Posts tagged brain
Articles and news from the latest research reports.
Ultrasound reveals autism risk at birth
Low-birth-weight babies with a particular brain abnormality are at greater risk for autism, according to a new study that could provide doctors a signpost for early detection of the still poorly understood disorder.
Led by Michigan State University, the study found that low-birth-weight newborns were seven times more likely to be diagnosed with autism later in life if an ultrasound taken just after birth showed they had enlarged ventricles, cavities in the brain that store spinal fluid. The results appear in the Journal of Pediatrics.
“For many years there’s been a lot of controversy about whether vaccinations or environmental factors influence the development of autism, and there’s always the question of at what age a child begins to develop the disorder,” said lead author Tammy Movsas, clinical assistant professor of pediatrics at MSU and medical director of the Midland County Department of Public Health.
“What this study shows us is that an ultrasound scan within the first few days of life may already be able to detect brain abnormalities that indicate a higher risk of developing autism.”
Movsas and colleagues reached that conclusion by analyzing data from a cohort of 1,105 low-birth-weight infants born in the mid-1980s. The babies had cranial ultrasounds just after birth so the researchers could look for relationships between brain abnormalities in infancy and health disorders that showed up later. Participants also were screened for autism when they were 16 years old, and a subset of them had a more rigorous test at 21, which turned up 14 positive diagnoses.
Ventricular enlargement is found more often in premature babies and may indicate loss of a type of brain tissue called white matter.
“This study suggests further research is needed to better understand what it is about loss of white matter that interferes with the neurological processes that determine autism,” said co-author Nigel Paneth, an MSU epidemiologist who helped organize the cohort. “This is an important clue to the underlying brain issues in autism.”
Prior studies have shown an increased rate of autism in low-birth-weight and premature babies, and earlier research by Movsas and Paneth found a modest increase in symptoms among autistic children born early or late.
Scientists Find Way to Image Brain Waste Removal Process Which May Lead to Alzheimer’s Diagnostic
A novel way to image the entire brain’s glymphatic pathway, a dynamic process that clears waste and solutes from the brain that otherwise might build-up and contribute to the development of Alzheimer’s disease, may provide the basis for a new strategy to evaluate disease susceptibility, according to a research paper published online in The Journal of Clinical Investigation. Through contrast enhanced magnetic resonance imaging (MRI) and other tools, a Stony Brook University-led research team successfully mapped this brain-wide pathway and identified key anatomical clearance routes of brain waste.
In their article titled “Brain-wide pathway for waste clearance captured by contrast enhanced MRI,” Principal Investigator Helene Benveniste, MD, PhD, a Professor in the Departments of Anesthesiology and Radiology at Stony Brook University School of Medicine, and colleagues built upon a previous finding by Jeffrey Iliff, PhD, and Maiken Nedergaard, MD, PhD, from University of Rochester that initially discovered and defined the glymphatic pathway, where cerebral spinal fluid (CSF) filters through the brain and exchanges with interstitial fluid (ISF) to clear waste, similar to the way lymphatic vessels clear waste from other organs of the body. Despite the discovery of the glymphatic pathway, researchers could not visualize the brain wide flow of this pathway with previous imaging techniques.
“Our experiments showed proof of concept that the glymphatic pathway function can be measured using a simple and clinically relevant imaging technique,” said Dr. Benveniste. “This technique provides a three-dimensional view of the glymphatic pathway that captures movement of waste and solutes in real time. This will help us to define the role of the pathway in clearing matter such as amyloid beta and tau proteins, which affect brain processes if they build up.”
Dr. Benveniste said that the pathology of certain neurological conditions is associated with the accumulation of these proteins and other large extracellular aggregates. In particular, she explained that plaque deposits of these proteins are implicated in the development of Alzheimer’s disease, as well as chronic traumatic encephalopathy that occurs after repetitive mild traumatic brain injuries.
Ability of brain to protect itself from damage revealed
(Image: Matthias Kulka / Corbis)
The origin of an innate ability the brain has to protect itself from damage that occurs in stroke has been explained for the first time.
The Oxford University researchers hope that harnessing this inbuilt biological mechanism, identified in rats, could help in treating stroke and preventing other neurodegenerative diseases in the future.
'We have shown for the first time that the brain has mechanisms that it can use to protect itself and keep brain cells alive,' says Professor Alastair Buchan, Head of the Medical Sciences Division and Dean of the Medical School at Oxford University, who led the work.
The researchers report their findings in the journal Nature Medicine and were funded by the UK Medical Research Council and National Institute for Health Research.
Stroke is the third most common cause of death in the UK. Every year around 150,000 people in the UK have a stroke.
It occurs when the blood supply to part of the brain is cut off. When this happens, brain cells are deprived of the oxygen and nutrients they need to function properly, and they begin to die.
'Time is brain, and the clock has started immediately after the onset of a stroke. Cells will start to die somewhere from minutes to at most 1 or 2 hours after the stroke,' says Professor Buchan.
This explains why treatment for stroke is so dependent on speed. The faster someone can reach hospital, be scanned and have drugs administered to dissolve any blood clot and get the blood flow re-started, the less damage to brain cells there will be.
It has also motivated a so-far unsuccessful search for ‘neuroprotectants’: drugs that can buy time and help the brain cells, or neurons, cope with damage and recover afterwards.
The Oxford University research group have now identified the first example of the brain having its own built-in form of neuroprotection, so-called ‘endogenous neuroprotection’.
They did this by going back to an observation first made over 85 years ago. It has been known since 1926 that neurons in one area of the hippocampus, the part of the brain that controls memory, are able to survive being starved of oxygen, while others in a different area of the hippocampus die. But what protected that one set of cells from damage had remained a puzzle until now.
'Previous studies have focused on understanding how cells die after being depleted of oxygen and glucose. We considered a more direct approach by investigating the endogenous mechanisms that have evolved to make these cells in the hippocampus resistant,' explains first author Dr Michalis Papadakis, Scientific Director of the Laboratory of Cerebral Ischaemia at Oxford University.
Working in rats, the researchers found that production of a specific protein called hamartin allowed the cells to survive being starved of oxygen and glucose, as would happen after a stroke.
They showed that the neurons die in the other part of the hippocampus because of a lack of the hamartin response.
The team was then able to show that stimulating production of hamartin offered greater protection for the neurons.
Professor Buchan says: ‘This is causally related to cell survival. If we block hamartin, the neurons die when blood flow is stopped. If we put hamartin back, the cells survive once more.’
Finally, the researchers were able to identify the biological pathway through which hamartin acts to enable the nerve cells to cope with damage when starved of energy and oxygen.
The group points out that knowing the natural biological mechanism that leads to neuroprotection opens up the possibility of developing drugs that mimic hamartin’s effect.
Professor Buchan says: ‘There is a great deal of work ahead if this is to be translated into the clinic, but we now have a neuroprotective strategy for the first time. Our next steps will be to see if we can find small molecule drug candidates that mimic what hamartin does and keep brain cells alive.
'While we are focussing on stroke, neuroprotective drugs may also be of interest in other conditions that see early death of brain cells including Alzheimer's and motor neurone disease,' he suggests.
(Source: eurekalert.org)
London neuroscience centre to map ‘connectome’ of foetal brain
A state-of-the-art imaging facility at St Thomas’ Hospital in London has been awarded a 15m euro grant to map the development of nerve connections in the brain before and just after birth.
The Centre for the Developing Brain — which is partly funded by King’s College London (KCL) — has built a unique neonatal Magnetic Resonance Imaging Clinical Research Facility based in the intensive care unit of the Evelina Children’s Hospital at St Thomas’. It is one of two centres in the world — the other being at Imperial College — to have such a clinical research facility and associated scanner within a neonatal intensive care unit.
Over the next few years a team headed up by David Edwards, a consultant neonatologist and KCL Professor of Paediatrics and Neonatal Medicine, will build up a diagram of connections in the brain of babies as they develop in the womb and then after they are born. The aim is to understand how the human brain assembles itself from a functional and structural perspective. The resulting map is called a connectome and is the brain equivalent of the human genome. It will be made available to the research community to help improve understanding of neurological disorders.
Concepts in our minds – from Luke Skywalker to our grandmother - are represented by their own distinct group of neurons, according to new research involving a University of Leicester neuroscientist.
The research, by neuroscientist Professor Rodrigo Quian Quiroga from the University of Leicester Centre for Systems Neuroscience together with Professor Itzhak Fried, of the UCLA David Geffen School of Medicine, Tel Aviv Sourasky Medical Center and Tel Aviv University, and Professor Christof Koch, of the California Institute of Technology and Allen Institute for Brain Science, Seattle, is featured in a recent article of the prestigious Scientific American magazine.
Recent experiments during brain surgeries have shown that small groups of brain cells are responsible for encoding memories of specific people or objects.
These neurons may also represent different variations of one thing – from the name of a person to their appearance from many different viewpoints.
The researchers believe that single concepts may be held in as little as thousands of neurons or less – a tiny fraction of the billion or so neurons contained in the medial temporal lobe, which is a memory related structure within the brain.
The group were able to monitor the brain activity of consenting patients undergoing surgery to treat epilepsy. This allowed the team to monitor the activity of single neurons in conscious patients while they looked at images on laptop screens, creating and recalling memories.
In previous experiments, they had found that single neurons would ‘fire’ for specific concepts – such as Luke Skywalker – even when they were viewing images of him from different angles or simply hearing or reading his name.
They have also found that single neurons can also fire to related people and objects – for instance, the neuron that responded to Luke Skywalker also fired to Yoda, another Jedi from Star Wars.
They argue that relatively small groups of neurons hold concepts like Luke Skywalker and that related concepts such as Yoda are held by some but not all of the same neurons. At the same time, a completely separate set of neurons would hold an unrelated concept like Jennifer Aniston.
The group believes this partially overlapping representation of related concepts are the neural underpinnings of encoding associations, a key memory function.
Professor Quian Quiroga said: “After the first thrill when finding neurons in the human hippocampus with such remarkable firing characteristics, converging evidence from experiments we have been carrying out in the last years suggests that we may be hitting one of the key mechanisms of memory formation and recall.
“The abstract representation of concepts provided by these neurons is indeed ideal for representing the meaning of the sensory stimuli around us, the internal representation we use to form and retrieve memories. These concepts cells, we believe, are the building blocks of memory functions.”
Has evolution given humans unique brain structures?
Humans have at least two functional networks in their cerebral cortex not found in rhesus monkeys. This means that new brain networks were likely added in the course of evolution from primate ancestor to human. These findings, based on an analysis of functional brain scans, were published in a study by neurophysiologist Wim Vanduffel (KU Leuven and Harvard Medical School) in collaboration with a team of Italian and American researchers.
Our ancestors evolutionarily split from those of rhesus monkeys about 25 million years ago. Since then, brain areas have been added, have disappeared or have changed in function. This raises the question, ‘Has evolution given humans unique brain structures?’. Scientists have entertained the idea before but conclusive evidence was lacking. By combining different research methods, we now have a first piece of evidence that could prove that humans have unique cortical brain networks.
Professor Vanduffel explains: “We did functional brain scans in humans and rhesus monkeys at rest and while watching a movie to compare both the place and the function of cortical brain networks. Even at rest, the brain is very active. Different brain areas that are active simultaneously during rest form so-called ‘resting state’ networks. For the most part, these resting state networks in humans and monkeys are surprisingly similar, but we found two networks unique to humans and one unique network in the monkey.”
“When watching a movie, the cortex processes an enormous amount of visual and auditory information. The human-specific resting state networks react to this stimulation in a totally different way than any part of the monkey brain. This means that they also have a different function than any of the resting state networks found in the monkey. In other words, brain structures that are unique in humans are anatomically absent in the monkey and there no other brain structures in the monkey that have an analogous function. Our unique brain areas are primarily located high at the back and at the front of the cortex and are probably related to specific human cognitive abilities, such as human-specific intelligence.”
The study used fMRI (functional Magnetic Resonance Imaging) scans to visualise brain activity. fMRI scans map functional activity in the brain by detecting changes in blood flow. The oxygen content and the amount of blood in a given brain area vary according to a particular task, thus allowing activity to be tracked.
How human language could have evolved from birdsong
Linguistics and biology researchers propose a new theory on the deep roots of human speech.
“The sounds uttered by birds offer in several respects the nearest analogy to language,” Charles Darwin wrote in “The Descent of Man” (1871), while contemplating how humans learned to speak. Language, he speculated, might have had its origins in singing, which “might have given rise to words expressive of various complex emotions.”
Now researchers from MIT, along with a scholar from the University of Tokyo, say that Darwin was on the right path. The balance of evidence, they believe, suggests that human language is a grafting of two communication forms found elsewhere in the animal kingdom: first, the elaborate songs of birds, and second, the more utilitarian, information-bearing types of expression seen in a diversity of other animals.
“It’s this adventitious combination that triggered human language,” says Shigeru Miyagawa, a professor of linguistics in MIT’s Department of Linguistics and Philosophy, and co-author of a new paper published in the journal Frontiers in Psychology.
The idea builds upon Miyagawa’s conclusion, detailed in his previous work, that there are two “layers” in all human languages: an “expression” layer, which involves the changeable organization of sentences, and a “lexical” layer, which relates to the core content of a sentence. His conclusion is based on earlier work by linguists including Noam Chomsky, Kenneth Hale and Samuel Jay Keyser.
Based on an analysis of animal communication, and using Miyagawa’s framework, the authors say that birdsong closely resembles the expression layer of human sentences — whereas the communicative waggles of bees, or the short, audible messages of primates, are more like the lexical layer. At some point, between 50,000 and 80,000 years ago, humans may have merged these two types of expression into a uniquely sophisticated form of language.
“There were these two pre-existing systems,” Miyagawa says, “like apples and oranges that just happened to be put together.”
These kinds of adaptations of existing structures are common in natural history, notes Robert Berwick, a co-author of the paper, who is a professor of computational linguistics in MIT’s Laboratory for Information and Decision Systems, in the Department of Electrical Engineering and Computer Science.
“When something new evolves, it is often built out of old parts,” Berwick says. “We see this over and over again in evolution. Old structures can change just a little bit, and acquire radically new functions.”
A new chapter in the songbook
The new paper, “The Emergence of Hierarchical Structure in Human Language,” was co-written by Miyagawa, Berwick and Kazuo Okanoya, a biopsychologist at the University of Tokyo who is an expert on animal communication.
To consider the difference between the expression layer and the lexical layer, take a simple sentence: “Todd saw a condor.” We can easily create variations of this, such as, “When did Todd see a condor?” This rearranging of elements takes place in the expression layer and allows us to add complexity and ask questions. But the lexical layer remains the same, since it involves the same core elements: the subject, “Todd,” the verb, “to see,” and the object, “condor.”
Birdsong lacks a lexical structure. Instead, birds sing learned melodies with what Berwick calls a “holistic” structure; the entire song has one meaning, whether about mating, territory or other things. The Bengalese finch, as the authors note, can loop back to parts of previous melodies, allowing for greater variation and communication of more things; a nightingale may be able to recite from 100 to 200 different melodies.
By contrast, other types of animals have bare-bones modes of expression without the same melodic capacity. Bees communicate visually, using precise waggles to indicate sources of foods to their peers; other primates can make a range of sounds, comprising warnings about predators and other messages.
Humans, according to Miyagawa, Berwick and Okanoya, fruitfully combined these systems. We can communicate essential information, like bees or primates — but like birds, we also have a melodic capacity and an ability to recombine parts of our uttered language. For this reason, our finite vocabularies can generate a seemingly infinite string of words. Indeed, the researchers suggest that humans first had the ability to sing, as Darwin conjectured, and then managed to integrate specific lexical elements into those songs.
“It’s not a very long step to say that what got joined together was the ability to construct these complex patterns, like a song, but with words,” Berwick says.
As they note in the paper, some of the “striking parallels” between language acquisition in birds and humans include the phase of life when each is best at picking up languages, and the part of the brain used for language. Another similarity, Berwick notes, relates to an insight of celebrated MIT professor emeritus of linguistics Morris Halle, who, as Berwick puts it, observed that “all human languages have a finite number of stress patterns, a certain number of beat patterns. Well, in birdsong, there is also this limited number of beat patterns.”
Birds and bees
Norbert Hornstein, a professor of linguistics at the University of Maryland, says the paper has been “very well received” among linguists, and “perhaps will be the standard go-to paper for language-birdsong comparison for the next five years.”
Hornstein adds that he would like to see further comparison of birdsong and sound production in human language, as well as more neuroscientific research, pertaining to both birds and humans, to see how brains are structured for making sounds.
The researchers acknowledge that further empirical studies on the subject would be desirable.
“It’s just a hypothesis,” Berwick says. “But it’s a way to make explicit what Darwin was talking about very vaguely, because we know more about language now.”
Miyagawa, for his part, asserts it is a viable idea in part because it could be subject to more scrutiny, as the communication patterns of other species are examined in further detail. “If this is right, then human language has a precursor in nature, in evolution, that we can actually test today,” he says, adding that bees, birds and other primates could all be sources of further research insight.
MIT-based research in linguistics has largely been characterized by the search for universal aspects of all human languages. With this paper, Miyagawa, Berwick and Okanoya hope to spur others to think of the universality of language in evolutionary terms. It is not just a random cultural construct, they say, but based in part on capacities humans share with other species. At the same time, Miyagawa notes, human language is unique, in that two independent systems in nature merged, in our species, to allow us to generate unbounded linguistic possibilities, albeit within a constrained system.
“Human language is not just freeform, but it is rule-based,” Miyagawa says. “If we are right, human language has a very heavy constraint on what it can and cannot do, based on its antecedents in nature.”
(Source: web.mit.edu)
Cigarette smoke damages the lungs, but it also wreaks havoc in the brain, a study in mice suggests. Signs of Alzheimer’s disease increased in the brains of animals that breathed cigarette smoke for four months, scientists report February 19 in Nature Communications.
The relationship between smoking and Alzheimer’s in people is murky. Some evidence from the 1990s suggested that smoking actually protected people against Alzheimer’s, presumably by stimulating nicotine-detecting brain cells. More recent studies have found that smoking ups the odds of the disease.
To see what cigarettes do to the brain, scientists led by Claudio Soto of the University of Texas Medical School at Houston turned to mice. In animals bred to show signs of Alzheimer’s, cigarette smoke (one cigarette’s worth in air the mouse breathed for an hour, five days a week) worsened aspects of the disease. Compared with mice that weren’t exposed, mice exposed to smoke had several signs of Alzheimer’s: they had more amyloid beta plaques, a higher load of abnormal tau protein and more severe inflammation in their brains.
The scientists don’t know yet how cigarette smoke causes these changes, or whether a similar process happens in people.
Hypnosis study unlocks secrets of unexplained paralysis
Hypnosis has begun to attract renewed interest from neuroscientists interested in using hypnotic suggestion to test predictions about normal cognitive functioning.
To demonstrate the future potential of this growing field, guest editors Professor Peter Halligan from the School of Psychology at Cardiff University and David A. Oakley of University College London, brought together leading researchers from cognitive neuroscience and hypnosis to contribute to this month’s special issue of the international journal, Cortex.
The issue illustrates how methodological and theoretical advances, using hypnotic suggestion, can return novel and experimentally verifiable insights for the neuroscience of consciousness and motor control. The research also includes novel brain imaging studies, which address sceptics’ concerns regarding the subjective reality and comparability of hypnotically suggested phenomena that previously depended on subjects’ largely unverifiable report and behaviour.
Halligan and Oakley also contribute to a new and revealing brain imaging study in the special issue that explores the brain systems involved in hypnotic paralysis. This research follows their earlier pioneering work on hypnotic leg paralysis reported in the Lancet in 2000.
Patients with “functional” or “psychogenic” conversion disorders present symptoms, such as paralyses, are clinically challenging. They comprise between 30 and 40% of patients attending neurology outpatient clinics and place a huge strain on public health services.
Professor Halligan of Cardiff University’s School of Psychology said: “This new study, working with colleagues at the Institute of Psychiatry in London, suggests that hypnosis can provide insights into of the brain systems involved in patients who display symptoms of neurological illness, but without evidence of brain damage. New insights show that symptoms experienced by patients with functional or dissociative conversion disorders (e.g. medically unexplained paralysis) can be simulated using targeted hypnotic suggestion.
"In this study we monitored brain activations of healthy volunteers with hypnosis induction who experienced paralysis-like experiences which could be turned ‘on’ and ‘off’. The suggestion resulted in subjects being unable to move a joystick together with a realistic and compelling experience of being unable to move and control their left hand despite trying.
"When compared to the completed movements, the suggested paralysis condition revealed increased activity in brain regions know to be active during motor planning and intention to move – and also brain areas involved in response selection and inhibition."
Comparing symptoms conveyed by conversion disorder patients and those produced by ‘paralysis’ suggestions in hypnosis, has revealed similar patterns of brain activation associated with attempted movement of the affected limb.
These findings could inform future studies of the brain mechanisms underpinning limb paralysis in patients with conversion disorders. More importantly they could lead to effective treatments.
(Source: cardiff.ac.uk)
First snaps made of fetal brains wiring themselves up
The first images have been captured of the fetal brain at different stages of its development. The work gives a glimpse of how the brain’s neural connections form in the womb, and could one day lead to prenatal diagnosis and treatment of conditions such as autism and schizophrenia.
We know little about how the fetal brain grows and functions – not only because it is so small, says Moriah Thomason of Wayne State University in Detroit, but also because “a fetus is doing backflips as we scan it”, making it tricky to get a usable result.
Undeterred, Thomason’s team made a series of functional magnetic resonance imaging (fMRI) scans of the brains of 25 fetuses between 24 and 38 weeks old. Each scan lasted just over 10 minutes, and the team kept only the images taken when the fetus was relatively still.
The researchers used the scans to look at two well-understood features of the developing brain: the spacing of neural connections and the time at which they developed. As expected, the two halves of the fetal brain formed denser and more numerous connections between themselves from one week to the next. The earliest connections tended appear in the middle of the brain and spread outward as the brain continued to develop.
Thomason says that the team is now scanning up to 100 fetuses at different stages of development. These scans might allow them to start to see variation between individuals. They are also applying algorithms to the scanning program that will help correct for the fetus’s movements, so fewer scans will be needed in future.
Once they understand what a normal fetal brain looks like, the researchers hope to study brains that are forming abnormal connections. Disorders such as schizophrenia or autism, for instance, are believed to start during development and might be due to faulty brain connections. Understanding the patterns that characterise these diseases might one day allow physicians to spot early warning signs and intervene sooner. Just as importantly, such images might improve our understanding of how these conditions develop in the first place, Thomason says.
Emi Takahashi of Boston Children’s Hospital says that one way to do this would be to follow a large group of children after they are born, and look back at the prenatal scans of those who later develop a brain disorder. Although she says the study is a very good first step, understanding the miswiring of the brain is so difficult that it may be some time before the results of such work become useful in clinical settings.
(Source: newscientist.com)