jueves, 30 de junio de 2011

Researchers can predict future actions from human brain activity

Researchers can predict future actions from human brain activity

Bringing the real world into the brain scanner, researchers at The University of Western Ontario from The Centre for Brain and Mind can now determine the action a person was planning, mere moments before that action is actually executed.

"Neuroimaging allows us to look at how action planning unfolds within human brain areas without having to insert electrodes directly into the human brain. This is obviously far less intrusive," explains Western Psychology professor Jody Culham, who was the paper's senior author.ls from many brain regions, they could predict, better than chance, which of the actions the volunteer was merely intending to do, seconds later.The findings were published this week in the prestigious Journal of Neuroscience, in the paper, "Decoding Action Intentions from Preparatory Brain Activity in Human Parieto-Frontal Networks."

"This is a considerable step forward in our understanding of how the human brain plans actions," says Jason Gallivan, a Western Neuroscience PhD student, who was the first author on the paper.

[This video is not supported by your browser at this time.]

University of Western Ontario researchers Jody Culham and Jason Gallivan describe how they can use a fMRI to determine the action a person was planning, mere moments before that action is actually executed. Credit: The University of Western Ontario
Over the course of the one-year study, human subjects had their brain activity scanned using functional magnetic resonance imaging (fMRI) while they performed one of three hand movements: grasping the top of an object, grasping the bottom of the object, or simply reaching out and touching the object. The team found that by using the signals from many brain regions, they could predict, better than chance, which of the actions the volunteer was merely intending to do, seconds later.

Gallivan says the new findings could also have important clinical implications: "Being able to predict a human's desired movements using brain signals takes us one step closer to using those signals to control prosthetic limbs in movement-impaired patient populations, like those who suffer from spinal cord injuries or locked-in syndrome."

Provided by University of Western Ontario

"Researchers can predict future actions from human brain activity." June 29th, 2011. http://medicalxpress.com/news/2011-06-future-actions-human-brain.html

martes, 28 de junio de 2011

Exhumation of Shakespeare to determine cause of death and drug test

Director of the Institute for Human Evolution, anthropologist Francis Thackeray has formally petitioned the Church of England to allow him to exhume the body of William Shakespeare in order to determine the cause of his death.

Thackeray is best known for his controversial suggestion nearly a decade ago which pointed to the possibility that Shakespeare had been a regular cannabis smoker. Utilizing forensic techniques, Thackeray examined 24 pipes which had been discovered in Shakespeare’s garden and determined that they had been used to smoke the drug.

Citing that even after 400 years, Shakespeare is still one of the most famous people in history, Thackeray hopes to be able to end the question of how he died and establish a health history. With new state-of-the-art computer equipment he hopes to create a three dimensional reconstruction of Shakespeare. The hope is to be able to determine the kind of life he led, any diseases of medical conditions he may have suffered from and what ultimately caused his death.

The new technology, nondestructive analysis, will not require the remains to be moved but will instead scan the bones. They are also hoping to collect DNA from Shakespeare and his wife and sister, all who are buried at Holy Trinity Church.

Thackeray also hopes to find evidence to back his controversial claims years ago regarding Shakespeare’s marijuana smoking. Examining the teeth could provide the evidence they need. If they are able to discover grooves between the incisor and canine teeth, it could show them he was chewing on a pipe.

This plan however goes against the final wishes of Shakespeare himself who had the following words engraved on his tomb: “Good frend for Jesus sake forebeare, To dig the dust encloased heare, Bleste be the man that spares thes stones, And curst be he that moves my bones.”

The Church of England denies that any requests have been made to exhume Shakespeare’s body but Thackeray and his team hopes to gain approval in time to be able to make the determination before the 400th anniversary of his death in 2016.

A little practice can change the brain in a lasting way: study

A little practice can change the brain in a lasting way: study
June 27th, 2011 in Psychology & Psychiatry

A little practice goes a long way, according to researchers at McMaster University, who have found the effects of practice on the brain have remarkable staying power.

The study, published this month in the journal Psychological Science, found that when participants were shown visual patterns—faces, which are highly familiar objects, and abstract patterns, which are much less frequently encountered—they were able to retain very specific information about those patterns one to two years later.

"We found that this type of learning, called perceptual learning, was very precise and long-lasting," says Zahra Hussain, lead author of the study who is a former McMaster graduate student in the Department of Psychology, Neuroscience & Behaviour and now a Research Fellow at the University of Nottingham. "These long-lasting effects arose out of relatively brief experience with the patterns – about two hours, followed by nothing for several months, or years."

Over the course of two consecutive days, participants were asked to identify a specific face or pattern from a larger group of images. The task was challenging because images were degraded—faces were cropped, for example—and shown very briefly. Participants had difficulty identifying the correct images in the early stages, but accuracy rates steadily climbed with practice.

About one year later, a group of participants were called back and their performance on the task was re-measured, both with the same set of items they'd been exposed to earlier, and with a new set from the same class of images. Researchers found that when they showed participants the original images, accuracy rates were high. When they showed participants new images, accuracy rates plummeted, even though the new images closely resembled the learned ones, and they hadn't seen the original images for at least a year.

"During those months in between visits to our lab, our participants would have seen thousands of faces, and yet somehow maintained information about precisely which faces they had seen over a year ago," says Allison Sekuler, co-author of the study and professor and Canada Research Chair in Cognitive Neuroscience in the Department of Psychology, Neuroscience & Behaviour. "The brain really seems to hold onto specific information, which provides great promise for the development of brain training, but also raises questions about what happens as a function of development. How much information do we store as we grow, older and how does the type of information we store chage across our lifetimes? And what is the impact of storing all that potentially irrelevant information on our ability to learn and remember more relevant information?"

She and her colleagues point to children today who are growing up in a world in which they are bombarded with sensory information, and wonders what will happen.

"We don't yet know the long-term implications of retaining all this information, which is why it is so important to understand the physiological underpinnings," says Patrick Bennett, co-author and professor and Canada Research Chair in Vision Science in the Department of Psychology, Neuroscience & Behaviour. "This result warrants further study on how we can optimize our ability to train the brain to preserve what would be considered the most valuable information."

More information: A pdf of the study can be found at: http://dailynews.m … SciFinal.pdf

Provided by McMaster University

sábado, 18 de junio de 2011

Restoring memory, repairing damaged brains

Restoring memory, repairing damaged brains

June 17th, 2011 in Neuroscience

In the experiment, the researchers had rats learn a task, pressing one lever rather than another to receive a reward. Using embedded electrical probes, the experimental research team recorded changes in the rat's brain activity between the two major internal divisions of the hippocampus, known as subregions CA3 and CA1. The experimenters then blocked the normal neural interactions between the two areas using pharmacological agents. The previously trained rats then no long displayed the long-term learned behavior. But long-term memory capability returned to the pharmacologically blocked rats when the team activated the electronic device programmed to duplicate the memory-encoding function. Credit: USC Viterbi School of Engineering
Scientists have developed a way to turn memories on and off -- literally with the flip of a switch.

Using an electronic system that duplicates the neural signals associated with memory, they managed to replicate the brain function in rats associated with long-term learned behavior, even when the rats had been drugged to forget.

"Flip the switch on, and the rats remember. Flip it off, and the rats forget," said Theodore Berger of the USC Viterbi School of Engineering's Department of Biomedical Engineering.

Berger is the lead author of an article that will be published in the Journal of Neural Engineering. His team worked with scientists from Wake Forest University in the study, building on recent advances in our understanding of the brain area known as the hippocampus and its role in learning.

In the experiment, the researchers had rats learn a task, pressing one lever rather than another to receive a reward. Using embedded electrical probes, the experimental research team, led by Sam A. Deadwyler of the Wake Forest Department of Physiology and Pharmacology, recorded changes in the rat's brain activity between the two major internal divisions of the hippocampus, known as subregions CA3 and CA1. During the learning process, the hippocampus converts short-term memory into long-term memory, the researchers prior work has shown.

"No hippocampus," says Berger, "no long-term memory, but still short-term memory." CA3 and CA1 interact to create long-term memory, prior research has shown.

In a dramatic demonstration, the experimenters blocked the normal neural interactions between the two areas using pharmacological agents. The previously trained rats then no longer displayed the long-term learned behavior.

"The rats still showed that they knew 'when you press left first, then press right next time, and vice-versa,'" Berger said. "And they still knew in general to press levers for water, but they could only remember whether they had pressed left or right for 5-10 seconds."

Using a model created by the prosthetics research team led by Berger, the teams then went further and developed an artificial hippocampal system that could duplicate the pattern of interaction between CA3-CA1 interactions.

Long-term memory capability returned to the pharmacologically blocked rats when the team activated the electronic device programmed to duplicate the memory-encoding function.

In addition, the researchers went on to show that if a prosthetic device and its associated electrodes were implanted in animals with a normal, functioning hippocampus, the device could actually strengthen the memory being generated internally in the brain and enhance the memory capability of normal rats.

"These integrated experimental modeling studies show for the first time that with sufficient information about the neural coding of memories, a neural prosthesis capable of real-time identification and manipulation of the encoding process can restore and even enhance cognitive mnemonic processes," says the paper.

Next steps, according to Berger and Deadwyler, will be attempts to duplicate the rat results in primates (monkeys), with the aim of eventually creating prostheses that might help the human victims of Alzheimer's disease, stroke or injury recover function.

The paper is entitled "A Cortical Neural Prosthesis for Restoring and Enhancing Memory." Besides Deadwyler and Berger, the other authors are, from USC, BME Professor Vasilis Z. Marmarelis and Research Assistant Professor Dong Song, and from Wake Forest, Associate Professor Robert E. Hampson and Post-Doctoral Fellow Anushka Goonawardena.

Berger, who holds the David Packard Chair in Engineering, is the Director of the USC Center for Neural Engineering, Associate Director of the National Science Foundation Biomimetic MicroElectronic Systems Engineering Research Center, and a Fellow of the IEEE, the AAAS, and the AIMBE

jueves, 16 de junio de 2011

A fossil of modern humans, dating back 160,000 years.

A fossil of modern humans, dating back 160,000 years.

At Britain's Royal Society, Dr. Marta Lahr from Cambridge University's Leverhulme Centre for Human Evolutionary Studies presented her findings that the height and brain size of modern-day humans is shrinking.

Looking at human fossil evidence for the past 200,000 years, Lahr looked at the size and structure of the bones and skulls found across Europe, Africa and Asia. What they discovered was that the largest Homo sapiens lived 20,000 to 30,000 years ago with an average weight between 176 and 188 pounds and a brain size of 1,500 cubic centimeters.

They discovered that some 10,000 years ago however, size started getting smaller both in stature and in brain size. Within the last 10 years, the average human size has changed to a weight between 154 and 176 pounds and a brain size of 1,350 cubic centimeters.

While large size remained static for close to 200,000 years, researchers believe the reduction in stature can be connected to a change from the hunter-gatherer way of life to that of agriculture which began some 9,000 years ago.

The fossilized skull of an adult male hominid unearthed in 1997 from a site near the village of Herto, Middle Awash, Ethiopia. The skull, reconstructed by UC Berkeley paleoanthropologist Tim White, is slightly larger than the most extreme adult male humans today, but in other ways is more similar to modern humans than to earlier hominids, such as the neanderthals. White and his team concluded that the 160,000 year old hominid is the oldest known modern human, which they named Homo sapiens idaltu. Image © J. Matternes
While the change to agriculture would have provided a plentiful crop of food, the limiting factor of farming may have created vitamin and mineral deficiencies and resulted in a stunted growth. Early Chinese farmers ate cereals such as rice which lacks the B vitamin niacin which is essential for growth.

Agriculture however does not explain the reduction in brain size. Lahr believes that this may be a result of the energy required to maintain larger brains. The human brain accounts for one quarter of the energy the body uses. This reduction in brain size however does not mean that modern humans are less intelligent. Human brains have evolved to work more efficiently and utilize less energy.

martes, 14 de junio de 2011

Brain structure adapts to environmental change

Brain structure adapts to environmental change
June 13th, 2011 in Neuroscience

Scientists have known for years that neurogenesis takes place throughout adulthood in the hippocampus of the mammalian brain. Now Columbia researchers have found that under stressful conditions, neural stem cells in the adult hippocampus can produce not only neurons, but also new stem cells. The brain stockpiles the neural stem cells, which later may produce neurons when conditions become favorable. This response to environmental conditions represents a novel form of brain plasticity. The findings were published online in Neuron on June 9, 2011.

The hippocampus is involved in memory, learning, and emotion. A research team led by Alex Dranovsky, MD, PhD, assistant professor of clinical psychiatry at Columbia University Medical Center and research scientist in the Division of Integrative Neuroscience at the New York State Psychiatric Institute/Columbia Psychiatry, compared the generation of neural stem cells and neurons in mice housed in isolation and in mice housed in enriched environments. They then used lineage studies, a technique that traces stem cells from their formation to their eventual differentiation into specific cell types, to see what proportion of neural stem cells produced neurons.

Deprived and enriched environments had opposite effects. The brains of the socially isolated mice accumulated neural stem cells but not neurons. The brains of mice housed in enriched environments produced far more neurons, but not more stem cells. The average mouse dentate gyrus, the area of the hippocampus where neurogenesis takes place, has about 500,000 neurons; the enriched environment caused an increase of about 70,000 neurons.

"We already knew that enriching environments are neurogenic, but ours is the first report that neural stem cells, currently thought of as 'quiescent,' can accumulate in the live animal," said Dr. Dranovsky. "Since this was revealed simply by changing the animal's living conditions, we think that it is an adaptation to stressful environments. When conditions turn more favorable, the stockpiled stem cells have the opportunity to produce more neurons—a form of 'neurons on demand.'"

The researchers also looked at neuronal survival. They found that social isolation did not cause it to decrease. Scientists already knew that environmental enrichment increased neuronal survival―further increasing the neuron population.

To a lesser extent, location within the hippocampus affected whether stem cells became neurons. While the ratio of stem cells to neurons remained constant in the lower blade of the dentrate gyrus, it varied in the upper blade.

Age also affected the results. After three months, the brains of the isolated mice stopped accumulating neural stem cells. But the mice in enriched environments continued to produce more neurons.

Dranovsky and his team now want to see whether this hippocampal response is specific to social isolation or is a more general response to stress. Another question is whether all neural stem cells have the same potential to produce neurons.

"The long-term goal." Said Dr. Dranovsky, "is to figure out how to instruct neural stem cells to produce neurons or more stem cells. This could lead to the eventual use of stem cells in neuronal replacement therapy for neurodegenerative diseases and other central nervous system conditions."

Provided by Columbia University

lunes, 13 de junio de 2011

Can Brain Scans Predict Music Sales?

Can Brain Scans Predict Music Sales?
by Greg Miller on 10 June 2011, 11:35 AM

Rock my accumbens. A study inspired by a performance of OneRepublic's hit Apologize finds that activity in the nucleus accumbens correlates with music sales.
Credit: Kevin Winter/Tonight Show/Getty Images
Scientific inspiration sometimes comes from unlikely sources. Two years ago, Gregory Berns, a neuroeconomist at Emory University in Atlanta, was on the couch with his kids watching American Idol. One of the contestants sang the melancholy hit song Apologize by the alternative rock band OneRepublic, and something clicked in Berns's mind.

He'd used the song a few years earlier in a study on the neural mechanisms of peer pressure, in this case, how teenagers' perceptions of a song's popularity influence how they rate the song themselves. At the time, OneRepublic had yet to sign its first record deal. A student in Bern's lab had pulled a clip of Apologize from the band's MySpace page to use in the study. When Berns heard the song on American Idol, he wondered whether anything in the brain scan data his team had collected could have predicted it would become a hit. At the time, all 120 songs used in the experiment were by artists who were unsigned and not widely known. "The next day, in the lab, we talked about it."

To find out what had become of the songs, the lab bought a subscription to Nielsen SoundScan, a service that tracks music sales. The database contained sales data for 87 of the 120 songs (not surprisingly, many songs had languished in MySpace obscurity). Berns reexamined the functional magnetic resonance imaging scans his group had collected from 27 adolescents in 2007, looking for regions of the brain where neural activity during a 15-second clip of a song correlated with the subject's likeability ratings. Two regions stood out: the orbitofrontal cortex and the nucleus accumbens. "That was a good check that we were on the right track, because we knew from a ton of other studies that those regions are heavily linked to reward and anticipation," Berns says.

Next, the researchers looked to see whether the activity in either of these two brain regions, averaged across subjects for each song, correlated with the song's sales through May 2010. It did, Berns and co-author Sara Moore report in a paper in press at the Journal of Consumer Psychology. The correlations were statistically significant but modest. Activity in the nucleus accumbens, the best predictor of song sales, accounts for about 10% of the variance in sales, Berns says. "It's not a hit maker," he cautions.

Intriguingly, the brain scan data predicted commercial success better than the subjects' likeability ratings, which did not correlate with sales. "What is new and interesting about this study is that brain signals predict sales in a situation where the ratings of the participants don't," says John-Dylan Haynes of the Bernstein Center for Computational Neuroscience in Berlin. Although several recent studies have shown it's possible to predict consumer choices from brain activity, Haynes says, it hasn't been clear whether brain scans can reveal anything about people's product preferences that couldn't be gained by simply asking them. In this case, at least, it seems they can.

"This is a really cool result," says Brian Knutson, a cognitive neuroscientist at Stanford University in Palo Alto, California. Showing that brain activity in a small group of people can predict the buying behavior of a much larger group of people is a novel and provocative finding, he says. But how does it work, and why would brain activity be better than the subjects' ratings? Knutson suggests that activity in the nucleus accumbens may provide a more pure indication of how much people actually want something, unencumbered by economic and social considerations that might influence their ratings—for example, whether one's credibility as a hard-rocking heavy metal fan would be undermined by a fondness for, well, Apologize.

There have been many dubious claims about "neuromarketing" strategies for using brain activity to assess consumer sentiment, says Antonio Rangel, a neuroeconomist at the California Institute of Technology in Pasadena. He sees the new study as an exciting proof of principle that in some cases neuroimaging can provide useful information not picked up by traditional methods such as consumer surveys and focus groups. Still, Rangel says, it's a long way from being a viable marketing tool. "I would not invest in a company based on this."

viernes, 10 de junio de 2011

Scientists find gene vital to nerve cell development

Scientists find gene vital to nerve cell development
June 9th, 2011 in Medicine & Health / Genetics

In healthy mice, individual Schwann cells wrap their membranes around a nerve cell’s axon many times. A cross-section of the resulting myelin sheath is visible as a thick band surrounding the axon in the “Normal” image on the left. In mice with a mutation in Gpr126, Schwann cells cannot make myelin and no thick layer surrounding axons is visible in the “Mutant” image on the right. KELLY R. MONK

The body’s ability to perform simple tasks like flex muscles or feel heat, cold and pain depends, in large part, on myelin, an insulating layer of fats and proteins that speeds the propagation of nerve cell signals.

Now, scientists have identified a gene in mice that controls whether certain cells in the peripheral nervous system can make myelin. Called Gpr126, the gene encodes a cellular receptor that could play a role in diseases affecting peripheral nerves, says Kelly R. Monk, PhD, assistant professor of developmental biology at Washington University School of Medicine in St. Louis.

“Researchers knew Gpr126 existed in humans, but no one knew what it did,” says Monk, who did this work while a postdoctoral researcher at Stanford University. “For 30 years or so, scientists have been looking for a cell receptor that controls myelination by raising levels of an important chemical messenger. We found it in zebrafish. And now we’ve shown that it’s present in mammals. It’s the first known function for this receptor, and it solved a decades-old mystery, which is exciting.”

The work is currently available online and will be published in the July 1 issue of the journal Development.

In a paper published in Science in 2009, Monk and her colleagues first showed that zebrafish require Gpr126 to make myelin in their peripheral nerves, but not in the brain or spinal cord of the central nervous system.

When a gene works a certain way in zebrafish, it likely works that way in mammals, according to William S. Talbot, PhD, professor of developmental biology at Stanford University and Monk’s postdoctoral advisor.

“The brain and spinal cord are fine in mice without the Gpr126 gene,” Talbot says. “But there is no myelin in the peripheral nerves, very much like in zebrafish. This is evidence that Gpr126 probably has a general role in myelin formation and nerve development in all vertebrates, including humans.”

The missing gene appears to disrupt specialized cells in the peripheral nervous system called Schwann cells, stopping those cells from enveloping and providing nutrients to the axons of nerves. Healthy Schwann cells wrap their membranes around nerve cell axons many times to form the myelin sheath that speeds the transmission of nerve cell signals.

In zebrafish without Gpr126, Schwann cells appear to develop and arrange themselves with individual axons normally at first. But when it comes time to wrap around the axon and make myelin, they stop short.

“From zebrafish, we thought this gene controlled only one very specific step of Schwann cell development,” Monk says. “But in mice the story is more complex.”

In mice without the gene, problems begin much earlier. The Schwann cells take longer to associate with individual axons and, compared to normal mice, there are many fewer axons. Such evidence leads Monk to speculate that the delayed sorting and failure of Schwann cells to wrap around axons causes the associated neurons to die. Because of these and other problems seen in mice without Gpr126 (including defects in the lungs, kidneys and cardiovascular system), Monk proposes that it plays more diverse roles in mice than in zebrafish. Although mice without Gpr126 never lived beyond two weeks, zebrafish with the same mutation survived to reproduce.

Because of its clear role in forming myelin, Gpr126 could be a possible target for therapies to treat peripheral neuropathies, common conditions where peripheral nerves are damaged. Such damage causes an array of problems including pain and numbness in the hands and feet, muscle weakness and even problems involving functions of internal organs such as digestion. Some peripheral neuropathies are genetic, but many result from diseases of aging and poor health, including complications from diabetes or side effects of chemotherapy.

With these conditions in mind, Monk and Talbot point out that Gpr126 is a member of a large family of cell surface receptors that are common targets for most commercially available drugs, treating conditions as diverse as allergies, ulcers and schizophrenia.

“We don’t know yet whether Gpr126 itself can be a drug target. But the fact that its relatives can,” Talbot says, “makes it especially interesting.”

Ongoing work in Monk’s lab seeks to further define the many roles of Gpr126 in mammals, including whether it could help direct Schwann cells to repair or regrow damaged myelin.

More information: Monk KR, Oshima K, Jors S, Heller S, Talbot WS. Gpr126 is essential for peripheral nerve development and myelination in mammals. Development. 138(13). July 2011.

Monk et al. A G protein-coupled receptor is essential for Schwann cells to initiate myelination. Science. 325. Sept. 2009.

Provided by Washington University School of Medicine in St. Louis

martes, 7 de junio de 2011

Attention and awareness aren't the same

Attention and awareness aren't the same
June 6th, 2011 in Psychology & Psychiatry

Paying attention to something and being aware of it seems like the same thing -they both involve somehow knowing the thing is there. However, a new study, which will be published in an upcoming issue of Psychological Science, a journal of the Association for Psychological Science, finds that these are actually separate; your brain can pay attention to something without you being aware that it's there.

"We wanted to ask, can things attract your attention even when you don't see them at all?" says Po-Jang Hsieh, of Duke-NUS Graduate Medical School in Singapore and MIT. He co-wrote the study with Jaron T. Colas and Nancy Kanwisher of MIT. Usually, when people pay attention to something, they also become aware of it; in fact, many psychologists assume these two concepts are inextricably linked. But more evidence has suggested that's not the case.

To test this, Hsieh and his colleagues came up with an experiment that used the phenomenon called "visual pop-out." They set each participant up with a display that showed a different video to each eye. One eye was shown colorful, shifting patterns; all awareness went to that eye, because that's the way the brain works. The other eye was shown a pattern of shapes that didn't move. Most were green, but one was red. Then subjects were tested to see what part of the screen their attention had gone to. The researchers found that people's attention went to that red shape – even though they had no idea they'd seen it at all.

In another experiment, the researchers found that if people were distracted with a demanding task, the red shape didn't attract attention unconsciously anymore. So people need a little brain power to pay attention to something even if they aren't aware of it, Hsieh and his colleagues concluded.

Hsieh suggests that this could have evolved as a survival mechanism. It might have been useful for an early human to be able to notice and process something unusual on the savanna without even being aware of it, for example. "We need to be able to direct attention to objects of potential interest even before we have become aware of those objects," he says.

Provided by Association for Psychological Science

viernes, 3 de junio de 2011

Examining the brain as a neural information super-highway

Examining the brain as a neural information super-highway
June 2nd, 2011 in Neuroscience

An article demonstrating how tools for modeling traffic on the Internet and telephone systems can be used to study information flow in brain networks will be published in the open-access journal PLoS Computational Biology on 2nd June 2011.

The brain functions as a complex system of regions that must communicate with each other to enable everyday activities such as perception and cognition. This need for networked computation is a challenge common to multiple types of communication systems. Thus, important questions about how information is routed and emitted from individual brain regions may be addressed by drawing parallels with other well-known types of communication systems, such as the Internet.

The authors, from the Rotman Research Institute at Baycrest Centre, Toronto, Canada, showed that – similar to other communication networks – the timing pattern of information emission is highly indicative of information traffic flow through the network. In this study the output of information was sensitive to subtle differences between individual subjects, cognitive states and brain regions.

The researchers recorded electrical activity from the brain and used signal processing techniques to precisely determine exactly when units of information get emitted from different regions. They then showed that the times between successive departures are distributed according to a specific distribution. For instance, when research study participants were asked to open their eyes in order to allow visual input, emission times became significantly more variable in parts of the brain responsible for visual processing, reflecting and indicating increased neural "traffic" through the underlying brain regions.

This method can be broadly applied in neuroscience and may potentially be used to study the effects of neural development and aging, as well as neurodegenerative disease, where traffic flow would be compromised by the loss of certain nodes or disintegration of pathways.

More information: Mišić B, Vakorin VA, Kovačević N, Paus T, McIntosh AR (2011) Extracting Message Inter-Departure Time Distributions from the Human Electroencephalogram. PLoS Comput Biol 7(6): e1002065. doi:10.1371/journal.pcbi.1002065

Provided by Public Library of Science

jueves, 2 de junio de 2011

Researchers map, measure brain's neural connections

Researchers at Brown University have created a computer program to advance analysis of the neural connections in the human brain. The program's special features include a linked view for users to view both the 3-D image (top) and 2-D closeups of the neural bundles. Credit: Radu Jianu, Brown University

Medical imaging systems allow neurologists to summon 3-D color renditions of the brain at a moment's notice, yielding valuable insights. But sometimes there can be too much detail; important elements can go unnoticed.

The bundles of individual nerves that transmit information from one part of the brain to the other, like fiber-optic cables, are so intricate and so interwoven that they can be difficult to trace through standard imaging techniques. To help, computer science researchers at Brown University have produced 2-D maps of the neural circuitry in the human brain.

The goal is simplicity. The planar maps extract the neural bundles from the imaging data and present them in 2-D – a format familiar to medical professionals working with brain models. The Brown researchers also provide a web interface by integrating the neural maps into a geographical digital maps framework that professionals can use seamlessly to explore the data.

"In short, we have developed a new way to make 2-D diagrams that illustrate 3-D connectivity in human brains," said David Laidlaw, professor of computer science at Brown and corresponding author on the paper published in IEEE Transactions on Visualization and Computer Graphics. "You can see everything here that you can't really see with the bigger (3-D) images."

The 2-D neural maps are simplified representations of neural pathways in the brain. These representations are created using a medical imaging protocol that measures the water diffusion within and around nerves of the brain. The sheathing is composed of myelin, a fatty membrane that wraps around axons, the threadlike extensions of neurons that make up nerve fibers.

Medical investigators can use the 2-D neural maps to pinpoint spots where the myelin may be compromised, which could affect the vitality of the neural circuits. That can help identify pathologies, such as autism, that brain scientists increasingly believe manifest themselves in myelinated axons. Diseases associated with the loss of myelin affect more than 2 million people worldwide, according to the Myelin Project, an organization dedicated to advancing myelin-related research.

Researchers can use the 2-D neural maps to help identify whether the structure or the size of neural bundles differs among individuals and how any differences may relate to performance, skills or other traits. "It's an anatomical measure," Laidlaw said. "It's a tool that we hope will help the field."

While zeroing in on the brain's wiring, the team, including graduate students Radu Jianu and Çağatay Demiralp, added a "linked view" so users can toggle back and forth between the neural bundles in the 2-D image and the larger 3-D picture of the brain.

"What you see is what you operate," said Jianu, the paper's lead author. "There's no change in perspective with what you're working with on the screen."

Users can export the 2-D brain representations as images and display them in Web browsers using Google Maps. "The advantage of using this mode of distribution is that users don't have to download a large dataset, put it in the right format, and then use a complicated software to try and look at it, but can simply load a webpage," Jianu explained.

The program is designed to share research. Scientists can use the Web to review brain research in other labs that may be useful to their own work.

Provided by Brown University