Posts tagged science
Articles and news from the latest research reports.
New Alzheimer’s Marker Strongly Predicts Mental Decline
ScienceDaily (Mar. 5, 2012) — A new marker of Alzheimer’s disease can predict how rapidly a patient’s memory and other mental abilities will decline after the disorder is diagnosed, researchers at Washington University School of Medicine in St. Louis have found.
In 60 patients with early Alzheimer’s disease, higher levels of the marker, visinin-like protein 1 (VILIP-1), in the spinal fluid were linked to a more rapid mental decline in the years that followed.
Scientists need to confirm the results in larger studies, but the new data suggest that VILIP-1 potentially may be a better predictor of Alzheimer’s progression than other markers.
“VILIP-1 appears to be a strong indicator of ongoing injury to brain cells as a result of Alzheimer’s disease,” says lead author Rawan Tarawneh, MD, now an assistant professor of neurology at the University of Jordan. “That could be very useful in predicting the course of the disease and in evaluating new treatments in clinical trials.”
Scientists Search for Source of Creativity
It takes two to tango. Two hemispheres of your brain, that is.
USC researchers are working to pin down the exact source of creativity in the brain and have found that the left hemisphere of your brain, thought to be the logic and math portion, actually plays a critical role in creative thinking. “We want to know how does creativity work in the brain?” said Lisa Aziz-Zadeh, assistant professor of neuroscience at the USC Dornsife College of Letters, Arts and Sciences.
If you paint or sculpt, you may think of yourself as right-brained. The right hemisphere of your brain often is thought to be the creative half, while the left is thought to be the rational, logical side.
But a new study from a team led by Aziz-Zadeh demonstrated that while the right half of your brain performs the bulk of the heavy lifting when you’re being creative, it does call for help from the left half of your noggin.
The study, which focuses on how the brain tackles visual creative tasks, supports previous findings about how the brain handles musical improvisation.
Co-authored by USC graduate student Sook-Lei Liew and USC undergraduate Francesco Dandekar, the study was posted online last month in Social Cognitive and Affective Neuroscience.
“We need both hemispheres for creative processing,” Aziz-Zadeh said.
The USC scholar and her team used functional magnetic resonance imaging (fMRI) to scan the brains of architecture students, who tend to be visually creative.
While being scanned, the subjects were shown three shapes: a circle, a C and an 8. They then were asked to visualize images that could be made by rearranging those shapes – for example, a face (with the 8 on its side to become the eyes, the C on its side to become the smiling mouth and the circle in the center as the nose).
The students also were asked to simply try to piece three geometric shapes together with their minds and see if they formed a square or a rectangle – a task that requires similar spatial processing but not necessarily creativity.
Even though it mainly was handled by the right hemisphere, the creative task actually lit up the left hemisphere more than the noncreative task. The results indicated that the left brain potentially is a crucial supporter of creativity in the brain.
Aziz-Zadeh said she plans to explore more of how different types of creativity (painting, acting, singing) are created by the brain, what they have in common and what makes them different.
Source: Neuroscience News
Neuroscientist group finds daydreaming uses same parts of the brain as social skills
March 5, 2012 by Bob Yirka
(Medical Xpress) — A group of Australian neuroscientists have been reviewing the results of many studies done over the years regarding the parts of the brain that are thought to be used in different real world scenarios and have found that many of them appear to be involved when people go into what is called a default network - more commonly known as daydreaming, or running on auto-pilot. Their findings suggest, as they write in their paper published in Nature Reviews Neurology, that the default network is tied very closely with the same areas of the brain generally thought of as those used for social skills.
To find connections, the team looked at studies of elderly people that had fallen victim to two distinct forms of early onset dementia. One involved damage to the frontal lobe, the other to the temporal lobe. Damage to the frontal lobe, they point out, generally results in patients displaying an inability to understand why they should curb their language. They’re impulsive and aren’t able to understand the repercussions of their words or actions as they pertain to other people. Those with damage to the temporal lobe on the other hand, have trouble understanding the subtle cues that go on between people when interacting. They generally run into trouble in trying to read emotion in others and also tend to have difficulty remembering faces or other everyday objects. Both conditions obviously have a very direct and troublesome impact on social interaction.
They also found that when people without dementia are placed in an fMRI machine and who are allowed to daydream, various parts of their brain light up, indicating that the default network is quite complicated and involved. But of specific interest to this group of researchers was the fact that many of those areas that light up when transitioning to the default network, are the same ones that are used for social interaction, memory and imagination.
This means, they say, that the default network is more than just daydreaming because for it to occur, there needs to be memory of events that have transpired, imagination to guess about things that might happen in the future and the consequences of different happenings. Not coincidentally, they add, all these things are necessary for social interaction as well. This, they say, is why it’s time to stop looking at individual brain functions as separate events and instead to start looking at events as multi-brain activities that all together add up to the richness of thought we all experience as thinking human beings.
Source: medicalxpress.com
Researchers gain new insight into prefrontal cortex activity
March 5, 2012
The brain has a remarkable ability to learn new cognitive tasks while maintaining previously acquired knowledge about various functions necessary for everyday life. But exactly how new information is incorporated into brain systems that control cognitive functions has remained a mystery.
A study by researchers at Wake Forest Baptist Medical Center and the McGovern Institute of the Massachusetts Institute of Technology shows how new information is encoded in neurons of the prefrontal cortex, the area of the brain involved in planning, decision making, working memory and learning.
"In this study we were able to isolate activity directly from the brain, allowing us to ‘see’ what was happening in the prefrontal cortex before and after a new task was learned," said Christos Constantinidis, Ph.D., associate professor of neurobiology and anatomy at Wake Forest Baptist and senior author of the study, published in the March 5 online edition of Proceedings of the National Academy of Sciences.
To gain insight into how learning a new task affects the prefrontal cortex, the researchers analyzed the electrical activity of neurons before and after training for the performance in two short-term memory tests. Two monkeys initially looked at a computer screen while various shapes, such as squares and circles, were displayed, and researchers recorded the electrical activity occurring in the brain. The same animals were then trained to recognize the various shapes, and to remember whether two symbols matched each other.
Using computational analysis of the neuronal recordings, the researchers compared data to assess what information was present before training and what new information arose while learning a new task. They found that learning was associated with activation of a small number of neurons that were highly specialized for the new task, while the same neurons maintained the existing information that was present before training.
"In essence, this select group of neurons was able to multitask by learning new information while retaining information they were already specialized for," Constantinidis said. "Our results show that although there was little change in the amount of basic stimulus information that neurons encoded before training, more complex information about whether the symbols matched became incorporated throughout the prefrontal cortex after training."
Overall these findings shed light on how new information is incorporated into the prefrontal cortex activity and how neural activity codes information, which should lead to richer theories of how the prefrontal cortex controls behavior and how information is encoded in neural activity more generally.
"We hope that our findings will help others who work with patients who have short-term memory problems resulting from strokes or traumatic brain injuries," Constantinidis said. "Computerized training to perform cognitive tasks, like those used in our study, has shown promise in cognitive rehabilitation, and for treatment of mental illnesses and conditions, such as schizophrenia and ADHD."
Provided by Wake Forest Baptist Medical Center
Source: medicalxpress.com
Study suggest that conscious perception has little to do with the primary visual cortex
When the rings of dynamic patterns are presented to the same eye (left column), the subject is able to consciously perceive the target pattern-the stripes in the center of the ring. When the two are presented to different eyes (right column), the dynamic pattern suppresses perception of the target pattern. Under both conditions, participants were asked to perform a task that focused attention on the target (top row) or on letters presented outside the target area (bottom row). Credit: 2012 Masataka Watanabe
From a purely intuitive point of view, it is easy to believe that our ability to actively pay attention to a target is inextricably connected with our capacity to consciously perceive it. However, this proposition remains the subject of extensive debate in the research community, and surprising new findings from a team of scientists in Japan and Europe promise to fuel the debate.
Resolving how these aspects of perception are managed requires a detailed understanding of how the visual centers in our brain process information. A region known as V1 has been investigated as it represents the first portion of the visual cortex to receive and process signals transmitted from the retina.
Many researchers favor a model in which functions pertaining consciousness are widely spread among the whole visual system, including V1. The classical model, which assumes that the neural mechanism of consciousness is integrated into a narrow subset of brain structures, referred to as a homunculus, or ‘little human’, is almost defunct. However, a modern version of this model is under debate. It proposes that the neural mechanism of consciousness is a privileged set of cortical areas, a subpopulation of neurons, or certain neural dynamics (e.g. oscillations); while there are also visual systems that have nothing to do with conscious vision, explains Masataka Watanabe a researcher investigating brain function at the University of Tokyo, Japan.
Watanabe cites studies proposing that visual attention as processed within V1 may be only minimally impacted by conscious perception; but, the experimental data have been contradictory. For example, studies using a technique called functional magnetic resonance imaging (fMRI) to map brain activity have indicated that V1 contributes to both attention and awareness in humans. However, invasive electrophysiological studies in non-human primates yielded different results. “You would find only 10 to 15% of neurons in V1 that are barely modulated by awareness, and 85% or so that are not modulated at all,” says Watanabe. To resolve this ambiguity, he, Kang Cheng from the RIKEN Brain Science Institute, Wako, and their colleagues designed an experiment that examined both processes independently. Surprisingly, their results may lend support the modern homunculus model.
Making Memories: How One Protein Does It
ScienceDaily (Mar. 5, 2012) — Studying tiny bits of genetic material that control protein formation in the brain, Johns Hopkins scientists say they have new clues to how memories are made and how drugs might someday be used to stop disruptions in the process that lead to mental illness and brain wasting diseases.
Neuron (red) accumulates messages (green) when treated with BDNF. (Credit: Image courtesy of Johns Hopkins Medicine)
In a report published in the March 2 issue of Cell, the researchers said certain microRNAs — genetic elements that control which proteins get made in cells — are the key to controlling the actions of so-called brain-derived neurotrophic factor (BDNF), long linked to brain cell survival, normal learning and memory boosting.
During the learning process, cells in the brain’s hippocampus release BDNF, a growth-factor protein that ramps up production of other proteins involved in establishing memories. Yet, by mechanisms that were never understood, BDNF is known to increase production of less than 4 percent of the different proteins in a brain cell.
That led Mollie Meffert, M.D., Ph.D., associate professor of biological chemistry and neuroscience at the Johns Hopkins University School of Medicine to track down how BDNF specifically determines which proteins to turn on, and to uncover the role of regulatory microRNAs.
MicroRNAs are small molecules that bind to and block messages that act as protein blueprints from being translated into proteins. Many microRNAs in a cell shut down protein production, and, conversely, the loss of certain microRNAs can cause higher production of specific proteins.
The researchers measured microRNA levels in brain cells treated with BDNF and compared them to microRNA levels in neurons not treated with BDNF. The researchers noticed that levels of certain microRNAs were lower in brain cells treated with BDNF, suggesting that BDNF controls the levels of these microRNAs and, through this control, also affects protein production. Homing in on those specific microRNAS that disappeared when cells were treated with BDNF, the team found all were of the same type, so-called Let-7 microRNAs, and that all shared a common genetic sequence.
"This short genetic sequence has been shown by other researchers to behave like a bar code that can selectively prevent production of Let-7 microRNAs," says Meffert.
To test if the loss of Let-7 microRNAs lets BDNF increase production of specific proteins, Meffert’s team genetically engineered neurons so they could no longer decrease Let-7 microRNAs. They found that treating these neurons with BDNF no longer resulted in decreased microRNA levels or an increase in learning and memory proteins.
In measuring microRNA levels in cells treated with BDNF, the researchers also found more than 174 microRNAs that increased with BDNF treatment. This suggested to the research team that BNDF treatment also can increase other microRNAs and, thereby, decrease production of certain proteins. Says Meffert, some of these proteins may need to be decreased during learning and memory, whereas others may not contribute to the process at all.
To confirm that BDNF, via microRNA action, halts the production of certain proteins, the researchers monitored living brain cells to find out where messages go in response to BDNF. Messages that aren’t translated into proteins can accumulate inside small formations within cells. Using a microscope, the researchers watched a lab dish containing brain cells that had been marked with a fluorescent molecule that labels these formations as glowing spots. Treating cells with BDNF caused the number and size of the glowing spots to increase. The researchers determined that BDNF uses microRNA to send messages to these spots where they can be exiled away from the translating machinery that turns them into protein.
"Monitoring these fluorescent complexes gave us a window that we needed to understand how BDNF is able to target the production of only certain proteins that help neurons to grow and make learning possible," Meffert says.
Adds Meffert, “Now that we know how BDNF boosts production of learning and memory proteins, we have an opportunity to explore whether therapeutics can be designed to enhance this mechanism for treatment of patients with mental disorders and neurodegenerative diseases like Alzheimer’s disease.”
Source: Science Daily
Research shows brain more flexible, trainable than previously thought
March 4, 2012
Brain diagram. Credit: dwp.gov.uk
Opening the door to the development of thought-controlled prosthetic devices to help people with spinal cord injuries, amputations and other impairments, neuroscientists at the University of California, Berkeley, and the Champalimaud Center for the Unknown in Portugal have demonstrated that the brain is more flexible and trainable than previously thought.
Their new study, to be published Sunday, March 4, in the advanced online publication of the journal Nature, shows that through a process called plasticity, parts of the brain can be trained to do something it normally does not do. The same brain circuits employed in the learning of motor skills, such as riding a bike or driving a car, can be used to master purely mental tasks, even arbitrary ones.
Over the past decade, tapping into brain waves to control disembodied objects has moved out of the realm of parlor tricks and parapsychology and into the emerging field of neuroprosthetics. This new study advances work by researchers who have been studying the brain circuits used in natural movement in order to mimic them for the development of prosthetic devices.
"What we hope is that our new insights into the brain’s wiring will lead to a wider range of better prostheses that feel as close to natural as possible," said Jose Carmena, UC Berkeley associate professor of electrical engineering, cognitive science and neuroscience. "They suggest that learning to control a BMI (brain-machine interface), which is inherently unnatural, may feel completely normal to a person, because this learning is using the brain’s existing built-in circuits for natural motor control."
Carmena and co-lead author Aaron Koralek, a UC Berkeley graduate student in Carmena’s lab, collaborated on this study with Rui Costa, co-principal investigator of the study and principal investigator at the Champalimaud Neuroscience Program, and co-lead author Xin Jin, a post-doctoral fellow in Costa’s lab.
Previous studies have failed to rule out the role of physical movement when learning to use a prosthetic device.
"This is key for people who can’t move," said Carmena, who is also co-director of the UC Berkeley-UCSF Center for Neural Engineering and Prostheses. "Most brain-machine interface studies have been done in healthy, able-bodied animals. What our study shows is that neuroprosthetic control is possible, even if physical movement is not involved."
To clarify these issues, the scientists set up a clever experiment in which rats could only complete an abstract task if overt physical movement was not involved. The researchers decoupled the role of the targeted motor neurons needed for whisker twitching with the action necessary to get a food reward.
The rats were fitted with a brain-machine interface that converted brain waves into auditory tones. To get the food reward – either sugar-water or pellets – the rats had to modulate their thought patterns within a specific brain circuit in order to raise or lower the pitch of the signal.
Auditory feedback was given to the rats so that they learned to associate specific thought patterns with a specific pitch. Over a period of just two weeks, the rats quickly learned that to get food pellets, they would have to create a high-pitched tone, and to get sugar water, they needed to create a low-pitched tone.
If the group of neurons in the task were used for their typical function – whisker twitching – there would be no pitch change to the auditory tone, and no food reward.
"This is something that is not natural for the rats," said Costa. "This tells us that it’s possible to craft a prosthesis in ways that do not have to mimic the anatomy of the natural motor system in order to work."
The study was also set up in a way that demonstrated intentional, as opposed to habitual, behavior. The rats were able to vary the amount of pellets or sugar water received based upon their own level of hunger or thirst.
"The rats were aware; they knew that controlling the pitch of the tone was what gave them the reward, so they controlled how much sugar water or how many pellets to take, when to do it, and how to do it in absence of any physical movement," said Costa.
Researchers hope these findings will lead to a new generation of prosthetic devices that feel natural.
"We don’t want people to have to think too hard to move a robotic arm with their brain," said Carmena.
Provided by University of California - Berkeley
Source: medicalxpress.com
Finding unseen damage of traumatic brain injury
This undated handout artist rendering provided by the Schneider Lab, University of Pittsburgh shows an experimental type of scan showing damage to the brain’s nerve fibers after a traumatic brain injury. The yellow shows missing fibers on one side of the brain, as compared to the uninjured side in green, in a man left with limited use of his left arm and hand. The soldier on the fringes of an explosion. The survivor of a car wreck. The football player who took yet another skull-rattling hit. Too often, only time can tell when a traumatic brain injury will leave lasting harm _ there’s no good way to diagnose the damage. Now scientists are testing a tool that promises to light up breaks that these injuries leave in the brain’s wiring, much like X-rays show broken bones. (AP Photo/Schneider Lab, University of Pittsburgh)
The soldier on the fringes of an explosion. The survivor of a car wreck. The football player who took yet another skull-rattling hit. Too often, only time can tell when a traumatic brain injury will leave lasting harm - there’s no good way to diagnose the damage.
Now scientists are testing a tool that lights up the breaks these injuries leave deep in the brain’s wiring, much like X-rays show broken bones.
Research is just beginning in civilian and military patients to learn if this new kind of MRI-based test really could pinpoint their injuries and one day guide rehabilitation. It’s an example of the hunt for better brain scans, maybe even a blood test, to finally tell when a blow to the head causes damage that today’s standard testing simply can’t see.
New High Definition Fiber Tracking Reveals Damage Caused by Traumatic Brain Injury
ScienceDaily (Mar. 2, 2012) — A powerful new imaging technique called High Definition Fiber Tracking (HDFT) will allow doctors to clearly see for the first time neural connections broken by traumatic brain injury (TBI) and other neurological disorders, much like X-rays show a fractured bone, according to researchers from the University of Pittsburgh in a report published online in the Journal of Neurosurgery.
High definition fiber-tracking map of a million brain fibers. (Credit: Walt Schneider Laboratory)
In the report, the researchers describe the case of a 32-year-old man who wasn’t wearing a helmet when his all-terrain vehicle crashed. Initially, his CT scans showed bleeding and swelling on the right side of the brain, which controls left-sided body movement. A week later, while the man was still in a coma, a conventional MRI scan showed brain bruising and swelling in the same area. When he awoke three weeks later, the man couldn’t move his left leg, arm and hand.