Posts tagged brain

ScienceDaily (July 12, 2012) — University of Kansas researchers have found larger resting pupil size and lower levels of a salivary enzyme associated with the neurotransmitter norepinephrine in children with autism spectrum disorder.

However, even though the levels of the enzyme, salivary alpha-amylase (sAA), were lower than those of typically-developing children in samples taken in the afternoon in the lab, samples taken at home throughout the day showed that sAA levels were higher in general across the day and much less variable for children with ASD.

"What this says is that the autonomic system of children with ASD is always on the same level," Christa Anderson, assistant research professor, said. "They are in overdrive."

The sAA levels of typically-developing children gradually rise and fall over the day, said Anderson, who co-directed the study with John Colombo, professor of psychology.

Norepinephrine (NE) has been found in the blood plasma levels of individuals with ASD but some researchers have questioned whether these levels were just related to the stress from blood draws.

The KU study addressed this by collecting salivary measures by simply placing a highly absorbent sponge swab under the child’s tongue and confirmed that this method of collection did not stress the children by assessing their stress levels through cortisol, another hormone.

Collecting sAA levels has the potential for physicians to screen children for ASD much earlier, noninvasively and relatively inexpensively, said Anderson.

But Anderson and Colombo also see pupil size and sAA levels as biomarkers that could be the physiological signatures of a possible dysfunction in the autonomic nervous system.

"Many theories of autism propose that the disorder is due to deficits in higher-order brain areas," said Colombo. "Our findings, however, suggest that the core deficits may lie in areas of the brain typically associated with more fundamental, vital functions."

The study, published online in the May 29, 2012 Developmental Psychobiology compared children between the ages of 20 and 72 months of age diagnosed with ASD to a group of typically developing children and a third group of children with Down Syndrome.

Both findings address the Centers for Disease Control’s urgent public health priority goals for ASD: to find biological indicators that can both help screen children earlier and lead to better understanding of how the nervous system develops and functions in the disorder.

Source: Science Daily

ScienceDaily (July 12, 2012) — Researchers at Emory University School of Medicine have identified five rare mutations in a single gene that appear to increase the chances that a boy will develop an autism spectrum disorder (ASD).

Mutations in the AFF2 gene, and other genes like it on the X chromosome, may explain why autism spectrum disorders affect four times as many boys as girls.

The mutations in AFF2 appeared in 2.5 percent (5 out of 202) boys with an ASD. Mutations in X chromosome genes only affect boys, who have one X chromosome. Girls have a second copy of the gene that can compensate.

The results were published July 5 in the journal Human Molecular Genetics.

"Our data suggest that AFF2 could be one of the major X-linked risk factors for ASD’s," says senior author Michael Zwick, PhD, assistant professor of human genetics at Emory University School of Medicine.

The finding bolsters a growing consensus among geneticists that rare variants in many different genes contribute significantly to risk for autism spectrum disorders.

The mutations in the AFF2 gene probably do not cause ASDs all by themselves, Zwick says.

"We do not think that the variants we have identified are monogenic causes of autism," he says. "Our data does support the idea that this is an autism susceptibility gene."

In some situations, mutations in a single gene are enough by themselves to lead to a neurodevelopmental disorder with autistic features, such as fragile X syndrome or tuberous sclerosis complex. But these types of mutations are thought to account for a small number of ASD cases.

Recent large-scale genetic studies of autism spectrum disorders have identified several “rare variants” that sharply increase ASD risk. Scientists believe rare variants could explain up to 15 or 20 percent of ASD cases. However, until now no single variant has been found in more than one percent of ASD cases.

Working with Zwick, postdoctoral fellow Kajari Mondal and her colleagues read the sequence of the AFF2 gene in DNA from 202 boys diagnosed with autism spectrum disorders. The patient samples came from the Autism Genetic Resource Exchange and the Simons Simplex Collection.

Tests showed that in four cases, the affected boys had inherited the risk-conferring mutations from their mothers. One boy had a “de novo” (not coming from the parents) mutation. Compared with X-linked genes in unaffected people, mutations in AFF2 were five times more abundant in the boys with ASDs.

The AFF2 gene had already been identified as responsible for a rare inherited form of intellectual disability with autistic features. This effect is seen when the AFF2 gene is deleted or silenced completely.

AFF2 has some similarity to FMR1, the gene responsible for fragile X syndrome. Like FMR1, it can be silenced by a triplet repeat. In these cases, the presence of the triplet repeat (three genetic bases repeated dozens of times) triggers a change in chromosomal structure that prevents the gene from being turned on.

In contrast, the mutations Zwick’s team found are more subtle, slightly changing the sequence of the protein AFF2 encodes. Little is known about the precise function of the AFF2 protein. A related gene in fruit flies called lilliputian also appears to regulate the development of neurons.

Zwick says one of his laboratory’s projects is to learn more about the function of the AFF2 gene, and to probe how the mutations identified by his team affect the function. His team is also working on gauging the extent to which other genes on the X chromosome contribute to autism risk.

Source: Science Daily

ScienceDaily (July 12, 2012) — Diagnosing multiple sclerosis (MS) is a challenge even for experienced neurologists. This autoimmune disease has many symptoms and rarely presents a uniform clinical picture. New scientific findings on the immune response involved in MS could now help improve the diagnosis of this illness. Scientists analyzing the blood of MS patients have discovered antibodies that attack a specific potassium channel in the cell membrane. Potassium channels play an important role in transmitting impulses to muscle and nerve cells and it is exactly these processes that are inhibited in MS patients.

Right: The autoantibody can be seen binding to the membrane of glial cells in the MS serum. By comparison, the image on the left shows a blood sample from a patient with another neurological disease. (Credit: KKNMS)

The results are published in the current issue of the New England Journal of Medicine.

For the first time, scientists in Germany’s multiple sclerosis competence network have been able to identify an antibody that bonds with the potassium channel KIR4.1. “We found this autoantibody in almost half of the MS patients in our study,” explains Bernhard Hemmer, Professor of Neurology at the Klinikum rechts der Isar hospital at Technische Universität München (TUM). The biomarker was not present in healthy patients. The findings could therefore indicate that KIR4.1 is one of the targets of the autoimmune response in MS. Humans and animals without the KIR4.1 channel experience neurological failure and cannot coordinate their movements properly. Furthermore, their bodies do not create sufficient amounts of myelin, a layer of insulation that protects the nerve cells.

KIR4.1 is primarily present in the membrane of glial cells, which are responsible for controlling metabolism in the brain and forming myelin. The neurologists will now be conducting follow-up studies into how KIR4.1 antibodies influence the development of MS. This autoantibody is extremely rare in people with other neurological diseases, making it an important potential diagnostic marker for MS in the future. “This autoantibody could improve diagnosis of MS and help us differentiate it more clearly from other neurological diseases,” continues Hemmer. This will also be the focus of further research.

Source: Science Daily

July 12, 2012

(HealthDay) — A supplement mixture (Souvenaid) containing dietary precursors and specific nutrients can improve memory in drug-naive patients with mild Alzheimer’s disease (AD), according to a study published in the July issue of the Journal of Alzheimer’s Disease.

Philip Scheltens, M.D., from the VU University Medical Center in Amsterdam, and colleagues conducted a 24-week, randomized, controlled trial in which drug-naive patients with mild AD were randomized in a 1:1 ratio to receive Souvenaid or an iso-caloric control product once daily. Memory function was assessed using the domain z-score of the Neuropsychological Test Battery (NTB).

The researchers found that, over the intervention period, the NTB memory domain z-score was significantly increased in patients taking Souvenaid versus the control group (P = 0.023), with a trend toward improvement in the NTB total composite z- score (P = 0.053). Functional connectivity in the delta band, as measured by an electroencephalography, was significantly different between the study groups in favor of the active group. There was very high adherence to the intervention (96.6 percent for the control and 97.1 percent for the active group). Both products were well tolerated and there was no between-group difference in the occurrence of serious adverse events.

"In conclusion, this study confirms that Souvenaid is well tolerated and improves memory performance,” the authors write. “Our results warrant further investigation of the clinical potential of Souvenaid in preclinical or clinical conditions characterized by synaptic loss, in particular AD.”

Several authors disclosed financial ties to Danone Research BV and Nutricia Advanced Medical Nutrition, which sponsored the study and manufacture Souvenaid.

Source: medicalxpress.com

ScienceDaily (July 12, 2012) — Obesity is not to blame for poor educational performance, according to early findings from research funded by the Economic and Social Research Council (ESRC). In a study that combines statistical methods with genetic information, researchers dispel the false idea that being overweight has damaging educational consequences.

Previous studies have shown that children who are heavier are less likely to do well at school. However, Dr Stephanie von Hinke Kessler Scholder from University of York argues it’s vital to understand what drives this association. “We sought to test whether obesity ‘directly’ hinders performance due to bullying or health problems, or whether kids who are obese do less well because of other factors that are associated with both obesity and lower exam results, such as coming from a disadvantaged family,” Dr Scholder explains.

Researchers examined data on almost 4,000 members of the Children of the 90s Birth Cohort Study. These data include the children’s DNA. It is well known that genes are randomly allocated within a population, irrespective of factors such as socio-economic position. The researchers combined the latest developments from genetic epidemiology with statistical methodologies in economic and econometric research. Using two carefully chosen ‘genetic markers’, the research team was able to identify children with a slightly higher genetic pre-disposition to obesity.

“Based on a simple correlation between children’s obesity as measured by their fat mass and their exam results, we found that heavier children did do slightly worse in school,” Dr Scholder points out. “But, when we used children’s genetic markers to account for potentially other factors, we found no evidence that obesity causally affects exam results. So, we conclude that obesity is not a major factor affecting children’s educational outcomes.”

These findings suggest that the previously found negative relationship between weight and educational performance is driven by factors that affect both weight and educational attainment. Future research should focus on other determinants of poor educational outcomes, such as social class or a family’s socio-economic circumstances, Dr Scholder points out.

The finding that obesity is not a cause of poorer educational performance is, the researchers suggest, a positive thing. “Clearly there are reasons why there are differences in educational outcomes, but our research shows that obesity is not one of them,” Dr Scholder argues.

Source: Science Daily

July 12, 2012

Biologists at UC San Diego have discovered a chemical that offers a completely new and promising direction for the development of drugs to treat metabolic disorders such as type 2 diabetes—a major public health concern in the United States due to the current obesity epidemic.

Their discovery, detailed in a paper published July 13 in an advance online issue of the journal Science, initially came as a surprise because the chemical they isolated does not directly control glucose production in the liver, but instead affects the activity of a key protein that regulates the internal mechanisms of our daily night and day activities, which scientists call our circadian rhythm or biological clock.

Scientists had long suspected that diabetes and obesity could be linked to problems in the biological clock. Laboratory mice with altered biological clocks, for example, often become obese and develop diabetes. Two years ago, a team headed by Steve Kay, dean of the Division of Biological Sciences at UC San Diego, discovered the first biochemical link between the biological clock and diabetes. It found that a key protein, cryptochrome, that regulates the biological clocks of plants, insects and mammals also regulates glucose production in the liver and that altering the levels of this protein could improve the health of diabetic mice.

Now Kay and his team have discovered a small molecule—one that can be easily developed into a drug—that controls the intricate molecular cogs or timekeeping mechanisms of cryptochrome in such a manner that it can repress the production of glucose by the liver. Like mice and other animals, humans have evolved biochemical mechanisms to keep a steady supply of glucose flowing to the brain at night, when we’re not eating or otherwise active.

"At the end of the night, our hormones signal that we’re in a fasting state," said Kay. "And during the day, when we’re active, our biological clock shuts down those fasting signals that tell our liver to make more glucose because that’s when we’re eating."

Read more …

ScienceDaily (July 11, 2012) — Widely held beliefs about Neuro-Linguistic Programming and lying are unfounded.

Twenty portrait of a woman with different expressions. (Credit: © gemenacom / Fotolia)

Proponents of Neuro-Linguistic Programming (NLP) have long claimed that it is possible to tell whether a person is lying from their eye movements.  Research published July 11 in the journal PLoS ONE reveals that this claim is unfounded, with the authors calling on the public and organisations to abandon this approach to lie detection.

For decades many NLP practitioners have claimed that when a person looks up to their right they are likely to be lying, whilst a glance up to their left is indicative of telling the truth.

Professor Richard Wiseman (University of Hertfordshire, UK) and Dr Caroline Watt (University of Edinburgh, UK) tested this idea by filming volunteers as they either lied or told the truth, and then carefully coded their eye movements.  In a second study another group of participants was asked to watch the films and attempt to detect the lies on the basis of the volunteers’ eye movements.

"The results of the first study revealed no relationship between lying and eye movements, and the second showed that telling people about the claims made by NLP practitioners did not improve their lie detection skills,” noted Wiseman. 

A final study involved moving out of the laboratory and was conducted in collaboration with Dr Leanne ten Brinke and Professor Stephen Porter from the University of British Columbia, Canada.  The team analysed films of liars and truth tellers from high profile press conferences in which people were appealing for missing relatives or claimed to have been the victim of a crime. 

"Our previous research with these films suggests that there are significant differences in the behaviour of liars and truth tellers," noted Dr Leanne ten Brinke. "However, the alleged tell-tale pattern of eye movements failed to emerge."

"A large percentage of the public believes that certain eye movements are a sign of lying, and this idea is even taught in organisational training courses.  Our research provides no support for the idea and so suggests that it is time to abandon this approach to detecting deceit" remarked Watt.

Source: Science Daily

ScienceDaily (July 11, 2012) — When humans learn, their brains relate new information with past experiences to derive new knowledge, according to psychology research from The University of Texas at Austin.

The study, led by Alison Preston, assistant professor of psychology and neurobiology, shows this memory-binding process allows people to better understand new concepts and make future decisions. The findings could lead to better teaching methods, as well as treatment of degenerative neurological disorders, such as dementia, Preston says.

"Memories are not just for reflecting on the past; they help us make the best decisions for the future," says Preston, a research affiliate in the Center for Learning and Memory, which is part of the university’s College of Natural Sciences. "Here, we provide a direct link between these derived memories and the ability to make novel inferences."

The paper was published online in July in the journal Neuron. The authors include University of Texas at Austin researchers Dagmar Zeithamova and April Dominick.

In the study, 34 subjects were shown a series of paired images composed of different elements (for example, an object and an outdoor scene). Each of the paired images would then reappear in more presentations. A backpack, paired with a horse in the first presentation, would appear alongside a field in a later presentation. The overlap between the backpack and outdoor scenery (horse and field) would cause the viewer to associate the backpack with the horse and field. The researchers used this strategy to see how respondents would delve back to a recent memory while processing new information.

Using functional Magnetic Resonance Imaging (fMRI) equipment, the researchers were able to look at the subjects’ brain activity as they looked at image presentations. Using this technique, Preston and her team were able to see how the respondents thought about past images while looking at overlapping images. For example, they studied how the respondents thought about a past image (a horse) when looking at the backpack and the field. The researchers found the subjects who reactivated related memories while looking at overlapping image pairs were able to make associations between individual items (i.e. the horse and the field) despite the fact that they had never studied those images together.

To illustrate the ways in which this cognitive process works, Preston describes an everyday scenario.

Imagine you see a new neighbor walking a Great Dane down the street. At a different time and place, you may see a woman walking the same dog in the park. When experiencing the woman walking her dog, the brain conjures images of the recent memory of the neighbor and his Great Dane, causing an association between the dog walkers to be formed in memory. The derived relationship between the dog walkers would then allow you to infer the woman is also a new neighbor even though you have never seen her in your neighborhood.

"This is just a simple example of how our brains store information that goes beyond the exact events we experience," Preston says. "By combining past events with new information, we’re able to derive new knowledge and better anticipate what to expect in the future."

During the learning tasks, the researchers were able to pinpoint the brain regions that work in concert during the memory-binding process. They found the hippocampal-ventromedial prefrontal cortex (VMPFC) circuit is essential for binding reactivated memories with current experience.

Source: Science Daily