Neuroscience

The hallmark of an excellent researcher is an open mind. That flexibility and openness is what led Nina Schor, M.D., Ph.D., the William H. Eilinger Chair of Pediatrics at the University of Rochester, to follow a hunch about a brain receptor – resulting in a new mouse model that may give researchers a new avenue for testing drugs for autism. Nature Publishing Groups’ Translational Psychiatry published the study online today.

Schor had been studying p75 neurotrophin receptors in her long-standing neuroblastoma research, but she also knew that p75NTR is involved in the reaction to oxidative stress in the brain, which some research posits plays a role in the development of autism. The receptor is also prevalent in the developing brain and drops off as a child reaches 2 to 3 years old, which is when autism symptoms often begin to appear. P75NTR stays present in the typically developing cerebellum, hippocampus and basal forebrain, parts of the brain that are anatomically abnormal in autism.

“Science doesn’t always travel in a straight line,” Schor said. “Sometimes the importance of a scientific study in one field is what it unexpectedly tells us about another field.”

While other researchers are focused on the proteins found to be abnormal in patients with autism, Schor approached her investigation from the opposite direction. She thought about what characteristics a protein would have to have to be involved in processes thought to play a role in autism. “That list of characteristics looked suspiciously like those we had found to be associated with p75NTR.”

Then, Schor and her colleagues prevented mouse brains from making p75NTR in one autism-associated type of cell in the cerebellum. What they found was that not only does the mouse’s cerebellum resemble that of children with autism, but the mouse also behaves much like children with autism. They don’t engage in typical social behaviors of mice and instead, ignore stranger mice and lack curiosity about their surroundings. They also jump twice as much as typical mice, which is like a “stimming,” or self-stimulatory, behavior typical in children with autism.

“Whether or not p75NTR turns out to be abnormal in children with autism,” Schor explained, “these studies still hold the promise of helping us explain the mechanisms behind the component behaviors of children with autism.

Schor plans to continue the research, focusing on more behavioral testing, finding evidence of whether children with autism have a p75NTR deficit in their cerebellum and starting pharmaceutical testing to see whether there is a drug that can replace the role p75NTR plays in that part of the brain.

“It’s a long way from a mouse model to a successful treatment in humans, but this is a good clue,” Schor said.

Research to be presented at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB), the foremost society for research into all aspects of eating and drinking behavior, describes a way that brain chemistry may make some people notice food more easily, which can tempt overeating even in people who are not overweight. Dopamine activity in the striatum, an area of the brain sensitive to food reward, was linked to how quickly men noticed a food picture hidden among neutral pictures. In turn, the men who quickly noticed food pictures also ate more.

From rodent research it is clear that dopamine action in the striatum motivates eating, and this goes awry in obesity. “We do know that in human obesity the striatal dopamine system is affected, but interesting enough we know little about the striatal dopamine system of young, healthy individuals and how it relates to the motivation to eat” says Susanne la Fleur from the Academic Medical Center in Amsterdam, who directed the study linking dopamine, attention to food, and eating.

Ordinarily the burst of dopamine during a rewarding activity is eventually stopped when it is re-absorbed into the cells it came from. That re-uptake process requires a brain chemical called “dopamine transporter” (DAT). Lower DAT means dopamine is reabsorbed more slowly, causing it to keep acting on the brain. The researchers scanned brains of healthy, non-obese young men to determine available DAT. The men completed a computerized visual attention task to see how quickly they could detect food pictures among neutral pictures. Subjects were also asked to report food intake during 7 days.

The researchers found that the men with lower DAT, which means higher dopamine activity, showed a stronger visual attention bias towards food, detecting food pictures more quickly. “We could speculate that in healthy humans dopamine does motivate eating, however although we did observe a correlation between striatal dopamine transporter binding and the visual attention bias for food; and between visual attention bias for food and actual food intake, we did not observe a correlation between striatal dopamine transporter binding and actual food intake. Thus, a factor in addition to dopamine must be involved in going from being motivated to actual eating”, la Fleur concluded.

People who have the most common genetic mutation linked to obesity respond differently to pictures of appetizing foods than overweight or obese people who do not have the genetic mutation, according to a new study published in the Endocrine Society’s Journal of Clinical Endocrinology & Metabolism (JCEM).

More than one-third of adults are obese. Obesity typically results from a combination of eating too much, getting too little physical activity and genetics. In particular, consumption of appetizing foods that are high in calories can lead to weight gain. Highly palatable foods such as chocolate trigger signals in the brain that give a feeling of pleasure and reward. These cravings can contribute to overeating. Reward signals are processed in specific areas of the brain, where sets of neurons release chemicals such as dopamine. However, very little is known about whether the reward centers of the brain work differently in some people who are overweight or obese.

The most common genetic cause of obesity involves mutations in the melanocortin 4 receptor (MC4R), which occur in about 1 percent of obese people and contribute to weight gain from an early age. The researchers compared three groups of people: eight people who were obese due to a problem in the MC4R gene, 10 people who were overweight or obese without the gene mutation and eight people who were normal weight. They performed functional Magnetic Resonance Imaging (fMRI) scans to look at how the reward centers in the brain were activated by pictures of appetizing food such as chocolate cake compared to bland food such as rice or broccoli and non-food items such as staplers.

“In our study, we found that people with the MC4R mutation responded in the same way as normal weight people, while the overweight people without the gene problem had a lower response,” said lead researcher Agatha van der Klaauw, MD, PhD, of the Wellcome Trust-MRC Institute of Metabolic Science at Addenbrooke’s Hospital in Cambridge, U.K. “In fact, the brain’s reward centers light up when people with the mutation and normal weight people viewed pictures of appetizing foods. But overweight people without the mutation did not have the same level of response.”

The scans revealed that obese people with the MC4R mutation had similar activity in the reward centers of the brain when shown a picture of a dessert like cake or chocolate as normal weight people. The researchers found that, in contrast, the reward centers were underactive in overweight and obese volunteers who did not have the gene mutation. This finding is intriguing as it shows a completely different response in two groups of people of the same age and weight.

“For the first time, we are seeing that the MC4R pathway is involved in the brain’s response to food cues and its underactivity in some overweight people,” van der Klaauw said. “Understanding this pathway may help in developing interventions to limit the overconsumption of highly palatable foods that can lead to weight gain.”

To address the obesity epidemic, the Cambridge team is continuing to study the pathways in the brain that coordinate the need to eat and the reward and pleasure of eating

A study published in the American Journal of Geriatric Psychiatry indicates that middle-aged adults with a history of problem drinking are more than twice as likely to suffer from severe memory impairment in later life.

The study highlights the hitherto largely unknown link between harmful patterns of alcohol consumption and problems with memory later in life – problems which may place people at a high risk of developing dementia.

The study was carried out by researchers from the University of Exeter Medical School with support from the NIHR Collaboration for Leadership in Applied Health Research and Care South West Peninsula (NIHR PenCLAHRC).

The research team studied the association between a history of alcohol use disorders (AUDs) and the onset of severe cognitive and memory impairment in 6542 middle-aged adults born between 1931 and 1941. These individuals participated in the Health and Retirement Study in the US.

Participants were first assessed in 1992 and follow-up assessments took place every other year from 1996 to 2010.

A history of AUDs was identified using the CAGE* questionnaire (short for Cut down, Annoyed, Guilty, Eye-opener). Where participants registered a history of AUDs their chances of developing severe memory impairment more than doubled.

The study was led by Dr Iain Lang. He commented: “We already know there is an association between dementia risk and levels of current alcohol consumption – that understanding is based on asking older people how much they drink and then observing whether they develop problems. But this is only one part of the puzzle and we know little about the consequences of alcohol consumption earlier in life. What we did here is investigate the relatively unknown association between having a drinking problem at any point in life and experiencing problems with memory later in life.”

He added: “This finding – that middle-aged people with a history of problem drinking more than double their chances of memory impairment when they are older – suggests three things: that this is a public health issue that needs to be addressed; that more research is required to investigate the potential harms associated with alcohol consumption throughout life; and that the CAGE questionnaire may offer doctors a practical way to identify those at risk of memory/cognitive impairment and who may benefit from help to tackle their relationship with alcohol.”

Dr Doug Brown, Director of Research and Development at Alzheimer’s Society said: “When we talk about drinking too much, the media often focuses on young people ending up in A&E after a night out. However, there’s also a hidden cost of alcohol abuse given the mounting evidence that alcohol abuse can also impact on cognition later in life. This small study shows that people who admitted to alcohol abuse at some point in their lives were twice as likely to have severe memory problems, and as the research relied on self-reporting that number may be even higher.

"This isn’t to say that people need to abstain from alcohol altogether. As well as eating a healthy diet, not smoking and maintaining a healthy weight, the odd glass of red wine could even help reduce your risk of developing dementia."

* The CAGE asks four questions (and the acronym comes from words in each question: Cut down, Annoyed, Guilty, Eye-opener):

1. Have you ever felt you should cut down on your drinking?
2. Have people annoyed you by criticising your drinking?
3. Have you ever felt bad or guilty about your drinking?
4. Have you ever had a drink first thing in the morning to steady your nerves or get rid of a hangover (eye-opener)?

A team of scientists has identified the neurons used in certain types of motion detection—findings that deepen our understanding of how the visual system functions.

“Our results show how neurons in the brain work together as part of an intricate process used to detect motion,” says Claude Desplan, a professor in NYU’s Department of Biology and the study’s senior author.

The study, whose authors included Rudy Behnia, an NYU post-doctoral fellow, as well as researchers from the NYU Center for Neural Science and Yale and Stanford universities, appears in the journal Nature.

The researchers sought to explain some of the neurological underpinnings of a long-established and influential model, the Hassenstein–Reichardt correlator. It posits that motion detection relies on separate input channels that are processed in the brain in ways that coordinate these distinct inputs. The Nature study focused on neurons acting in this processing.

The researchers examined the fruit fly Drosophila, which is commonly used in biological research as a model system to decipher basic principles that direct the functions of the brain.

Previously, scientists studying Drosophila have identified two parallel pathways that respond to either moving light, or dark edges—a dynamic that underscores much of what flies see in detecting motion. For instance, a bird is an object whose dark edges flies see as it first moves across the bright light of the sky; after it passes through their field of view, flies see the light edge of the background sky.

However, the nature of the underlying neurological processing had not been clear.

In their study, the researchers analyzed the neuronal activity of particular neurons used to detect these movements. Specifically, they found that four neurons in the brain’s medulla implement two processing steps. Two neurons— Tm1 and Tm2—respond to brightness decrements (central to the detection of moving dark edges); by contrast, two other neurons— Mi1 and Tm3—respond to brightness increments (or light edges). Moreover, Tm1 responds slower than does Tm2 while Mi1 responds slower than does Tm3, a difference in kinetics that fundamental to the Hassenstein-Reichardt correlator.

In sum, these neurons process the two inputs that precede the coordination outlined by the Hassenstein–Reichardt correlator, thereby revealing elements of the long-sought neural activity of motion detection in the fly.

Johns Hopkins researchers say they have discovered a chemical alteration in a single human gene linked to stress reactions that, if confirmed in larger studies, could give doctors a simple blood test to reliably predict a person’s risk of attempting suicide.

The discovery, described online in The American Journal of Psychiatry, suggests that changes in a gene involved in the function of the brain’s response to stress hormones plays a significant role in turning what might otherwise be an unremarkable reaction to the strain of everyday life into suicidal thoughts and behaviors.

“Suicide is a major preventable public health problem, but we have been stymied in our prevention efforts because we have no consistent way to predict those who are at increased risk of killing themselves,” says study leader Zachary Kaminsky, Ph.D., an assistant professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine. “With a test like ours, we may be able to stem suicide rates by identifying those people and intervening early enough to head off a catastrophe.”

For his series of experiments, Kaminsky and his colleagues focused on a genetic mutation in a gene known as SKA2. By looking at brain samples from mentally ill and healthy people, the researchers found that in samples from people who had died by suicide, levels of SKA2 were significantly reduced.

Within this common mutation, they then found in some subjects an epigenetic modification that altered the way the SKA2 gene functioned without changing the gene’s underlying DNA sequence. The modification added chemicals called methyl groups to the gene. Higher levels of methylation were then found in the same study subjects who had killed themselves. The higher levels of methylation among suicide decedents were then replicated in two independent brain cohorts.

In another part of the study, the researchers tested three different sets of blood samples, the largest one involving 325 participants in the Johns Hopkins Center for Prevention Research Study found similar methylation increases at SKA2 in individuals with suicidal thoughts or attempts. They then designed a model analysis that predicted which of the participants were experiencing suicidal thoughts or had attempted suicide with 80 percent certainty. Those with more severe risk of suicide were predicted with 90 percent accuracy. In the youngest data set, they were able to identify with 96 percent accuracy whether or not a participant had attempted suicide, based on blood test results.

The SKA2 gene is expressed in the prefrontal cortex of the brain, which is involved in inhibiting negative thoughts and controlling impulsive behavior. SKA2 is specifically responsible for chaperoning stress hormone receptors into cells’ nuclei so they can do their job. If there isn’t enough SKA2, or it is altered in some way, the stress hormone receptor is unable to suppress the release of cortisol throughout the brain. Previous research has shown that such cortisol release is abnormal in people who attempt or die by suicide.

Kaminsky says a test based on these findings might best be used to predict future suicide attempts in those who are ill, to restrict lethal means or methods among those a risk, or to make decisions regarding the intensity of intervention approaches.

He says that it might make sense for use in the military to test whether members have the gene mutation that makes them more vulnerable. Those at risk could be more closely monitored when they returned home after deployment. A test could also be useful in a psychiatric emergency room, he says, as part of a suicide risk assessment when doctors try to assess level of suicide risk.

The test could be used in all sorts of safety assessment decisions like the need for hospitalization and closeness of monitoring. Kaminsky says another possible use that needs more study could be to inform treatment decisions, such as whether or not to give certain medications that have been linked with suicidal thoughts.

“We have found a gene that we think could be really important for consistently identifying a range of behaviors from suicidal thoughts to attempts to completions,” Kaminsky says. “We need to study this in a larger sample but we believe that we might be able to monitor the blood to identify those at risk of suicide.”

The brains of children with autism are relatively inflexible at switching from rest to task performance, according to a new brain-imaging study from the Stanford University School of Medicine.

Instead of changing to accommodate a job, connectivity in key brain networks of autistic children looks similar to connectivity in the resting brain. And the greater this inflexibility, the more severe the child’s manifestations of repetitive and restrictive behaviors that characterize autism, the study found.

The study, published online July 29 in Cerebral Cortex, used functional magnetic resonance imaging, or fMRI, to examine children’s brain activity at rest and during two tasks: solving simple math problems and looking at pictures of different faces. The study included an equal number of children with and without autism. The developmental disorder, which now affects one of every 68 children in the United States, is characterized by social and communication deficits, repetitive behaviors and sensory problems.

“We wanted to test the idea that a flexible brain is necessary for flexible behaviors,” said Lucina Uddin, PhD, a lead author of the study. “What we found was that across a set of brain connections known to be important for switching between different tasks, children with autism showed reduced ‘brain flexibility’ compared with typically developing peers.” Uddin, who is now an assistant professor of psychology at the University of Miami, was a postdoctoral scholar at Stanford when the research was conducted.

“The fact that we can tie this neurophysiological brain-state inflexibility to behavioral inflexibility is an important finding because it gives us clues about what kinds of processes go awry in autism,” said Vinod Menon, PhD, the Rachel L. and Walter F. Nichols, MD, professor of psychiatry and behavioral sciences at Stanford and the senior author of the study.

Tracking shifts in connectivity

The researchers focused on a network of brain areas they have studied before. These areas are involved in making decisions, performing social tasks and identifying relevant events in the environment to guide behavior. The team’s prior work showed that, in children with autism, activity in these areas was more tightly connected when the brain was at rest than it was in children who didn’t have autism.

The new research shows that, in autism, connectivity in these networks that can be seen on fMRI scans is fairly similar regardless of whether the brain is at rest or performing a task. In contrast, typically developing children have a larger shift in brain connectivity when they perform tasks.

The study looked at 34 kids with autism and 34 typically developing children. All of the children with autism received standard clinical evaluations to characterize the severity of their disorder. Then, the two groups were split in half: 17 children with autism and 17 typically developing children had their brains scanned with fMRI while at rest and while performing simple arithmetic problems. The remaining children had their brains scanned at rest and during a task that asked them to distinguish between different people’s faces. The facial recognition task was chosen because autism is characterized by social deficits; the math task was chosen to reflect an area in which children with autism do not usually have deficits.

Children with autism performed as well as their typically developing peers on both tasks — that is, they were as good at distinguishing between the faces and solving the math problems. However, their brain scan results were different. In addition to the reduced brain flexibility, the researchers showed a correlation between the degree of inflexibility and the severity of restrictive and repetitive behaviors, such as performing the same routine over and over or being obsessed with a favorite topic.

“This is the first study that has examined how the patterns of intrinsic brain connectivity change with a cognitive load in children with autism,” Menon said. The research is the first to demonstrate that brain connectivity in children with autism changes less, relative to rest, in response to a task than the brains of other children, he added.

Guidance for new therapies

“The findings may help researchers evaluate the effects of different autism therapies,” said Kaustubh Supekar, PhD, a research associate and the other lead author of the study. “Therapies that increase the brain’s flexibility at switching from rest to goal-directed behaviors may be a good target, for instance.”

“We’re making progress in identifying a brain basis of autism, and we’re starting to get traction in pinpointing systems and signaling mechanisms that are not functioning properly,” Menon said. “This is giving us a better handle both in thinking about treatment and in looking at change or plasticity in the brain.”

Some people can handle stressful situations better than others, and it’s not all in their genes: Even identical twins show differences in how they respond.

(Image: iStockphoto)

Researchers have identified a specific electrical pattern in the brains of genetically identical mice that predicts how well individual animals will fare in stressful situations.

The findings, published July 29 in Nature Communications, may eventually help researchers prevent potential consequences of chronic stress — such as post-traumatic stress disorder, depression and other psychiatric disorders — in people who are prone to these problems.

“In soldiers, we have this dramatic, major stress exposure, and in some individuals it’s leading to major issues, such as problems sleeping or being around other people,” said senior author Kafui Dzirasa, M.D., Ph.D., an assistant professor of psychiatry and behavioral sciences at Duke University Medical Center and a member of the Duke Institute for Brain Sciences. “If we can find that common trigger or common pathway and tune it, we may be able to prevent the emergence of a range of mental illnesses down the line.”

In the new study, Dzirasa’s team analyzed the interaction between two interconnected brain areas that control fear and stress responses in both mice and men: the prefrontal cortex and the amygdala. The amygdala plays a role in the ‘fight-or-flight’ response. The prefrontal cortex is involved in planning and other higher-level functions. It suppresses the amygdala’s reactivity to danger and helps people continue to function in stressful situations.

Implanting electrodes into the brains of the mice allowed the researchers to listen in on the tempo at which the prefrontal cortex and the amygdala were firing and how tightly the two areas were linked — with the ultimate goal of figuring whether the electrical pattern of cross talk could help decide how well animals would respond when faced with an acute stressor.

Indeed, in mice that had been subjected to a chronically stressful situation — daily exposure to an aggressive male mouse for about two weeks — the degree to which the prefrontal cortex seemed to control amygdala activity was related to how well the animals coped with the stress, the group found.

Next the group looked at how the brain reacted to the first instance of stress, before the mice were put in a chronically stressful situation. The mice more sensitive to chronic stress showed greater activation of their prefrontal cortex-amygdala circuit, compared with resilient mice.

“We were really both surprised and excited to find that this signature was present in the animals before they were chronically stressed,” Dzirasa said. “You can find this signature the very first time they were ever exposed to this aggressive dangerous experience.”

Dzirasa hopes to use the signatures to come up with potential treatments for stress. “If we pair the signatures and treatments together, can we prevent symptoms from emerging, even when an animal is stressed? That’s the first question,” he said.

The group also hopes to delve further into the brain, to see whether the circuit-level patterns can interact with genetic variations that confer risk for psychiatric disorders such as schizophrenia. The new study will enable Dzirasa and other basic researchers to segregate stress-susceptible and resilient animals before they are subjected to stress and look at their molecular, cellular and systemic differences.

By studying the injuries and aptitudes of Vietnam War veterans who suffered penetrating head wounds during the war, scientists are tackling — and beginning to answer — longstanding questions about how the brain works.

The researchers found that brain regions that contribute to optimal social functioning also are vital to general intelligence and to emotional intelligence. This finding bolsters the view that general intelligence emerges from the emotional and social context of one’s life.

The findings are reported in the journal Brain.

“We are trying to understand the nature of general intelligence and to what extent our intellectual abilities are grounded in social cognitive abilities,” said Aron Barbey, a University of Illinois professor of neuroscience, of psychology, and of speech and hearing science. Barbey (bar-BAY), an affiliate of the Beckman Institute and of the Institute for Genomic Biology at the U. of I., led the new study with an international team of collaborators.

Studies in social psychology indicate that human intellectual functions originate from the social context of everyday life, Barbey said.

“We depend at an early stage of our development on social relationships — those who love us care for us when we would otherwise be helpless,” he said.

Social interdependence continues into adulthood and remains important throughout the lifespan, Barbey said.

“Our friends and family tell us when we could make bad mistakes and sometimes rescue us when we do,” he said. “And so the idea is that the ability to establish social relationships and to navigate the social world is not secondary to a more general cognitive capacity for intellectual function, but that it may be the other way around. Intelligence may originate from the central role of relationships in human life and therefore may be tied to social and emotional capacities.”

The study involved 144 Vietnam veterans injured by shrapnel or bullets that penetrated the skull, damaging distinct brain tissues while leaving neighboring tissues intact. Using CT scans, the scientists painstakingly mapped the affected brain regions of each participant, then pooled the data to build a collective map of the brain.

The researchers used a battery of carefully designed tests to assess participants’ intellectual, emotional and social capabilities. They then looked for patterns that tied damage to specific brain regions to deficits in the participants’ ability to navigate the intellectual, emotional or social realms. Social problem solving in this analysis primarily involved conflict resolution with friends, family and peers at work.

As in their earlier studies of general intelligence and emotional intelligence, the researchers found that regions of the frontal cortex (at the front of the brain), the parietal cortex (further back near the top of the head) and the temporal lobes (on the sides of the head behind the ears) are all implicated in social problem solving. The regions that contributed to social functioning in the parietal and temporal lobes were located only in the brain’s left hemisphere, while both left and right frontal lobes were involved.

The brain networks found to be important to social adeptness were not identical to those that contribute to general intelligence or emotional intelligence, but there was significant overlap, Barbey said.

“The evidence suggests that there’s an integrated information-processing architecture in the brain, that social problem solving depends upon mechanisms that are engaged for general intelligence and emotional intelligence,” he said. “This is consistent with the idea that intelligence depends to a large extent on social and emotional abilities, and we should think about intelligence in an integrated fashion rather than making a clear distinction between cognition and emotion and social processing. This makes sense because our lives are fundamentally social — we direct most of our efforts to understanding others and resolving social conflict. And our study suggests that the architecture of intelligence in the brain may be fundamentally social, too.”

U of T researchers have found a missing link that helps to explain how ALS, one of the world’s most feared diseases, paralyses and ultimately kills its victims. The breakthrough is helping them trace a path to a treatment or even a cure.

“ALS research has been taking baby steps for decades, but this has recently started changing to giant leaps,” said Karim Mekhail, professor in the Faculty of Medicine’s Department of Laboratory Medicine and Pathobiology.  “The disease is linked to a large number of genes, and previously, every time someone studied one of them, it took them off in a different direction. Nobody could figure out how they were all connected.”

Mekhail and his team discovered the function of a crucial gene called PBP1 or ATAXIN2 that’s often missing in ALS, also known as Lou Gehrig’s Disease.  Learning how this gene functions has helped them connect a lot of dots.

“This is an extremely important finding that may help us to better understand and target the pathways involved in neurodegenerative disease,” said Lorne Zinman, professor of medicine at U of T and medical director of the ALS/Neuromuscular Clinic at Sunnybrook Health Sciences Centre. “The next step will be to determine if this finding is applicable to patients with ALS.”

The key lies in a peculiarity of the human genome. It starts with the DNA, the blueprint that contains all our genetic information. The DNA passes its information to the RNA, which floats off to make proteins that help run our bodies. However, without ATAXIN2, the RNA fails to float away. It becomes glued to the DNA and forms RNA-DNA hybrids, said Mekhail. These hybrids gum up the works and stop other RNA from fully forming. Pieces of half-created RNA debris clutter the cell, and cause more hybrids.

“We think the debris and hybrids are on the same team in a never-ending Olympic relay race,” said Mekhail. “Over time there’s a vicious cycle building up. If we can find a way to disrupt that cycle, theoretically we can control or reverse the disease.”

On that front, Mekhail made a very surprising discovery: reducing calories to the minimum necessary amount stops the hybrids from forming in cells missing ATAXIN2. He and his team are studying whether a simple, non-toxic dietary restriction could be used with ALS patients, especially in the early stages or for those at risk of ALS.

Mekhail discovered the hybrids and missing genes in yeast cells and his results were published as the cover article for the July 28 edition of the journal Developmental Cell. Now his team is replicating this research on tissue from ALS patients – with very encouraging preliminary results.

“Within the next decade or two, I think there’s going to be a revolution in treatment for ALS and all kinds of brain disease,” he said. “These hybrids are going to play a role not just in ALS but in a lot of disease.”

Babies can learn what to fear in the first days of life just by smelling the odor of their distressed mothers, new research suggests. And not just “natural” fears: If a mother experienced something before pregnancy that made her fear something specific, her baby will quickly learn to fear it too — through the odor she gives off when she feels fear.

In the first direct observation of this kind of fear transmission, a team of University of Michigan Medical School and New York University studied mother rats who had learned to fear the smell of peppermint – and showed how they “taught” this fear to their babies in their first days of life through their alarm odor released during distress.

In a new paper in the Proceedings of the National Academy of Sciences, the team reports how they pinpointed the specific area of the brain where this fear transmission takes root in the earliest days of life.

Their findings in animals may help explain a phenomenon that has puzzled mental health experts for generations: how a mother’s traumatic experience can affect her children in profound ways, even when it happened long before they were born. 

The researchers also hope their work will lead to better understanding of why not all children of traumatized mothers, or of mothers with major phobias, other anxiety disorders or major depression, experience the same effects.

“During the early days of an infant rat’s life, they are immune to learning information about environmental dangers. But if their mother is the source of threat information, we have shown they can learn from her and produce lasting memories,” says Jacek Debiec, M.D., Ph.D., the U-M psychiatrist and neuroscientist who led the research.  

“Our research demonstrates that infants can learn from maternal expression of fear, very early in life,” he adds. “Before they can even make their own experiences, they basically acquire their mothers’ experiences. Most importantly, these maternally-transmitted memories are long-lived, whereas other types of infant learning, if not repeated, rapidly perish.”

Peering inside the fearful brain

Debiec, who treats children and mothers with anxiety and other conditions in the U-M Department of Psychiatry, notes that the research on rats allows scientists to see what’s going on inside the brain during fear transmission, in ways they could never do in humans.

He began the research during his fellowship at NYU with Regina Marie Sullivan, Ph.D., senior author of the new paper, and continues it in his new lab at U-M’s Molecular and Behavioral Neuroscience Institute.

The researchers taught female rats to fear the smell of peppermint by exposing them to mild, unpleasant electric shocks while they smelled the scent, before they were pregnant. Then after they gave birth, the team exposed the mothers to just the minty smell, without the shocks, to provoke the fear response. They also used a comparison group of female rats that didn’t fear peppermint.

They exposed the pups of both groups of mothers to the peppermint smell, under many different conditions with and without their mothers present.

Using special brain imaging, and studies of genetic activity in individual brain cells and cortisol in the blood, they zeroed in on a brain structure called the lateral amygdala as the key location for learning fears. During later life, this area is key to detecting and planning response to threats – so it makes sense that it would also be the hub for learning new fears.

But the fact that these fears could be learned in a way that lasted, during a time when the baby rat’s ability to learn any fears directly was naturally suppressed, is what makes the new findings so interesting, says Debiec.

The team even showed that the newborns could learn their mothers’ fears even when the mothers weren’t present. Just the piped-in scent of their mother reacting to the peppermint odor she feared was enough to make them fear the same thing.

Even when just the odor of the frightened mother was piped in to a chamber where baby rats were exposed to peppermint smell, the babies developed a fear of the same smell, and their blood cortisol levels rose when they smelled it.

And when the researchers gave the baby rats a substance that blocked activity in the amygdala, they failed to learn the fear of peppermint smell from their mothers. This suggests, Debiec says, that there may be ways to intervene to prevent children from learning irrational or harmful fear responses from their mothers, or reduce their impact.

 From animals to humans: next steps

The new research builds on what scientists have learned over time about the fear circuitry in the brain, and what can go wrong with it. That work has helped psychiatrists develop new treatments for human patients with phobias and other anxiety disorders – for instance, exposure therapy that helps them overcome fears by gradually confronting the thing or experience that causes their fear.

In much the same way, Debiec hopes that exploring the roots of fear in infancy, and how maternal trauma can affect subsequent generations, could help human patients. While it’s too soon to know if the same odor-based effect happens between human mothers and babies, the role of a mother’s scent in calming human babies has been shown.

Debiec, who hails from Poland, recalls working with the grown children of Holocaust survivors, who experienced nightmares, avoidance instincts and even flashbacks related to traumatic experiences they never had themselves. While they would have learned about the Holocaust from their parents, this deeply ingrained fear suggests something more at work, he says.

An evolutionarily ancient and tiny part of the brain tracks expectations about nasty events, finds new UCL research.

The study, published in Proceedings of the National Academy of Sciences, demonstrates for the first time that the human habenula, half the size of a pea, tracks predictions about negative events, like painful electric shocks, suggesting a role in learning from bad experiences.

Brain scans from 23 healthy volunteers showed that the habenula activates in response to pictures associated with painful electric shocks, with the opposite occurring for pictures that predicted winning money.

Previous studies in animals have found that habenula activity leads to avoidance as it suppresses dopamine, a brain chemical that drives motivation. In animals, habenula cells have been found to fire when bad things happen or are anticipated.

"The habenula tracks our experiences, responding more the worse something is expected to be," says senior author Dr Jonathan Roiser of the UCL Institute of Cognitive Neuroscience. "For example, the habenula responds much more strongly when an electric shock is almost certain than when it is unlikely. In this study we showed that the habenula doesn’t just express whether something leads to negative events or not; it signals quite how much bad outcomes are expected."

During the experiment, healthy volunteers were placed inside a functional magnetic resonance imaging (fMRI) scanner, and brain images were collected at high resolution because the habenula is so small. Volunteers were shown a random sequence of pictures each followed by a set chance of a good or bad outcome, occasionally pressing a button simply to show they were paying attention. Habenula activation tracked the changing expectation of bad and good events.

"Fascinatingly, people were slower to press the button when the picture was associated with getting shocked, even though their response had no bearing on the outcome." says lead author Dr Rebecca Lawson, also at the UCL Institute of Cognitive Neuroscience. "Furthermore, the slower people responded, the more reliably their habenula tracked associations with shocks. This demonstrates a crucial link between the habenula and motivated behaviour, which may be the result of dopamine suppression."

The habenula has previously been linked to depression, and this study shows how it could be involved in causing symptoms such low motivation, pessimism and a focus on negative experiences. A hyperactive habenula could cause people to make disproportionately negative predictions.

"Other work shows that ketamine, which has profound and immediate benefits in patients who failed to respond to standard antidepressant medication, specifically dampens down habenula activity," says Dr Roiser. "Therefore, understanding the habenula could help us to develop better treatments for treatment-resistant depression."

A study involving nearly 27,000 older adults on five continents found that nearly 1 in 10 met criteria for pre-dementia based on a simple test that measures how fast people walk and whether they have cognitive complaints. People who tested positive for pre-dementia were twice as likely as others to develop dementia within 12 years. The study, led by scientists at Albert Einstein College of Medicine of Yeshiva University and Montefiore Medical Center, was published online on July 16, 2014 in Neurology®, the medical journal of the American Academy of Neurology.

The new test diagnoses motoric cognitive risk syndrome (MCR). Testing for the newly described syndrome relies on measuring gait speed (our manner of walking) and asking a few simple questions about a patient’s cognitive abilities, both of which take just seconds. The test is not reliant on the latest medical technology and can be done in a clinical setting, diagnosing people in the early stages of the dementia process. Early diagnosis is critical because it allows time to identify and possibly treat the underlying causes of the disease, which may delay or even prevent the onset of dementia in some cases.

“In many clinical and community settings, people don’t have access to the sophisticated tests—biomarker assays, cognitive tests or neuroimaging studies—used to diagnose people at risk for developing dementia,” said Joe Verghese, M.B.B.S., professor in the Saul R. Korey Department of Neurology and of medicine at Einstein, chief of geriatrics at Einstein and Montefiore, and senior author of the Neurology paper. “Our assessment method could enable many more people to learn if they’re at risk for dementia, since it avoids the need for complex testing and doesn’t require that the test be administered by a neurologist. The potential payoff could be tremendous—not only for individuals and their families, but also in terms of healthcare savings for society. All that’s needed to assess MCR is a stopwatch and a few questions, so primary care physicians could easily incorporate it into examinations of their older patients.”

The U.S. Centers for Disease Control and Prevention estimates that up to 5.3 million Americans—about 1 in 9 people age 65 and over—have Alzheimer’s disease, the most common type of dementia. That number is expected to more than double by 2050 due to population aging.

“As a young researcher, I examined hundreds of patients and noticed that if an older person was walking slowly, there was a good chance that his cognitive tests were also abnormal,” said Dr. Verghese, who is also the Murray D. Gross Memorial Faculty Scholar in Gerontology at Einstein. “This gave me the idea that perhaps we could use this simple clinical sign—how fast someone walks—to predict who would develop dementia. In a 2002 New England Journal of Medicine study, we reported that abnormal gait patterns accurately predict whether people will go on to develop dementia. MCR improves on the slow gait concept by evaluating not only patients’ gait speed but also whether they have cognitive complaints.”

The Neurology paper reported on the prevalence of MCR among 26,802 adults without dementia or disability aged 60 years and older enrolled in 22 studies in 17 countries. A significant number of adults—9.7 percent—met the criteria for MCR (i.e., abnormally slow gait and cognitive complaints). While the syndrome was equally common in men and women, highly educated people were less likely to test positive for MCR compared with less-educated individuals. A slow gait, said Dr. Verghese, is a walking speed slower than about one meter per second, which is about 2.2 miles per hour (m.p.h.). Less than 0.6 meters per second (or 1.3 m.p.h.) is “clearly abnormal.”

To test whether MCR predicts future dementia, the researchers focused on four of the 22 studies that tested a total of 4,812 people for MCR and then evaluated them annually over an average follow-up period of 12 years to see which ones developed dementia. Those who met the criteria for MCR were nearly twice as likely to develop dementia over the following 12 years compared with people who did not.

Dr. Verghese emphasized that a slow gait alone is not sufficient for a diagnosis of MCR. “Walking slowly could be due to conditions such as arthritis or an inner ear problem that affects balance, which would not increase risk for dementia. To meet the criteria for MCR requires having a slow gait and cognitive problems. An example would be answering ‘yes’ to the question, ‘Do you think you have more memory problems than other people?’”

For patients meeting MCR criteria, said Dr. Verghese, the next step is to look for the causes of their slow gait and cognitive complaints. The search may reveal underlying—and controllable—problems. “Evidence increasingly suggests that brain health is closely tied to cardiovascular health—meaning that treatable conditions such as hypertension, smoking, high cholesterol, obesity and diabetes can interfere with blood flow to the brain and thereby increase a person’s risk for developing Alzheimer’s and other dementias,” said Dr. Verghese.

What about people who meet MCR criteria but no treatable underlying problems can be found?

“Even in the absence of a specific cause, we know that most healthy lifestyle factors, such as exercising and eating healthier, have been shown to reduce the rate of cognitive decline,” said Dr. Verghese. “In addition, our group has shown that cognitively stimulating activities—playing board games, card games, reading, writing and also dancing—can delay dementia’s onset. Knowing they’re at high risk for dementia can also help people and their families make arrangements for the future, which is an aspect of MCR testing that I’ve found is very important in my own clinical practice.”

Boston University School of Medicine researchers may have found a way to delay or even prevent Alzheimer’s disease (AD). They discovered that pre-treatment of neurons with the anti-aging protein Klotho can prevent neuron death in the presence of the toxic amyloid protein and glutamate. These findings currently appear in the Journal of Biological Chemistry.

Alzheimer’s disease is the most frequent age-related dementia affecting 5.4 million Americans including 13 percent of people age 65 and older and more than 40 percent of people over the age of 85. In AD the cognitive decline and dementia result from the death of nerve cells that are involved in learning and memory. The amyloid protein and the excess of the neurotransmitter, glutamate are partially responsible for the neuronal demise.

Nerve cells were grown in petri dishes and treated with or without Klotho for four hours. Amyloid or glutamate then were added to the dish for 24 hours. In the dishes where Klotho was added, a much higher percentage of neurons survived than in the dishes without Klotho.

"Finding a neuroprotective agent that will protect nerve cells from amyloid that accumulates as a function of age in the brain is novel and of major importance," explained corresponding author Carmela R. Abraham, PhD, professor of biochemistry and pharmacology at BUSM. "We now have evidence that if more Klotho is present in the brain, it will protect the neurons from the oxidative stress induced by amyloid and glutamate.

According to the researchers, Klotho is a large protein that cannot penetrate the blood brain barrier so it can’t be administered by mouth or injection. However in a separate study the researchers have identified small molecules that can enter the brain and increase the levels of Klotho. “We believe that increasing Klotho levels with such compounds would improve the outcome for Alzheimer’s patients, and if started early enough would prevent further deterioration. This potential treatment has implications for other neurodegenerative diseases such as Parkinson’s, Huntington’s, ALS and brain trauma, as well,” added Abraham.

An experimental anti-inflammatory drug can protect vulnerable neurons and reduce motor deficits in a rat model of Parkinson’s disease, researchers at Emory University School of Medicine have shown.

The results were published Thursday, July 24 in the Journal of Parkinson’s Disease.

The findings demonstrate that the drug, called XPro1595, can reach the brain at sufficient levels and have beneficial effects when administered by subcutaneous injection, like an insulin shot. Previous studies of XPro1595 in animals tested more invasive modes of delivery, such as direct injection into the brain.

“This is an important step forward for anti-inflammatory therapies for Parkinson’s disease,” says Malu Tansey, PhD, associate professor of physiology at Emory University School of Medicine. “Our results provide a compelling rationale for moving toward a clinical trial in early Parkinson’s disease patients.”

The new research on subcutaneous administration of XPro1595 was funded by the Michael J. Fox Foundation for Parkinson’s Research (MJFF). XPro1595 is licensed by FPRT Bio, and is seeking funding for a clinical trial to test its efficacy in the early stages of Parkinson’s disease.

“We are proud to have supported this work and glad to see positive pre-clinical results,” said Marco Baptista, PhD, MJFF associate director of research programs. “A therapy that could slow Parkinson’s progression would be a game changer for the millions living with this disease, and this study is a step in that direction.”

In addition, Tansey and Yoland Smith, PhD, from Yerkes National Primate Research Center, were awarded a grant this week from the Parkinson’s Disease Foundation to test XPro1595 in a non-human primate model of Parkinson’s.

Evidence has been piling up that inflammation is an important mechanism driving the progression of Parkinson’s disease. XPro1595 targets tumor necrosis factor (TNF), a critical inflammatory signaling molecule, and is specific to the soluble form of TNF. This specificity would avoid compromising immunity to infections, a known side effect of existing anti-TNF drugs used to treat disorders such as rheumatoid arthritis.

“Inflammation is probably not the initiating event in Parkinson’s disease, but it is important for the neurodegeneration that follows,” Tansey says. “That’s why we believe that an anti-inflammatory agent, such as one that counteracts soluble TNF, could substantially slow the progression of the disease.”

Postdoctoral fellow Christopher Barnum, PhD and colleagues used a model of Parkinson’s disease in rats in which the neurotoxin 6-hydroxydopamine (6-OHDA) is injected into only one side of the brain. This reproduces some aspects of Parkinson’s disease: neurons that produce dopamine in the injected side of the brain die, leading to impaired movement on the opposite side of the body.

When XPro1595 is given to the animals 3 days after 6-OHDA injection, just 15 percent of the dopamine-producing neurons were lost five weeks later. That compares to controls in which 55 percent of the same neurons were lost. By reducing dopamine neuron loss with XPro1595, the researchers were also able to reduce motor impairment. In fact, the degree of dopamine cell loss was highly correlated both with the degree of motor impairment and immune cell activation.

When XPro1595 is given two weeks after injection, 44 percent of the vulnerable neurons are still lost, suggesting that there is a limited window of opportunity to intervene.

“Recent clinical studies indicates there is a four or five year window between diagnosis of Parkinson’s disease and the time when the maximum number of vulnerable neurons are lost,” Dr. Tansey says. “If this is true, and if inflammation is playing a key role during this window, then we might be able to slow or halt the progression of Parkinson’s with a treatment like XPro1595.”

Early life experiences, such as childhood socioeconomic status and literacy, may have greater influence on the risk of cognitive impairment late in life than such demographic characteristics as race and ethnicity, a large study by researchers with the UC Davis Alzheimer’s Disease Center and the University of Victoria, Canada, has found.

“Declining cognitive function in older adults is a major personal and public health concern,” said Bruce Reed professor of neurology and associate director of the UC Davis Alzheimer’s Disease Center.

“But not all people lose cognitive function, and understanding the remarkable variability in cognitive trajectories as people age is of critical importance for prevention, treatment and planning to promote successful cognitive aging and minimize problems associated with cognitive decline.”

The study, “Life Experiences and Demographic Influences on Cognitive Function in Older Adults,” is published online in Neuropsychology, a journal of the American Psychological Association. It is one of the first comprehensive examinations of the multiple influences of varied demographic factors early in life and their relationship to cognitive aging.

The research was conducted in a group of over 300 diverse men and women who spoke either English or Spanish. They were recruited from senior citizen social, recreational and residential centers, as well as churches and health-care settings. At the time of recruitment, all study participants were 60 or older, and had no major psychiatric illnesses or life threatening medical illnesses. Participants were Caucasian, African-American or Hispanic.

The extensive testing included multidisciplinary diagnostic evaluations through the UC Davis Alzheimer’s Disease Center in either English or Spanish, which permitted comparisons across a diverse cohort of participants.

Consistent with previous research, the study found that non-Latino Caucasians scored 20 to 25 percent higher on tests of semantic memory (general knowledge) and 13 to 15 percent higher on tests of executive functioning compared to the other ethnic groups. However, ethnic differences in executive functioning disappeared and differences in semantic memory were reduced by 20 to 30 percent when group differences in childhood socioeconomic status, adult literacy and extent of physical activity during adulthood were considered. 

“This study is unusual in that it examines how many different life experiences affect cognitive decline in late life,” said Dan Mungas, professor of neurology and associate director of the UC Davis Alzheimer’s Disease Research Center. 

“It shows that variables like ethnicity and years of education that influence cognitive test scores in a single evaluation are not associated with rate of cognitive decline, but that specific life experiences like level of reading attainment and intellectually stimulating activities are predictive of the rate of late-life cognitive decline. This suggests that intellectual stimulation throughout the life span can reduce cognitive decline in old age.”

Regardless of ethnicity, advanced age and apolipoprotein-E (APOE genotype) were associated with increased cognitive decline over an average of four years that participants were followed. APOE is the largest known genetic risk factor for late-onset Alzheimer’s. Less decline was experienced by persons who reported more engagement in recreational activities in late life and who maintained their levels of activity engagement from middle age to old age. Single-word reading — the ability to decode a word on sight, which often is considered an indication of quality of educational experience — was also associated with less cognitive decline, a finding that was true for both English and Spanish readers, irrespective of their race or ethnicity. These findings suggest that early life experiences affect late-life cognition indirectly, through literacy and late-life recreational pursuits, the authors said.

“These findings are important,” explained Paul Brewster, lead author of the study, a doctoral student at the University of Victoria, Canada, and a pre-doctoral psychology intern at the UC San Diego Department of Psychiatry, “because it challenges earlier research that suggests associations between race and ethnicity, particularly among Latinos, and an increased risk of late-life cognitive impairment and dementia.

”Our findings suggest that the influences of demographic factors on late-life cognition may be reflective of broader socioeconomic factors, such as educational opportunity and related differences in physical and mental activity across the life span.”

Researchers at UC San Francisco have discovered that endostatin, a protein that once aroused intense interest as a possible cancer treatment, plays a key role in the stable functioning of the nervous system.

A substance that occurs naturally in the body, endostatin potently blocks the formation of new blood vessels. In studies in mice in the late 1990s, endostatin treatment virtually eliminated cancer by shutting down the blood supply to tumors, but subsequent human clinical trials proved disappointing.

“It was a very big surprise” to find that endostatin, through some other mechanism, helps to maintain the proper workings of synapses, the sites where communication between nerve cells takes place, said Graeme W. Davis, PhD, Hertzstein Distinguished Professor of Medicine in the Department of Biochemistry and Biophysics at UCSF and senior author of the new study. “Endostatin was not on our radar.”

The findings were reported online July 24 in the journal Neuron.

Synapses are continually shaped and reshaped by experience, a phenomenon known as plasticity. But for those changes to be meaningful, said Davis, they must take place against a stable background, which paradoxically requires another form of change that he and colleagues call “homeostatic plasticity.” Just as we change our pace, slowing down or speeding up, to keep abreast of a running partner, neurons adjust aspects of their function at synapses to compensate for changes in their synaptic partners brought on by aging, illness, or other factors.

In an example of homeostatic plasticity, in the neuromuscular disease myasthenia gravis, as muscle cells become less responsive to the neurotransmitter acetylcholine, nerve cells ramp up their secretion of the neurotransmitter to keep the system in balance for as long as possible. Some researchers believe that in other disorders, including autism and schizophrenia, a failure in such homeostatic mechanisms keeps synapses from functioning properly.

In previous research Davis noticed that applying a toxin to a muscle cell in the fruit fly Drosophila melanogaster triggers homeostatic plasticity in the neuron that forms a synapse on that muscle cell: the neuron—which is called presynaptic, because it is “before” the synapse with the muscle cell—reliably releases more neurotransmitter, just as happens when muscle cells begin to malfunction in myasthenia gravis.

Davis has since built on this model of homeostatic plasticity by painstakingly knocking out Drosophila genes one by one and recording from presynaptic neurons to see which genes are necessary for the homeostatic response, because it is these genes that may be compromised in diseases affecting the process.

“So far we’ve tested about 1,000 genes this way, which has entailed close to 10,000 recordings,” Davis said.

Using this technique Davis and colleagues observed at one point that knocking out a gene called multiplexin significantly hampered homeostatic plasticity in presynaptic neurons. But because that gene helps to form a structural protein known as collagen—which in humans is a component of ligaments, tendons, and cartilage—the finding wasn’t immediately considered relevant to synaptic function.

The team learned that the multiplexin protein can be snipped by an enzyme to produce endostatin, so in experiments led by postdoctoral fellow Tingting Wang, PhD, they tested whether endostatin might play a role in homeostatic plasticity.

“Nobody picked up multiplexin to work on for a couple of years, because we didn’t think a collagen could be that interesting,” Davis said. “Then, when a new postdoc, Tingting Wang, came to the lab, we started thinking about it harder.”

When the group genetically deleted the portion of Drosophila multiplexin that forms endostatin, presynaptic neurons behaved normally, but homeostatic plasticity was severely compromised when toxin was applied to postsynaptic muscle cells. On the opposite side of the coin, when the team overexpressed endostatin at Drosophila synapses lacking multiplexin, homeostasis was restored, whether endostatin was expressed in muscle cells or presynaptic neurons.

The research team is unsure precisely how and where endostatin exerts its effects on homeostatic plasticity, but they believe that multiplexin is cleaved at the postsynaptic site to form endostatin, and that the endostatin signal is conveyed to the presynaptic neuron to alter its function. “Because so many people in the cancer world have studied endostatin, there is a great set of tools available” to study the protein, Davis said, so he expects his group to make rapid progress in addressing these questions.

“Despite its checkered history in cancer, we know endostatin is a signaling molecule and we know that the brain has a great deal of collagen—we just haven’t known what it does, and we certainly don’t know what endostatin’s receptors in the brain might be.” Davis said. “But it’s pretty exciting to think about a new signaling molecule with a profound role in the stabilization of the function of neural circuits.”

A research team led by Jackson Laboratory Professor and Howard Hughes Investigator Susan Ackerman, Ph.D., has pinpointed a surprising mechanism behind neurodegeneration in mice, one that involves a defect in a key component of the cellular machinery that makes proteins, known as transfer RNA or tRNA.

The researchers report in the journal Science that a mutation in a gene that produces tRNAs operating only in the central nervous system results in a “stalling” or pausing of the protein production process in the neuronal ribosomes. When another protein the researchers identified, GTPBP2, is also missing, neurodegeneration results.

“Our study demonstrates that individual tRNA genes can be tissue-specifically expressed in vertebrates,” Ackerman says, “and mutations in such genes may cause disease or modify other phenotypes. This is a new area to look for disease mechanisms.”

Neurodegeneration—the process through which mature neurons decay and ultimately die—is poorly understood, yet it underlies major human diseases, such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease and ALS (amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease).

While the causes of neurodegeneration are still coming to light, there is mounting evidence that neurons are exquisitely sensitive—much more so than other types of cells—to disruptions in how proteins are made and how they fold.

tRNAs are critical in translating the genetic code into proteins, the workhorses of the cell. tRNAs possess a characteristic cloverleaf shape with two distinct “business” ends—one that reads out the genetic code in three-letter increments (or triplets), and another that transports the protein building block specified by each triplet (known as an amino acid).

In higher organisms, tRNAs are strikingly diverse. For example, while there are 61 distinct triplets that are recognized by tRNAs in humans, the human genome contains roughly 500 tRNA genes. To date little is known about why they are so numerous, whether they carry out overlapping or redundant functions, or whether they possibly have roles beyond the making of proteins.

“Multiple genes encode almost all tRNA types,” Ackerman says. “In fact, AGA codons are decoded by five tRNAs in mice. Until now, this apparent redundancy has caused us to completely overlook the disease-causing potential of mutations in tRNAs, as well as other repetitive genes.”

Ackerman and her colleagues at The Jackson Laboratory in Bar Harbor, Maine, and Farmington, Conn., The Scripps Research Institute in LaJolla, Calif., and Kumamoto University in Japan pinpointed a mutation in the tRNA gene n-Tr20 as a genetic culprit behind the neurodegeneration observed in mice lacking GTPBP2.

Remarkably, the tRNA’s activity is confined to the brain and other parts of the central nervous system, in both mice and humans. The tRNA encoded by n-Tr20 recognizes the triplet code, AGA (which specifies the amino acid arginine).

The n-Tr20 defect disrupts how proteins are made. Specifically, it causes the “factories” responsible for synthesizing proteins, called ribosomes, to stall when they encounter an AGA triplet.

Such stalling can be largely overcome, thanks to the work of a partner protein called GTPBP2. But when this partner is missing—as it is in the mutant mice that Ackerman and her colleagues studied—the stalling intensifies. This is thought to be a driving force behind the neurodegeneration seen in these mice.

Unlocking the secrets to better treating the pernicious disorders of obesity and dementia reside in the brain, according to a paper from American University’s Center for Behavioral Neuroscience. In the paper, researchers make the case for treating obesity with therapies aimed at areas of the brain responsible for memory and learning. Furthermore, treatments that focus on the hippocampus could play a role in reducing certain dementias.

"In the struggle to treat these diseases, therapies and preventive measures often fall short. This is a new way for providers who treat people with weight problems and for researchers who study dementias to think about obesity and cognitive decline," said Prof. Terry Davidson, center director and lead study author.

In the paper, published in the journal Physiology & Behavior, Davidson and colleague Ashley A. Martin review research findings linking obesity with cognitive decline, including the center’s findings about the “vicious cycle” model, which explains how weight-challenged individuals who suffer from particular kinds of cognitive impairment are more susceptible to overeating.

Obesity, Memory Deficits and Lasting Effects

It is widely accepted that overconsumption of dietary fats, sugar and sweeteners can cause obesity. These types of dietary factors are also linked to cognitive dysfunction. Foods that are risk factors for cognitive impairment (i.e., foods high in saturated fats and simple carbohydrates that make up the modern Western diet) are so widespread and readily available in today’s food environment, their consumption is all but encouraged, Davidson said.

Across age groups, evidence reveals links between excess food intake, body weight and cognitive dysfunction. Childhood obesity and consumption of the Western diet can have lasting effects, as seen through the normal aging process, cognitive deficits and brain pathologies. Several analyses of cases of mild cognitive impairment progressing to full-blown cases of Alzheimer’s disease show that the first signs of brain disease can occur at least 50 years prior to the emergence of serious cognitive dysfunction. These signs originate in the hippocampus, the area of the brain where memory, learning, decision making, behavior control and other cognitive functions come into play.

Still, most research on the role of the brain in obesity focuses on areas thought to be involved with hunger motivation (e.g., hypothalamus), taste (e.g., brain stem), reinforcement (e.g., striatum) and reward (e.g., nucleus accumbens) or with hormonal or metabolic disorders. This research has not yet been successful in generating therapies that are effective in treating or preventing obesity, Davidson says.

Vicious Cycle

Experiments in rats by Davidson and colleagues show that overconsumption of the Western diet can damage or change the blood-brain barrier, the tight network of blood vessels protecting the brain and substrates for cognition. Certain kinds of dementias are known to arise from the breakdown in these brain substrates.

"Breakdown in the blood-brain barrier is more rationale for treating obesity as a learning and memory disorder," Davidson said. "Treating obesity successfully may also reduce the incidence of dementias, because the deterioration in the brain is often produced by the same diets that promote obesity."

The “vicious cycle” model AU researchers put forth says eating a Western diet high in saturated fats, sugar and simple carbohydrates produces pathologies in brain structures and circuits, ultimately changing brain pathways and disrupting cognitive abilities.

It works like this: People become less able to resist temptation when they encounter environmental cues (e.g., food itself or the sight of McDonald’s Golden Arches) that remind them of the pleasures of consumption. They then eat more of the same type of foods that produce the pathological changes in the brain, leading to progressive deterioration in those areas and impairments in cognitive processes important for providing control over one’s thoughts and behaviors. These cognitive impairments can weaken a person’s ability to resist thinking about food, making them more easily distracted by food cues in the environment and more susceptible to overeating and weight gain.

"People have known at least since the time of Hippocrates that one key to a healthy life is to eat in moderation. Yet many of us are unable to follow that good advice," Davidson said. "Our work suggests that new therapeutic interventions that target brain regions involved with learning and memory may lead to success in controlling both the urge to eat, as well as the undesirable consequences produced by overeating."

Mozart, Beethoven or even Shakespeare — pregnant mothers have been known to expose their babies to many forms of auditory stimulation. But according to researchers at the University of Florida, all a baby really needs is the music of mom’s voice.

Research published in the most recent issue of the journal Infant Behavior and Development shows that babies in utero begin to respond to the rhythm of a nursery rhyme — showing evidence of learning — by 34 weeks of pregnancy and are capable of remembering a set rhyme until just prior to birth. Nursing researcher Charlene Krueger and her team studied pregnant women who recited a rhyme to their babies three times a day for six weeks, beginning at 28 weeks’ gestational age, which is the start of the third trimester of pregnancy.

“The mother’s voice is the predominant source of sensory stimulation in the developing fetus,” said Krueger, an associate professor in the UF College of Nursing. “This research highlights just how sophisticated the third trimester fetus really is and suggests that a mother’s voice is involved in the development of early learning and memory capabilities. This could potentially affect how we approach the care and stimulation of the preterm infant.”

Krueger’s team recruited 32 pregnant women during their 28th week of pregnancy, as determined by fetal ultrasound. The participants were between 18 and 39 years of age, spoke English as a primary language and were pregnant with their first baby. Once recruited, the women were randomly assigned to either an experimental or a control group. The mean age of the women in the group was 25. In addition, 68 percent of the women were white, 28 percent were black and 4 percent were of another race or ethnicity.

From 28 to 34 weeks of pregnancy, all mothers in the study recited a passage or nursery rhyme out loud twice a day and then came in for testing at 28, 32, 33 and 34 weeks’ gestation. To determine whether the fetus could remember the pattern of speech at 34 weeks of age, all mothers were asked to stop speaking the passage. Then the fetuses were tested again at 36 and 38 weeks’ gestational age.

During testing, researchers used a fetal heart monitor, similar to what is used during traditional labor and delivery, to record heart rate and determine any changes. Researchers interpret a small heart rate deceleration in the fetus as an indicator of learning or familiarity with a stimulus.

At testing, the fetuses in the experimental group were played a recording of the same rhyme their mother had been reciting at home but spoken by a female stranger. Those in the control group heard a different rhyme also spoken by a stranger. This was to help determine if the fetus was responding simply to its mother’s voice or to a familiar pattern of speech, which is a more difficult task, Krueger said.

The researchers found that the fetus’ heart rate began to respond to the familiar rhyme recited by a stranger’s voice by 34 weeks of gestational age — once the mother had spoken the rhyme out loud at home for six weeks. They continued to respond with a small cardiac deceleration for as long as four weeks after the mother had stopped saying the rhyme until about 38 weeks. At 38 weeks, there was a statistically significant difference between the two groups in responding to the strangers’ recited rhymes — the experimental group who heard the original rhyme responded with a deeper and more sustained cardiac deceleration, whereas the control group who heard a new rhyme responded with a cardiac acceleration.

Further research is needed to more fully understand how ongoing development affects learning and memory, Krueger said. Her aim is to recognize how this type of research can influence care in preterm infants and their long-term outcomes.

“This study helped us understand more about how early a fetus could learn a passage of speech and whether the passage could be remembered weeks later even without daily exposure to it,” Krueger said. “This could have implications to those preterm infants who are born before 37 weeks of age and the impact an intervention such as their mother’s voice may have on influencing better outcomes in this high-risk population.”

Contrary to previous assumptions, researchers find that preschoolers are able to gauge the strength of their memories and make decisions based on their self-assessments. The study findings are published in Psychological Science, a journal of the Association for Psychological Science.

“Previously, developmental researchers assumed that preschoolers did not introspect much on their mental states, and were not able to reflect on their own uncertainty when problem solving,” says psychological scientist Emily Hembacher of the University of California, Davis, lead author of the study. “This is partly because young children are not usually able to tell us much about their own mental processes due to verbal limitations.”

In several previous studies in their lab, Hembacher and co-author Simona Ghetti observed that preschoolers reported feeling uncertain after giving wrong answers during tasks, suggesting the preschoolers were capable of metacognition — the ability to evaluate one’s own thoughts and mental states.

The researchers decided to examine preschoolers’ metacognition about their memories, given its importance for learning.  They investigated whether kids could assess their confidence in their memories and use those assessments in deciding whether to exclude answers they had generated but were unsure of when given the option.

Eighty-one children ages 3, 4, and 5 participated in the study.  The preschoolers viewed a series of drawings of various items, such as a piano or a balloon.  Half of the images were presented once, and the other half were shown twice.  Next, the children were presented with a pair of images: one they had seen, and a new one they had not seen.  The children were instructed to pick which image they’d seen before in the previous task.

After making their choice, the preschoolers rated how confident they were that their choice was correct.  They then sorted their answers into two boxes.  One box was for the responses that children were confident about and wanted researchers to evaluate for a prize.  The other one was for responses the children thought might be mistaken and that they didn’t want researchers to see.

The data revealed that only 4- and 5-year-olds reported being less confident in their incorrect than their correct memory responses.  They were also more confident about images they’d seen twice, suggesting that they could distinguish between stronger and weaker memories. Older preschoolers were also more likely to decide whether they wanted researchers to see their answers based on their confidence level.

Although 3-year-olds didn’t display the same kind of metacognitive capability on individual responses, the data showed that 3-year-olds who had scored well reported higher confidence overall than kids who hadn’t scored as well.

When the researchers analyzed just the correct answers, they found that preschoolers of all ages sorted responses they weren’t as confident about to the box they didn’t want researchers to evaluate.  So, while they may not be as advanced as their older peers, even children as young as 3 seem to display some ability to reflect on their own knowledge.

The findings contribute to research on the reliability of children’s eyewitness testimony in a court of law, and they carry important implications for educational practices.

“Previous emphasis on the development of metacognition during middle childhood has influenced education practices aimed at strengthening children’s monitoring and control of their own learning,” says Hembacher. “Now we know that some of these ideas may be adapted to meet preschoolers’ learning needs.”

A type of immune cell widely believed to exacerbate chronic adult brain diseases, such as Alzheimer’s disease and multiple sclerosis (MS), can actually protect the brain from traumatic brain injury (TBI) and may slow the progression of neurodegenerative diseases, according to Cleveland Clinic research published today in the online journal Nature Communications.

The research team, led by Bruce Trapp, PhD, Chair of the Department of Neurosciences at Cleveland Clinic’s Lerner Research Institute, found that microglia can help synchronize brain firing, which protects the brain from TBI and may help alleviate chronic neurological diseases. They provided the most detailed study and visual evidence of the mechanisms involved in that protection.

"Our findings suggest the innate immune system helps protect the brain after injury or during chronic disease, and this role should be further studied," Dr. Trapp said. "We could potentially harness the protective role of microglia to improve prognosis for patients with TBI and delay the progression of Alzheimer’s disease, MS, and stroke. The methods we developed will help us further understand mechanisms of neuroprotection."

Microglias are primary responders to the brain after injury or during illness. While researchers have long believed that activated microglia cause harmful inflammation that destroys healthy brain cells, some speculate a more protective role. Dr. Trapp’s team used an advanced technique called 3D electron microscopy to visualize the activation of microglia and subsequent events in animal models.

They found that when chemically activated, microglia migrate to inhibitory synapses, connections between brain cells that slow the firing of impulses. They dislodge the synapse (called “synaptic stripping”), thereby increasing neuronal firing and leading to a cascade of events that enhance survival of brain cells.

Trapp is internationally known for his work on mechanisms of neurodegeneration and repair in multiple sclerosis. His past research has included investigation of the cause of neurological disability in MS patients, cellular mechanisms of brain repair in neurodegenerative diseases, and the molecular biology of myelination in the central and peripheral nervous systems.

With enough practice, some learners of a second language can process their new language as well as native speakers, research at the University of Kansas shows.

(Credit: bigstockphoto)

Using brain imaging, a trio of KU researchers was able to examine to the millisecond how the brain processes a second language. They then compared their findings with their previous results for native speakers and saw both followed similar patterns.

The research by Robert Fiorentino and Alison Gabriele, both associate professors in the linguistics department, and José Alemán Bañón, a former KU graduate student who is now a postdoctoral researcher at the University of Reading in the United Kingdom, was published this month in the journal Second Language Research.

For years, linguists have debated whether second-language learners would ever resemble native speakers in their ability to process language properties that differ between the first and second language, such as gender agreement, which is a property of Spanish but not English. In Spanish, all nouns are categorized as masculine or feminine, and various elements in the sentence, such as adjectives, need to carry the gender feature of the noun as well.

Some researchers argued that even those who spoke a second language with a high level of accuracy were using a qualitatively different mechanism than native speakers.

“We realized that these different theories proposing that either second-language learners use the same mechanism, or a different mechanism could actually be teased apart by using brain-imaging techniques,” Gabriele said.

The team studied 26 high-level Spanish speakers who hadn’t learned to speak Spanish until after age 11 and grew up with English as the majority language. The speakers used Spanish on a daily basis and had spent an average of a year and a half in a Spanish-speaking country.

They were compared with 24 native speakers, who were raised in Spanish-speaking countries and stayed in their home country until age 17.

To measure language processing as it happens, the team used a method known as electroencephalography (EEG), which uses an array of electrodes placed on the scalp to detect patterns of brain activity with high accuracy in timing.

Once hooked up to the EEG, the test subjects were asked to read sentences, some of which had grammatical errors in either number agreement or gender agreement.

The researchers then compared the results of the second-language learners to native speakers. They found that the highly proficient second-language speakers showed the same patterns of brain activity as native speakers when processing grammatical violations in sentences.

“We show that the learners’ brain activity looks qualitatively similar to that of native speakers, suggesting that they are using the same mechanisms,” Fiorentino said.

The study highlights the brain’s plasticity and its ability to acquire a new complex system even in adulthood.

“A lot of researchers have argued that there is some sort of language learning mechanism that might atrophy over the life span, particularly before puberty. And, we certainly have a lot of evidence that it is difficult to process your second language at nativelike levels and you have to go through quite a bit of effort to find people who can,” Gabriele said. “But I think what this paper shows is that it is possible.”

Gabriele and Fiorentino are working on a second phase of the research, studying how the brain processes a second language at the initial stages of exposure. Their preliminary results suggest that properties that are shared between the first and second language show patterns of brain activity that are very similar in learners and native speakers. This suggests that learners build on the representation for language that is already in place when learning a second language.

Scientists from the Sloan-Kettering Institute for Cancer Research in New York with the help of  Plymouth University Peninsula Schools of Medicine and Dentistry have completed research which for the first time brings us nearer to understanding how some cells in the brain and nervous system become cancerous.

The results of their study are published in the prestigious journal Cancer Cell.

The research team led by Sloan-Kettering researchers studied a tumour suppressor called Merlin. 

The results of the study have identified a new  mechanism whereby Merlin suppresses tumours, and that the mechanism operates within the nucleus. The research team has discovered that unsuppressed tumour cells increase via a core signalling system, the hippo pathway, and they have identified the route and method by which this signalling occurs.

By identifying the signalling system and understanding how, when present, Merlin suppresses it, the way is open for research into drug therapies which may suppress the signalling in a similar way to Merlin. 

Tumour suppressors exist in cells to prevent abnormal cell division in our bodies. The loss of Merlin leads to tumours in many cell types within our nervous systems. There are two copies of a tumour suppressor, one on each chromosome that we inherit from our parents. The loss of Merlin can be caused by random loss of both copies in a single cell, causing sporadic tumours, or by inheriting one abnormal copy and losing the second copy throughout our lifetime as is seen in the inherited condition of neurofibromatosis type 2 (NF2). 

No effective therapy for these tumours exists, other than repeated invasive surgery aiming at a single tumour at a time and which is unlikely to eradicate the full extent of the tumours, or radiotherapy.

Professor Oliver Hanemann, Director of the Institute of Translational and Stratified Medicine at Plymouth University Peninsula Schools of Medicine and Dentistry, and who led the Plymouth aspect of the study, commented:

“We have known for some time that the loss of the tumour suppressor Merlin resulted in the development of nervous system tumours, and we have come tantalisingly close to understanding how this occurs. Our joint study with colleagues at the Sloan-Kettering Institute for Cancer Research shows for the first time how this mechanism works. By understanding the mechanism, we can use this knowledge to develop effective drug therapies – in some cases adapting existing drugs – to treat patients for whom current therapies are limited and potentially devastating.”

A recent scientific discovery showed that mutations in prickle genes cause epilepsy, which in humans is a brain disorder characterized by repeated seizures over time. However, the mechanism responsible for generating prickle-associated seizures was unknown.

A new University of Iowa study, published online July 14 in the Proceedings of the National Academy of Sciences, reveals a novel pathway in the pathophysiology of epilepsy. UI researchers have identified the basic cellular mechanism that goes awry in prickle mutant flies, leading to the epilepsy-like seizures.

“This is to our knowledge the first direct genetic evidence demonstrating that mutations in the fly version of a known human epilepsy gene produce seizures through altered vesicle transport,” says John Manak, senior author and associate professor of biology in the College of Liberal Arts and Sciences and pediatrics in the Carver College of Medicine.

Seizure suppression in flies

A neuron has an axon (nerve fiber) that projects from the cell body to different neurons, muscles, and glands. Information is transmitted along the axon to help a neuron function properly.

Manak and his fellow researchers show that seizure-prone prickle mutant flies have behavioral defects (such as uncoordinated gait) and electrophysiological defects (problems in the electrical properties of biological cells) similar to other fly mutants used to study seizures. The researchers also show that altering the balance of two forms of the prickle gene disrupts neural information flow and causes epilepsy.

Further, they demonstrate that reducing either of two motor proteins responsible for directional movement of vesicles (small organelles within a cell that contain biologically important molecules) along tracks of structural proteins in axons can suppress the seizures.

“The reduction of either of two motor proteins, called Kinesins, fully suppressed the seizures in the prickle mutant flies,” says Manak, faculty member in the Interdisciplinary Graduate Programs in Genetics, Molecular and Cellular Biology, and Health Informatics. “We were able to use two independent assays to show that we could suppress the seizures, effectively ‘curing’ the flies of their epileptic behaviors.”

Genetic link between epilepsy and Alzheimer’s

This new epilepsy pathway was previously shown to be involved in neurodegenerative diseases, including Alzheimer’s and Parkinson’s.

Manak and his colleagues note that two Alzheimer’s-associated proteins, amyloid precursor protein and presenilin, are components of the same vesicle, and mutations in the genes encoding these proteins in flies affect vesicle transport in ways that are strikingly similar to how transport is impacted in prickle mutants.

“We are particularly excited because we may have stumbled upon one of the key genetic links between epilepsy and Alzheimer’s, since both disorders are converging on the same pathway,” Manak says. “This is not such a crazy idea. In fact, Dr. Jeff Noebels, a leading epilepsy researcher, has presented compelling evidence suggesting a link between these disorders. Indeed, patients with inherited forms of Alzheimer’s disease also present with epilepsy, and this has been documented in a number of published studies.”

Manak adds, “If this connection is real, then drugs that have been developed to treat neurodegenerative disorders could potentially be screened for anti-seizure properties, and vice versa.”

Manak’s future research will involve treating seizure-prone flies with such drugs to see if he can suppress their seizures.