Posts tagged brain
Articles and news from the latest research reports.
Genetics of Obsessive-Compulsive Disorder Narrowed Down
The first genome-wide searches for the genes responsible for Tourette syndrome and obsessive-compulsive disorder have uncovered a few clues to the underpinnings of both disorders.
Tourette syndrome is a neurological disorder characterized by muscle and vocal tics such as eye blinking, throat clearing and uttering taboo words or phrases. Tourette’s often co-occurs with obsessive-compulsive disorder (OCD), a mental illness marked by repetitive behaviors and anxiety-producing intrusive thoughts.
Neither Tourette syndrome nor OCD are simple enough to be traced to a single gene, but two new studies detailed today (Aug. 14) in the journal Molecular Psychiatry find several locations on the human chromosome that may contribute to the conditions.
A DNA molecule.
CREDIT: Giovanni Cancemi | Shutterstock
"Both disorders clearly have a complex underlying genetic architecture, and these two studies lay the foundation for understanding the underlying genetic etiology of Tourette syndrome and OCD," said Jeremiah Scharf, a neurologist at Massachusetts General Hospital in Boston, who worked on both projects.
Genetics of Tourette Syndrome
In the Tourette syndrome study, Scharf and his colleagues compared the genomes of more than 1,200 people with the disorder with the genomes of nearly 5,000 healthy individuals. They conducted what’s called a genome-wide association study, scanning hundreds of thousands of genetic variants from across the genomes to see if any were more common in the people with the disorder.
They found that no single genetic signal was significantly different between the two genomes, meaning that the researchers could not rule out random chance as the reason for any given difference. But among the top genetic variations, the researchers found an unusually high number that influence levels of gene expression in the frontal lobe of the brain — a region important in both Tourette syndrome and OCD, Scharf said.
One intriguing gene that varied the most between Tourette- and non-Tourette genomes was called COL27A1, a gene that encodes a collagen protein found in cartilage. The same gene is also active in the cerebellum, a brain region important for motor control during development. More research will be necessary to find what link, if any, COL27A1 has to Tourette syndrome, Scharf said.
The architecture of OCD
In a separate study, the scientists carried out the same analysis on healthy genomes as well as about 1,500 people with obsessive-compulsive disorder. Again, no one gene rose to the top as a definitive OCD gene, but the results revealed a good candidate near a gene called BTBD3, which is involved in multiple cellular functions. BTBD3 is very active in the brain during childhood and adolescent development, when OCD often first appears. It’s also related to a gene called BTBD9, which has been linked to Tourette syndrome in the past.
This first genome-wide pass is bound to turn up some false positives, Scharf said, so researchers will now need to home in on the intriguing genes in larger samples of people. They are also merging the two studies to look for genetic linkages that might explain why Tourette syndrome and OCD so frequently co-occur.
"The important thing this study does is that it really brings Tourette syndrome and OCD into the company of a number of other psychiatric diseases, which people have studied using genome-wide association," Scharf said, citing autism, schizophrenia and bipolar disorder as examples. “Now that we have these data for Tourette syndrome and OCD, we can work with investigators who are studying those other diseases to try to see what we can learn about what variants are shared between different neurodevelopment disorders.”
Source: Live Science
A young autistic boy has found his outlet in making science videos. Jordan Hilkowitz was diagnosed with autism when he was just 18 months old, he didn’t begin to speak until he was 5. His mother Stacey remembers the heartbreak she experienced as she watched her young son bang his head against the wall out of frustration at not being able to communicate.
It was his babysitter’s idea for Jordan to start making science videos. He’d always had an interest in science, and she felt that this could be an outlet for him to communicate to a larger audience. Larger indeed! Jordan’s channel, Doctor Mad Science, has received over 2.4 million views to date – and he’s become a local celebrity for his scientific knowhow.
(Source: blogs.scientificamerican.com)
Palaeontologists from the University of Zurich have “rediscovered” a skull bone that was thought to have been lost during the course of evolution for many mammals.
Mammals’ skulls are composed of around 20 bones — fewer than those of fish, reptiles and birds. This is because when mammals evolved from reptile-like vertebrates 320 million years ago, the skull structure simplified. Some bones were lost in the process, particularly some of the skull roof bones. The interparietal is one such bone, but it has perplexed researchers since it had survived in some mammals, such as horses and cats (and 2.8 percent of humans) but not in others.
The interparietal is clearly discernible in the embryo, but fuses with other bones beyond recognition shortly afterwards. As a result it’s often been missed. However, new imaging techniques have been able to detect its presence in all mammals.
In a new study, scientists at the Wisconsin Institute for Discovery (WID) at UW-Madison develop a computational approach to determine whether individuals behave predictably. With data from previous fights, the team looked at how much memory individuals in the group would need to make predictions themselves. The analysis proposes a novel estimate of “cognitive burden,” or the minimal amount of information an organism needs to remember to make a prediction.
The research draws from a concept called “sparse coding,” or the brain’s tendency to use fewer visual details and a small number of neurons to stow an image or scene. Previous studies support the idea that neurons in the brain react to a few large details such as the lines, edges and orientations within images rather than many smaller details.
"So what you get is a model where you have to remember fewer things but you still get very high predictive power — that’s what we’re interested in," says Bryan Daniels, a WID researcher who led the study.
Levels of sleep problems in the developing world are approaching those seen in developed nations, linked to an increase in problems like depression and anxiety.
According to the first ever pan-African and Asian analysis of sleep problems, led by Warwick Medical School at the University of Warwick, an estimated 150 million adults are suffering from sleep-related problems across the developing world.
The results are published in a study in the journal Sleep.
Source: The University of Warwick
According to new research, meerkats enhance their intelligence through nine different social and asocial mechanisms. What really makes these animals stand out is their intelligent coordinated behaviour, which rivals that of chimps, baboons, dolphins and even humans in its complexity and efficiency.
A team led by William Hoppitt of the University of St. Andrews presented wild meerkats with a novel foraging task to investigate the animal’s learning mechanisms. ‘The model deals with the rate at which individuals interact with the task, solve the task once they are interacting with it, or give up on the task when they are manipulating it,’ said Hoppitt.
They found that the meerkats engaged in a wide variety of social and asocial behaviours to learn to solve the task, and that in general the social factors helped draw the meerkats into the task, while the asocial processes helped them actually solve the task.
The model may also be more broadly applicable and can be used to investigate the relationship between social learning mechanisms and so-called ‘behavioural traditions’ that together can constitute a culture.
A new study from The University of Queensland shows monitoring the brain of stroke patients using Quantitative EEG (QEEG) studies could inform treatments and therefore, minimising brain damage of stroke victims.
“The main goals of this research were to evaluate key findings, identify common trends and determine what the future priorities should be, both for research and for translating this to best inform clinical management of stroke patients,” Dr Finnigan from UQ’s Centre for Clinical Research said.
The review of outcomes from hundreds of patients has highlighted that QEEG indicators are particularly informative in two ways.
“Firstly they can help predict long-term deficits caused by stroke, … In addition, they could provide immediate information on how patients are responding to treatments and guide decisions about follow-on treatments, even before stroke symptoms change,” Dr Finnigan said.
A condition believed to be a normal part of the ageing process has been found to have a negative effect on the brain function of older adults.
Leukoaraiosis, also known as small vessel ischemia, is a condition in which diseased blood vessels lead to small areas of damage in the white matter of the brain. The lesions are common in the brains of people over the age of 60, although the amount of disease varies among individuals.
"We know that aging is a risk factor for leukoaraiosis, and we suspect that high blood pressure may also play a role, … Different systems of the brain respond differently to disease, … White matter damage affects connections within the brain’s language network, which leads to an overall reduction in network activity." -Kirk M. Welker, M.D., assistant professor of radiology in the College of Medicine at Mayo Clinic in Rochester, Minn.
(Source: medicalxpress.com)
Mount Sinai Researchers Identify New Drug Target for Schizophrenia
August 13, 2012
Researchers at Mount Sinai School of Medicine may have discovered why certain drugs to treat schizophrenia are ineffective in some patients. Published online in Nature Neuroscience, the research will pave the way for a new class of drugs to help treat this devastating mental illness, which impacts one percent of the world’s population, 30 percent of whom do not respond to currently available treatments.
A team of researchers at Mount Sinai School of Medicine set out to discover what epigenetic factors, or external factors that influence gene expression, are involved in this treatment-resistance to atypical antipsychotic drugs, the standard of care for schizophrenia. They discovered that, over time, an enzyme in the brains of schizophrenic patients analyzed at autopsy begins to compensate for the prolonged chemical changes caused by antipsychotics, resulting in reduced efficacy of the drugs.
"These results are groundbreaking because they show that drug resistance may be caused by the very medications prescribed to treat schizophrenia, when administered chronically," said Javier Gonzalez-Maeso, PhD, Assistant Professor of Psychiatry and Neurology at Mount Sinai School of Medicine and lead investigator on the study.
They found that an enzyme called HDAC2 was highly expressed in the brain of mice chronically treated with antipsychotic drugs, resulting in lower expression of the receptor called mGlu2, and a recurrence of psychotic symptoms. A similar finding was observed in the postmortem brains of schizophrenic patients. The research team administered a chemical called suberoylanilide hydroxamic acid (SAHA), which inhibits the entire family of HDACs. They found that this treatment prevented the detrimental effect of the antipsychotic called clozapine on mGlu2 expression, and also improved the therapeutic effects of atypical antipsychotics in mouse models.
Previous research conducted by the team showed that chronic treatment with the antipsychotic clozapine causes repression of mGlu2 expression in the frontal cortex of mice, a brain area key to cognition and perception. The researchers hypothesized that this effect of clozapine on mGlu2 may play a crucial role in restraining the therapeutic effects of antipsychotic drugs.
"We had previously found that chronic antipsychotic drug administration causes biochemical changes in the brain that may limit the therapeutic effects of these drugs,"said Dr. Gonzalez-Maeso. "We wanted to identify the molecular mechanism responsible for this biochemical change, and explore it as a new target for new drugs that enhance the therapeutic efficacy of antipsychotic drugs."
Mitsumasa Kurita, PhD, a postdoctoral fellow at Mount Sinai and the lead author of the study, said, “We found that atypical antipsychotic drugs trigger an increase of HDAC2 in frontal cortex of individuals with schizophrenia, which then reduces the presence of mGlu2, and thereby limits the efficacy of these drugs,” said
Dr. Gonzalez-Maeso’s team is now developing compounds that specifically inhibit HDAC2 as adjunctive treatments to antipsychotics. The study was funded by the National Institutes of Health.
Source: The Mount Sinai Hospital
Dr Kristin Hillman and Professor David Bilkey have found that neurons in a specific region of the frontal cortex, called the anterior cingulate cortex, become active during decisions involving competitive effort.
The researchers have discovered that neurons in this region appear to store information on whether a course of action demands competition, what the intensity of that competition will be, and critically, whether or not the competition is ‘worth it’ to achieve an end reward.
Their study, which appears online in the journal Nature Neuroscience, is the first to examine how competitive behaviour is encoded by neurons in the brain.
Source: University of Otago