Posts tagged science
Articles and news from the latest research reports.
Eating Baked or Broiled Fish Weekly Boosts Brain Health
Eating baked or broiled fish once a week is good for the brain, regardless of how much omega-3 fatty acid it contains, according to researchers at the University of Pittsburgh School of Medicine. The findings, published online recently in the American Journal of Preventive Medicine, add to growing evidence that lifestyle factors contribute to brain health later in life.
Scientists estimate that more than 80 million people will have dementia by 2040, which could become a substantial burden to families and drive up health care costs, noted senior investigator James T. Becker, Ph.D., professor of psychiatry, Pitt School of Medicine. Some studies have predicted that lifestyle changes such as a reduction in rates of physical inactivity, smoking and obesity could lead to fewer cases of Alzheimer’s disease and other conditions of cognitive impairment in the elderly. The anti-oxidant effect of omega-3 fatty acids, which are found in high amounts in fish, seeds and nuts, and certain oils, also have been associated with improved health, particularly brain health.
“Our study shows that people who ate a diet that included baked or broiled, but not fried, fish have larger brain volumes in regions associated with memory and cognition,” Dr. Becker said. “We did not find a relationship between omega-3 levels and these brain changes, which surprised us a little. It led us to conclude that we were tapping into a more general set of lifestyle factors that were affecting brain health of which diet is just one part.”
Lead investigator Cyrus Raji, M.D., Ph.D., who now is in radiology residency training at UCLA, and the research team analyzed data from 260 people who provided information on their dietary intake, had high-resolution brain MRI scans, and were cognitively normal at two time points during their participation in the Cardiovascular Health Study (CHS), a 10-year multicenter effort that began in 1989 to identify risk factors for heart disease in people over 65.
“The subset of CHS participants answered questionnaires about their eating habits, such as how much fish did they eat and how was it prepared,” Dr. Raji said. “Baked or broiled fish contains higher levels of omega-3s than fried fish because the fatty acids are destroyed in the high heat of frying, so we took that into consideration when we examined their brain scans.”
People who ate baked or broiled fish at least once a week had greater grey matter brain volumes in areas of the brain responsible for memory (4.3 percent) and cognition (14 percent) and were more likely to have a college education than those who didn’t eat fish regularly, the researchers found. But no association was found between the brain differences and blood levels of omega-3s.
“This suggests that lifestyle factors, in this case eating fish, rather than biological factors contribute to structural changes in the brain,” Dr. Becker noted. “A confluence of lifestyle factors likely are responsible for better brain health, and this reserve might prevent or delay cognitive problems that can develop later in life.”
Phases of clinical depression could affect treatment
Research led by the University of Adelaide has resulted in new insights into clinical depression that demonstrate there cannot be a “one-size-fits-all” approach to treating the disease.
As part of their findings, the researchers have developed a new model for clinical depression that takes into account the dynamic role of the immune system. This neuroimmune interaction results in different phases of depression, and has implications for current treatment practices.
"Depression is much more complex than we have previously understood," says senior author Professor Bernhard Baune, Head of Psychiatry at the University of Adelaide.
"Past research has shown that there are inflammatory mechanisms at work in depression. But in the last 10 years there has been much research into the complexities of how the immune system interacts with brain function, both in healthy brains and in people experiencing depression.
"Unfortunately, much of the research is contradictory - and in asking ourselves why, we undertook a review of all the studies conducted to date on these issues.
"This has led us to the conclusion that there are different immune factors at work in depression depending on the clinical phase of depression, and that the genes for this immune response are switched on and off at different times according to phases.
"What we see in the clinical states of acute depression, relapse, remission, and recovery is a highly complex interaction between inflammatory and other immunological cells, brain cells and systems.
"This new model helps us to overcome the simplistic notion that depression is the same kind of disease for everyone, behaving in the same way regardless of the timing of the disease. We can now see that depression is a much more neurobiologically dynamic disease, and this has many implications for both research and treatment," Professor Baune says.
Professor Baune says clinicians and patients alike should be aware that common treatments for depression may, at times, not work based on this new understanding of neuroimmune phases in the disease.
"We are urging caution on the use of blanket anti-inflammatory medication for the treatment of depression. This treatment may need to be tailored according to the phase of illness a patient is undergoing, and this would require an immune profile of the patient prior to treatment," Professor Baune says.
The results of this study are published in the international journal Progress in Neuro-Psychopharmacology & Biological Psychiatry
(Source: adelaide.edu.au)
(Image caption: LB1 in three different views to illustrate facial asymmetry. A is the actual specimen, B is the Right side doubled at the midline and mirrored, and C is the left side doubled and mirrored. Differences in left and right side facial architectures are apparent, and illustrate growth abnormalities of LB1. Credit: A, E. Indriati, B and C, D.W. Frayer)
Flores bones show features of Down syndrome, not a new “hobbit” human
In October 2004, excavation of fragmentary skeletal remains from the island of Flores in Indonesia yielded what was called “the most important find in human evolution for 100 years.” Its discoverers dubbed the find Homo floresiensis, a name suggesting a previously unknown species of human.
Now detailed reanalysis by an international team of researchers including Robert B. Eckhardt, professor of developmental genetics and evolution at Penn State, Maciej Henneberg, professor of anatomy and pathology at the University of Adelaide, and Kenneth Hsü, a Chinese geologist and paleoclimatologist, suggests that the single specimen on which the new designation depends, known as LB1, does not represent a new species. Instead, it is the skeleton of a developmentally abnormal human and, according to the researchers, contains important features most consistent with a diagnosis of Down syndrome.
"The skeletal sample from Liang Bua cave contains fragmentary remains of several individuals," Eckhardt said. "LB1 has the only skull and thighbones in the entire sample."
No substantial new bone discoveries have been made in the cave since the finding of LB1.
Initial descriptions of Homo floresiensis focused on LB1’s unusual anatomical characteristics: a cranial volume reported as only 380 milliliters (23.2 cubic inches), suggesting a brain less than one third the size of an average modern human’s and short thighbones, which were used to reconstruct a creature standing 1.06 meters (about 3.5 feet tall). Although LB1 lived only 15,000 years ago, comparisons were made to earlier hominins, including Homo erectus and Australopithecus. Other traits were characterized as unique and therefore indicative of a new species.
A thorough reexamination of the available evidence in the context of clinical studies, the researchers said, suggests a different explanation.
The researchers report their findings in two papers published today (Aug. 4) in the Proceedings of the National Academy of Sciences (1, 2).
In the first place, they write, the original figures for cranial volume and stature are underestimates, “markedly lower than any later attempts to confirm them.” Eckhardt, Henneberg, and other researchers have consistently found a cranial volume of about 430 milliliters (26.2 cubic inches).
"The difference is significant, and the revised figure falls in the range predicted for a modern human with Down syndrome from the same geographic region," Eckhardt said.
The original estimate of 3.5 feet for the creature’s height was based on extrapolation combining the short thighbone with a formula derived from an African pygmy population. But humans with Down syndrome also have diagnostically short thighbones, Eckhardt said.
Though these and other features are unusual, he acknowledged, “unusual does not equal unique. The originally reported traits are not so rare as to have required the invention of a new hominin species.”
Instead, the researchers build the case for an alternative diagnosis: that of Down syndrome, one of the most commonly occurring developmental disorders in modern humans.
"When we first saw these bones, several of us immediately spotted a developmental disturbance," said Eckhardt, "but we did not assign a specific diagnosis because the bones were so fragmentary. Over the years, several lines of evidence have converged on Down syndrome."
The first indicator is craniofacial asymmetry, a left-right mismatch of the skull that is characteristic of this and other disorders. Eckhardt and colleagues noted this asymmetry in LB1 as early as 2006, but it had not been reported by the excavating team and was later dismissed as a result of the skull’s being long buried, he said.
A previously unpublished measurement of LB1’s occipital-frontal circumference — the circumference of the skull taken roughly above the tops of the ears — allowed the researchers to compare LB1 to clinical data routinely collected on patients with developmental disorders. Here too, the brain size they estimate is within the range expected for an Australomelanesian human with Down syndrome.
LB1’s short thighbones not only match the height reduction seen in Down syndrome, Eckhardt said, but when corrected statistically for normal growth, they would yield a stature of about 1.26 meters, or just over four feet, a figure matched by some humans now living on Flores and in surrounding regions.
These and other Down-like characteristics, the researchers state, are present only in LB1, and not in the other Liang Bua skeletal remains, further evidence of LB1’s abnormality.
"This work is not presented in the form of a fanciful story, but to test a hypothesis: Are the skeletons from Liang Bua cave sufficiently unusual to require invention of a new human species?" Eckhardt said.
"Our reanalysis shows that they are not. The less strained explanation is a developmental disorder. Here the signs point rather clearly to Down syndrome, which occurs in more than one per thousand human births around the world."
Declining intelligence in old age linked to visual processing
Researchers have uncovered one of the basic processes that may help to explain why some people’s thinking skills decline in old age. Age-related declines in intelligence are strongly related to declines on a very simple task of visual perception speed, the researchers report in the Cell Press journal Current Biology on August 4.
The evidence comes from experiments in which researchers showed 600 healthy older people very brief flashes of one of two shapes on a screen and measured the time it took each of them to reliably tell one from the other. Participants repeated the test at ages 70, 73, and 76. The longitudinal study is among the first to test the hypothesis that the changes they observed in the measure known as “inspection time” might be related to changes in intelligence in old age.
"The results suggest that the brain’s ability to make correct decisions based on brief visual impressions limits the efficiency of more complex mental functions," says Stuart Ritchie of the University of Edinburgh. "As this basic ability declines with age, so too does intelligence. The typical person who has better-preserved complex thinking skills in older age tends to be someone who can accumulate information quickly from a fleeting glance."
Previous studies had shown that smarter people, as measured by standard IQ tests, tend to be better at discerning the difference between two briefly presented shapes, the researchers explain. But before now no one had looked to see how those two measures might change over time as people grow older. The findings were rather unexpected.
"What surprised us was the strength of the relation between the declines," Ritchie says. "Because inspection time and the intelligence tests are so very different from one another, we wouldn’t have expected their declines to be so strongly connected."
The results provide evidence that the slowing of simple, visual decision-making processes might be part of what underlies declines in the complex decision making that we recognize as general intelligence. The results might also find practical use given the simplicity of the inspection time measure, Ritchie says, noting that the test can be taken very simply on a computer and has been used with children, adults, and even patients with dementia or other medical disorders.
"Since the declines are so strongly related, it might be easier under some circumstances to use inspection time to chart a participant’s cognitive decline than it would be to sit them down and give them a full, complicated battery of IQ tests," he says.
(Source: eurekalert.org)
Uncovering the 3D structure of a key neuroreceptor
Neurons are the cells of our brain, spinal cord, and overall nervous system. They form complex networks to communicate with each other through electrical signals that are generated by chemicals. These chemicals bind to structures on the surface of neurons that are called neuroreceptors, opening or closing electrical pathways that allow transmission of the signal from neuron to neuron. One neuroreceptor, called 5HT3-R, is involved in conditions like chemotherapy-induced nausea, anxiety, and various neurological disorders such as schizophrenia. Despite its clinical importance, the exact way that 5HT3-R works has been elusive because its complexity has prevented scientists from determining its three-dimensional structure. Publishing in Nature, EPFL researchers have now uncovered for the first time the 3D structure of 5HT3-R, opening the way to understanding other neuroreceptors as well.
Neuroreceptors: structure and function
Communication between the neurons of our body is mediated by neuroreceptors that are embedded across the cell membrane of each neuron. Neuronal communication begins when a neuron releases a small molecule, called a ‘neurotransmitter’, onto a neighboring neuron, where it is identified by its specific neuroreceptor and binds to it. The neurotransmitter causes the neuroreceptor to open an electrically conducting channel, which allows the passage of electrical charge across the neuron’s membrane. The membrane then becomes electrically conducting for a fraction of a millisecond, generating an electrical pulse that travels across the neuron. The family of neuroreceptors that work in this way is widespread across the nervous system, and is referred to as the “ligand-gated channel” family.
The mystery is how the binding of the neurotransmitter can induce the opening of an electrical channel to transport a signal into the neuron. The understanding of these molecular machines is of great medical importance, especially since neuroreceptors are involved in many neurological diseases. Currently, none of the mammalian ligand-gated channel neuroreceptors have been structurally described, which significantly limits our understanding of their function on a molecular level.
Uncovering the structure of 5HT3-R
The team of Horst Vogel at EPFL has used X-ray crystallography to determine the 3D structure of a representative ligand-gated channel neuroreceptor, the type-3 serotonin receptor (5HT3-R). This neuroreceptor recognizes the neurotransmitter serotonin and opens a transmembrane channel that allows electrical signals to enter certain neurons. The 5HT3 receptor was grown in and then isolated from human cell cultures, and finally crystallized.
But before obtaining the 5HT3-R crystals, the EPFL team had to overcome a number of challenges. First, the relatively large size of the membrane-embedded 5HT3-R, like that of other similar channel neuroreceptors, makes it notoriously difficult to purify in sufficient quality and quantity. After years of painstaking work, the EPFL scientists succeeded in obtaining a few milligrams of 5HT3-R, which was still not enough to grow crystals using conventional methods.
Still, the crystal quality was insufficient. To address this, Vogel’s team used small antibodies, so-called nanobodies, which were obtained from llamas after the animals were injected with purified 5HT3-R. From a large library of isolated nanobodies, a particular one was found to form a stable complex with the 5HT3-R, and this complex eventually yielded crystals of exceptional quality.
After this, the procedure was straightforward: The crystals for X-ray crystallography were investigated at the synchrotron facilities at the Paul Scherrer Institut in Villigen and the European facilities in Grenoble. In this well-established technique, the crystals diffract X-rays in a characteristic pattern from which the 3D structure can be reconstructed.
The X-ray diffraction experiments yielded the 3D structure of 5HT3-R at an unprecedented resolution of 3.5 Ångstroms (3.5 millionths of a millimeter). The resulting 3D image shows a bullet-shaped 5HT3 receptor with its five subunits symmetrically arranged around a central water-filled channel that traverses the neuron’s cell membrane. The channel can adopt two states: a closed, electrically non-conducting state or, after binding a neurotransmitter, an open, electrically conducting state that allows the flow of electrical charges in and out of the neuron to generate an electrical signal.
“We have now elucidated the molecular anatomy of a receptor that plays a central role in neuronal transmission,” says Horst Vogel. “It is the first 3D structure of its kind and may serve as a blueprint for the other receptors of this family. In the next step, we have to improve the resolution of the structure, which might give us information on how to design novel medicines that influence this neuroreceptor’s function.”
(Source: actu.epfl.ch)
Prenatal Alcohol Exposure Alters Development of Brain Function
In the first study of its kind, Prapti Gautam, PhD, and colleagues from The Saban Research Institute of Children’s Hospital Los Angeles found that children with fetal alcohol spectrum disorders (FASD) showed weaker brain activation during specific cognitive tasks than their unaffected counterparts. These novel findings suggest a possible neural mechanism for the persistent attention problems seen in individuals with FASD. The results of this study will be published in Cerebral Cortex on August 4.
“Functional magnetic resonance imaging (fMRI) has been used to observe brain activity during mental tasks in children with FASD, but we are the first to utilize these techniques to look at brain activation over time,” says Gautam. “We wanted to see if the differences in brain activation between children with FASD and their healthy peers were static, or if they changed as children got older.”
FASD encompasses the broad spectrum of symptoms that are linked to in utero alcohol exposure, including cognitive impairment, deficits in intelligence and attention and central nervous system abnormalities. These symptoms can lead to attention problems and higher societal and economic burdens common in individuals with FASD.
During the period of childhood and adolescence, brain function, working memory and attention performance all rapidly improve, suggesting that this is a crucial time for developing brain networks. To study how prenatal alcohol exposure may alter this development, researchers observed a group of unaffected children and a group of children with FASD over two years. They used fMRI to observe brain activation through mental tasks such as visuo-spatial attention—how we visually perceive the spatial relationships among objects in our environment —and working memory.
“We found that there were significant differences in development brain activation over time between the two groups, even though they did not differ in task performance,” notes Elizabeth Sowell, PhD, director of the Developmental Cognitive Neuroimaging Laboratory at The Saban Research Institute and senior author on the manuscript. “While the healthy control group showed an increase in signal intensity over time, the children with FASD showed a decrease in brain activation during visuo-spatial attention, especially in the frontal, temporal and parietal brain regions.”
These results demonstrate that prenatal alcohol exposure can change how brain signaling develops during childhood and adolescence, long after the damaging effects of alcohol exposure in utero. The atypical development of brain activation observed in children with FASD could explain the persistent problems in cognitive and behavioral function seen in this population as they mature.
(Image caption: Part of a brain slice in which a transplanted induced neural stem cell is fully integrated in the neuronal network of the brain (blue) to develop into a complex and functional neuron.)
Implanted Neurons become Part of the Brain
Scientists at the Luxembourg Centre for Systems Biomedicine (LCSB) of the University of Luxembourg have grafted neurons reprogrammed from skin cells into the brains of mice for the first time with long-term stability. Six months after implantation, the neurons had become fully functionally integrated into the brain. This successful, because lastingly stable, implantation of neurons raises hope for future therapies that will replace sick neurons with healthy ones in the brains of Parkinson’s disease patients, for example. The Luxembourg researchers published their results in the current issue of ‘Stem Cell Reports’.
The LCSB research group around Prof. Dr. Jens Schwamborn and Kathrin Hemmer is working continuously to bring cell replacement therapy to maturity as a treatment for neurodegenerative diseases. Sick and dead neurons in the brain can be replaced with new cells. This could one day cure disorders such as Parkinson’s disease. The path towards successful therapy in humans, however, is long. “Successes in human therapy are still a long way off, but I am sure successful cell replacement therapies will exist in future. Our research results have taken us a step further in this direction,” declares stem cell researcher Prof. Schwamborn, who heads a group of 15 scientists at LCSB.
In their latest tests, the research group and colleagues from the Max Planck Institute and the University Hospital Münster and the University of Bielefeld succeeded in creating stable nerve tissue in the brain from neurons that had been reprogrammed from skin cells. The stem cell researchers’ technique of producing neurons, or more specifically induced neuronal stem cells (iNSC), in a petri dish from the host’s own skin cells considerably improves the compatibility of the implanted cells. The treated mice showed no adverse side effects even six months after implantation into the hippocampus and cortex regions of the brain. In fact it was quite the opposite – the implanted neurons were fully integrated into the complex network of the brain. The neurons exhibited normal activity and were connected to the original brain cells via newly formed synapses, the contact points between nerve cells.
The tests demonstrate that the scientists are continually gaining a better understanding of how to treat such cells in order to successfully replace damaged or dead tissue. “Building upon the current insights, we will now be looking specifically at the type of neurons that die off in the brain of Parkinson’s patients – namely the dopamine-producing neurons,” Schwamborn reports. In future, implanted neurons could produce the lacking dopamine directly in the patient’s brain and transport it to the appropriate sites. This could result in an actual cure, as has so far been impossible. The first trials in mice are in progress at the LCSB laboratories on the university campus Belval.
(Image caption: This is the happiness equation, where t is the trial number, w0 is a constant term, other weights w capture the influence of different event types, 0 ≤ γ ≤ 1 is a forgetting factor that makes events in more recent trials more influential than those in earlier trials, CRj is the CR if chosen instead of a gamble on trial j, EVj is the EV of a gamble (average reward for the gamble) if chosen on trial j, and RPEj is the RPE on trial j contingent on choice of the gamble. The RPE is equal to the reward received minus the expectation in that trial EVj. If the CR was chosen, then EVj = 0 and RPEj = 0; if the gamble was chosen, then CRj = 0. The variables in the equation are quantities that the neuromodulator dopamine has been associated with in previous neuroscience studies. Credit: Robb Rutledge, UCL)
The happiness of over 18,000 people worldwide has been predicted by a mathematical equation developed by researchers at UCL, with results showing that moment-to-moment happiness reflects not just how well things are going, but whether things are going better than expected.
The new equation accurately predicts exactly how happy people will say they are from moment to moment based on recent events, such as the rewards they receive and the expectations they have during a decision-making task. Scientists found that overall wealth accumulated during the experiment was not a good predictor of happiness. Instead, moment-to-moment happiness depended on the recent history of rewards and expectations. These expectations depended, for example, on whether the available options could lead to good or bad outcomes.
The study, published in the Proceedings of the National Academy of Sciences, investigated the relationship between happiness and reward, and the neural processes that lead to feelings that are central to our conscious experience, such as happiness. Before now, it was known that life events affect an individual’s happiness but not exactly how happy people will be from moment to moment as they make decisions and receive outcomes resulting from those decisions, something the new equation can predict.
Scientists believe that quantifying subjective states mathematically could help doctors better understand mood disorders, by seeing how self-reported feelings fluctuate in response to events like small wins and losses in a smartphone game. A better understanding of how mood is determined by life events and circumstances, and how that differs in people suffering from mood disorders, will hopefully lead to more effective treatments.
Research examining how and why happiness changes from moment to moment in individuals could also assist governments who deploy population measures of wellbeing to inform policy, by providing quantitative insight into what the collected information means. This is especially relevant to the UK following the launch of the National Wellbeing Programme in 2010 and subsequent annual reports by the Office for National Statistics on ‘Measuring National Wellbeing’.
For the study, 26 subjects completed a decision-making task in which their choices led to monetary gains and losses, and they were repeatedly asked to answer the question ‘how happy are you right now?’. The participant’s neural activity was also measured during the task using functional MRI and from these data, scientists built a computational model in which self-reported happiness was related to recent rewards and expectations. The model was then tested on 18,420 participants in the game ‘What makes me happy?’ in a smartphone app developed at UCL called 'The Great Brain Experiment'. Scientists were surprised to find that the same equation could be used to predict how happy subjects would be while they played the smartphone game, even though subjects could win only points and not money.
Lead author of the study, Dr Robb Rutledge (UCL Wellcome Trust Centre for Neuroimaging and the new Max Planck UCL Centre for Computational Psychiatry and Ageing), said: “We expected to see that recent rewards would affect moment-to-moment happiness but were surprised to find just how important expectations are in determining happiness. In real-world situations, the rewards associated with life decisions such as starting a new job or getting married are often not realised for a long time, and our results suggest expectations related to these decisions, good and bad, have a big effect on happiness.
"Life is full of expectations - it would be difficult to make good decisions without knowing, for example, which restaurant you like better. It is often said that you will be happier if your expectations are lower. We find that there is some truth to this: lower expectations make it more likely that an outcome will exceed those expectations and have a positive impact on happiness. However, expectations also affect happiness even before we learn the outcome of a decision. If you have plans to meet a friend at your favourite restaurant, those positive expectations may increase your happiness as soon as you make the plan. The new equation captures these different effects of expectations and allows happiness to be predicted based on the combined effects of many past events.
"It’s great that the data from the large and varied population using The Great Brain Experiment smartphone app shows that the same happiness equation applies to thousands people worldwide playing our game, as with our much smaller laboratory-based experiments which demonstrate the tremendous value of this approach for studying human well-being on a large scale."
The team used functional MRI to demonstrate that neural signals during decisions and outcomes in the task in an area of the brain called the striatum can be used to predict changes in moment-to-moment happiness. The striatum has a lot of connections with dopamine neurons, and signals in this brain area are thought to depend at least partially on dopamine. These results raise the possibility that dopamine may play a role in determining happiness.
(Image caption: A schematic of the interactions that occur between the saccade and reach brain systems when deciding where to look and reach. Credit: Bijan Pesaran, New York University)
Complexity of eye-hand coordination
People not only use their eyes to see, but also to move. It takes less than a fraction of a second to execute the loop that travels from the brain to the eyes, and then to the hands and/or arms. Bijan Pesaran is trying to figure out what occurs in the brain during this process.
"Eye-hand coordination is the result of a complex interplay between two systems of the brain, but there are many regions where this interaction takes place," says Pesaran, an associate professor of neural science at New York University. "One of the things about the current state of knowledge is that it is focused on the different pieces of the brain and how each works individually. Relatively little work has been done to link how they work together at the cellular level."
The thrust of his research involves studying how neurons in these parts of the brain communicate with one another.
"The cerebral cortex contains a mosaic of brain areas that are connected to form distributed networks," says the National Science Foundation (NSF)-funded scientist. "In the frontal and parietal cortex, these networks are specialized for movements such as saccadic (voluntary) eye movements and reaches, that is, hand and arm movements. Before each movement we decide to make, these areas contain specific patterns of neural activity which can be used to predict what we will do."
A more sophisticated understanding of the brain’s role in eye-hand coordination can be an important model for discovering how brain systems interact to carry out cognitive processes in general, he says. Such insights could lead to new neural technologies that translate thoughts into actions, for example, to control a robotic arm or prompt speech.
"There is a whole new set of technologies called neural prostheses," Pesaran says. "In the future, there could be devices in the brain that will help people remember, to think more clearly, and to help them move."
Using eye movements to prompt hand and arm movements involves building a spatial representation, “which is improved by moving our eyes,” he says. “The command that is sent to the eyes moves the eyes, which effectively measure space when they move, and that is used to improve the accuracy of the reach. We move our eyes to improve our movement, not just to see better.”
He often describes the behavior of high level ping pong players to explain how it works.
"You keep your eye on the ball so you know where it is, so you can hit it," he says. "But right up until the minute you hit the ball, something important is happening, which is that your brain is sending a command to your arm to hit the ball. But the visual signals are delayed. At the time you hit the ball, the vision of the ball won’t enter your brain for another fraction of a second, so there is no point in looking at the ball. You can look all you want, but your arm already has moved.
"When ping pong players are playing at a high level, they look at the ball up to the point where they hit it. As soon as the paddle makes contact with the ball, you can see their eyes and head turn to now look at their opponent. They think they are looking at their opponent when they are hitting the ball, but they are looking at ball. Their eyes are tracking the ball, even though they are aware of their opponent.
"This helps the brain keep a very high resolution of space to make the stroke more accurate," he continues. "It’s not about seeing the ball, because by then it’s too late. It’s about moving the eyes with the ball so that the stroke is more accurate. And the brain orchestrates this complicated pattern of behavior."
Visual signals always are delayed. They enter the brain, converted into a movement, and then leave the brain for the arm muscles. “It’s a loop that takes about 200 millisecond—about one-fifth of second—and in that time the ball is moved,” he says.
Pesaran is conducting his research under an NSF Faculty Early Career Development (CAREER) award, which he received in 2010. The award supports junior faculty who exemplify the role of teacher-scholars through outstanding research, excellent education and the integration of education and research within the context of the mission of their organization.
To prove his hypothesis that two regions in the brain (the parietal reach region and the parietal eye field, both in the parietal cortex) must talk to each other to prompt movement, Pesaran and his team are recording the activity of neurons, brain cells that send electrical signals to each other called “spikes.” They do so by placing micro-electrodes into the brains of animals that look and reach, much like humans, and study the correlation and patterns in those signals.
"We think we can measure these signals when they are leaving one area, and coming into another," he says. "How does this show that this reflects communication between those two areas? Because something happens, something changes. We set up these movements in a particular way that requires communication between the eye and the arm centers, and we then made measurements in the brain from those centers. Then we linked the changes in the activity between the two areas to the changes in how the eyes and arm move."
As part of the grant’s educational component, Pesaran is trying to show youngsters how far neuroscience has come, and encourage them to learn about it. He and his colleagues are working with middle school children in Brooklyn, and have presented demonstrations at the American Museum of Natural History about the field of brain science.
"We go into schools and teach children about what we know about the brain," he says. "We had a brain computer interface, where they had the chance to control the cursor on the screen with their minds. We placed an EEG sensor on their heads, which measures brain activity. When they concentrate, it changes the position of the ball, and moves it up or down."
School children typically are unaware of neuroscience as an emerging field “that involves medicine, biology, engineering, a whole range of disciplines that come together,” he says. “Increasing their sophistication and tools in this discipline early will be a hallmark of the next generation of brain scientists.”
Brain tumour cells found circulating in blood
German scientists have discovered rogue brain tumour cells in patient blood samples, challenging the idea that this type of cancer doesn’t generally spread beyond the brain.
Researchers from the University Medical Center Hamburg-Eppendorf, in Hamburg, found that patients with an aggressive form of brain tumour known as glioblastoma multiforme sometimes have tumour cells circulating in their blood.
The discovery could help doctors improve the way they monitor how the disease progresses, and could have implications for treatment.