Posts tagged psychology

Tuesday, July 31, 2012

TAU researchers develop bioactive coating to “camouflage” neutral electrodes

Brain-computer interfaces are at the cutting edge for treatment of neurological and psychological disorder, including Parkinson’s, epilepsy, and depression. Among the most promising advance is deep brain stimulation (DBS) — a method in which a silicon chip implanted under the skin ejects high frequency currents that are transferred to the brain through implanted electrodes that transmit and receive the signals. These technologies require a seamless interaction between the brain and the hardware.

But there’s a catch. Identified as foreign bodies by the immune system, the brain attacks the electrodes and forms a barrier to the brain tissue, making it impossible for the electrodes to communicate with brain activity. So while the initial implantation can diminish symptoms, after a few short years or even months, the efficacy of this therapy begins to wane.

Now Aryeh Taub of Tel Aviv University's School of Psychological Sciences, along with Prof. Matti Mintz, Roni Hogri and Ari Magal of TAU’s School of Psychological Sciences and Prof. Yosi Shacham-Diamand of TAU’s School of Electrical Engineering, has developed a bioactive coating which not only “camouflages” the electrodes in the brain tissue, but actively suppresses the brain’s immune response. By using a protein called an “interleukin (IL)-1 receptor antagonist” to coat the electrodes, the multi-disciplinary team of researchers has found a potential resolution to turn a method for short-term relief into a long-term solution. This development was reported in the Journal of Biomedical Materials Research.

Limiting the immune response

To overcome the creation of the barrier between the tissue and the electrode, the researchers sought to develop a method for placing the electrode in the brain tissue while hiding the electrode from the brain’s immune defenses. Previous research groups have coated the electrodes with various proteins, says Taub, but the TAU team decided to take a different approach by using a protein that is active within the brain itself, thereby suppressing the immune reaction against the electrodes.

In the brain, the IL-1 receptor antagonist is crucial for maintaining physical stability by localizing brain damage, Taub explains. For example, if a person is hit on the head, this protein works to create scarring in specific areas instead of allowing global brain scarring. In other words, it stops the immune system from overreacting. The team’s coating, the first to be developed from this particular protein, not only integrates the electrodes into the brain tissue, but allows them to contribute to normal brain functioning.

In pre-clinical studies with animal models, the researchers found that their coated electrodes perform better than both non-coated and “naïve protein”-coated electrodes that had previously been examined. Measuring the number of damaged cells at the site of implantation, researchers found no apparent difference between the site of electrode implantation and healthy brain tissue elsewhere, Taub says. In addition, evidence suggests that the coated electrodes will be able to function for long periods of time, providing a more stable and long-term treatment option.

Restoring brain function

Approximately 30,000 people worldwide are currently using deep brain stimulation (DBS) to treat neurological or psychological conditions. And DBS is only the beginning. Taub believes that, in the future, an interface with the ability to restore behavioral or motor function lost due to tissue damage is achievable — especially with the help of their new electrode coating.

"We duplicate the function of brain tissue onto a silicon chip and transfer it back to the brain," Taub says, explaining that the electrodes will pick up brain waves and transfer these directly to the chip. "The chip then does the computation that would have been done in the damaged tissue, and feeds the information back into the brain — prompting functions that would have otherwise gotten lost."

Source: Tel Aviv University

July 30, 2012

UC Irvine scientists have discovered intriguing differences in the brains and mental processes of an extraordinary group of people who can effortlessly recall every moment of their lives since about age 10.

The phenomenon of highly superior autobiographical memory – first documented in 2006 by UCI neurobiologist James McGaugh and colleagues in a woman identified as “AJ” – has been profiled on CBS’s “60 Minutes” and in hundreds of other media outlets. But a new paper in the peer-reviewed journal Neurobiology of Learning & Memory’s July issue offers the first scientific findings about nearly a dozen people with this uncanny ability.

All had variations in nine structures of their brains compared to those of control subjects, including more robust white matter linking the middle and front parts. Most of the differences were in areas known to be linked to autobiographical memory, “so we’re getting a descriptive, coherent story of what’s going on,” said lead author Aurora LePort, a doctoral candidate at UCI’s Center for the Neurobiology of Learning & Memory.

Surprisingly, the people with stellar autobiographical memory did not score higher on routine laboratory memory tests or when asked to use rote memory aids. Yet when it came to public or private events that occurred after age 10½, “they were remarkably better at recalling the details of their lives,” said McGaugh, senior author on the new work.

"These are not memory experts across the board. They’re 180 degrees different from the usual memory champions who can memorize pi to a large degree or other long strings of numbers," LePort noted. "It makes the project that much more interesting; it really shows we are homing in on a specific form of memory."

She said interviewing the subjects was “baffling. You give them a date, and their response is immediate. The day of the week just comes out of their minds; they don’t even think about it. They can do this for so many dates, and they’re 99 percent accurate. It never gets old.”

The study also found statistically significant evidence of obsessive-compulsive tendencies among the group, but the authors do not yet know if or how this aids recollection. Many of the individuals have large, minutely catalogued collections of some sort, such as magazines, videos, shoes, stamps or postcards.

UCI researchers and staff have assessed more than 500 people who thought they might possess highly superior autobiographical memory and have confirmed 33 to date, including the 11 in the paper. Another 37 are strong candidates who will be further tested.

"The next step is that we want to understand the mechanisms behind the memory," LePort said. "Is it just the brain and the way its different structures are communicating? Maybe it’s genetic; maybe it’s molecular."

McGaugh added: “We’re Sherlock Holmeses here. We’re searching for clues in a very new area of research.”

Provided by University of California, Irvine

Source: medicalxpress.com

July 30, 2012

Is attention-deficit/hyperactivity disorder (ADHD) due to a delay in brain development or the result of complete deviation from typical development? In the current issue of Biological Psychiatry, Dr. Philip Shaw and colleagues present evidence for delay based on a study by the National Institutes of Health.

The cerebral cortex is the folded gray tissue that makes up the outermost portion of the brain, covering the brain’s inner structures. This tissue has left and right hemispheres and is divided into lobes. Each lobe performs specific and vitally important functions, including attention, thought, language, and sensory processing.

Two dimensions of this structure are cortical thickness and cortical surface area, both of which mature during childhood as part of the normal developmental process. This group of scientists had previously found that the thickening process is delayed in children diagnosed with ADHD. So in this study, they set out to measure whether surface area development is similarly delayed.

They recruited 234 children with ADHD and 231 typically developing children and scanned each up to 4 times. The first scan was taken at about age 10, and the final scan was around age 17. Using advanced neuroimaging technology, they were able to map the trajectories of surface area development at over 80,000 points across the brain.

They found that the development of the cortical surface is delayed in frontal brain regions in children with ADHD. For example, the typically developing children attained 50% peak area in the right prefrontal cortex at a mean age of 12.7 years, whereas the ADHD children didn’t reach this peak until 14.6 years of age.

"As other components of cortical development are also delayed, this suggests there is a global delay in ADHD in brain regions important for the control of action and attention," said Dr. Shaw, a clinician studying ADHD at the National Institute of Mental Health and first author of this study.

"These data highlight the importance of longitudinal approaches to brain structure," commented Dr. John Krystal, Editor of Biological Psychiatry. "Seeing a lag in brain development, we now need to try to understand the causes of this developmental delay in ADHD."

Dr Shaw agrees, adding that this finding “guides us to search for genes that control the timing of brain development in the disorder, opening up new targets for treatment.”

Additional work expanding these measures into adulthood will also be important. Such data would help determine whether or when a degree of normalization occurs, or if these delays translate into long-lasting cortical deficits.

Provided by Elsevier

Source: medicalxpress.com

By Matthew Hutson  | July 30, 2012

Why we are biased toward things on our dominant side

Image: GETTY IMAGES

If you are right-handed, chances are you will make different choices than your left-handed friends. A series of recent studies shows that we associate our dominant side with good and our nondominant side with bad, preferring products and people that happen to be on our “good” side over those closer to the other half of our body.

The theory of embodied cognition, widely embraced by cognitive scientists in recent years, holds that our abstract ideas are grounded in our physical experiences in the world. (See above: “embraced,” “holds,” “grounded.”) Daniel Casasanto, a psychologist at the New School for Social Research, began to wonder: If our bodies shape our thinking, do people with different bodies think differently? He has been using handedness as a test bed for this body-specific hypothesis.

In a set of studies published in 2009 Casasanto found that right-handers associate right with good and left with bad and that left-handers make the reverse associations. People prefer objects, job candidates and images of alien creatures on their dominant side to those on their nondominant side. In 2010 he reported that presidential candidates (Kerry, Bush, Obama and McCain) gesture with their dominant hands when making positive points and their weak hands to emphasize darker matters. And he has collected data to suggest that lefties hold higher opinions of their flight attendants when seated on the right side of a plane.

To rule out the possibility that this bias is purely genetic, like handedness is, Casasanto handicapped people’s preferred hands. In a 2011 study he had subjects manipulate dominoes while wearing a bulky ski glove on their good hand. Afterward, they showed a bias against things on that side. The results suggest that we look kindly on half the world because we can interact with that side fluently. Make it a hassle, and opinions flip.

Most recently, Casasanto reported in January in Cognitive Science that children as young as six display a handedness bias. Kids were asked which animal in a series of cartoon pairs looked nicer or smarter. The right-handers more often chose the drawing on the right side, and the left-handers more often chose the animal on the left. They also elected to put away their preferred toys in boxes on their dominant side.

“We all walk around with these lopsided bodies and have to interact with our environment in systematically different ways,” Casasanto notes. Given how broadly those interactions can influence our thinking, he says, “body specificity may be shaping our judgments in the real world in ways that we never suspected.”

Source: Scientific American