Neuroscience

Articles and news from the latest research reports.

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Japan to field test rehabilitation robots
Ten hospitals in Japan are set to begin testing the use of a robot known as “Robot Suit HAL” starting next month. The purpose of the test will be to determine whether use of the robot is beneficial to patients needing physical therapy to regain normal use of their legs.
When people experience nerve or muscle damage to their lower backs or legs due to illness, stroke or injury, the normal course of treatment involves undergoing physical therapy. Doing so causes the body to slowly repair the damage that has been done. In order for it to work however, the parts of the body that work properly have to coax the parts that do not into action, a laborious and quite often painful process. For this reason, professional physical therapists assist patients with the process to ensure that all of the body parts are exercised and to offer emotional support. But such experts can only help so much, and for that reason, robots have been developed to help. The thinking is that because they are sensor based and lack emotional involvement in the process, robots are likely to do a better job.
The Robot Suit HAL (Hybrid Assistive Limb) has been designed and built by Cyberdyne Inc. with assistance from researchers around the country. It’s described by its makers as a cyborg-type robot meant to supplement human muscles or to assist in their rehabilitation. Its part handrail, part sensor and part hydraulically controlled machinery. A patient stands between two handrails, holding on, while sensors are affixed to the skin of the legs. The sensors pick up nerve signals which are sent to an onboard computer. Those signals are then converted to action by small motors and power units that cause the muscle to be worked in the same way it would be were the person’s body able to move it on their own. The end result is a direct connection between nerve signals and movement, which the researchers believe, will result in faster and perhaps better recovery for the patient.
Initial testing will involve 30 volunteer patients. Representatives for Cyberdyne have also announced that the company is in the process of making arrangements for testing the robot in hospitals in Europe as well.

Japan to field test rehabilitation robots

Ten hospitals in Japan are set to begin testing the use of a robot known as “Robot Suit HAL” starting next month. The purpose of the test will be to determine whether use of the robot is beneficial to patients needing physical therapy to regain normal use of their legs.

When people experience nerve or muscle damage to their lower backs or legs due to illness, stroke or injury, the normal course of treatment involves undergoing physical therapy. Doing so causes the body to slowly repair the damage that has been done. In order for it to work however, the parts of the body that work properly have to coax the parts that do not into action, a laborious and quite often painful process. For this reason, professional physical therapists assist patients with the process to ensure that all of the body parts are exercised and to offer emotional support. But such experts can only help so much, and for that reason, robots have been developed to help. The thinking is that because they are sensor based and lack emotional involvement in the process, robots are likely to do a better job.

The Robot Suit HAL (Hybrid Assistive Limb) has been designed and built by Cyberdyne Inc. with assistance from researchers around the country. It’s described by its makers as a cyborg-type robot meant to supplement human muscles or to assist in their rehabilitation. Its part handrail, part sensor and part hydraulically controlled machinery. A patient stands between two handrails, holding on, while sensors are affixed to the skin of the legs. The sensors pick up nerve signals which are sent to an onboard computer. Those signals are then converted to action by small motors and power units that cause the muscle to be worked in the same way it would be were the person’s body able to move it on their own. The end result is a direct connection between nerve signals and movement, which the researchers believe, will result in faster and perhaps better recovery for the patient.

Initial testing will involve 30 volunteer patients. Representatives for Cyberdyne have also announced that the company is in the process of making arrangements for testing the robot in hospitals in Europe as well.

Filed under HAL Robot Suit HAL robotics robots physical therapy rehabilitation science

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Neil Harbisson Is A Cyborg Who Hears More Of The World Than We See
What would your world be like if you couldn’t see color? For artist Neil Harbisson, a rare condition known as achromatopsia that made him completely color blind rendered that question meaningless. Not being able to see color at all meant that there was no blue in the sky or green in grass, and these descriptions were merely something to be taken on faith or memorized to get the correct answers in school.
But Neil’s life would change drastically when he met computer scientist Adam Montandon and with help from a few others, they developed the eyeborg, an electronic eye that transforms colors into sounds. Colors became meaningful for Neil in an experiential way, but one that was fundamentally different than how others described them.
This augmentation device wasn’t like a set of headphones that he could put on when he wanted to “listen” to the world around him, but became a permanent part of who he was. Though he had to memorize how the sounds corresponded to certain colors, in time the sounds became part of his perception and the way he “sees” the world. He even started to expand the range of what he could “see”, so that wavelengths of light outside of the visible range could be perceived.
In other words, he became cybernetic.
Not being readily accepted into society prompted the birth of a mission, as he explains in the phenomenal short film “Cyborg Foundation” that has won the Grand Jury Prize in GE’s $200,000 Focus Forward Filmmaker competition.
Neil recently gave a fascinating talk at TEDGlobal2012 describing how his life is different, including how he can “eat my favorite song: I can compose music with food” and “before I used to dress in a way that it looked good — now I dress in a way that it sounds good.” The foundation he co-launched aims to advocate the development and adoption of cybernetics into society. “Life will be much more exciting when we stop creating applications for mobile phones and start creating them for our body.”

Neil Harbisson Is A Cyborg Who Hears More Of The World Than We See

What would your world be like if you couldn’t see color? For artist Neil Harbisson, a rare condition known as achromatopsia that made him completely color blind rendered that question meaningless. Not being able to see color at all meant that there was no blue in the sky or green in grass, and these descriptions were merely something to be taken on faith or memorized to get the correct answers in school.

But Neil’s life would change drastically when he met computer scientist Adam Montandon and with help from a few others, they developed the eyeborg, an electronic eye that transforms colors into sounds. Colors became meaningful for Neil in an experiential way, but one that was fundamentally different than how others described them.

This augmentation device wasn’t like a set of headphones that he could put on when he wanted to “listen” to the world around him, but became a permanent part of who he was. Though he had to memorize how the sounds corresponded to certain colors, in time the sounds became part of his perception and the way he “sees” the world. He even started to expand the range of what he could “see”, so that wavelengths of light outside of the visible range could be perceived.

In other words, he became cybernetic.

Not being readily accepted into society prompted the birth of a mission, as he explains in the phenomenal short film “Cyborg Foundation” that has won the Grand Jury Prize in GE’s $200,000 Focus Forward Filmmaker competition.

Neil recently gave a fascinating talk at TEDGlobal2012 describing how his life is different, including how he can “eat my favorite song: I can compose music with food” and “before I used to dress in a way that it looked good — now I dress in a way that it sounds good.” The foundation he co-launched aims to advocate the development and adoption of cybernetics into society. “Life will be much more exciting when we stop creating applications for mobile phones and start creating them for our body.”

Filed under Neil Harbisson achromatopsia color blindness eyeborg cybernetics cyborg foundation science

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Cellular renewal process may underlie benefits of omega fatty acids
A search for genes that change their levels of expression in response to nutrient deprivation has uncovered potential clues to the mechanism underlying the health benefits of omega fatty acids. In the Feb. 15 issue of Genes & Development, Massachusetts General Hospital (MGH) researchers describe finding that feeding omega-6 fatty acids to C. elegans roundworms or adding them to cultured human cells activates a cellular renewal process called autophagy, which may be deficient in several important diseases of aging. A process by which defective or worn-out cellular components and molecules are broken down for removal or recycling, autophagy is also activated in metabolically stressful situations, allowing cells to survive by self-digesting nonessential components.
"Enhanced autophagy implies improved clearance of old or damaged cellular components and a more efficient immune response," says Eyleen O’Rourke, PhD, of MGH Molecular Biology, lead author of the report. "It has been suggested that autophagy can extend lifespan by maintaining cellular function, and in humans a breakdown in autophagic function may involved in diseases including inflammatory bowel disease, Parkinson’s disease, and in a more complex way in cancer and metabolic syndrome."
O’Rourke is a research fellow in the laboratory of MGH investigator Gary Ruvkun, PhD, whose team investigates the development, longevity and metabolism of C.elegans. Ruvkun and other researchers have discovered that simple mutations in genetic pathways conserved throughout evolution can double or triple the lifespan of C. elegans and that similar mutations in the corresponding mammalian pathways also regulate lifespan. Many of these mutations also make animals resistant to starvation, suggesting that common molecular mechanisms may underlie both response to nutrient deprivation and the regulation of lifespan.
To find these mechanisms O’Rourke searched genomic databases covering many types of animals for shared genes that respond to fasting by changing their expression. She found that expression of the C. elegans gene lipl-4 increases up to seven times in worms not given access to nutrients. A transgenic strain that constantly expresses elevated levels of lipl-4, even when given full access to food, was found to have increased levels of arachidonic acid (AA), an omega-6, and eicosapentanoic acid (EPA), an omega-3 fatty acid and to resist the effects of starvation.
(Image: The Herman Lab, Kansas State University)

Cellular renewal process may underlie benefits of omega fatty acids

A search for genes that change their levels of expression in response to nutrient deprivation has uncovered potential clues to the mechanism underlying the health benefits of omega fatty acids. In the Feb. 15 issue of Genes & Development, Massachusetts General Hospital (MGH) researchers describe finding that feeding omega-6 fatty acids to C. elegans roundworms or adding them to cultured human cells activates a cellular renewal process called autophagy, which may be deficient in several important diseases of aging. A process by which defective or worn-out cellular components and molecules are broken down for removal or recycling, autophagy is also activated in metabolically stressful situations, allowing cells to survive by self-digesting nonessential components.

"Enhanced autophagy implies improved clearance of old or damaged cellular components and a more efficient immune response," says Eyleen O’Rourke, PhD, of MGH Molecular Biology, lead author of the report. "It has been suggested that autophagy can extend lifespan by maintaining cellular function, and in humans a breakdown in autophagic function may involved in diseases including inflammatory bowel disease, Parkinson’s disease, and in a more complex way in cancer and metabolic syndrome."

O’Rourke is a research fellow in the laboratory of MGH investigator Gary Ruvkun, PhD, whose team investigates the development, longevity and metabolism of C.elegans. Ruvkun and other researchers have discovered that simple mutations in genetic pathways conserved throughout evolution can double or triple the lifespan of C. elegans and that similar mutations in the corresponding mammalian pathways also regulate lifespan. Many of these mutations also make animals resistant to starvation, suggesting that common molecular mechanisms may underlie both response to nutrient deprivation and the regulation of lifespan.

To find these mechanisms O’Rourke searched genomic databases covering many types of animals for shared genes that respond to fasting by changing their expression. She found that expression of the C. elegans gene lipl-4 increases up to seven times in worms not given access to nutrients. A transgenic strain that constantly expresses elevated levels of lipl-4, even when given full access to food, was found to have increased levels of arachidonic acid (AA), an omega-6, and eicosapentanoic acid (EPA), an omega-3 fatty acid and to resist the effects of starvation.

(Image: The Herman Lab, Kansas State University)

Filed under C. Elegans roundworm omega fatty acids omega-6 autophagy genetics science

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Chimpanzees have faster working memory than humans
Chimpanzees have a faster working memory than humans according to a remarkable study showing that it takes them a fraction of a second to remember something that it would take several seconds for humans to memorise. 
A Japanese scientist has demonstrated the prowess of chimps in remembering in less than half a second the precise position and correct sequence of up to nine numbers on a computer screen.
The numbers are shown together randomly distributed on a computer screen and as soon as the chimps press the number “one” the rest of the numerals are masked. However, they can almost invariably remember where each number was.
It is impossible for people to do the same cognitive task that quickly, said Tetsuro Matsuzawa, a primatologist at Kyoto University. “They have a better working memory than us,” he told the American Association for the Advancment of Science meeting in Boston.
Professor Matsuzawa had carried out the memory experiments on a female chimp called Ai, which means “love” in Japanese, and Ayumu, her son who was born in 2000 and has shown even better memory skills, he said.
Professor Matsuzawa suggested that chimps have developed this part of their memory because they live in the “here and now” whereas humans are thinking more about the past and planning for the future.

Chimpanzees have faster working memory than humans

Chimpanzees have a faster working memory than humans according to a remarkable study showing that it takes them a fraction of a second to remember something that it would take several seconds for humans to memorise.

A Japanese scientist has demonstrated the prowess of chimps in remembering in less than half a second the precise position and correct sequence of up to nine numbers on a computer screen.

The numbers are shown together randomly distributed on a computer screen and as soon as the chimps press the number “one” the rest of the numerals are masked. However, they can almost invariably remember where each number was.

It is impossible for people to do the same cognitive task that quickly, said Tetsuro Matsuzawa, a primatologist at Kyoto University. “They have a better working memory than us,” he told the American Association for the Advancment of Science meeting in Boston.

Professor Matsuzawa had carried out the memory experiments on a female chimp called Ai, which means “love” in Japanese, and Ayumu, her son who was born in 2000 and has shown even better memory skills, he said.

Professor Matsuzawa suggested that chimps have developed this part of their memory because they live in the “here and now” whereas humans are thinking more about the past and planning for the future.

Filed under primates memory working memory cognitive tasks psychology neuroscience science

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Hypothalamic control of energy balance: insights into the role of synaptic plasticity
The past 20 years witnessed an enormous leap in understanding of the central regulation of whole-body energy metabolism. Genetic tools have enabled identification of the region-specific expression of peripheral metabolic hormone receptors and have identified neuronal circuits that mediate the action of these hormones on behavior and peripheral tissue functions. One of the surprising findings of recent years is the observation that brain circuits involved in metabolism regulation remain plastic through adulthood. In this review, we discuss these findings and focus on the role of neurons and glial cells in the dynamic process of plasticity, which is fundamental to the regulation of physiological and pathological metabolic events.

Hypothalamic control of energy balance: insights into the role of synaptic plasticity

The past 20 years witnessed an enormous leap in understanding of the central regulation of whole-body energy metabolism. Genetic tools have enabled identification of the region-specific expression of peripheral metabolic hormone receptors and have identified neuronal circuits that mediate the action of these hormones on behavior and peripheral tissue functions. One of the surprising findings of recent years is the observation that brain circuits involved in metabolism regulation remain plastic through adulthood. In this review, we discuss these findings and focus on the role of neurons and glial cells in the dynamic process of plasticity, which is fundamental to the regulation of physiological and pathological metabolic events.

Filed under energy metabolism neuronal circuits plasticity neurons glial cells neuroscience science

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Low-protein diet slows Alzheimer’s in mice

Mice with many of the pathologies of Alzheimer’s Disease showed fewer signs of the disease when given a protein-restricted diet supplemented with specific amino acids every other week for four months.

Mice at advanced stages of the disease were put on the new diet. They showed improved cognitive abilities over their non-dieting peers when their memory was tested using mazes. In addition, fewer of their neurons contained abnormal levels of a damaged protein, called “tau,” which accumulates in the brains of Alzheimer’s patients.

Dietary protein is the major dietary regulator of a growth hormone known as IGF-1, which has been associated with aging and diseases in mice and several diseases in older adults.

Upcoming studies by USC Professor Valter Longo, the study’s corresponding author, will attempt to determine whether humans respond similarly – while simultaneously examining the effects of dietary restrictions on cancer, diabetes and cardiac disease.

"We had previously shown that humans deficient in Growth Hormone receptor and IGF-I displayed reduced incidence of cancer and diabetes. Although the new study is in mice, it raises the possibility that low protein intake and low IGF-I may also protect from age-dependent neurodegeneration," said Longo, who directs the Longevity Institute of the USC Davis School of Gerontology and has a joint appointment the USC Dornsife College of Letters, Arts and Sciences.

Longo worked with Pinchas Cohen, dean of the USC Davis School, as well as USC graduate students Edoardo Parrella, Tom Maxim, Lu Zhang, Junxiang Wan and Min Wei; Francesca Maialetti of the Istituto Superiore di Sanità in Rome; and Luigi Fontana of Washington University in St. Louis.

"Alzheimer’s Disease and other forms of neurodegeneration are a major burden on society, and it is a rising priority for this nation to develop new approaches for preventing and treating these conditions, since the frequencies of these disorders will be rising as the population ages over the next several decades," said Cohen, who became dean of the School of Gerontology in summer 2012. "New strategies to address this, particularly non-invasive, non-pharmacological approaches such as tested in Dr. Longo’s study are particularly exciting."

The results of their study were published online by Aging Cell last month.

The team found that a protein-restricted diet reduced levels of IGF-1 circulating through the body by 30 to 70 percent, and caused an eight-fold increase in a protein that blocks IGF-1’s effects by binding to it.

IGF-1 helps the body grow during youth but is also associated with several diseases later in life in both mice and humans. Exploring dietary solutions to those diseases as opposed to generating pharmaceuticals to manipulate IGF-1 directly allows Longo’s team to make strides that could help sufferers today or in the next few years.

"We always try to do things for people who have the problem now," Longo said. "Developing a drug can take 15 years of trials and a billion dollars.

"Although only clinical trials can determine whether the protein-restricted diet is effective and safe in humans with cognitive impairment, a doctor could read this study today and, if his or her patient did not have any other viable options, could consider introducing the protein restriction cycles in the treatment – understanding that effective interventions in mice may not translate into effective human therapies," he said.

Many elderly individuals may have already be frail, have lost weight or may not be healthy enough to eat a protein-restricted diet every other week. Longo strongly insisted that any dieting be monitored by a doctor or registered dietician to make sure that patients do not become amino acid deficient, lose additional weight or develop other side effects.

(Source: eurekalert.org)

Filed under dietary protein aging neurodegeneration azheimer's disease tau protein neuroscience science

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Threat bias interacts with combat, gene to boost PTSD risk
Soldiers preoccupied with threat at the time of enlistment or with avoiding it just before deployment were more likely to develop post-traumatic stress disorder (PTSD), in a study of Israeli infantrymen. Such pre-deployment threat vigilance and avoidance, interacting with combat experience and an emotion-related gene, accounted for more than a third of PTSD symptoms that emerged later, say National Institutes of Health scientists, who conducted the study in collaboration with American and Israeli colleagues.
“Since biased attention predicted future risk for PTSD, computerized training that helps modify such attention biases might help protect soldiers from the disorder,” said Daniel Pine, M.D., of the NIH’s National Institute of Mental Health (NIMH).
Pine, Yair Bar-Haim, Ph.D., of Tel Aviv University, and colleagues, report their findings, Feb.  13, 2013, in the journal JAMA Psychiatry.

Threat bias interacts with combat, gene to boost PTSD risk

Soldiers preoccupied with threat at the time of enlistment or with avoiding it just before deployment were more likely to develop post-traumatic stress disorder (PTSD), in a study of Israeli infantrymen. Such pre-deployment threat vigilance and avoidance, interacting with combat experience and an emotion-related gene, accounted for more than a third of PTSD symptoms that emerged later, say National Institutes of Health scientists, who conducted the study in collaboration with American and Israeli colleagues.

“Since biased attention predicted future risk for PTSD, computerized training that helps modify such attention biases might help protect soldiers from the disorder,” said Daniel Pine, M.D., of the NIH’s National Institute of Mental Health (NIMH).

Pine, Yair Bar-Haim, Ph.D., of Tel Aviv University, and colleagues, report their findings, Feb.  13, 2013, in the journal JAMA Psychiatry.

Filed under PTSD anxiety attention serotonin genes threat bias neuroscience science

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Parkinson’s patients advised to seek Deep Brain Stimulation treatment in early stages
People with Parkinson’s disease who receive Deep Brain Stimulation (DBS) therapy in the early stages of the condition will benefit from a significant increase in quality of life, a revolutionary study from The New England Journal of Medicine has found.
World-leading neurologist and lead clinician Professor Peter Silburn from the Asia-Pacific Centre for Neuromodulation (APCN), a joint initiative of The University of Queensland (UQ) and St Andrew’s Hospital, said the results published today in the medical journal would transform the way we treat people with Parkinson’s disease.
“Before the release of this study, a typical patient with Parkinson’s disease would need to wait around 10 years or until their motor complications could no longer be treated successfully with medicine alone, before DBS surgery was considered an option,” Professor Silburn said.
“This study has confirmed the best medical practice for a person with Parkinson’s disease is to perform DBS surgery around 4 to 7 years into the condition, as opposed to waiting until the medications stop working.”

Parkinson’s patients advised to seek Deep Brain Stimulation treatment in early stages

People with Parkinson’s disease who receive Deep Brain Stimulation (DBS) therapy in the early stages of the condition will benefit from a significant increase in quality of life, a revolutionary study from The New England Journal of Medicine has found.

World-leading neurologist and lead clinician Professor Peter Silburn from the Asia-Pacific Centre for Neuromodulation (APCN), a joint initiative of The University of Queensland (UQ) and St Andrew’s Hospital, said the results published today in the medical journal would transform the way we treat people with Parkinson’s disease.

“Before the release of this study, a typical patient with Parkinson’s disease would need to wait around 10 years or until their motor complications could no longer be treated successfully with medicine alone, before DBS surgery was considered an option,” Professor Silburn said.

“This study has confirmed the best medical practice for a person with Parkinson’s disease is to perform DBS surgery around 4 to 7 years into the condition, as opposed to waiting until the medications stop working.”

Filed under neuromodulation deep brain stimulation parkinson's disease neuroscience science

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Sticky Cells: Cyclic Mechanical Reinforcement Extends Longevity of Bonds Between Cells
Research carried out by scientists at the Georgia Institute of Technology and The University of Manchester has revealed new insights into how cells stick to each other and to other bodily structures, an essential function in the formation of tissue structures and organs. It’s thought that abnormalities in their ability to do so play an important role in a broad range of disorders, including cardiovascular disease and cancer.
The study’s findings are outlined in the journal Molecular Cell and describe a surprising new aspect of cell adhesion involving the family of cell adhesion molecules known as integrins, which are found on the surfaces of most cells. The research uncovered a phenomenon termed “cyclic mechanical reinforcement,” in which the length of time during which bonds exist is extended with repeated pulling and release between the integrins and ligands that are part of the extracellular matrix to which the cells attach.
Professor Martin Humphries, dean of the faculty of life sciences at the University of Manchester and one of the paper’s co-authors, says the study suggests some new capabilities for cells: “This paper identifies a new kind of bond that is strengthened by cyclical applications of force, and which appears to be mediated by complex shape changes in integrin receptors. The findings also shed light on a possible mechanism used by cells to sense extracellular topography and to aggregate information through ‘remembering’ multiple interaction events.”
The cyclic mechanical reinforcement allows force to prolong the lifetimes of bonds, demonstrating a mechanical regulation of receptor-ligand interactions and identifying a molecular mechanism for strengthening cell adhesion through cyclical forces.
“Many cell functions such as differentiation, growth and the expression of particular genes depend on cell interaction with the ligands of the intracellular matrix,” said Cheng Zhu, a professor in the Coulter Department of Biomedical Engineering at Georgia Tech and Emory University and the study’s corresponding author. “The cells respond to their environment, which includes many mechanical aspects. This study has extended our understanding of how connections are made and how mechanical forces regulate interactions.”
The research was published online by the journal on February 14th. The work was supported by the National Institutes of Health (NIH) and the Wellcome Trust.

Sticky Cells: Cyclic Mechanical Reinforcement Extends Longevity of Bonds Between Cells

Research carried out by scientists at the Georgia Institute of Technology and The University of Manchester has revealed new insights into how cells stick to each other and to other bodily structures, an essential function in the formation of tissue structures and organs. It’s thought that abnormalities in their ability to do so play an important role in a broad range of disorders, including cardiovascular disease and cancer.

The study’s findings are outlined in the journal Molecular Cell and describe a surprising new aspect of cell adhesion involving the family of cell adhesion molecules known as integrins, which are found on the surfaces of most cells. The research uncovered a phenomenon termed “cyclic mechanical reinforcement,” in which the length of time during which bonds exist is extended with repeated pulling and release between the integrins and ligands that are part of the extracellular matrix to which the cells attach.

Professor Martin Humphries, dean of the faculty of life sciences at the University of Manchester and one of the paper’s co-authors, says the study suggests some new capabilities for cells: “This paper identifies a new kind of bond that is strengthened by cyclical applications of force, and which appears to be mediated by complex shape changes in integrin receptors. The findings also shed light on a possible mechanism used by cells to sense extracellular topography and to aggregate information through ‘remembering’ multiple interaction events.”

The cyclic mechanical reinforcement allows force to prolong the lifetimes of bonds, demonstrating a mechanical regulation of receptor-ligand interactions and identifying a molecular mechanism for strengthening cell adhesion through cyclical forces.

“Many cell functions such as differentiation, growth and the expression of particular genes depend on cell interaction with the ligands of the intracellular matrix,” said Cheng Zhu, a professor in the Coulter Department of Biomedical Engineering at Georgia Tech and Emory University and the study’s corresponding author. “The cells respond to their environment, which includes many mechanical aspects. This study has extended our understanding of how connections are made and how mechanical forces regulate interactions.”

The research was published online by the journal on February 14th. The work was supported by the National Institutes of Health (NIH) and the Wellcome Trust.

Filed under cells cell interaction integrins cyclic mechanical reinforcement medicine science

52 notes

Limits on Brain’s Ability to Perceive Multifeatured Objects

New research sheds light on how the brain encodes objects with multiple features, a fundamental task for the perceptual system. The study, published in Psychological Science, a journal of the Association for Psychological Science, suggests that we have limited ability to perceive mixed color-shape associations among objects that exist in several locations.

Research suggests that neurons that encode a certain feature — shape or color, for example — fire in synchrony with neurons that encode other features of the same object. Psychological scientists Liat Goldfarb of the University of Haifa and Anne Treisman of Princeton University hypothesized that if this neural-synchrony explanation were true, then synchrony would be impossible in situations in which the same features are paired differently in different objects.

Say, for example, a person sees a string of letters, “XOOX,” and the letters are printed in alternating colors, red and green. Both letter shape and letter color need to be encoded, but the associations between letter shape and letter color are mixed (i.e., the first X is red, while the second X is green), which should make neural synchrony impossible.

“The perceptual system can either know how many Xs there are or how many reds there are, but it cannot know both at the same time,” Goldfarb and Treisman explain.

The researchers investigated their hypothesis in two experiments, in which they presented participants with strings of green and red Xs and Os and asked them to compare the number of Xs with the number of red letters (i.e., more Xs, more reds, or the same).

Participants’ responses to unique color-shape associations were significantly faster and more accurate than were their responses to displays with mixed color-shape associations.

The results show that relevant color and shape dimensions could be synchronized when the pairings between color and shape were unique, but not when the pairings were mixed.

These findings demonstrate a new behavioral principle that governs object representation. When shapes are repeated in several locations and have mixed color-shape associations, they are hard to perceive.

This research expands on Anne Treisman’s groundbreaking research on feature integration in visual perception, which shows that humans can encode characteristics such as color, form, and orientation, even in the absence of spatial attention.

Treisman is one of 12 scientists who received the National Medal of Science at the White House on February 1, 2013. The National Medal of Science, along with the National Medal of Technology and Innovation, is the highest honor that the US government grants to scientists, engineers, and inventors.

Filed under visual perception neural synchrony neurons brain psychology neuroscience science

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