Neuroscience
Month
"Pressing the button of the lift at your work place, or apartment building is an automatic action – a habit. You don’t even really look at the different buttons; your hand is almost reaching out and pressing on its own. But what happens when you use the lift in a new place? In this case, your hand doesn’t know the way, you have to locate the buttons, find the right one, and only then your hand can press a button. Here, pushing the button is a goal-directed action." It is with this example that Rui Costa, principal investigator at the Champalimaud Neuroscience Programme (CNP), explains how critical it is to be able to shift between habits and goal-direct actions, in a fast and accurate way, in everyday life.
To unravel the circuit that underlies this capacity, the capacity to “break habits”, was the goal of this study, carried out by Christina Gremel and Rui Costa, at NIAAA, National Institutes of Health, USA and the Champalimaud Foundation, in Portugal, that is published today (Date) in Nature Communications.
"We developed a task where mice would shift between making the same action in a goal-directed or habitual manner. We could then, for the first time, directly examine brain areas controlling the capacity to break habits," explains the study’s lead author Christina Gremel from NIAAA. Evidence from previous studies has shown that two neighbouring regions of the brain are necessary for these different functions – the dorsal medial striatum is necessary for goal-directed actions and the dorsal lateral striatum is necessary for habitual actions. What was not known, and this new study reveals, is that a third region, the orbital frontal cortex (OFC), is critical for shifting between these two types of actions. As explained by Rui Costa, "when neurons in the OFC were inhibited, the generation of goal-directed actions was disrupted, while activation of these neurons, by means of a technique called optogenetics, selectively increased goal-directed actions."
For Costa, the results of this study suggest “something quite extraordinary – the same neural circuits function in a dynamic way, enabling the learning of automatic and goal-directed actions in parallel.”
These results have important implications for understanding neuropsychiatric disorders where the balance between habits and goal-directed actions is disrupted, such as obsessive-compulsive disorder.
The neural bases of behaviour, and their connection to neuropsychiatric disorders, are at the core of ongoing work by neuroscientists and clinicians at the Champalimaud Foundation.
Not only does practice make perfect, it also makes for more efficient generation of neuronal activity in the primary motor cortex, the area of the brain that plans and executes movement, according to researchers from the University of Pittsburgh School of Medicine. Their findings, published online today in Nature Neuroscience, showed that practice leads to decreased metabolic activity for internally generated movements, but not for visually guided motor tasks, and suggest the motor cortex is “plastic” and a potential site for the storage of motor skills.
The hand area of the primary motor cortex is known to be larger among professional pianists than in amateur ones. This observation has suggested that extensive practice and the development of expert performance induces changes in the primary motor cortex, said senior investigator Peter L. Strick, Ph.D., Distinguished Professor and chair, Department of Neurobiology, Pitt School of Medicine.
Prior imaging studies have shown that markers of synaptic activity, meaning the input signals to neurons, decrease in the primary motor cortex as repeated actions become routine and an individual develops expertise at a motor skill. The researchers found that markers of synaptic activity also display a marked decrease in monkeys trained to perform sequences of movements that are guided from memory — an internally generated task — rather than from vision. They wondered whether the change in synaptic activity indicated that neuron firing also declined. To examine this issue they recorded neuron activity and sampled metabolic activity, a measure of synaptic activity in the same animals.
All the monkeys were trained on two tasks and were rewarded when they reached out to touch an object in front of them. In the visually guided task, a visual target showed the monkeys where to reach and the end point was randomly switched from trial to trial. In the internally generated task the monkeys were trained to perform short sequences of movements without visual cues. They practiced the sequences until they achieved a level of skill comparable to an expert typist.
The researchers found neuron activity was comparable between monkeys that performed visually guided and internally generated tasks. However, metabolic activity was high for the visually guided task, but only modest during the internally generated task.
“This tells us that practicing a skilled movement and the development of expertise leads to more efficient generation of neuron activity in the primary motor cortex to produce the movement. The increase in efficiency could be created by a number of factors such as more effective synapses, greater synchrony in inputs and more finely tuned inputs,” Dr. Strick noted. “What is really important is that our results indicate that practice changes the primary motor cortex so that it can become an important substrate for the storage of motor skills. Thus, the motor cortex is adaptable, or plastic.
Neuropathic pain — pain that results from a malfunction in the nervous system — is a daily reality for millions of Americans. Unlike normal pain, it doesn’t go away after the stimulus that provoked it ends, and it also behaves in a variety of other unusual and disturbing ways. Someone suffering from neuropathic pain might experience intense discomfort from a light touch, for example, or feel as though he or she were freezing in response to a slight change in temperature.
A major part of the answer to the problem of neuropathic pain, scientists believe, is found in spinal nerve cells that release a signaling chemical known as GABA. These GABA neurons act as a sort of brake on pain impulses; it’s thought that when they die or are disabled the pain system goes out of control. If GABA neurons could be kept alive and healthy after peripheral nerve or tissue injury, it’s possible that neuropathic pain could be averted.
Now, University of Texas Medical Branch at Galveston researchers have found a way to, at least partially, accomplish this objective. The key, they determined, is stemming the biochemical assault by reactive oxygen species that are generated in the wake of nerve injury.
"GABA neurons are particularly susceptible to oxidative stress, and we hypothesized that reactive oxygen species contribute to neuropathic sensitization by promoting the loss of GABA neurons as well as hindering GABA functions," said UTMB professor Jin Mo Chung, senior author of a paper on the research now online in the journal Pain.
To test this hypothesis — and determine whether GABA neurons could be saved — the researchers conducted a series of experiments in mice that had been surgically altered to simulate the conditions of neuropathic pain. In one key experiment, mice treated with an antioxidant compound for a week after surgery were compared with untreated mice. The antioxidant mice showed less pain-associated behavior and were found to have far more GABA neurons than the untreated mice.
"So by giving the antioxidant we lowered the pain behavior, and when we look at the spinal cords we see the GABA neuron population is almost the same as normal," Chung said. "That suggested we prevented those neurons from dying, which is a big thing."
One complication, Chung noted, is a “moderate quantitative mismatch” between the behavioral data and the GABA-neuron counts. While the anti-oxidant mice displayed less pain behavior, their behavioral improvement wasn’t as substantial as their high number of GABA neurons would suggest. One possibility is that the surviving neurons were somehow impaired — a hypothesis supported by electrophysiological data.
Although no clinical trials are planned in the immediate future, Chung believes anti-oxidants have great potential as a treatment for neuropathic pain. “If this is true and it works in humans — well, any time you can salvage neurons, it’s a good thing,” he said. “Neuropathic pain is very difficult to treat, and I think this is a possibility, a good possibility.”
About 15 percent of glioblastoma patients could receive personalized treatment with drugs currently used in other cancers
A team of researchers at the Herbert Irving Comprehensive Cancer Center at Columbia University Medical Center has identified 18 new genes responsible for driving glioblastoma multiforme, the most common—and most aggressive—form of brain cancer in adults. The study was published August 5, 2013, in Nature Genetics.
“Cancers rely on driver genes to remain cancers, and driver genes are the best targets for therapy,” said Antonio Iavarone, MD, professor of pathology and neurology at Columbia University Medical Center and a principal author of the study.
“Once you know the driver in a particular tumor and you hit it, the cancer collapses. We think our study has identified the vast majority of drivers in glioblastoma, and therefore a list of the most important targets for glioblastoma drug development and the basis for personalized treatment of brain cancer.”
Personalized treatment could be a reality soon for about 15 percent of glioblastoma patients, said Anna Lasorella, MD, associate professor of pediatrics and of pathology & cell biology at CUMC.
“This study—together with our study from last year, Research May Lead to New Treatment for Type of Brain Cancer—shows that about 15 percent of glioblastomas are driven by genes that could be targeted with currently available FDA-approved drugs,” she said. “There is no reason why these patients couldn’t receive these drugs now in clinical trials.”
New Bioinformatics Technique Distinguishes Driver Genes from Other Mutations
In any single tumor, hundreds of genes may be mutated, but distinguishing the mutations that drive cancer from mutations that have no effect has been a longstanding problem for researchers.
An analysis of all gene mutations in nearly 140 brain tumors has uncovered most of the genes responsible for driving glioblastoma. The analysis found 18 new driver genes (labeled red), never before implicated in glioblastoma and correctly identified the 15 previously known driver genes (labeled blue). The graphs show mutated genes that are commonly found in varying numbers in glioblastoma (left), that frequently contain insertions (middle), and that frequently contain deletions (right). Genes represented by blue dots in the graphs were statistically most likely to be driver genes. Image: Raul Rabadan/Columbia University Medical Center.
The Columbia team used a combination of high throughput DNA sequencing and a new method of statistical analysis to generate a short list of driver candidates. The massive study of nearly 140 brain tumors sequenced the DNA and RNA of every gene in the tumors to identify all the mutations in each tumor. A statistical algorithm designed by co-author Raul Rabadan, PhD, assistant professor of biomedical informatics and systems biology, was then used to identify the mutations most likely to be driver mutations. The algorithm differs from other techniques to distinguish drivers from other mutations in that it considers not only how often the gene is mutated in different tumors, but also the manner in which it is mutated.
“If one copy of the gene in a tumor is mutated at a single point and the second copy is mutated in a different way, there’s a higher probability that the gene is a driver,” Dr. Iavarone said.
The analysis identified 15 driver genes that had been previously identified in other studies—confirming the accuracy of the technique—and 18 new driver genes that had never been implicated in glioblastoma.
Significantly, some of the most important candidates among the 18 new genes, such as LZTR1 and delta catenin, were confirmed to be driver genes in laboratory studies involving cancer stem cells taken from human tumors and examined in culture, as well as after they had been implanted into mice.
A New Model for Personalized Cancer Treatment
Because patients’ tumors are powered by different driver genes, the researchers say that a complicated analysis will be needed for personalized glioblastoma treatment to become a reality. First, all the genes in a patient’s tumor must be sequenced and analyzed to identify its driver gene.
“In some tumors it’s obvious what the driver is; but in others, it’s harder to figure out,” said Dr.Iavarone.
Once the candidate driver is identified, it must be confirmed in laboratory tests with cancer stem cells isolated from the patient’s tumor.
About 15 percent of glioblastoma driver genes can be targeted with currently available drugs, suggesting that personalized treatment for some patients may be possible in the near future. Personalized therapy for glioblastoma patients could be achieved by isolating the most aggressive cells from the patient’s tumor and identifying the driver gene responsible for the tumor’s growth (different tumors will be driven by different genes). Drugs can then be tested on the isolated cells to find the most promising candidate. In this image, the gene mutation driving the malignant tumor has been replaced with the normal gene, transforming malignant cells back into normal brain cells. Image: Anna Lasorella.
“Cancer stem cells are the tumor’s most aggressive cells and the critical cellular targets for cancer therapies,” said Dr. Lasorella. “Drugs that prove successful in hitting driver genes in cancer stem cells and slowing cancer growth in cell culture and animal models would then be tried in the patient.”
Personalized Treatment Already Possible for Some Patients
For 85 percent of the known glioblastoma drivers, no drugs that target them have yet been approved.
But the Columbia team has found that about 15 percent of patients whose tumors are driven by certain gene fusions, FDA-approved drugs that target those drivers are available.
The study found that half of these patients have tumors driven by a fusion between the gene EGFR and one of several other genes. The fusion makes EGFR—a growth factor already implicated in cancer—hyperactive; hyperactive EGFR drives tumor growth in these glioblastomas.
“When this gene fusion is present, tumors become addicted to it—they can’t live without it,” Dr. Iavarone said. “We think patients with this fusion might benefit from EGFR inhibitors that are already on the market. In our study, when we gave the inhibitors to mice with these human glioblastomas, tumor growth was strongly inhibited.”
Other patients have tumors that harbor a fusion of the genes FGFR (fibroblast growth factor receptor) and TACC (transforming acidic coiled-coil), first reported by the Columbia team last year. These patients may benefit from FGFR kinase inhibitors. Preliminary trials of these drugs (for treatment of other forms of cancer) have shown that they have a good safety profile, which should accelerate testing in patients with glioblastoma.
Quick eye movements, called saccades, that enable us to scan a visual scene appear to act as a metronome for pushing information about that scene into memory.
Scientists at Yerkes National Primate Research Center, Emory University, have observed that in monkeys exploring images with their eyes, the onset of a saccade resets the rhythms of electrical activity (theta oscillations) in the hippocampus, a region of the brain important for memory formation.
Tracking eye movements is already a promising basis for diagnosing brain disorders such as Alzheimer’s disease and schizophrenia. A deeper understanding of how the rhythm of eye movements orchestrate memories could bolster the accuracy and power of eye-tracking diagnoses.
The findings were published this week in Proceedings of the National Academy of Sciences, Early Edition.
Senior author Elizabeth Buffalo was a researcher at the Yerkes National Primate Research Center and an associate professor of neurology at Emory University School of Medicine and is currently associate professor of physiology and biophysics at Universpity of Washington in Seattle. The first author of the paper is postdoctoral fellow Michael Jutras„ who is now an instructor at the University of Washington.
Theta oscillations are cycles of electrical activity in the brain occurring between 3 to 12 times per second. Scientists have previously seen theta oscillations in the hippocampus in rodents, when the rodents were actively exploring, sniffing or feeling something with their whiskers.
"Both animals and humans seem to take in sensory information at this theta rhythm," Buffalo says. "But one striking difference between rodents and primates is the way they gather information about the external world. Rodents are much more reliant on the senses of smell and touch."
She says the actions that are most comparable to rodents’ sniffing and whiskering in primates are saccades. When our eyes scan text or explore a picture, the eyes’ focus tends to jump from point to point several times per second.
Buffalo and Jutras examined electrical signals in the hippocampi of two rhesus monkeys while the monkeys were looking at a variety of pictures and the researchers tracked their eye movements. The researchers observed that after a saccade, the electrical signals in the hippocampus display a more coherent rhythm.
The rhythm reset a saccade imposes may be a way to ensure the hippocampus is receptive to new sensory information, the researchers propose.
“The eye movements are acting like the conductor of the hippocampal orchestra,” Jutras says, “The phase reset might be a mechanism to ensure the ongoing theta rhythm is in sync with incoming visual information.”
Scientists have previously hypothesized that theta oscillations in the hippocampus set the stage for memory formation. The researchers tested this idea by presenting the monkeys each image twice during a viewing session. Because all primates have an innate preference for novelty, monkeys tend to spend a longer time looking at new images and less time looking at repeated ones. The researchers inferred that the monkeys had a stronger memory of a given picture if, upon second viewing, they looked through it quickly. The theta rhythm reset was more consistent during the viewing of images that the monkeys remembered well.
"Based on this finding, we concluded that this resetting of the theta rhythm is an important part of the memory process," Jutras says.
"This study has given us a better understanding of the function of the hippocampal theta rhythm, which has been well characterized in rodents but isn’t well understood in primates," he says. "A future goal is to investigate the relationship between hippocampal theta and eye movements during memory formation and navigation in humans. This could be possible with epilepsy patients who undergo monitoring of hippocampal activity as part of their treatment."
Neuroimaging improves understanding of eating disorder
In a spacious hotel room not far from the beach in La Jolla, Calif., Kelsey Heenan gripped her fiancé’s hand. Heenan, a 20-year-old anorexic woman, couldn’t believe what she was hearing. Walter Kaye, director of the eating disorders program at the University of California, San Diego, was telling a handful of rapt patients and their family members what the latest brain imaging research suggested about their disorder.
It’s not your fault, he told them.
Heenan had always assumed that she was to blame for her illness. Kaye’s data told a different story. He handed out a pile of black-and-white brain scans — some showed the brains of healthy people, others were from people with anorexia nervosa. The scans didn’t look the same. “People were shocked,” Heenan says. But above all, she remembers, the group seemed to sigh in relief, breathing out years of buried guilt about the disorder. “It’s something in the way I was wired — it’s something I didn’t choose to do,” Heenan says. “It was pretty freeing to know that there could be something else going on.”
Years of psychological and behavioral research have helped scientists better understand some signs and triggers of anorexia. But that knowledge hasn’t straightened out the disorder’s tangled roots, or pointed scientists to a therapy that works for everyone. “Anorexia has a high death rate, it’s expensive to treat and people are chronically ill,” says Kaye.
Kaye’s program uses a therapy called family-based treatment, or FBT, to teach adolescents and their families how to manage anorexia. A year after therapy, about half of the patients treated with FBT recover. In the world of eating disorders, that’s success: FBT is considered one of the very best treatments doctors have. To many scientists, that just highlights how much about anorexia remains unknown.
Kaye and others are looking to the brain for answers. Using brain imaging tools and other methods to explore what’s going on in patients’ minds, researchers have scraped together clues that suggest anorexics are wired differently than healthy people. The mental brakes people use to curb impulsive instincts, for example, might get jammed in people with anorexia. Some studies suggest that just a taste of sugar can send parts of the brain barrelling into overdrive. Other brain areas appear numb to tastes — and even sensations such as pain. For people with anorexia, a sharp pang of hunger might register instead as a dull thud.
The mishmash of different brain imaging data is just beginning to highlight the neural roots of anorexia, Kaye says. But because starvation physically changes the brain, researchers can run into trouble teasing out whether glitchy brain wiring causes anorexia, or vice versa. Still, Kaye thinks understanding what’s going on in the brain may spark new treatment ideas. It may also help the eating disorder shake off some of its noxious stereotypes.
“One of the biggest problems is that people do not take this disease seriously,” says James Lock, an eating disorders researcher at Stanford University who cowrote the book on family-based treatment. “No one gets upset at a child who has cancer,” he says. “If the treatment is hard, parents still do it because they know they need to do it to make their child well.”
Pop culture often paints anorexics as willful young women who go on diets to be beautiful, he says. But, “you can’t just choose to be anorexic,” Lock adds. “The brain data may help counteract some of the mythology.”
Beyond dieting
A society that glamorizes thinness can encourage unhealthy eating behaviors in kids, scientists have shown. A 2011 study of Minnesota high school students reported that more than half of girls had dieted within the past year. Just under a sixth had used diet pills, vomiting, laxatives or diuretics.
But a true eating disorder goes well beyond an unhealthy diet. Anorexia involves malnutrition, excessive weight loss and often faulty thinking about one of the body’s most basic drives: hunger. The disorder is also rare. Less than 1 percent of girls develop anorexia. The disease crops up in boys too, but adolescent girls — especially in wealthy countries such as the U.S., Australia and Japan — are most likely to suffer from the illness.
As the disease progresses, people with anorexia become intensely afraid of getting fat and stick to extreme diets or exercise schedules to drop pounds. They also misjudge their own weight. Beyond these diagnostic hallmarks, patients’ symptoms can vary. Some refuse to eat, others binge and purge. Some live for years with the illness, others yo-yo between weight gain and loss. Though most anorexics gain back some weight within five years of becoming ill, anorexia is the deadliest of all mental disorders.
Though anorexia tends to run in families, scientists haven’t yet hammered out the suite of genes at play. Some individuals are particularly vulnerable to developing an eating disorder. In these people, stressful life changes, such as heading off to college, can tip the mental scales toward anorexia.
For decades, scientists have known that anorexic children behave a little differently. In school and sports, anorexic kids strive for perfection. Though Heenan, a former college basketball player, didn’t notice her symptoms creeping in until the end of high school, she remembers initiating strict practice regimens as a child. Starting in second grade, Heenan spent hours perfecting her jump shot, shooting the ball again and again until she had the technique exactly right — until her form was flawless.
“It’s very rare for me to see a person with anorexia in my office who isn’t a straight-A student,” Lock says. Even at an early age, people who later develop the eating disorder tend to exert an almost superhuman ability to practice, focus or study. “They will work and work and work,” says Lock. “The problem is they don’t know when to stop.”
In fact, many scientists think anorexics’ brains might be wired for willpower, for good and ill. Using new imaging tools that let scientists watch as a person’s mental gears grind through different tasks, researchers are starting to pin down how anorexic brains work overtime.
Different wiring: Studies of the brains of people with anorexia have revealed a number of complex brain circuits that show changes in activity compared with healthy people. Medical RF, adapted by M. Atarod
Control signs
To glimpse the circuits that govern self-control, experimental neuropsychologist Samantha Brooks uses functional magnetic resonance imaging, or fMRI, a tool that measures and maps brain activity. Last year, she and colleagues scanned volunteers as they imagined eating high-calorie foods, such as chocolate cake and French fries, or using inedible objects such as clothespins piled on a plate. One result gave Brooks a jolt. A center of self-control in anorexics’ brains sprung to life when the volunteers thought about food — but only in the women who severely restricted their calories, her team reported March 2012 in PLOS ONE.
The control center, two golf ball–sized chunks of tissue called the dorsolateral prefrontal cortex, or DLPFC, helps stamp out primitive urges. “They put a brake on your impulsive behaviors,” says Brooks, now at the University of Cape Town in South Africa.
For Brooks, discovering the DLPFC data was like finding a tiny vein of gold in a heap of granite. The control center could be the nugget that reveals how anorexics clamp down on their appetites. So she and her colleagues devised an experiment to test anorexics’ DLPFC. Using a memory task known to engage the brain region, the researchers quizzed volunteers while showing them subliminal images. The quizzes tested working memory, the mental tool that lets people hold phone numbers in their heads while hunting for a pen and paper. Compared with healthy people, anorexics tended to get more answers right, Brooks’ team wrote June 2012 in Consciousness and Cognition. “The patients were really good,” Brooks says. “They hardly made any mistakes.”
A turbocharged working memory could help anorexics hold on to rules they set for themselves about food. “It’s like saying ‘I will only eat a salad at noon, I will only eat a salad at noon,’ over and over in your mind,” says Brooks. These mantras may become so ingrained that an anorexic person can’t escape them.
But looking at subliminal images of food distracted anorexics from the memory task. “Then they did just as well as the healthy people,” Brooks says. The results suggest that anorexic people might tap into their DLPFC control circuits when faced with food.
James Lock has also seen signs of self-control circuits gone awry in people with eating disorders. In 2011, he and colleagues scanned the brains of teenagers with different eating disorders while signaling them to push a button. While volunteers lay inside the fMRI machine, researchers flashed pictures of different letters on an interior screen. For every letter but “X,” Lock’s group told the teens to push a button. During the task, anorexic teens who obsessively cut calories tended to have more active visual circuits than healthy teens or those with bulimia, a disorder that compels people to binge and purge. The result isn’t easy to explain, says Lock. “Anorexics may just be more focused in on the task.”
Bulimics’ brains told a simpler story. When teens with bulimia saw the letter “X,” broad swaths of their brains danced with activity — more so than the healthy or calorie-cutting anorexic volunteers, Lock’s team reported in the American Journal of Psychiatry. For bulimics, controlling the impulse to push the button may take more brain power than for others, Lock says.
Though the data don’t reveal differences in self-control between anorexics and healthy people, Lock thinks that anorexics’ well-documented ability to swat away urges probably does have signatures in the brain. He notes that his study was small, and that the “healthy” people he used as a control group might have shared similarities with anorexics. “The people who tend to volunteer are generally pretty high performers,” he says. “The chances are good that my controls are a little bit more like anorexics than bulimics.”
Still, Lock’s results offered another flicker of proof that people with eating disorders might have glitches in their self-control circuits. A tight rein on urges could help steer anorexics toward illness, but the parts of their brain tuned into rewards, such as sugary snacks, may also be a little off track.
Sugar low
When an anorexic woman unexpectedly gets a taste of sugar (yellow) or misses out on it (blue), her brain’s reward circuitry shows more activity than a healthy-weight or obese woman’s. Anorexics’ reward-processing systems may be out of order. Credit: G. Frank et al/ Neuropsychopharmacology 2012
For many anorexics, food just doesn’t taste very good. A classic symptom of the disorder is anhedonia, or trouble experiencing pleasure. Parts of Heenan’s past reflect the symptom. When she was ill, she had trouble remembering favorite dishes from childhood, for example — a blank spot common to anorexics. “I think I enjoyed some things,” she says. Beyond frozen yogurt, she can’t really rattle off a list.
After Heenan started seriously restricting her calories in college, only one aspect of food made her feel satisfied. Skipping, rather than eating, meals felt good, she says. Some of Heenan’s symptoms may have stemmed from frays in her reward wiring, the brain circuitry connecting food to pleasure. In the past few years, researchers have found that the chemicals coursing through healthy people’s reward circuits aren’t quite the same in anorexics. And studies in rodents have linked chemical changes in reward circuitry to under- and overeating.
To find out whether under- and overweight people had altered brain chemistry, eating disorder researcher Guido Frank of the University of Colorado Denver studied anorexic, healthy-weight and obese women. He and his colleagues trained volunteers to link images, such as orange or purple shapes, with the taste of a sweet solution, slightly salty water or no liquid. Then, the researchers scanned the women’s brains while showing them the shapes and dispensing tiny squirts of flavors. But the team threw in a twist: Sometimes the flavors didn’t match up with the right images.
When anorexics got an unexpected hit of sugar, a surge of activity bloomed in their brains. Obese people had the opposite response: Their brains didn’t register the surprise. Healthy-weight women fit somewhere in the middle, Frank’s team reported August 2012, in Neuropsychopharmacology. While obese people might not be sensitive to sweets anymore, a little sugar rush goes a long way for anorexics. “It’s just too much stimulation for them,” Frank says.
One of the lively regions in anorexics’ brains was the ventral striatum, a lump of nerve cells that’s part of a person’s reward circuitry. The lump picks up signals from dopamine, a chemical that rushes in when most people see a sugary treat.
Frank says that it’s possible cutting calories could sculpt a person’s brain chemistry, but he thinks some young people are just more likely to become sugar-sensitive than others. Frank suspects anorexics’ dopamine-sensing equipment might be out of alignment to begin with. And he may be onto something. Recently, researchers in Kaye’s lab at UCSD showed that the same chemical that makes people perk up when a coworker brings in a box of doughnuts might actually trigger anxiety in anorexics.
Mixed signals
Usually a rush of dopamine triggers euphoria or a boost of energy, says Ursula Bailer, a psychiatrist and neuroimaging researcher at UCSD. Anorexics don’t seem to pick up those good feelings.
When Bailer and colleagues gave volunteers amphetamine, a drug known to trigger dopamine release, and then asked them to rate their feelings, healthy people stuck to a familiar script. The drug made them feel intensely happy, Bailer’s team described March 2012 in the International Journal of Eating Disorders. Researchers linked the volunteers’ happy feelings to a wave of dopamine flooding the brain, using an imaging technique to track the chemical’s levels.
But anorexics said something different. “People with anorexia didn’t feel euphoria — they got anxious,” Bailer says. And the more dopamine coursing through anorexics’ brains, the more anxious they felt. Anorexics’ reaction to the chemical could help explain why they steer clear of food — or at least foods that healthy people find tempting. “Anorexics don’t usually get anxious if you give them a plate of cucumbers,” Bailer says.
Beyond the anxiety finding, one other aspect of the study sticks out: Instead of examining sick patients, Bailer, Kaye and colleagues recruited women who had recovered from anorexia. By studying people whose brains are no longer starving, Kaye’s team hopes to sidestep the chicken-and-egg question of whether specific brain signatures predispose people to anorexia or whether anorexia carves those signatures in the brain.
Though Kaye says that there’s still a lot scientists don’t know about anorexia, he’s convinced it’s a disorder that starts in the brain. Compared with healthy children, anorexic children’s brains are getting different signals, he says. “Parents have to realize that it’s very hard for these kids to change.”
Kaye thinks imaging data can help families reframe their beliefs about anorexia, which might help them handle tough treatments. He thinks the data can also offer new insights into therapies tailored for anorexics’ specific traits.
Sensory underload
One trait Kaye has focused on is anorexics’ sense of awareness of their bodies. Peel back the outer lobes of the brain by the temples, and the bit that handles body awareness pops into view. These regions, little islands of tissue called the insula, are one of the first brain areas to register pain, taste and other sensations. When people hold their breath, for example, and feel the panicky claws of air hunger, “the insula lights up like crazy,” Kaye says.
Kaye and colleagues have shown that the insulas of people with anorexia seem to be somewhat dulled to sensations. In a recent study, his team strapped heat-delivering gadgets to volunteers’ arms and cranked the devices to painfully hot temperatures while measuring insula activity via fMRI.
Compared with healthy volunteers, bits of recovered anorexics’ insulas dimmed when the researchers turned up the heat. But when researchers simply warned that pain was coming, other parts of the brain region flared brightly, Kaye’s team reported in January in the International Journal of Eating Disorders. For people who have had anorexia, actually feeling pain didn’t seem as bad as anticipating it. “They don’t seem to be sensing things correctly,” says Kaye.
If anorexics can’t detect sensations like pain properly, they may also have trouble picking up other signals from the body, such as hunger. Typically when people get hungry, their insulas rev up to let them know. And in healthy hungry people, a taste of sugar really gets the insula excited. For anorexics, this hunger-sensing part of the brain seems numb. Parts of the insula barely perked up when recovered anorexic volunteers tasted sugar, Kaye’s team showed this June in the American Journal of Psychiatry. The findings “may help us understand why people can starve themselves and not get hungry,” Kaye says.
Though the brain region that tells people they’re hungry might have trouble detecting sweet signals, some reward circuits seem to overreact to the same cues. Combined with a tendency to swap happiness for anxiety, and a mental vise grip on behavior, anorexics might have just enough snags in their brain wiring to tip them toward disease.
Now, Kaye’s group hopes to tap neuroimaging data for new treatment ideas. One day, he thinks doctors might be able to help anorexics “train” their insulas using biofeedback. With real-time brain scanning, patients could watch as their insulas struggle to pick up sugar signals, and then practice strengthening the response. More effective treatment options could potentially spare anorexics the relapses many patients suffer.
Heenan says she’s one of the lucky ones. Four years have passed since she first saw the anorexic brain images at UCSD. In the months following her treatment, Heenan and her family worked together to rebuild her relationship with food. At first, her fiancé picked out all her meals, but step by step, Heenan earned autonomy over her diet. Today, Heenan, a coordinator for Minneapolis’ public schools, is married and has a new puppy. “Life can be good,” she says. “Life can be fun. I want other people to know the freedom that I do.”
Searching for treatments
The bowl of pasta sitting in front of Kelsey Heenan didn’t look especially scary.
Spaghetti, chopped asparagus and chunks of chicken glistened in an olive oil sauce. Usually, such savory fare might make a person’s mouth water. But when Heenan’s fiancé served her a portion, she started sobbing. “You can’t do this to me,” she told him. “I thought you loved me!”
Heenan was confronting her “fear foods” at the Eating Disorders Center for Treatment and Research at UCSD. Therapists in her treatment program, Intensive Multi-Family Therapy, spend five days teaching anorexic patients and families about the disorder and how to encourage healthy eating. “There’s no blame,” says Christina Wierenga, a clinical neuropsychologist at UCSD. “The focus is just on having the parent refeed the child.” Therapists lay out healthy meals and portion sizes for teens, bolster parents’ self-confidence and hammer home the dangers of not eating. Heenan compares the experience to boot camp. But by the end of her time at the center, she says, “I was starting to see glimpses of what life could be like as a healthy person.”
Treatment options for anorexia include a broad mix of behavioral and medication-based therapies. Most don’t work very well, and many lack the support of evidence-based trials. Hospitalizing patients can boost short-term weight gain, “but when people go home they lose all the weight again,” says Stanford University’s James Lock, one of the architects of family-based treatment. That treatment is currently considered the most effective therapy for adolescent anorexics.
In a 2010 clinical trial, half of teens who underwent FBT maintained a normal weight a year after therapy. In contrast, only a fifth of teens treated with adolescent-focused individual therapy, which aims to help kids cope with emotions without using starvation, hit the healthy weight goal.
Few good options exist for adult anorexics, a group notorious for dropping out of therapy. New work hints that cognitive remediation therapy, or CRT, which uses cognitive exercises to change anorexics’ behaviors, has potential. After two months of CRT, only 13 percent of patients abandoned treatment, and most regained some weight, Lock and colleagues reported in the April International Journal of Eating Disorders. Researchers still need to find out, however, if CRT helps patients keep weight on long-term.
Next-generation drugs designed to fight Alzheimer’s disease look very promising. Scientists have unveiled the mechanisms behind two classes of compound currently being tested in clinical trials. They have also identified a likely cause of early-onset hereditary forms of the disease.
The future is looking good for drugs designed to combat Alzheimer’s disease. EPFL scientists have unveiled how two classes of drug compounds currently in clinical trials work to fight the disease. Their research suggests that these compounds target the disease-causing peptides with high precision and with minimal side-effects. At the same time, the scientists offer a molecular explanation for early-onset hereditary forms of Alzheimer’s, which can strike as early as thirty years of age. The conclusions of their research, which has been published in the journal Nature Communications, are very encouraging regarding the future of therapeutic means that could keep Alzheimer’s disease in check.
Alzheimer’s disease is characterized by an aggregation of small biological molecules known as amyloid peptides. We all produce these molecules; they play an essential antioxidant role. But in people with Alzheimer’s disease, these peptides aggregate in the brain into toxic plaques – called “amyloid plaques” – that destroy the surrounding neurons.
The process starts with a long protein, “APP”, which is located across the neuron’s membrane. This protein is cut into several pieces by an enzyme, much like a ribbon is cut by scissors. The initial cut generates a smaller intracellular protein that plays a useful role in the neuron. Another cut releases the rest of APP outside the cell – this part is the amyloid peptide.
For reasons not yet well understood, APP protein can be cut in several different places, producing amyloid peptides that are of varying lengths. Only the longer forms of the amyloid peptide carry the risk of aggregating into plaques, and people with Alzheimer’s disease produce an abnormally high number of these.
A favorite Alzheimer’s target: gamma secretase
The two next-generation classes of compound that are currently in clinical trials target an enzyme that cuts APP, known as gamma secretase. Until now, our understanding of the mechanism involved has been lacking. But with this work, the EPFL researchers were able to shed some more light on it by determining how the drug compounds affect gamma secretase and its cutting activity.
In most forms of Alzheimer’s, abnormally large quantities of the long amyloid peptide 42 – named like that because it contains 42 amino acids – are formed. The drug compounds change the location where gamma secretase cuts the APP protein, thus producing amyloid peptide 38 instead of 42, which is shorter and does not aggregate into neurotoxic plaques.
Compared to previous therapeutic efforts, this is considerable progress. In 2010, Phase III clinical trials had to be abandoned, because the compound being tested inhibited gamma-secretase’s function across the board, meaning that the enzyme was also deactivated in essential cellular differentiation processes, resulting to side-effects like in gastrointestinal bleeding and skin cancer.
“Scientists have been trying to target gamma secretase to treat Alzheimer’s for over a decade,” explains Patrick Fraering, senior author on the study and Merck Serono Chair of Neurosciences at EPFL. “Our work suggests that next-generation molecules, by modulating rather than inhibiting the enzyme, could have few, if any, side-effects. It is tremendously encouraging.”
New insights into hereditary forms of the disease
During their investigation, the scientists also identified possible causes behind some hereditary forms of Alzheimer’s disease. Early-onset Alzheimer’s can appear as early as thirty years of age, with a life expectancy of only a few years. In vitro experiments and numerical simulations show that in early-onset patients, mutations in the APP protein gene modify the way by which APP is cut by the gamma-secretase enzyme. This results in overproduction of amyloid peptide 42, which then aggregates into amyloid plaques.
This research illuminates much that is unknown about Alzheimer’s disease. “We have obtained extraordinary knowledge about how gamma secretase can be modulated,” explains co-author Dirk Beher, scientific chief officer of Asceneuron, a spin-off of Merck Serono, the biopharmaceutical division of Merck KGaA, Darmstadt, Germany. “This knowledge will be invaluable for developing even better targeted drugs to fight the disease.”
Scientists from the Florida campus of The Scripps Research Institute have described findings that could enable the development of more effective drugs for addiction with fewer side effects.
The study, published in the August 2, 2013 issue of the Journal of Biological Chemistry, showed in a combination of cell and animal studies that one active compound maintains a strong bias towards a single biological pathway, providing insight into what future drugs could look like.
The compound examined in the study, known as 6’- guanidinonaltrindole (6’-GNTI), targets the kappa opioid receptor (KOR). Located on nerve cells, KOR plays a role in the release of dopamine, a neurotransmitter that plays a key role in drug addiction. Drugs of abuse often cause the brain to release large amounts of dopamine, flooding the brain’s reward system and reinforcing the addictive cycle.
“There are a number of drug discovery efforts ongoing for KOR,” said Laura Bohn, a TSRI associate professor, who led the study. “The ultimate question is how this receptor should be acted upon to achieve the best therapeutic effects. Our study identifies a marker that shows how things normally happen in live neurons—a critically important secondary test to evaluate potential compounds.”
While KOR has become the focus for drug discovery efforts aimed at treating addiction and mood disorders, KOR can react to signals that originate independently from multiple biological pathways, so current drug candidates targeting KOR often produce unwanted side effects. Compounds that activate KOR can decrease the rewarding effects of abused drugs, but also induce sedation and depression.
The new findings, from studies of nerve cells in the striatum (an area of the brain involved in motor activity and higher brain function), reveal a point on the KOR signaling pathway that may prove to be an important indicator of whether drug candidates can produce effects similar to the natural biological effects.
“Standard screening assays can catch differences but those differences may not play out in live tissue,” Bohn noted. “Essentially, we have shown an important link between cell-based screening assays and what occurs naturally in animal models.”
Those vulnerable to alcoholism may experience an unusually large response in the brain’s reward-seeking pathway when they take a drink
Research from McGill University suggests that people who are vulnerable to developing alcoholism exhibit a distinctive brain response when drinking alcohol, according to a new study by Prof. Marco Leyton, of McGill University’s Department of Psychiatry. Compared to people at low risk for alcohol-use problems, those at high risk showed a greater dopamine response in a brain pathway that increases desire for rewards. These findings, published in the journal Alcoholism: Clinical & Experimental Research, could help shed light on why some people are more at risk of suffering from alcoholism and could mark an important step toward the development of treatment options.
“There is accumulating evidence that there are multiple pathways to alcoholism, each associated with a distinct set of personality traits and neurobiological features”, said Prof. Leyton, a researcher in the Mental Illness and Addiction axis at the Research Institute of the McGill University Health Centre (RI-MUHC). “These individual differences likely influence a wide range of behaviors, both positive and problematic. Our study suggests that a tendency to experience a large dopamine response when drinking alcohol might contribute to one (or more) of these pathways.”
For the study, researchers recruited 26 healthy social drinkers (18 men, 8 women), 18 to 30 years of age, from the Montreal area. The higher-risk subjects were then identified based on personality traits and having a lower intoxication response to alcohol (they did not feel as drunk despite having drunk the same amount). Finally, each participant underwent two positron emission tomography (PET) brain scan exams after drinking either juice or alcohol (about 3 drinks in 15 minutes).
“We found that people vulnerable to developing alcoholism experienced an unusually large brain dopamine response when they took a drink,” said Leyton. “This large response might energize reward-seeking behaviors and counteract the sedative effects of alcohol. Conversely, people who experience minimal dopamine release when they drink might find the sedative effects of alcohol especially pronounced.”
“Although preliminary, the results are compelling,” said Dr. Leyton. “A much larger body of research has identified a role for dopamine in reward-seeking behaviors in general. For example, in both laboratory animals and people, increased dopamine transmission seems to enhance the attractiveness of reward-related stimuli. This effect likely contributes to why having one drink increases the probability of getting a second one – the alcohol-induced dopamine response makes the second drink look all the more desirable. If some people are experiencing unusually large dopamine responses to alcohol, this might put them at risk.”
“People with loved ones struggling with alcoholism often want to know two things: How did they develop this problem? And what can be done to help? Our study helps us answer the first question by furthering our understanding of the causes of addictions. This is an important step toward developing treatments and preventing the disorder in others.”
Physicists and neuroscientists from The University of Nottingham and University of Birmingham have unlocked one of the mysteries of the human brain, thanks to new research using functional Magnetic Resonance Imaging (fMRI) and electroencephalography (EEG).
The work will enable neuroscientists to map a kind of brain function that up to now could not be studied, allowing a more accurate exploration of how both healthy and diseased brains work.
Functional MRI is commonly used to study how the brain works, by providing spatial maps of where in the brain external stimuli, such as pictures and sounds, are processed. The fMRI scan does this by detecting indirect changes in the brain’s blood flow in response to changes in electrical signalling during the stimulus.
Combining techniques
A signal change that happens after the stimulus has stopped is also observed with the fMRI scan. This is called the post-stimulus signal and up until now it has not been used to study how the brain works because its origin was uncertain.
In novel experiments, the research team has now combined fMRI techniques with EEG, which measures electrical activity in the brain, to show that the post-stimulus signal also actually reflects changes in brain signalling.
18 healthy volunteers were monitored by using EEG to measure the electrical activity generated by their brains’ neurons (the signalling cells) while simultaneously recording fMRI measurements. A stimulus of electrical pulses was used to activate the part of the brain that controls movement in the right thumb.
The scientists then compared the EEG and fMRI signals and found that they both vary in the same way after the stimulus stops. This provides compelling evidence that the post-stimulus fMRI signal is a measure of neuronal activity rather than just changes in the brain’s blood flow. Curiously, the team also found the post-stimulus fMRI signal was not consistent, even though the stimulus input to the brain was the same each time. This natural variability in the brain response was also reflected by the EEG activity and the researchers suggest that this signal might help the brain make the transition from processing stimuli back to their internal thoughts in different ways.
New window
Dr Karen Mullinger from The University of Nottingham’s Sir Peter Mansfield Magnetic Resonance Centre said: “This work opens a new window of time in the fMRI signal in which we can look at what the brain is doing. It may also open up new research avenues in exploring the function of the healthy brain and the study of neurological diseases.”
Dr Stephen Mayhew from Birmingham University Imaging Centre said “We do not know what the exact role of the post-stimulus activity is or why this response is not always consistent when the stimulus input to the brain is the same. We have already secured funding through the Birmingham-Nottingham Strategic Collaboration Fund to continue this research into further understanding of human brain function using combinations of neuroimaging methods.”
Director of the Sir Peter Mansfield Magnetic Resonance Centre, Professor Peter Morris, said: “Functional magnetic resonance imaging is the main tool available to cognitive neuroscientists for the investigation of human brain function. The demonstration in this paper, that the secondary fMRI response (the post-stimulus undershoot) is not simply a passive blood flow response, but is directly related to synchronous neural activity, as measured with EEG, heralds an exciting new chapter in our understanding of the workings of the human mind.”
The work has been funded by the Medical Research Council (MRC), Engineering and Physical Science Research Council (EPSRC), The University of Nottingham Anne McLaren Fellowships and University of Birmingham Fellowship and is published in the Proceedings of the National Academy of Sciences (PNAS).
A boost in the speed of brain scans is unveiling new insights into how brain regions work with each other in cooperative groups called networks.
Scientists at Washington University School of Medicine in St. Louis and the Institute of Technology and Advanced Biomedical Imaging at the University of Chieti, Italy, used the quicker scans to track brain activity in volunteers at rest and while they watched a movie.
“Brain activity occurs in waves that repeat as slowly as once every 10 seconds or as rapidly as once every 50 milliseconds,” said senior researcher Maurizio Corbetta, MD, the Norman J. Stupp Professor of Neurology. “This is our first look at these networks where we could sample activity every 50 milliseconds, as well as track slower activity fluctuations that are more similar to those observed with functional magnetic resonance imaging (fMRI). This analysis performed at rest and while watching a movie provides some interesting and novel insights into how these networks are configured in resting and active brains.”
Understanding how brain networks function is important for better diagnosis and treatment of brain injuries, according to Corbetta.
The study appears online in Neuron.
Researchers know of several resting-state brain networks, which are groups of different brain regions whose activity levels rise and fall in sync when the brain is at rest. Scientists used fMRI to locate and characterize these networks, but the relative slowness of this approach limited their observations to activity that changes every 10 seconds or so. A surprising result from fMRI was that the spatial pattern of activity (or topography) of these brain networks is similar at rest and during tasks.
In contrast, a faster technology called magnetoencephalography (MEG) can detect activity at the millisecond level, letting scientists examine waves of activity in frequencies from slow (0.1-4 cycles per second) to fast (greater than 50 cycles per second).
“Interestingly, even when we looked at much higher temporal resolution, brain networks appear to fluctuate on a relatively slow time scale,” said first author Viviana Betti, PhD, a postdoctoral researcher at Chieti. “However, when the subjects went from resting to watching a movie, the networks appeared to shift the frequency channels in which they operate, suggesting that the brain uses different frequencies for rest and task, much like a radio.”
In the study, the scientists asked one group of volunteers to either rest or watch the movie during brain scans. A second group was asked to watch the movie and look for event boundaries, moments when the plot or characters or other elements of the story changed. They pushed a button when they noticed these changes.
As in previous studies, most subjects recognized similar event boundaries in the movie. The MEG scans showed that the communication between regions in the visual cortex was altered near the movie boundaries, especially in networks in the visual cortex.
“This gives us a hint of how cognitive activity dynamically changes the resting-state networks,” Corbetta said. “Activity locks and unlocks in these networks depending on how the task unfolds. Future studies will need to track resting-state networks in different tasks to see how correlated activity is dynamically coordinated across the brain.”
Anemia, or low levels of red blood cells, may increase the risk of dementia, according to a study published in the July 31, 2013, online issue of Neurology®, the medical journal of the American Academy of Neurology.
“Anemia is common in the elderly and occurs in up to 23 percent of adults ages 65 and older,” said study author Kristine Yaffe, MD, with the University of California – San Francisco and a member of the American Academy of Neurology. “The condition has also been linked in studies to an increased risk of early death.”
For the study, 2,552 older adults between the ages of 70-79 were tested for anemia and also underwent memory and thinking tests over 11 years. Of those, 393 had anemia at the start of the study. At the end of the study, 445, or about 18 percent of participants, developed dementia.
The research found that people who had anemia at the start of the study had a nearly 41 percent higher risk of developing dementia than those who were not anemic. The link remained after considering other factors, such as age, race, sex and education. Of the 393 people with anemia, 89 people, or 23 percent, developed dementia, compared to 366 of the 2,159 people who did not have anemia, or 17 percent.
“There are several explanations for why anemia may be linked to dementia. For example, anemia may be a marker for poor health in general, or low oxygen levels resulting from anemia may play a role in the connection. Reductions in oxygen to the brain have been shown to reduce memory and thinking abilities and may contribute to damage to neurons,” said Yaffe.
In a retrospective study, Saint Louis University researchers have found that patients with melanoma brain metastases can be treated with large doses of interleukin-2 (HD IL-2), a therapy that triggers the body’s own immune system to destroy the cancer cells.
The study that was recently published in Chemotherapy Research and Practice, reviews cases of eight patients who underwent this therapy at Saint Louis University.
John Richart, M.D., associate professor of internal medicine at SLU and principal investigator of the study, first treated a patient with the disease using the HD IL-2 treatment in 1999.
"Traditionally, melanoma patients with brain metastases have not been considered for HD IL-2 because treatment was thought to be futile," Richart said. "Our study shows that having this condition does not exclude a patient from getting this treatment and can in fact improve the length of their life."
Melanoma is the most dangerous form of skin cancer that begins in the melanin-producing cells called melanocytes. In some melanoma patients, the cancer spreads to the brain, causing multiple tumors that are difficult to treat. According to the CDC, melanoma is the third most common cancer causing brain metastases in the U.S. Richart said the median overall survival of patients with melanoma brain metastases is approximately four months whereas in the study, the median overall survival for patients was 8.7 months.
During the treatment, patients are given an IV medication - a chemical the body naturally makes that stimulates the immune system to recognize and destroy melanoma cells - for a period of six days while they are admitted to the hospital and are closely monitored by doctors and nurses. A patient requires four such six-day admission cycles in order to complete the course of the treatment.
To be eligible for HD IL-2 treatment, melanoma patients with brain metastases have to be in healthy shape with good brain function - that is they cannot have brain lesions that are growing rapidly or show any symptoms of brain lesions. In the past, melanoma patients with brain metastases have been considered ineligible for this treatment because doctors thought that the treatment would cause life-threatening cerebral edema, a complication that causes excess accumulation of fluids in the brain, and neurotoxicity, or irreversible damage to the brain or the nervous system.
"In this review, we found that there were no episodes of treatment-related mortality. Our findings demonstrate that HD IL-2 can be considered as an option for patients with melanoma brain metastases," said Melinda Chu, M.D., a first year dermatology resident at SLU and first author of the study.
SLU is the only medical center in the region that provides this treatment.
"We need a highly skilled nursing staff for the HD-IL-2 program to be successful," Richart said. "Our nursing team at SLU is with each patient every step of the way, 24 hours a day. They help patients get through and continue the treatment."
New projects will target Fragile X syndrome, nicotine addiction, and age-related macular degeneration
The National Institutes of Health has launched three innovative projects that will focus on development of therapeutics for Fragile X syndrome, nicotine addiction, and age-related macular degeneration (AMD). These projects are funded through the NIH Blueprint Neurotherapeutics Network which provides access to a variety of drug development resources.
“We are excited about the opportunity to apply cutting-edge science to the pursuit of novel treatments for these debilitating disorders” said Rebecca Farkas, Ph.D., program director at NIH’s National Institute of Neurological Disorders and Stroke (NINDS), Office of Translational Research.
The purpose of the NIH Blueprint is to provide in-depth research capabilities to increase the success rate of innovative drug discovery efforts. The program uses a virtual pharma model to provide researchers with access to support and resources that have been traditionally available to large pharmaceutical companies.
Partnerships between NIH program staff and awarded research teams are designed to bridge the funding gap between ground-breaking laboratory research and industry adoption. NIH staff helps investigators work with veteran industry drug development consultants and contract research organization capabilities from the discovery stage through preliminary clinical trials. In addition, each investigator maintains sole ownership of intellectual property associated with his or her project
NIH launched the Blueprint Neurotherapeutics Network in 2011. Including these three awards, 14 drug discovery programs have been funded as part of the program and 10 are currently active (see: http://neuroscienceblueprint.nih.gov/bpdrugs/bpn.htm).
The newly-funded investigators and their organizations are:
The work of two University of Alberta researchers and their teams has contributed to an important next step in finding a cure for deadly prion-folding diseases in humans and animals.
Professor Michael James of the Department of Biochemistry, professor Nat Kav of the Department of Agricultural, Food and Nutritional Science and their labs collaborated to produce mini-antibodies and antibody fragments, using data provided by principal researchers in Switzerland.
The fragments were then used by the lead researchers at the Institute of Neuropathology in Zurich to study interactions between the antibodies and the prion protein and how it results in cell death.
The work conducted at the U of A helps to open the door to designing a molecule that would block prion infection.
“We hope to design a chemical compound that would bind to some part of the prion molecule to prevent the conversion of the normal form of the protein to the disease-causing form,” said James.
Prion protein infections, caused by structural misfolding within the prion protein, lead to fatal neurodegenerative disorders such as Creutzfeldt-Jakob Disease in humans, Bovine Spongiform Encephalopathy (BSE) in cattle and Chronic Wasting Disease in deer. There is currently no cure.
Using recombinant DNA technology, Kav and his lab produced the mini-antibodies and antibody fragments that were then used by James and ultimately studied biologically in the Zurich lab. Using a process called X-ray crystallography, James’s lab was able to identify the three-dimensional structure of where antibodies and antibody fragments bind to the prion molecule, pinpointing regions that are susceptible to changing to a diseased state.
The discovery now makes it possible to begin designing ways to prevent prion disease, in everything from developing treatment for human victims to creating a preventative additive for livestock feed.
The work done by the U of A teams was crucial to the overall research conducted in Zurich, and reflects the high calibre of quality research conducted on campus, Kav noted.
“The U of A collaborated with one of the leading labs in the world, which demonstrates our own level of excellence.”
It also reinforces the U of A’s standing as a leading site of prion research through such institutions as the university’s Centre for Prions and Protein Folding Diseases, James said.
“This latest work advances that.”
The U of A portion of the research was supported by the Alberta Prion Research Institute and PrioNet Canada. The research appears in Nature.
About nine months after suffering a stroke, the patient noticed that words written in a certain shade of blue evoked a strong feeling of disgust. Yellow was only slightly better. Raspberries, which he never used to eat very often, now tasted like blue – and blue tasted like raspberries.
High-pitched brass instruments—specifically the brass theme from James Bond movies—elicited feelings of ecstasy and light blue flashes in his peripheral vision and caused large parts of his brain to light up on an MRI. Music played by a euphonium, a tenor-pitched brass instrument, shut down those sensations.
The patient said he was initially frightened by the mixed messages his brain was sending him and the conflicting senses he was experiencing. He was so worried that something was seriously wrong with him that he raised it with a nurse only as he was leaving an appointment at St. Michael’s Hospital in downtown Toronto.
Physicians and researchers immediately recognized he had synesthesia, a neurological condition in which people experience more than one sense at the same time. They may “see” words or numbers as colours, hear sounds in response to smells or feel something in response to sight.
Most synesthetes are born with the condition, and include some of the world’s most famous authors and artists, including author Vladimir Nabakov, composer Franz Liszt, painter Vasily Kandinsky and singer-songwriter Billy Joel.
The Toronto patient is only the second known person to have acquired synesthesia as a result of a brain injury, in this case a stroke. His case was described in the August issue of the journal Neurology by Dr. Tom Schweizer, a neuroscientist and director of the Neuroscience Research Program at St. Michael’s Li Ka Shing Knowledge Institute.
Dr. Schweizer examined the patient’s brain activity in a functional MRI and compared it to six men of similar age (45) and education (18 years) as each listened to the James Bond Theme and a euphonium solo.
When the James Bond Theme was played, large areas of the patient’s brain lit up including the thalamus (the brain’s information switchboard), the hippocampus (which deals with memory and spatial navigation) and the auditory cortex (which processes sound).
"The areas of the brain that lit up when he heard the James Bond Theme are completely different from the areas we would expect to see light up when people listen to music," Dr. Schweizer said. "Huge areas on both sides of the brain were activated that were not activated when he listened to other music or other auditory stimuli and were not activated in the control group."
The patient and members of the control group also viewed 10-second blocks of words presented in black (which elicits no emotional response in the patient), yellow (mild disgust response) and blue (intense disgust response).
Reading blue letters produced extensive activity in the parts of the patient’s brain responsible for sensory information and processing emotional stimuli and similar but less intense responses for yellow letters. Control groups showed no heightened brain activity in response to the different coloured letters.
Dr. Schweizer said the fact that the patient had very targeted and specific responses to certain stimuli – and that these responses were not experienced by the control group – suggests that his synesthesia was caused as his brain tried to repair itself after his stroke and got cross-wired.
The patient’s stroke occurred in the thalamus, the brain’s central relay station. That’s the same part of the brain affected by the only other reported case of acquired synesthesia.
Higher variability in visit-to-visit blood pressure readings, independent of average blood pressure, could be related to impaired cognitive function in old age in those already at high risk of cardiovascular disease, suggests a paper published today on BMJ.
There is increasing evidence that vascular factors contribute in development and progression of dementia. This is of special interest as cardiovascular factors may be amendable and thus potential targets to reduce cognitive decline and the incidence of dementia. Visit-to-visit blood pressure variability has been linked to cerebrovascular damage (relating to the brain and its blood vessels). It has also been shown that this variability can increase the risk of stroke.
It has been suggested that higher blood pressure variability might potentially lead to cognitive impairment through changes in the brain structures.
Researchers from the Leiden University Medical Center (Netherlands), University College Cork (Ireland) and the Glasgow University (UK) therefore investigated the association of visit-to-visit blood pressure variability (independent of average blood pressure) with cognitive function in older subjects at high risk of cardiovascular disease.
All data were obtained from the PROSPER study, which investigated the effect of statins in prevention of vascular events in older men and women. This study took data on 5,461 individuals aged 70-82 years old in Ireland, Scotland and the Netherlands. Average follow-up was three years.
Both systolic (peak pressure) and diastolic (minimum pressure) blood pressures were measured every three months in the same clinical setting. The variability between these measurements were calculated and used in the analyses.
The study used data on cognitive function where the following was tested: selective attention and reaction time; general cognitive speed; immediate and delayed memory performance.
Results showed that visit-to-visit blood pressure variability was associated with worse performance on all cognitive tests. The results were consistent after adjusting for cardiovascular disease and other risk factors.
The main findings of the study were: higher visit-to-visit blood pressure variability is associated with worse performance in different cognitive tests; higher variability is associated with higher risk of stroke and both these associations are independent of various cardiovascular risk factors, in particular, average blood pressure.
Researcher Simon Mooijaart, (Leiden University Medical Centre, Leiden, the Netherlands) says that by using a population of “over five thousand participants and over three years of blood pressure measurements, we showed that high visit-to-visit systolic and diastolic blood pressure variability associates with worse performance in different domains of cognitive function including selection attention, processing speed, immediate verbal memory and delayed verbal memory”. The researchers do add though that it is still unclear whether higher blood pressure variability is a cause or consequence of impaired cognitive function.
They suggest several explanations for their findings: firstly that blood pressure variability and cognitive impairment could stem from a common cause, with cardiovascular risk factors being the most likely candidate; secondly that variability might reflect a long term instability in the regulation of blood pressure and blood flow to the key organs in the body; thirdly that exaggerated fluctuations in blood pressure could result in the brain not receiving enough blood, which can cause brain injury, leading to impairment of cognitive function.
The researchers conclude that “higher visit-to-visit blood pressure variability independent of average blood pressure might be a potential risk factor with worse cognitive performance in older subjects at high risk of cardiovascular disease”. Given that dementia is a major public health issue, they say that further interventional studies are warranted to establish whether reducing blood pressure variability can decrease the risk of cognitive impairment in old age.
Small study could lead to identification of treatable diseases for some with chronic pain syndrome
About half of a small group of patients with fibromyalgia – a common syndrome that causes chronic pain and other symptoms – was found to have damage to nerve fibers in their skin and other evidence of a disease called small-fiber polyneuropathy (SFPN). Unlike fibromyalgia, which has had no known causes and few effective treatments, SFPN has a clear pathology and is known to be caused by specific medical conditions, some of which can be treated and sometimes cured. The study from Massachusetts General Hospital (MGH) researchers will appear in the journal PAIN and has been released online.
"This provides some of the first objective evidence of a mechanism behind some cases of fibromyalgia, and identifying an underlying cause is the first step towards finding better treatments," says Anne Louise Oaklander, MD, PhD, director of the Nerve Injury Unit in the MGH Department of Neurology and corresponding author of the Pain paper.
The term fibromyalgia describes a set of symptoms – including chronic widespread pain, increased sensitivity to pressure, and fatigue – that is believed to affect 1 to 5 percent of individuals in Western countries, more frequently women. While a diagnosis of fibromyalgia has been recognized by the National Institutes of Health and the American College of Rheumatology, its biologic basis has remained unknown. Fibromyalgia shares many symptoms with SFPN, a recognized cause of chronic widespread pain for which there are accepted, objective tests.
Designed to investigate possible connections between the two conditions, the current study enrolled 27 adult patients with fibromyalgia diagnoses and 30 healthy volunteers. Participants went through a battery of tests used to diagnose SFPN, including assessments of neuropathy based on a physical examination and responses to a questionnaire, skin biopsies to evaluate the number of nerve fibers in their lower legs, and tests of autonomic functions such as heart rate, blood pressure and sweating.
The questionnaires, exam assessments, and skin biopsies all found significant levels of neuropathy in the fibromyalgia patients but not in the control group. Of the 27 fibromyalgia patients, 13 had a marked reduction in nerve fiber density, abnormal autonomic function tests or both, indicating the presence of SFPN. Participants who met criteria for SFPN also underwent blood tests for known causes of the disorder, and while none of them had results suggestive of diabetes, a common cause of SFPN, two were found to have hepatitis C virus infection, which can be successfully treated, and more than half had evidence of some type of immune system dysfunction.
"Until now, there has been no good idea about what causes fibromyalgia, but now we have evidence for some but not all patients. Fibromyalgia is too complex for a ‘one size fits all’ explanation," says Oaklander, an associate professor of Neurology at Harvard Medical School. "The next step of independent confirmation of our findings from other laboratories is already happening, and we also need to follow those patients who didn’t meet SFPN criteria to see if we can find other causes. Helping any of these people receive definitive diagnoses and better treatment would be a great accomplishment."