Highways of the brain: High-cost and high-capacity

June 18th, 2012 in Neuroscience

A new study proposes a communication routing strategy for the brain that mimics the American highway system, with the bulk of the traffic leaving the local and feeder neural pathways to spend as much time as possible on the longer, higher-capacity passages through an influential network of hubs, the so-called rich club.

The study, published this week online in the Early Edition of the Proceedings of the National Academy of Sciences, involves researchers from Indiana University and the University Medical Center Utrecht in the Netherlands and advances their earlier findings that showed how select hubs in the brain not only are powerful in their own right but have numerous and strong connections between each other.

The current study characterizes the influential network within the rich club as the "backbone" for global brain communication. A costly network in terms of the energy and space consumed, said Olaf Sporns, professor in the Department of Psychological and Brain Sciences at IU Bloomington, but one with a big pay-off: providing quick and effective communication between billions and billions of brain cells.

"Until now, no one knew how central the brain's rich club really was," Sporns said. "It turns out the rich club is always right in the middle when it comes to how brain regions talk to each other. It absorbs, transforms and disseminates information. This underscores its importance for brain communication."

In earlier work, using diffusion imaging, the researchers found a group of 12 strongly interconnected bihemispheric hub regions, comprising the precuneus, superior frontal and superior parietal cortex, as well as the subcortical hippocampus, putamen and thalamus. Together, these regions form the brain's "rich club." Most of these areas are engaged in a wide range of complex behavioral and cognitive tasks, rather than more specialized processing such as vision and motor control.

For the current study, Martijn van den Heuvel, a professor at the Rudolf Magnus Institute of Neuroscience at University Medical Center Utrecht, used diffusion tensor imaging data for two sets of 40 healthy subjects to map the large-scale connectivity structure of the brain. The cortical sheet was divided into 1,170 regions, and then pathways between the regions were reconstructed and measured. As in the previous study, the rich club nodes were widely distributed and had up to 40 percent more connectivity compared to other areas.

The connections measured -- almost 700,000 in total -- were classified in one of three ways: as rich club connections if they connected nodes within the rich club; as feeder connections if they connected a non-rich club node to a rich club node; and as local connections if they connected non-rich club nodes. Rich club connections made up the majority of all long-distance neural pathways. The study also found that connections classified as rich club connections were used more heavily for communication than other feeder and local connections. A path analysis showed that when a minimally short path is traced from one area of the brain to another, it travels through the rich club network 69 percent of the time, even though the network accounts for only 10 percent of the brain.

A common pattern in communication paths spanning long distances, Sporns said, was that such paths involved sequences of steps leading across local, feeder, rich club, feeder and back to local connections. In other words, he said, many communication paths first traveled toward the rich club before reaching their destinations.

"It is as if the rich club acts as an attractor for signal traffic in the brain," Sporns said. "It soaks up information which is then integrated and sent back out to the rest of the brain."

Van den Heuvel agreed.

"It's like a big 'neuronal magnet' for communication and information integration in our brains," he said. "Seeking out the rich club may offer a strategy for neurons and brain regions to find short communication paths across the brain, and might provide insight into how our brain manages to be so highly efficient."

From an evolutionary standpoint, it was important for the brain to minimize energy consumption and wiring volume, but if these were the only factors, there would be no rich club because of the extra resources it requires, Sporns said. The rich club is expensive, at least in terms of wiring volume, and perhaps also in terms of metabolic cost. The trade-off for higher cost, Sporns said, is higher performance -- the integration of diverse signals and the ability to select short paths across the network.

"Brain neurons don't have maps; how do they find paths to get in touch? Perhaps the rich club helps with this, offering the brain's neurons and regions a way to communicate efficiently based on a routing strategy that involves the rich club."

People use related strategies to navigate social networks.

"Strangely, neurons may solve their communication problems just like the people to which they belong," Sporns said.

More information: "High-cost, high-capacity backbone for global brain communication" PNAS, 2012.

Provided by Indiana University

"Highways of the brain: High-cost and high-capacity." June 18th, 2012. http://medicalxpress.com/news/2012-06-highways-brain-high-cost-high-capacity.html

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'Hallucinating' robots arrange objects for human use

June 18th, 2012 in Electronics / Robotics
A robot populates a room with imaginary human stick figures in order to decide where objects should go to suit the needs of humans.

(Phys.org) -- If you hire a robot to help you move into your new apartment, you won't have to send out for pizza. But you will have to give the robot a system for figuring out where things go. The best approach, according to Cornell researchers, is to ask "How will humans use this?"

Researchers in the Personal Robotics Lab of Ashutosh Saxena, assistant professor of computer science, have already taught robots to identify common objects, pick them up and place them stably in appropriate locations. Now they've added the human element by teaching robots to "hallucinate" where and how humans might stand, sit or work in a room, and place objects in their usual relationship to those imaginary people.

Their work will be reported at the International Symposium on Experimental Robotics, June 21 in Quebec, and the International Conference of Machine Learning, June 29 in Edinburgh, Scotland.

Previous work on robotic placement, the researchers note, has relied on modeling relationships between objects. A keyboard goes in front of a monitor, and a mouse goes next to the keyboard. But that doesn't help if the robot puts the monitor, keyboard and mouse at the back of the desk, facing the wall.

Above left, random placing of objects in a scene puts food on the floor, shoes on the desk and a laptop teetering on the top of the fridge. Considering the relationships between objects (upper right) is better, but he laptop is facing away from a potential user and the food higher than most humans would like. Adding human context (lower left) makes things more accessible. Lower right: how an actual robot carried it out. (Personal Robotics Lab)

Relating objects to humans not only avoids such mistakes but also makes computation easier, the researchers said, because each object is described in terms of its relationship to a small set of human poses, rather than to the long list of other objects in a scene. A computer learns these relationships by observing 3-D images of rooms with objects in them, in which it imagines human figures, placing them in practical relationships with objects and furniture. You don't don't put a sitting person where there is no chair. You can put a sitting person on top of a bookcase, but there are no objects there for the person to use, so that''s ignored. It The computer calculates the distance of objects from various parts of the imagined human figures, and notes the orientation of the objects.

Eventually it learns commonalities: There are lots of imaginary people sitting on the sofa facing the TV, and the TV is always facing them. The remote is usually near a human's reaching arm, seldom near a standing person's feet. "It is more important for a robot to figure out how an object is to be used by humans, rather than what the object is. One key achievement in this work is using unlabeled data to figure out how humans use a space," Saxena said.

In a new situation the a robot places human figures in a 3-D image of a room, locating them in relation to objects and furniture already there. "It puts a sample of human poses in the environment, then figures out which ones are relevant and ignores the others," Saxena explained. It decides where new objects should be placed in relation to the human figures, and carries out the action.

The researchers tested their method using images of living rooms, kitchens and offices from the Google 3-D Warehouse, and later, images of local offices and apartments. Finally, they programmed a robot to carry out the predicted placements in local settings. Volunteers who were not associated with the project rated the placement of each object for correctness on a scale of 1 to 5.

Comparing various algorithms, the researchers found that placements based on human context were more accurate than those based solely in relationships between objects, but the best results of all came from combining human context with object-to-object relationships, with an average score of 4.3. Some tests were done in rooms with furniture and some objects, others in rooms where only a major piece of furniture was present. The object-only method performed significantly worse in the latter case because there was no context to use. "The difference between previous works and our [human to object] method was significantly higher in the case of empty rooms," Saxena reported.

The research was supported by a Microsoft Faculty Fellowship and a gift from Google. Marcus Lin, M.Eng. '12, received an Academic Excellence Award from the Department of Computer Science in part for his work on this project.

Provided by Cornell University

"'Hallucinating' robots arrange objects for human use." June 18th, 2012. http://phys.org/news/2012-06-hallucinating-robots-human.html

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The neurological basis for fear and memory

June 18th, 2012 in Neuroscience
Credit: Thinkstock

Fear conditioning using sound and taste aversion, as applied to mice, have revealed interesting information on the basis of memory allocation.

European 'Cellular mechanisms underlying formation of the fear memory trace in the mouse amygdala' (FEAR Memory TRACE) project is investigating memory allocation and the recruitment of certain neurons to encode a memory. By studying conditioned fear memory in response to an auditory stimulus, the researchers have delved into pathological emotional states and neural mechanisms involved in memory allocation, retrieval and extinction.

Prior research has revealed that the conditioned fear response in mice is located in a specific bundle of neurons in the amygdala. Memory allocation modulation is due to expression of the transcription factor, cyclic adenosine 3', 5'-monophosphate response element binding protein (CREB) and possibly neuronal excitability.

FEAR Memory TRACE focused on the electrophysiological properties of neurons encoding the same memory. The project also aimed to ascertain the biophysical mechanisms in the plasticity changes recorded in the specific set of neurons in the fear memory trace.

Recording information on auditory fear conditioning and conditioned taste aversion, the scientists used intra-amygdala surgery using viral vectors and electrophysiological experiments to detect neuronal excitability.

Transfected by virus, CREB tagged with green fluorescent protein together with the gene for channelrhodopsin2 were used in neural control experiments. Combined, these two elements caused neuron firing in specific nerve cells. Molecular techniques included western blot for protein detection, genotyping and viral DNA preparation.

Behavioural tests on long- and short-term memory of mice involving fear conditioning and taste aversion showed increased memory performance at the three-hour point rather than the five-hour point. The intrinsic excitability of the mice receiving both shock and the tone was increased at three hours, not five, compared to mice that only received the tone.

As the project continues to its close in two years, the aim is to identify biophysical mechanisms involved in recruiting neurons that compete with each other for a specific memory. FEAR Memory TRACE will also develop computational models to assess the role of these mechanisms in memory performance.

Information on biochemical processes in neural mechanisms has wide application in many clinical situations including patients suffering memory loss, such as stroke victims. Fear response manipulation can be applied in treatment of neuroses and phobias.

Provided by CORDIS

"The neurological basis for fear and memory." June 18th, 2012. http://medicalxpress.com/news/2012-06-neurological-basis-memory.html

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Robots equipped with tactile sensor able to identify materials through touch

June 18th, 2012 in Electronics / Robotics

What does a robot feel when it touches something? Little or nothing until now. But with the right sensors, actuators and software, robots can be given the sense of feel – or at least the ability to identify different materials by touch.

Researchers at the University of Southern California's Viterbi School of Engineering published a study today in Frontiers in Neurorobotics showing that a specially designed robot can outperform humans in identifying a wide range of natural materials according to their textures, paving the way for advancements in prostheses, personal assistive robots and consumer product testing.

The robot was equipped with a new type of tactile sensor built to mimic the human fingertip. It also used a newly designed algorithm to make decisions about how to explore the outside world by imitating human strategies. Capable of other human sensations, the sensor can also tell where and in which direction forces are applied to the fingertip and even the thermal properties of an object being touched.

Like the human finger, the group's BioTac® sensor has a soft, flexible skin over a liquid filling. The skin even has fingerprints on its surface, greatly enhancing its sensitivity to vibration. As the finger slides over a textured surface, the skin vibrates in characteristic ways. These vibrations are detected by a hydrophone inside the bone-like core of the finger. The human finger uses similar vibrations to identify textures, but the robot finger is even more sensitive.

When humans try to identify an object by touch, they use a wide range of exploratory movements based on their prior experience with similar objects. A famous theorem by 18th century mathematician Thomas Bayes describes how decisions might be made from the information obtained during these movements. Until now, however, there was no way to decide which exploratory movement to make next. The article, authored by Professor of Biomedical Engineering Gerald Loeb and recently graduated doctoral student Jeremy Fishel, describes their new theorem for solving this general problem as "Bayesian Exploration."

Built by Fishel, the specialized robot was trained on 117 common materials gathered from fabric, stationery and hardware stores. When confronted with one material at random, the robot could correctly identify the material 95% of the time, after intelligently selecting and making an average of five exploratory movements. It was only rarely confused by pairs of similar textures that human subjects making their own exploratory movements could not distinguish at all.

So, is touch another task that humans will outsource to robots? Fishel and Loeb point out that while their robot is very good at identifying which textures are similar to each other, it has no way to tell what textures people will prefer. Instead, they say this robot touch technology could be used in human prostheses or to assist companies who employ experts to assess the feel of consumer products and even human skin.

Loeb and Fishel are partners in SynTouch LLC, which develops and manufactures tactile sensors for mechatronic systems that mimic the human hand. Founded in 2008 by researchers from USC's Medical Device Development Facility, the start-up is now selling their BioTac sensors to other researchers and manufacturers of industrial robots and prosthetic hands.

More information: Another paper from this research group in the same issue of Frontiers in Neurorobotics describes the use of their BioTac sensor to identify the hardness of materials like rubber.

Provided by University of Southern California

"Robots equipped with tactile sensor able to identify materials through touch." June 18th, 2012. http://phys.org/news/2012-06-robots-equipped-tactile-sensor-materials.html

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Buying life experiences to impress others removes happiness boost

June 18th, 2012 in Psychology & Psychiatry

Spending money on activities and events, such as concert tickets or exotic vacations, won't make you happier if you're doing it to impress others, according to findings published in the Journal of Happiness Studies.

Research has shown that consumers gain greater happiness from buying life experiences rather than material possessions, but only if they choose experiences for the right reasons says the new study.

"Why you buy is just as important as what you buy," said Ryan Howell, assistant professor of psychology at San Francisco State University. "When people buy life experiences to impress others, it wipes out the well-being they receive from the purchase. That extrinsic motivation appears to undermine how the experiential purchase meets their key psychological needs."

The study builds on Howell's previous findings, which suggest that people who buy life experiences are happier because experiential purchasing helps fulfill psychological needs that are vital for human growth and well-being. These include the need to feel competent, autonomous -- or self-directed -- and connected to others.

For the present study, Howell and colleagues surveyed 241 participants and found that a person's motivation for making a purchase predicts whether these needs will be met. Howell conducted the research with Jia Wei Zhang, a student in his lab, and University of Rochester researcher Peter Caprariello.

They found that people who choose to buy life experiences because it is in line with their desires, interests and values reported a greater sense of fulfillment and well-being. They felt more autonomous, competent and connected to others, less loneliness and a greater sense of vitality.

Individuals who choose life experiences to gain recognition from others reported feeling less autonomous, competent and connected to others.

"The biggest question you have to ask yourself is why you are buying something," Howell said. "Motivation appears to amplify or eliminate the happiness effect of a purchase."

As part of the study, the researchers developed and validated a new survey to measure individuals' motivations for experiential buying. Members of the public can take the survey by visiting the "Beyond the Purchase" website. Howell and colleagues launched the website to collect data for academic studies and allow members of the public to take free psychology quizzes to find out what kind of shopper they are and how their spending choices affect them. Visit the Beyond the Purchase website at http://www.beyondthepurchase.org

"Buying Life Experiences for the "Right" Reasons: a Validation of the Motivations for Experiential Buying Scale" was published online on June 13, 2012 in the Journal of Happiness Studies. Co-author Jia Wei Zhang is a former SF State undergraduate who graduated in 2011.

Provided by San Francisco State University

"Buying life experiences to impress others removes happiness boost." June 18th, 2012. http://medicalxpress.com/news/2012-06-life-happiness-boost.html

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Researchers develop new drug that blocks traumatic memories

June 19th, 2012 in Medical research

Understanding memory is still one of the greatest challenges in science. In recent years, no one doubted the role that neurons played in the formation of cerebral networks. A few years ago however, the scientific world turned to the study of astrocytes with more attention.

A collaborative research project led by experts from the Universidad Andrés Bello in Chile, Ghent University and Catholic University of Leuven in Belgium, recently proved that astrocyte cells play a crucial role in the formation of memories.

The finding gives doctors a new target for medication to combat neurological diseases, such as Alzheimer’s disease or post-traumatic stress disorder. Their work was recently published in FASEB Journal.

Astrocyte cells account for 85 percent of cells in the brain and until recently, they were considered to be the "assistants" to neurons, since they were in charge of collecting the waste produced by the sinapsis used to speed up the neuron's reuse.

But scientists have now discovered that these "assistants" play a more important role than was previously thought.

Despite the fact that astrocytes are abundant, studying them was always complicated by the lack of tools used to isolate their function in the neurological connections as well the fragile nature of the cells themselves.

Jimmy Stehberg, leader of the Neurobiological Lab in the Universidad Andrés Bello explains that in conjunction with other investigators, they were able to create a compound that blocks a specific astrocyte connecting channel, one that the experts assumed was involved in the process of the formation of memory.

In order to prove their theory they injected the compound into the brain of a group of mice which were previously subjected to a traumatic experience

The mice that had the compound injected into them did not show any physical or cerebral reactions, while the ones who hadn't received the injection showed signs of stress.

With this, scientists demonstrated that blocking this channel in the astrocyte also blocks the process of the consolidation of memory. This proves that memory does not only depend upon neurons, but that it also needs the astrocytes, to be able to consolidate short-term memories.

The discovery could position the astrocyte as a focal point of investigation for neurological and psychiatric science. In their paper, the authors said that astroctytes are “a novel pharmacological target for the treatment of psychiatric disorders, particularly for memory-related disorders like post-traumatic stress disorder”.

More information: Release of gliotransmitters through astroglial connexin 43 hemichannels is necessary for fear memory consolidation in the basolateral amygdala, http://www.fasebj. … 416.abstract

Provided by Andres Bello University

"Researchers develop new drug that blocks traumatic memories." June 19th, 2012. http://medicalxpress.com/news/2012-06-drug-blocks-traumatic-memories.html

Comment:
You take it for 'nam flashbacks and find that you forget your wedding day?

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Short-term memory is more flexible than thought

June 19th, 2012 in Psychology & Psychiatry

(Medical Xpress) -- A theory that has been widely accepted for many years can be overturned: our short-term memory does not limit itself to remembering four to seven things at the same time. Groundbreaking research demonstrates that we can remember far more elements at once. However, the more we remember the poorer the quality of the information we retain. NWO researcher Dr. Ronald van den Berg and his supervisor professor Whee Ky Ma conclude this on the basis of various experiments. The researchers recently published their findings in the renowned scientific journal Proceedings of the National Academy of Sciences (PNAS).

Up until now it has been assumed that thanks to our short-term memory we could remember four to seven elements at once, such as numbers, letters or images. Anything else we wanted to remember was instantly forgotten. Recent research from Dutch neuroscientists Ronald van den Berg and Whee Ky Ma, both working at Baylor College of Medicine in Houston, overturns this established theory. "Our research shows it is not true that you either remember everything really well or not at all," explains Van den Berg. "Your short-term memory divides its attention over the several elements you want to remember, even if these are more than four elements. Due to the competition for attention there are gradations in how well you remember things. For example, later you might remember one thing partially, forget something else completely and remember a last thing perfectly."

Experiment

In one of the researchers' experiments, study subjects briefly saw circles with random colours on a computer screen. They subsequently had to state which color they had seen at a certain point. The greater the number of colors that appeared on the screen, the more difficulty study subjects had in stating the correct color. The researchers subsequently tested a series of mathematical models on the data obtained. This revealed that the new theory was the most successful in explaining the answer pattern from the study subjects.

Quality versus quantity

"In effect it is just like watering plants with a watering can," explains Van den Berg. "The more plants there are the less water each can receive. The same is true for our memory: the more you want to remember, the less well each element is retained."  Furthermore the quality of your memory of each element is subject to fluctuations. "For example, if you only have a limited amount of time to water your plants then you will not give each one exactly the same amount. That is also the case with the short-term memory: you remember one thing better than another," says Van den Berg.

Temporary buffer

Our short-term memory can be compared with the buffer in the computer. It ensures we retain information relevant for subsequent actions for several seconds to minutes. A football player who scans the field searching for the right path to the goal, imprints the position of his opponents in this scan. Without the several seconds of storage in the short-term memory it would be impossible for the footballer to remember where each player is located and to determine the route to the goal.

Van den Berg carried out his research with a Rubicon grant from the Netherlands Organisation for Scientific Research. Rubicon offers scientists who have recently gained their PhD the opportunity to gain experience at a top institute in the Netherlands or abroad for a maximum period of two years. The aim of the programme is to keep talented researchers in science after they have completed their PhD research.

Provided by Netherlands Organisation for Scientific Research (NWO)

"Short-term memory is more flexible than thought." June 19th, 2012. http://medicalxpress.com/news/2012-06-short-term-memory-flexible-thought.html

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Psychopaths not all psychos

June 19th, 2012 in Psychology & Psychiatry
“There is no real recipe for psychopathic personality disorder,” says Jennifer Skeem, UCI professor of psychology & social behavior. “The environmental factors are as ill-defined as the genetic factors, although antisocial behavior mixed with a history of punitive discipline, abuse and neglect seems to apply in many cases.” Credit: Steve Zylius / University Communications

Jennifer Skeem’s research requires that she spend time inside the minds of individuals most of us try to avoid: psychopaths.

Psychopathy is a complicated and widely misunderstood personality disorder, says the UC Irvine professor of psychology & social behavior, marked by boldness, fearlessness, cruelty, aggression and impulsivity.

While some people believe psychopaths are born, not made, Skeem stresses that the condition is shaped by the complex interaction of both environmental and genetic factors.

“There is no real recipe for psychopathic personality disorder,” she says. “The environmental factors are as ill-defined as the genetic factors, although antisocial behavior mixed with a history of punitive discipline, abuse and neglect seems to apply in many cases.”

Some of Skeem’s findings might come as a surprise to a public that equates the condition with serial killers and fictional characters such as Hannibal Lecter.

Psychopathy is not synonymous with violence, Skeem notes. In fact, she has found that psychopathic people often have no history of violent behavior or criminal convictions.

“An individual doesn’t necessarily need to be physically violent or a common street criminal to have psychopathic traits,” she says. Researchers estimate that about 1 percent of the general population are psychopaths.

Skeem points to Gordon Gekko, the unscrupulous financial executive played by Michael Douglas in the 1987 film “Wall Street,” as someone with all the signs of psychopathy.

She cites Ponzi scheme mastermind Bernie Madoff and Enron executive Andrew Fastow – ruthless, detached individuals who showed little remorse for robbing victims of their life savings – as real-life examples. Psychopathic traits helped them quickly climb the corporate ladder yet ultimately led to their downfall.

Can such traits ever be used for good? Skeem notes that the bold, risk-taking bomb squad leader in the Academy Award-winning movie “The Hurt Locker” succeeded in a high-pressure environment thanks to psychopathic tendencies.

Of course, some psychopaths do resort to violence and crime. But according to Skeem, youth and adults with high scores on measures of psychopathy can exhibit reduced violent and criminal behavior after intensive treatment, such as mental health counseling and drug abuse rehabilitation.

“There is scant scientific evidence to support the claim of ‘once a psychopath, always a psychopath,’” she says.

While not necessarily destructive or physically threatening, psychopaths are usually unpleasant people. Callousness, selfishness and lack of guilt make personal and professional relationships with them unbearable.

So how should you handle a psychopath in the workplace or at your next family reunion?

“You can try to work with the individual to get him or her therapy and treatment,” Skeem says. “But if you don’t have that kind of investment in the person, it’s best to keep a distance.”

She directs the School of Social Ecology’s Risk Reduction Research Lab, where her team focuses on understanding why some people with mental disorders engage in self-harm, violence and criminal behavior – and others do not.

Skeem hopes her work can be used to inform legal decisions – on sentencing and parole, for example – concerning high-risk, high-need individuals. Decisions based on faulty assumptions about risk for violence and amenability to treatment can have adverse consequences for both offenders and the public, she notes.

“Research on psychopathy has evolved to a level that it can greatly improve on the current one-size-fits-all policy approach,” Skeem says.

Provided by University of California, Irvine

"Psychopaths not all psychos." June 19th, 2012. http://medicalxpress.com/news/2012-06-psychopaths-psychos.html

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