inflict lasting damage to brain regions associated with fear and anxiety. Previous imaging studies of people with post-traumatic stress disorder, or PTSD, have shown that these brain regions can over-or under-react in response to stressful tasks, such as recalling a traumatic event or reacting to a photo of a threatening face. Now, researchers at NYU School of Medicine have explored for the first time what happens in the brains of combat veterans with PTSD in the absence of external triggers.

Their results, published in Neuroscience Letters, and presented today at the annual meeting of the American Psychiatry Association in San Francisco, show that the effects of trauma persist in certain brain regions even when combat veterans are not engaged in cognitive or emotional tasks, and face no immediate external threats. The findings shed light on which areas of the brain provoke traumatic symptoms and represent a critical step toward better diagnostics and treatments for PTSD.

A chronic condition that develops after trauma, PTSD can plague victims with disturbing memories, flashbacks, nightmares and emotional instability. Among the 1.7 million men and women who have served in the wars in Iraq and Afghanistan, an estimated 20% have PTSD. Research shows that suicide risk is higher in veterans with PTSD. Tragically, more soldiers committed suicide in 2012 than the number of soldiers who were killed in combat in Afghanistan that year.

“It is critical to have an objective test to confirm PTSD diagnosis as self reports can be unreliable,” says co-author Charles Marmar, MD, the Lucius N. Littauer Professor of Psychiatry and chair of NYU Langone’s Department of Psychiatry. Dr. Marmar, a nationally recognized expert on trauma and stress among veterans, heads The Steven and Alexandra Cohen Veterans Center for the Study of Post-Traumatic Stress and Traumatic Brain Injury at NYU Langone Medical Center.

The study, led by Xiaodan Yan, a research fellow at NYU School of Medicine, examined “spontaneous” or “resting” brain activity in 104 veterans of combat from the Iraq and Afghanistan wars using functional MRI, which measures blood-oxygen levels in the brain. The researchers found that spontaneous brain activity in the amygdala, a key structure in the brain’s “fear circuitry” that processes fearful and anxious emotions, was significantly higher in the 52 combat veterans with PTSD than in the 52 combat veterans without PTSD. The PTSD group also showed elevated brain activity in the anterior insula, a brain region that regulates sensitivity to pain and negative emotions.

Moreover, the PTSD group had lower activity in the precuneus, a structure tucked between the brain’s two hemispheres that helps integrate information from the past and future, especially when the mind is wandering or disengaged from active thought. Decreased activity in the precuneus correlates with more severe “re-experiencing” symptoms—that is, when victims re-experience trauma over and over again through flashbacks, nightmares and frightening thoughts.

(via scinerds)

neuromorphogenesis:

Imagine A Flying Pig: How Words Take Shape In The Brain

This is a story about a duck. More precisely, it’s a story about what your brain just did when you read the word “duck.”

Chances are, your brain created an image of a web-footed waterfowl. It also may have recalled the sound of quacking or the feel of feathers. And new research suggests that these mental simulations are essential to understanding language.

Just a few decades ago, many linguists thought the human brain had evolved a special module for language. It seemed plausible that our brains have some unique structure or system. After all, no animal can use language the way people can.

But in the 1990s, scientists began testing the language-module theory using “functional” MRI technology that let them watch the brain respond to words. And what they saw didn’t look like a module, says Benjamin Bergen, a researcher at the University of California, San Diego, and author of the book Louder Than Words.

“They found something totally surprising,” Bergen says. “It’s not just certain specific little regions in the brain, regions dedicated to language, that were lighting up. It was kind of a whole-brain type of process.”

If someone read a sentence like, “the shortstop threw the ball to first base,” parts of the brain dedicated to vision and movement would light up, Bergen says. “The question was, why?” he says. “They’re just listening to language. Why would they be preparing to act? Why would they be thinking that they were seeing something?”

The answer that emerged from this research is that when you encounter words describing a particular action, your brain simulates the experience, Bergen says.

“The way that you understand an action is by recreating in your vision system what it would look like to perceive that event and recreating in your motor system what it would be like to be that shortstop, to have the ball in your hand and release it,” Bergen says.

The brain appears to be taking words, which are just arbitrary symbols, and translating them into things we can see or hear or do, Bergen says.

That’s not much of a stretch when it comes to words for things like throwing a baseball or seeing a duck. But what about words for things we’ve probably never seen? Like a flying pig.

“A flying pig isn’t something that actually exists in the real world,” Bergen says. Yet when we read those words we see one in our mind’s eye. Most people see a pig with wings above its shoulders, Bergen says. But some people imagine a pig with a cape, flying like Superman.

A flying pig has meaning to us because our brain is using things we have seen — pigs and birds — to create something we’ve never seen. And Bergen says we also draw on personal experience when we use language to convey abstract ideas — like truth, or justice, or even the word “meaning.”

“What we actually say when we talk about meaning is, do you see what I mean? Is my point crystal clear? Maybe, let’s shed a little light on the subject,” Bergen says. What we’re doing, he says, is extending our physical experiences — in this case things we’ve seen — by turning them into metaphors.

We use this sort of metaphor all the time in conversation, Bergen says. We “grasp” the truth. We “dodge” questions. We “fall” in love.

Philosophers have been debating the importance of metaphors like these since the time of Aristotle. But now, brain researchers like Krish Sathian at Emory University are getting involved.

Sathian has been studying an area of the brain that responds to the texture of an object — whether it feels smooth or rough. And he wondered whether the same area would respond when we use textures like smooth or rough as metaphors.

So he had people lie in an fMRI scanner while they listened to metaphors like, “he had a rough day,” as well as similar sentences with no metaphor like, “he had a bad day.”

The results suggest that, at least to the brain, a rough day has something in common with a sheet of sandpaper, Sathian says. “When listening to these sentences containing textural metaphors, we found activity in the part of the brain that’s involved when we feel surfaces,” he says

Research like this adds to the evidence that the human brain is not processing language in some special module, Sathian says. “The brain is really working as a very highly distributed system.”

What’s amazing is that people have been able to do so much with language using the same basic brain structures found in monkeys and apes, Bergen says.

“What evolution has done is to build a new machine, a capacity for language, something that nothing else in the known universe can do,” he says. “And it’s done so using the spare parts that it had lying around in the old primate brain.”

Image: Although a flying pig doesn’t exist in the real world, our brains use what we know about pigs and birds — and superheroes — to create one in our mind’s eye when we hear or read those words.

neuromorphogenesis:

A “baseball-playing” robot with a 100,000-neuron “brain”

That’s a lot of quotation marks. Also the robot’s baseball bat looks a bit like an oversized fly swatter. Whatever – this thing is still impressive.

The real-time cerebellum was created by Tadashi Yamazaki and Jun Igarashi, of Japan’s RIKEN Brain Science Institute. An accelerometer located at the rear of the batting cage detects the flight path of the ball, and relays that information to a graphics processor (GPU), similar to what you might find in a gaming computer.

This GPU is the robot’s artificial brain. According to the researchers, it comprises a large-scale spiking network model of a cerebellum, including “more than 100,000 spiking neuron units within realistic parameters.” (The neurons in a spiking neural network, like the neurons in your brain, fire in accordance with the propagation of simulated neuron potentials. Basically, the GPU’s artificial neurons obey the same go/no-go rules as the neurons in your head, making spiking neural networks some of the most realistic brain simulators out there.) The GPU does some number-crunching and tells the robot how best to move in order to make contact. But the GPU also learns from its mistake. Even if the robot swings and misses, it’s only a matter of time until it’s nailing every pitch (provided the ball is tossed at the same speed and along the same flight path every time). If the pitch-speed and path are changed, the robot learns again.

As Wired’s Daniela Hernandez points out, this is not the first time researchers have used a neural network to control a robot:

A team of scientists in Europe, for instance, have used an artificial cerebellum to control a robotic limb. But according to [Yamazaki]… the baseball-playing robot is the second largest model of its kind and it runs in realtime, meaning its much faster than other systems. That means the GPU brain is better suited to controlling external hardware, he says.

The paper describing the research is published, in Neural Networks.

neuromorphogenesis:

Building a Better Brain

The next generation of brain-machine interfaces (B-MI) may rapidly enhance health and improve the quality of life for those with reduced function due to disease or disability. They may also allow people to control drones with just their thoughts or even add new human senses, which raise important ethical considerations.

At the recent meeting of the American Association for the Advancement for Science in Boston, neuroscientists outlined several lines of promising B-MI research. Advances in microprocessors, computing, and materials science, for example, have facilitated the development of “epidermal electronics,” which combine wireless communications, neural sensors, and other medical sensors into patches small and flexible enough to serve as temporary tattoos. These electronics have obvious clinical use, such as for unobtrusive monitoring of vital signs or symptoms of brain disease, said principal investigator Todd P. Coleman of the University of California, San Diego. In fact, he has created a company, Neuroverse, to commercialize this type of application. But Coleman also sees more wide-ranging deployment in the near future. His work was partially inspired by previous experiments in which people controlled virtual or model airplanes via a cap of electrodes; flexible B-MIs might provide similar abilities without tying people down to bulky electronics. Applying the tattoos near the vocal cords might also allow for subvocal wireless communication with electronics such as smartphones. “The things you can pick up non-invasively are much richer than you might imagine at first glance,” he said. “Things we thought were hoaxes and science fiction are fast approaching fruition.”

And that may only be the tip of the iceberg: Miguel Nicolelis and his colleagues at Duke University have developed a means to create entirely new sense modalities. They connected infrared light sensors to dense three-dimensional arrays of electrodes implanted into the somatosensory cortex of rats. This allowed the rats to track food by “feeling” light that they physiologically have no way to detect. Think of it as an artificially induced form of synesthesia, Nicolelis said. “The rats learned to ‘touch’ a source of invisible light — they acquired new modality of touch.” The researchers have already extended the research to monkeys, raising the possibility that people might eventually be able to “augment” themselves with new abilities using this technology. “When you deliver signals from devices directly to brain,” Nicolelis said, “you can create a new sensation, a new feeling.”

The ethical implications of these B-MI projects and similar technology were not lost on session participants. All medical innovations raise legal and moral questions, said neuroethicist Martha Farah of the University of Pennsylvania. However, B-MI and other fields such as neuropsychiatry that directly affect people’s abilities raise particularly difficult questions about what it means to be human and what kind of relationship people have with technology. It’s difficult not to draw on iconic images of cyborgs from science fiction when discussing the long-term possibilities of B-MIs, which might include providing people new ways to sense the world, methods of augmenting cognition and memory, and even the ability to communicate brain-to-brain or merge identities.

“Ethical considerations such as those raised in the B-MI panel are important for all scientists,” said Michael Zigmond, professor of neurology at the University of Pittsburgh and secretary of the AAAS Neuroscience Section. “As scientific development and technological advances increasingly change the ways we deal with the human condition, we must continue to have conversations about how those changes might affect society. Such discussions are well-informed by the wide array of scientists who attend the AAAS annual meeting and can provide valuable insights and guidance.”

Additionally, Farah noted that focusing only on “sexy sci-fi long-term issues” ignores many serious short-term challenges more relevant to the day-to-day life of brain researchers and policymakers. “I’m not dismissing concerns about radically altered human brains that push us beyond what a human being is,” she said. “Before we get there, there are some other pretty serious ethical challenges — mundane, yet very important issues,” such as funding sources, conflicts of interest, and intellectual property protection. For example, rethinking clinical trial rules and practice might be necessary. In the United States, medical devices are regulated differently than pharmaceuticals, even though B-MIs are increasingly serving as a substitute for testing and treatment. Who funds current B-MI research may also have a disproportionate influence on the field, as aggressive pursuit of patents might constrain many promising avenues of research.

Between 10 and 30 years from now, people will need to make difficult decisions about access to B-MI technology, its appropriate uses, and risks, Farah added. Cochlear implants, retinal implants, and similar devices are already used regularly, but deciding what level of impairment is appropriate for treatment is not easy — especially as temptations grow to use this technology for frank enhancement or “making a person better than normal.” B-MIs that communicate wirelessly also expose people to hackers, computer viruses, and similar cybersecurity risks. “What if they hack into your brain?” Farah asked. With B-MIs, such inference could affect eyesight, memory, or even vital functions such as heart rate. People will also have to decide how to manage the costs of B-MI technology to ensure fair access. “Undoubtedly these technologies will be available to the rich before anyone else,” Farah said. “How would we like our society to manage these? How much do we guide the scientists and the health system to enforce as much equity as we can?”

(image: At the recent meeting of the American Association for the Advancement for Science in Boston, neuroscientists outlined several lines of promising brain-machine interface research.)

neuromorphogenesis:

After freezing and fixing, the brains have a jaundiced pallor and a pronounced bounce, like pickled eggs.

- A human brain dissection

Photograph: Graeme Robertson

(Source: Guardian)

neuromorphogenesis:

Mom’s love good for child’s brain

School-age children whose mothers nurtured them early in life have brains with a larger hippocampus, a key structure important to learning, memory and response to stress.

The new research, by child psychiatrists and neuroscientists at Washington University School of Medicine in St. Louis, is the first to show that changes in this critical region of children’s brain anatomy are linked to a mother’s nurturing.

Their research is published online in theProceedings of the National Academy of SciencesEarly Edition.

“This study validates something that seems to be intuitive, which is just how important nurturing parents are to creating adaptive human beings,” says lead author Joan L. Luby, MD, professor of child psychiatry. “I think the public health implications suggest that we should pay more attention to parents’ nurturing, and we should do what we can as a society to foster these skills because clearly nurturing has a very, very big impact on later development.”

The brain-imaging study involved children ages 7 to 10 who had participated in an earlier study of preschool depression that Luby and her colleagues began about a decade ago. That study involved children, ages 3 to 6, who had symptoms of depression, other psychiatric disorders or were mentally healthy with no known psychiatric problems.

As part of the initial study, the children were closely observed and videotaped interacting with a parent, almost always a mother, as the parent was completing a required task, and the child was asked to wait to open an attractive gift. How much or how little the parent was able to support and nurture the child in this stressful circumstance — which was designed to approximate the stresses of daily parenting — was evaluated by raters who knew nothing about the child’s health or the parent’s temperament.

“It’s very objective,” Luby says. “Whether a parent was considered a nurturer was not based on that parent’s own self-assessment. Rather, it was based on their behavior and the extent to which they nurtured their child under these challenging conditions.”

The study didn’t observe parents and children in their homes or repeat stressful exercises, but other studies of child development have used similar methods as valid measurements of whether parents tend to be nurturers when they interact with their children.

For the current study, the researchers conducted brain scans on 92 of the children who had had symptoms of depression or were mentally healthy when they were studied as preschoolers. The imaging revealed that children without depression who had been nurtured had a hippocampus almost 10 percent larger than children whose mothers were not as nurturing.

“For years studies have underscored the importance of an early, nurturing environment for good, healthy outcomes for children,” Luby says. “But most of those studies have looked at psychosocial factors or school performance. This study, to my knowledge, is the first that actually shows an anatomical change in the brain, which really provides validation for the very large body of early childhood development literature that had been highlighting the importance of early parenting and nurturing. Having a hippocampus that’s almost 10 percent larger just provides concrete evidence of nurturing’s powerful effect.”

Luby says the smaller volumes in depressed children might be expected because studies in adults have shown the same results. What did surprise her was that nurturing made such a big difference in mentally healthy children.

“We found a very strong relationship between maternal nurturing and the size of the hippocampus in the healthy children,” she says.

Although 95 percent of the parents whose nurturing skills were evaluated during the earlier study were biological mothers, the researchers say that the effects of nurturing on the brain are likely to be the same for any primary caregiver — whether they are fathers, grandparents or adoptive parents.

The fact that the researchers found a larger hippocampus in the healthy children who were nurtured is striking, Luby says, because the hippocampus is such an important brain structure.

When the body faces stresses, the brain activates the autonomic nervous system, an involuntary system of nerves that controls the release of stress hormones. Those hormones help us cope with stress by increasing the heart rate and helping the body adapt. The hippocampus is the main brain structure involved in that response. It’s also key in learning and memory, and larger volumes would suggest a link to improved performance in school, among other things.

Past animal studies have indicated that a nurturing mother can influence brain development, and many studies in human children have identified improvements in school performance and healthier development in children raised in a nurturing environment. But until now, there has not been solid evidence linking a nurturing parent to changes in brain anatomy in children.

“Studies in rats have shown that maternal nurturance, specifically in the form of licking, produces changes in genes that then produce changes in receptors that increase the size of the hippocampus,” Luby says. “That phenomenon has been replicated in primates, but it hasn’t really been clear whether the same thing happens in humans. Our study suggests a clear link between nurturing and the size of the hippocampus.”

She says educators who work with families who have young children may improve school performance and child development by not only teaching parents to work on particular tasks with their children but by showing parents how to work with their children.

“Parents should be taught how to nurture and support their children,” Luby says. “Those are very important elements in healthy development.”

(Image: The hippocampus (highlighted in fuchsia) is a key brain structure important to learning, memory and stress response. New research shows that children who were nurtured by their mothers early in life have a larger hippocampus than children who were not nurtured as much. Credit: Washington University Medical School from press release)

(Source: news.wustl.edu)