Posts tagged neuroscience
Articles and news from the latest research reports.
Baby brains are tuned to the specific actions of others
Imitation may be the sincerest form of flattery for adults, but for babies it’s their foremost tool for learning. As renowned people-watchers, babies often observe others demonstrate how to do things and then copy those body movements. It’s how little ones know, usually without explicit instructions, to hold a toy phone to the ear or guide a spoon to the mouth.
Now researchers from the University of Washington and Temple University have found the first evidence revealing a key aspect of the brain processing that occurs in babies to allow this learning by observation.
The findings, published online Oct. 30 by PLOS ONE, are the first to show that babies’ brains showed specific activation patterns when an adult performed a task with different parts of her body. When 14-month-old babies simply watched an adult use her hand to touch a toy, the hand area of the baby’s brain lit up. When another group of infants watched an adult touch the toy using only her foot, the foot area of the baby’s brain showed more activity.
"Babies are exquisitely careful people-watchers, and they’re primed to learn from others," said Andrew Meltzoff, co-author and co-director of the UW Institute for Learning & Brain Sciences. "And now we see that when babies watch someone else, it activates their own brains. This study is a first step in understanding the neuroscience of how babies learn through imitation."
The study took advantage of how the brain is organized. The sensory and motor area of the cortex, the outer portion of the brain known for its creased appearance, is arranged by body part with each area of the body represented in identifiable neural real estate. Prick your finger, stick out your tongue, or kick a ball and distinct areas of the brain light up according to a somatotopic map.
Other studies show that adults show this somatotopic brain activation while watching someone else use different body parts, suggesting that adults understand the actions of others in relation to their own bodies. The researchers wondered whether the same would be true in babies.
The 70 infants in the study wore electroencephalogram, or EEG, caps with embedded sensors that detected brain activity in the regions of the cortex that respond to movement or touch of the feet and hands. Sitting on a parent’s lap, each baby watched as an experimenter touched a toy placed on a low table between the baby and the experimenter.
The toy had a clear plastic dome and was mounted on a sturdy base. When the experimenter pressed the dome with her hand or foot, music played and confetti in the dome spun. The experimenter repeated the action – taking breaks after every four presses – until the baby lost interest.
"Our findings show that when babies see others produce actions with a particular body part, their brains are activated in a corresponding way," said Joni Saby, lead author and a psychology graduate student at Temple University in Philadelphia. "This mapping may facilitate imitation and could play a role in the baby’s ability to then produce the same actions themselves."
One of the basics for babies to learn is how to copy what they see adults do. In other words, they must first know that it is indeed their hand and not their foot, mouth or other body part that is needed.
The new study shows that babies’ brains are organized in a somatotopic way that helps crack the interpersonal code. The connection between doing and seeing actions maps hand to hand, foot to foot, all before they can name those body parts through language.
"The reason this is exciting is that it gives insight into a crucial aspect of imitation," said co-author Peter Marshall, an associate psychology professor at Temple University. "To imitate the action of another person, babies first need to register what body part the other person used. Our findings suggest that babies do this in a particular way by mapping the actions of the other person onto their own body."
Meltzoff added, “The neural system of babies directly connects them to other people, which jump-starts imitation and social-emotional connectedness and bonding. Babies look at you and see themselves.”
Research Finds Pain In Infancy Alters Response To Stress, Anxiety Later In Life
Early life pain alters neural circuits in the brain that regulate stress, suggesting pain experienced by infants who often do not receive analgesics while undergoing tests and treatment in neonatal intensive care may permanently alter future responses to anxiety, stress and pain in adulthood, a research team led by Dr. Anne Murphy, associate director of the Neuroscience Institute at Georgia State University, has discovered.
An estimated 12 percent of live births in the U.S. are considered premature, researchers said. These infants often spend an average of 25 days in neonatal intensive care, where they endure 10-to-18 painful and inflammatory procedures each day, including insertion of feeding tubes and intravenous lines, intubation and repeated heel lance. Despite evidence that pain and stress circuitry in the brain are established and functional in preterm infants, about 65 percent of these procedures are performed without benefit of analgesia. Some clinical studies suggest early life pain has an immediate and long-term impact on responses to stress- and anxiety-provoking events.
The Georgia State study examined whether a single painful inflammatory procedure performed on male and female rat pups on the day of birth alters specific brain receptors that affect behavioral sensitivity to stress, anxiety and pain in adulthood. The findings demonstrated that such an experience is associated with site-specific changes in the brain that regulate how the pups responded to stressful situations. Alterations in how these receptors function have also been associated with mood disorders.
The study findings mirror what is now being reported clinically. Children who experienced unresolved pain following birth show reduced responsiveness to pain and stress.
“While a dampened response to painful and stressful situations may seem advantageous at first, the ability to respond appropriately to a potentially harmful stimulus is necessary in the long term,” Dr. Murphy said.
“The fact that less than 35 percent of infants undergoing painful and invasive procedures receive any sort of pre- or post-operative pain relief needs to be re-evaluated in order to reduce physical and mental health complications associated with preterm birth.”
Scientists shed light on brain computations
University of Queensland (UQ) scientists have made a fundamental breakthrough into how the brain decodes the visual world.
Using advanced electrical recording techniques, researchers at UQ’s Queensland Brain Institute (QBI) have discovered how output cells of the eye’ balls retina compute the direction of a moving object.
QBI’s Dr Ben Sivyer and Associate Professor Stephen Williams have found that dendrites – the branching process of a neuron that conducts impulses toward the cell – play a critical role in decoding images.
“In the past decade our research shows that dendrites provide neurons with powerful processing capabilities,” Associate Professor Williams said.
“However the function of dendritic processing in the real-time operation of neuronal networks has remained elusive.”
To gain further insight, the group measured electrical activity from multiple sites in retinal ganglion cells when visual stimuli moved through space.
“The retina, a thin neuronal network at the posterior part of the eyeball, is ideal for investigating the role of active dendritic integration in neuronal circuit function,” he said.
“This is because this network can be maintained intact in a dish and retains its responsiveness to natural stimuli.”
He said while it had long been known that the retinal network extracted and signalled specific aspects of visual stimuli, the new work has discovered how such responses are computed.
“We found that retinal ganglion cells compute the direction of light stimuli through exquisitely controlled local integration compartments in the dendritic tree, a finding which highlights the key function that dendrites play in brain computations,” said Associate Professor Williams.
QBI Director Professor Perry Bartlett said this new insight was vital to brain research.
“Discovering how nerve cells process information is fundamental to understanding how we learn, and to developing new strategies to enhance learning in education and in disease processes in the brain,” he said.
Queensland Minister for Science and Innovation Ian Walker congratulated Dr Sivyer and Associate Professor Williams on their internationally significant findings.
“This is another example of Queensland leading the world in health and medical research,” he said.
“Dendrite research also has flow-on implications for brain-function studies in a range of areas.
“While all of these areas are important, I will be particularly interested to see its application to dementia research, which has been a major focus for recent Queensland Government support.”
The paper, Direction selectivity is computed by active dendritic integration in retinal ganglion cells, is published in the prestigious journal Nature Neuroscience.
Find a space with total darkness and slowly move your hand from side to side in front of your face. What do you see?
If the answer is a shadowy shape moving past, you are probably not imagining things. With the help of computerized eye trackers, a new cognitive science study finds that at least 50 percent of people can see the movement of their own hand even in the absence of all light.
"Seeing in total darkness? According to the current understanding of natural vision, that just doesn’t happen," says Duje Tadin, a professor of brain and cognitive sciences at the University of Rochester who led the investigation. "But this research shows that our own movements transmit sensory signals that also can create real visual perceptions in the brain, even in the complete absence of optical input."
Through five separate experiments involving 129 individuals, the authors found that this eerie ability to see our hand in the dark suggests that our brain combines information from different senses to create our perceptions. The ability also “underscores that what we normally perceive of as sight is really as much a function of our brains as our eyes,” says first author Kevin Dieter, a post-doctoral fellow in psychology at Vanderbilt University.
The study seems to confirm anecdotal reports that spelunkers in lightless caves often are able to see their hands. In other words, the “spelunker illusion,” as one blogger dubbed it, is likely not an illusion after all.
For most people, this ability to see self-motion in darkness probably is learned, the authors conclude. “We get such reliable exposure to the sight of our own hand moving that our brains learn to predict the expected moving image even without actual visual input,” says Dieter.
Tadin, Dieter, and their team from the University of Rochester and Vanderbilt University reported their findings online October 30 in Psychological Science, the flagship journal of the Association for Psychological Science.
Although seeing one’s hand move in the dark may seem simple, the experimental challenge in this study was to measure objectively a perception that is, at its core, subjective. That hurdle at first stumped Tadin and his postdoctoral advisor at Vanderbilt Randolph Blake after they initially stumbled upon the puzzling observation in 2005. “While the phenomenon looked real to us, how could we determine if other people were really seeing their own moving hand rather than just telling us what they thought we wanted to hear?” asks Blake, the Centennial Professor of Psychology at Vanderbilt and a co-author on the paper.
Years later, Dieter, at the time a doctoral student working in Tadin’s Rochester lab, helped devise several experiments to probe the sight-without-light mystery. For starters, the researchers set up false expectations. In one scenario, they led subjects to expect to see “motion under low lighting conditions” with blindfolds that appeared to have tiny holes in them. In a second set up, the same participants had similar blindfolds without the “holes” and were led to believe they would see nothing. In both set ups, the blindfolds were, in fact, equally effective at blocking out all light. A third experiment consisted of the experimenter waving his hand in front of the blindfolded subject. Ultimately, participants were fitted with a computerized eye tracker in total darkness to confirm whether self-reported perceptions of movement lined up with objective measures.
In addition to testing typical subjects, the team also recruited people who experience a blending of their senses in daily life. Known as synesthetes, these individuals may, for example, see colors when they hear music or even taste sounds. This study focused on grapheme-color synesthetes, individuals who always see numbers or letters in specific colors.
The researchers enlisted individuals from Rochester, Nashville, Fenton, Michigan, and Seoul, South Korea, but, in a lucky coincidence, one synesthete could not have been closer. At the time, Lindsay Bronnenkant was working as a lab technician for co-author David Knill, a professor of brain and cognitive sciences at Rochester.
"As a child, I just assumed that everybody associated colors with letters," says the 2010 Rochester graduate who majored in brain and cognitive sciences. For Bronnenkant, "A is always yellow, but Y is an oranger yellow." B is navy, C burnt orange, and so on. She thought of these associations as normal, "like when you smell apple pie and you think of grandma." She doesn’t remember a time when she did not see numbers and letters in color, but she does wonder if the particular colors she associates with numbers derived from the billiard balls her family had going up. When she donned the blindfold and waved her hand in the experiment, "what I saw was a blur. It was very dim, but it was almost like I was looking at a light source."
Bronnenkant was not atypical in that respect. Across all types of participants, about half detected the motion of their own hand and they did so consistently, despite the expectations created with the faux holes. And very few subjects saw motion when the experimenter waved his hand, underscoring the importance of self-motion in this visual experience. As measured by the eye tracker, subjects who reported seeing motion were also able to smoothly track the motion of their hand in darkness more accurately than those who reported no visual sensation—46 percent versus 20 percent of the time.
Reports of the strength of visual images varied widely among participants, but synesthetes were strikingly better at not just seeing movement, but also experiencing clear visual form. As an extreme example in the eye tracking experiment, one synesthete exhibited near perfect smooth eye movement—95 percent accuracy—as she followed her hand in darkness. In other words, she could track her hand in total darkness as well as if the lights were on.
"You can’t just imagine a target and get smooth eye movement," explains Knill. "If there is no moving target, your eye movements will be noticeably jerky."
The link with synesthesia suggests that our human ability to see self-motion is based on neural connections between the senses, says Knill. “We know that sensory cross talk underlies synesthesia. But seeing color with numbers is probably just the tip of the iceberg; synesthesia may involve many areas of atypical brain processing.”
Does that mean that most humans are preprogrammed to see themselves in the dark? Not likely, says Tadin. “Innate or experience? I’m pretty sure it’s experience,” he concludes. “Our brains are remarkably good at finding such reliable patterns. The brain is there to pick up patterns—visual, auditory, thinking, movement. And this is one association that is so highly repeatable that it is logical our brains picked up on it and exploited it.”
Whether hardwired or learned, Bronnenkant finds the cross talk between her senses a potent reminder of the underlying interconnectivity of nature. “It’s almost a spiritual thing,” she says. “Sometimes, yeah, I think to myself, ‘I just got this sense from a billiard ball,’ but other times I think that being able to cross modalities actually reflects how unified the world is. We think of math and chemistry and art as different fields, but really they are facets of the same world; they are just ways of looking at the world through different lenses.”
Scientists reduce behaviours associated with problem gambling in rats
With the help of a rat casino, University of British Columbia brain researchers have successfully reduced behaviours in rats that are commonly associated with compulsive gambling in humans.
The study, which featured the first successful modeling of slot machine-style gambling with rats in North America, is the first to show that problem gambling behaviours can be treated with drugs that block dopamine D4 receptors. The findings have been published in Biological Psychiatry journal.
“More work is needed, but these findings offer new hope for the treatment of gambling addiction, which is a growing public health concern,” says Paul Cocker, lead author of the study and a PhD student in UBC’s Dept. of Psychology. “This study sheds important new light on the brain processes involved with gambling and gambling addictions.”
For the study, rats gambled for sugar pellets using a slot machine-style device that featured three flashing lights and two levers they could push with their paws. The rats exhibited several behaviours associated with problem gambling such as the tendency to treat “near misses” similar to wins.
Building on previous research, the team focused on the dopamine D4 receptor, which has been linked to a variety of behavioural disorders, but never proven useful in treatment. The study found that rats treated with a dopamine D4 receptor-blocking medication exhibited reduced levels of behaviours associated with problem gambling.
While findings suggest that blocking the D4 dopamine receptor may help to reduce pathological gambling behaviours in humans, the researchers note that further research is needed before the drugs can be considered a viable pharmaceutical treatment for pathological gambling in humans.
BACKGROUND
“Pathological gambling is increasingly seen as a behavioural addiction similar to drug or alcohol addiction, but we know comparatively little about how to treat problem gambling,” says Cocker. “Our study is the first to show that by blocking these receptors we might be able to reduce the rewarding aspects of near-misses that appear to be important in gambling.”
Methods: In the 16-month study,a cohort of 32 laboratory rats responded to a series of three flashing lights before choosing between two levers. One combination of lights (all lights illuminated) signaled a win and seven combinations (zero, one or two lights) signaled a loss. A “cash-out” lever rewarded the rat with 10 sugar pellets on winning trials, but gave a 10-second “time out” penalty on losing trails. The “roll again” lever allowed the rats to begin a new trial without penalty, but provided no sugar pellets.
Interestingly, the rats showed a tendency towards choosing the cash-out lever when two lights (near-miss) illuminated, suggesting that rats, like people, are susceptible to the near-miss effect. By blocking the D4 receptors with drugs, the researchers were successfully able to reduce the rat’s choice of the “cash-out” lever on non-winning trials.
The D4 blocker drug used in the study has previously been tested on humans in attempts to treat behaviour disorders like schizophrenia but appeared to have no effect.
Near misses: This common cognitive bias is considered an important factor in the development of pathological gambling problems. The fact that slot machines tend to have a relatively high proportion of near-misses in comparison to other gambling games may be the reason that slot machines are such a particularly addictive form of gambling.
Study authors: Paul Cocker and Prof.Catharine Winstanley (UBC Dept. of Psychology), Bernard Le Foll (University of Toronto, Centre for Addiction and Mental Health) and Robert D. Rogers (Bangor University). The study, A Selective Role for Dopamine D4 Receptors in Modulating Reward Expectancy in a Rodent Slot Machine Task, is available upon request.
UBC’s Laboratory of Molecular and Behavioural Neuroscience, led by Psychology Prof. Catharine Winstanley, focuses on understanding the biological mechanisms of functions such as impulse control and gambling, leading to new and improved treatments for disorders like attention deficit hyperactivity disorder, bipolar disorder, personality disorders, and drug addiction.
Problem gambling: Compulsive gambling affects between three and five percent of North Americans, according to recent statistics.
It’s shocking: Ultra-focused electric current helps brain curb pain
Imagine significantly reducing a persistent migraine or fibromyalgia by a visit to a doctor who delivers low doses of electricity to the brain.
Alex DaSilva, assistant professor of prosthodontics at the University of Michigan, and colleagues are optimizing the next generation for such a technique, called high-definition transcranial direct current stimulation, or HD-tDCS.
The researchers have published several studies with the conventional tDCS, which also treats pain by “shocking” the brain with low doses of electrical current delivered noninvasively through electrodes placed on the scalp. The current modulates targeted areas of the brain, and one of the mechanisms is by activating the release of opioid-like painkillers.
HD-tDCS delivers an even more precisely focused current to the targeted areas of the brain. Preliminary reports have shown better pain relief in patients and a longer and more pronounced effect on the brain, said DaSilva, who heads the Headache and Orofacial Pain Effort Laboratory at the U-M School of Dentistry.
The increased precision of HD-tDCS means researchers can custom-place the electrodes to the skull. In this way, they can modulate specific areas in the brain to treat a wider range of conditions, such as neuropathic pain and stroke. Other uses include neurophysiological studies and cognitive and behavioral assessments.
One 20-minute session of HD-tDCS significantly reduced overall pain perception in fibromyalgia patients as described in one of the studies.
Researchers control the current by a portable device, which they hope physicians can eventually use in the clinic as a noninvasive treatment for chronic pain patients.
"We are working hard to make the technology available for clinical use at U-M," DaSilva said. "Our lab is getting a good number of emails from chronic pain patients looking for treatment."
The conventional technology is already available for many companies, and the HD-tDCS is being patented by the company of one of the developers.
To allow broad access and further investigation of the HD-tDCS technology by other researchers, DaSilva and colleagues released a scientific video demonstrating the step-by-step guideline of the research protocol: www.jove.com/embed/directions/50309?key=uahsva6y
High blood sugar makes Alzheimer’s plaque more toxic to the brain
High blood-sugar levels, such as those linked with Type 2 diabetes, make beta amyloid protein associated with Alzheimer’s disease dramatically more toxic to cells lining blood vessels in the brain, according to a new Tulane University study published in latest issue of the Journal of Alzheimer’s Disease.
The study supports growing evidence pointing to glucose levels and vascular damage as contributors to dementia.
“Previously, it was believed that Alzheimer’s disease was due to the accumulation of ‘tangles’ in neurons in the brain from overproduction and reduced removal of beta amyloid protein,” said senior investigator Dr. David Busija, regents professor and chair of pharmacology at Tulane University School of Medicine. “While neuronal involvement is a major factor in Alzheimer’s development, recent evidence indicates damaged cerebral blood vessels compromised by high blood sugar play a role. Even though the links among Type 2 diabetes, brain blood vessels and Alzheimer’s progression are unclear, hyperglycemia appears to play a role.”
Drs. Cristina Carvalho and Paula Moreira from the University of Coimbra in Portugal were co-investigators in the study.
Researchers studied cell cultures taken from the lining of cerebral blood vessels, one from normal rats and another from mice with uncontrolled chronic diabetes. They exposed the cells to beta amyloid and different levels of glucose and later measured their viability. Cells exposed to high glucose or beta amyloid alone showed no changes in viability. However, when exposed to hyperglycemic conditions and beta amyloid, viability decreased by 40 percent. Researchers suspect the damage is due to oxidative stress from the mitochondria of the cell.
The cells from diabetic mice were more susceptible to damage and death to beta amyloid protein − even at normal glucose levels. The increased toxicity of beta amyloid may damage the blood-brain barrier, disrupt normal blood flow to the brain and decrease clearance of beta amyloid protein.
The study’s findings underscore the need to aggressively control blood sugar levels in diabetic individuals, Busija said.
(Source: tulane.edu)
Unravelling the true identity of the brain of Carl Friedrich Gauss
Preserved specimens of the brains of mathematician Carl Friedrich Gauss and Göttingen physician Conrad Heinrich Fuchs, taken over 150 years ago, were switched – and this probably happened soon after the death of both men in 1855. This is the surprising conclusion reached by Renate Schweizer, a neuroscientist at Biomedizinische NMR Forschungs GmbH at the Max Planck Institute for Biophysical Chemistry. She has now correctly identified the two brains, both of which are archived in a collection at the University Medical Center Göttingen. Working with experts from other disciplines, she extensively documented brain slices with a magnetic resonance imaging scanner.
Walnut-like structures appear on the computer screen. They reveal what’s inside the MRI scanner at Biomedizinische NMR Forschungs GmbH: a 150-year-old slice from the brain of mathematician Carl Friedrich Gauss. Renate Schweizer monitors the measurements as the internal tissue comes into view layer by layer. Then she carefully places another brain on the examination table, more commonly used to slowly move test subjects into the “tube”. This is the brain of Conrad Heinrich Fuchs – who, like Gauss, died in 1855 and was a medical scholar and founder of the University of Göttingen’s anatomical pathology collection. There is a specific reason for this latest examination of the historical brains from the collection at the Institute of Ethics and History of Medicine at University Medical Center Göttingen: “What scientists had long been examining in the belief that it was Gauss’s brain was not his brain at all, but actually belonged to Fuchs. The two scientists’ brains had been switched many years ago, and so they need to be documented again,” says Schweizer, a biologist and psychologist, describing the surprising findings of her investigations.
The scientist made this unexpected discovery while working in her research field – the region of the brain around the so-called central fissure. The gyri running along the central fissure are where the brain processes stimuli, like touch, heat or pain, and where it controls movements. Renate Schweizer suspected that Gauss’s brain featured a rare anatomical variation: a visible division of the central fissure. This is found in less than one percent of the population. Normally, it is of no significance to the people affected, though in a few cases it can cause minimal changes in motor and sensory function.
Schweizer spotted one of those central fissure divisions in the MRI scans believed to be of Gauss’s brain, taken in 1998 by Jens Frahm and his team at Biomedizinische NMR Forschungs GmbH and searched through the primary literature to confirm her findings. Rudolf Wagner, an anatomist in Göttingen and friend of Gauss, had prepared the brain slices of both Gauss and Fuchs before studying them and documenting the images in publications dating back to 1860 and 1862. But contrary to what she expected to see, Schweizer did not find the divided central fissure in the images of Gauss’s brain. Instead, her MRI images were a perfect match for Wagner’s picture of Fuchs’s brain.
When Schweizer visited the collection at the Institute of Ethics and History of Medicine, her initial suspicion was confirmed: the original brain taken from Gauss was indeed in a glass jar labelled ‘C. H. Fuchs’, while Fuchs’s brain was in a jar marked ‘C. F. G__ss’. “My theory, according to the information currently available, is that the brains were probably put into the wrong jars relatively soon after Wagner’s examinations, at the time when the surface of the cerebral cortex was being measured again,” says the neuroscientist. After that, there were no further comparative studies of the brains of Gauss and Fuchs, which is why no one noticed the subsequent mix-up. It is also significant for the Göttingen-based Gauss Society to know that the brains of Gauss and Fuchs are now assigned to their proper owners once more. “The Gauss Society’s Director, Axel Wittmann, was an active supporter of the project from the start and his extensive knowledge was extremely helpful in uncovering the mistake made so many years ago,” reports Schweizer.
Her discovery shows how important historic collections are for modern-day research. Schweizer confirms: “It’s a stroke of luck that the brains in the collection, which are in perfect condition, are still accessible to researchers more than 150 years down the line.” That is what enabled the mix-up to be identified without a shadow of a doubt and the historical brains to be examined in the MRI scanner. Schweizer collaborated closely with former team colleague Gunther Helms, who works with brain slice MRIs in the MR Research Service Unit at the Department of Cognitive Neurology at University Medical Center Göttingen. As Jens Frahm, Director of Biomedizinische NMR Forschungs GmbH, emphasises: “We are not looking for the genie in the gyri of the brain. What we are most interested in is documenting specimens for the long term future to provide a foundation for continuing basic research.” All MRI images and photographs of the historic brains are therefore being digitally archived, thus protecting them as long-term scientific assets. They are a significant impetus for new research projects: Schweizer herself is currently using the MRI images to study the divided central fissure in Fuchs’s brain both above and below the surface of the cerebral cortex.
The MRI images also enable the scientists to demonstrate that earlier publications on what was believed to be Gauss’s brain did not contain incorrect information. In those works, the mathematician’s brain was described as normal. Walter Schulz-Schaeffer, who is head of the Prion and Dementia Research Unit of the Institute of Neuropathology at University Medical Center Göttingen, made a first examination of the recent MRI images and was able to confirm that the brain of the brilliant mathematician and astronomer Gauss, like that of the physician Fuchs, is largely anatomically unremarkable. The two organs are also similar in size and weight. “The age-related changes in Gauss’s brain are normal for a man of 78. Changes in the basal ganglia are indicative of high blood pressure,” comments the neuropathologist.
Not every MRI scan of a historical slice allows for such a clear assertion. That is why neuropathologists and MRI scientists are currently working together to study how tissue and organs change as a result of decades or centuries of storage in alcohol, and how adapted MRI methods can improve the interpretation of the images obtained.
The historical brains have, meanwhile, again found their well-earned rest in the university collection – with no chance of a mix-up ever again.
Study with totally blind people shows how light helps activate the brain
Light enhances brain activity during a cognitive task even in some people who are totally blind, according to a study conducted by researchers at the University of Montreal and Boston’s Brigham and Women’s Hospital. The findings contribute to scientists’ understanding of everyone’s brains, as they also revealed how quickly light impacts on cognition. “We were stunned to discover that the brain still respond significantly to light in these rare three completely blind patients despite having absolutely no conscious vision at all,” said senior co-author Steven Lockley. “Light doesn’t just allow us to see, it tells the brain whether it’s night or day which in –turn ensures that our physiology, metabolism and behavior are synchronized with environmental time”. “For diurnal species like ours, light stimulates day-like brain activity, improving alertness and mood, and enhancing performance on many cognitive tasks,” explained senior co-author Julie Carrier. The results indicate that their brains can still “see”, or detect, light via a novel photoreceptor in the ganglion cell layer of the retina, different from the rods and cones we use to see.
Scientists believe, however, that these specialized photoreceptors in the retina also contribute to visual function in the brain even when cells in the retina responsible for normal image formation have lost their ability to receive or process light. A previous study in a single blind patient suggested that this was possible but the research team wanted to confirm this result in different patients. To test this hypothesis, the three participants were asked to say whether a blue light was on or off, even though they could not see the light. “We found that the participants did indeed have a non-conscious awareness of the light – they were able to determine correctly when the light was on greater than chance without being able to see it,” explained first author Gilles Vandewalle.
The next steps involved looking closely at what happened to brain activation when light was flashed at their eyes at the same time as their attentiveness to a sound was monitored. “The objective of this second test was to determine whether the light affected the brain patterns associated with attentiveness – and it did,” said first author Olivier Collignon.
Finally, the participants underwent a functional MRI brain scan as they performed a simple sound matching task while lights were flashed in their eyes. “The fMRI further showed that during an auditory working memory task, less than a minute of blue light activated brain regions important to perform the task. These regions are involved in alertness and cognition regulation as well being as key areas of the default mode network,” Vandewalle explained. Researchers believe that the default network is linked to keeping a minimal amount of resources available for monitoring the environment when we are not actively doing something. “If our understanding of the default network is correct, our results raise the intriguing possibility that light is key to maintaining sustained attention” agreed Lockley and Carrier. “This theory may explain why the brain’s performance is improved when light is present during tasks.”
(Source: nouvelles.umontreal.ca)
New imaging research shows increased iron in the brain in earliest stages of MS
While it’s been known for over a century that iron deposits in the brain play a role in the pathology of Multiple Sclerosis (MS), new imaging research from Western University (London, Canada) helps to answer the question of whether these accumulations are a cause or consequence of the disease. The study led by Ravi Menon, PhD, of the Robarts Research Institute found iron deposits in deep gray matter, suggesting the accumulation occurs very early in the disease course. The researchers also found evidence casting further doubt on the controversial liberation therapy for MS. The research is in early publication online in Multiple Sclerosis and Related Disorders.
Menon and PhD candidate Matthew Quinn used 3-Tesla Magnetic Resonance Imaging (MRI) to scan 22 patients with clinically isolated syndrome (CIS). These are patients who’ve had a single clinical attack, at least half of whom will go on to be diagnosed with MS. The others may have a different disease. Sixteen age and sex matched controls were also studied.
"We wanted to know if the iron deposits happen early in the process, or whether it’s something that accumulates with time as the disease progresses," says Menon, who holds a Canada Research Chair in Functional Magnetic Imaging. "We also studied the veins that drain from the brain and looked for a correlation between the diameter of of these veins and iron accumulation. One of the reasons to do this, of course was the hypothesis proposed by Paolo Zamboni that if you had narrow jugular veins, this would give rise to additional iron and in turn cause MS."
The scientists found iron deposits in the CIS group were well above the amounts found in the control group. The MRIs also revealed for the first time, subtle damage to the brain’s white matter even at this early stage. The researchers also found no correlation between the iron deposits and diameter of the veins.
"So while the iron in the brain correlates with the disability of the subjects, the iron in the brain does not correlate with the actual diameter of the jugular veins. So the Zamboni hypothesis is incorrect as far as the iron being related to some kind of obstruction." Menon found narrowed veins in the control group as well as the CIS group, and both groups had narrower veins on one side compared to the other.
Menon hopes this imaging research will lead to the earlier diagnosis of MS. He plans to follow the patients every four months for the next two years, to see retrospectively, what characterizes those patients that go on to be diagnosed with MS compared to those who do not.
"We’re looking at a couple of different approaches to diagnostics using this imaging research. In suspected MS cases –the very first time they appear in clinic, if they have an abnormally high amount of iron in the frontal cortex of the brain –that’s probably a pretty good sign they have MS or some other white matter disease." This research was funded primarily by the Canadian Institutes of Health Research.
MS is the most common neurological disease affecting young adults, with symptoms that include loss of balance, impaired speech, double vision, extreme fatigue and paralysis.