Posts tagged science
Articles and news from the latest research reports.
Brief exercise immediately enhances memory
A short burst of moderate exercise enhances the consolidation of memories in both healthy older adults and those with mild cognitive impairment, scientists with UC Irvine’s Center for the Neurobiology of Learning & Memory have discovered.
Most research has focused on the benefits of a long-term exercise program on overall health and cognitive function with age. But the UCI work is the first to examine the immediate effects of a brief bout of exercise on memory.
In their study, post-doctoral researcher Sabrina Segal and neurobiologists Carl Cotman and Lawrence Cahill had people 50 to 85 years old with and without memory deficits view pleasant images – such as photos of nature and animals – and then exercise on a stationary bicycle for six minutes at 70 percent of their maximum capacity immediately afterward.
One hour later, the participants were given a surprise recall test on the previously viewed images. Results showed a striking enhancement of memory by exercise in both the healthy and cognitively impaired adults, compared with subjects who did not ride the bike.
“We found that a single, short instance of moderately intense exercise particularly improved memory in individuals with memory deficits,” Segal said. “Because of its implications and the need to better understand the mechanism by which exercise may enhance memory, we’re following up this study with an investigation of potential underlying biological factors.”
She believes the improved memory may be related to the exercise-induced release of norepinephrine, a chemical messenger in the brain known to play a strong role in memory modulation. This hypothesis is based on previous work demonstrating that increasing norepinephrine through pharmacological manipulation sharpens memory and that blocking norepinephrine impairs memory.
In the more recent research, Segal and her colleagues discovered that levels of salivary alpha amylase, a biomarker that reflects norepinephrine activity in the brain, significantly increased in participants after exercise. This correlation was especially strong in people with memory impairment.
“The current findings offer a natural and relatively safe alternative to pharmacological interventions for memory enhancement in healthy older individuals as well as those who suffer from cognitive deficits,” Segal noted. “With a growing population of the aged, the need for improvement of quality of life and prevention of mental decline is more important than ever before.”
Study results appear in the November issue (Volume 32, Number 4) of the Journal of Alzheimer’s Disease.
(Source: news.uci.edu)
Researchers Identify Physiological Evidence of ‘Chemo Brain’
Chemotherapy can induce changes in the brain that may affect concentration and memory, according to a study presented at the annual meeting of the Radiological Society of North America (RSNA). Using positron emission tomography combined with computed tomography (PET/CT), researchers were able to detect physiological evidence of chemo brain, a common side effect in patients undergoing chemotherapy for cancer treatment.
"The chemo brain phenomenon is described as ‘mental fog’ and ‘loss of coping skills’ by patients who receive chemotherapy," said Rachel A. Lagos, D.O., diagnostic radiology resident at the West Virginia University School of Medicine and West Virginia University Hospitals in Morgantown, W.V. "Because this is such a common patient complaint, healthcare providers have generically referred to its occurrence as ‘chemo brain’ for more than two decades."
While the complaint may be common, the cause of chemo brain phenomenon has been difficult to pinpoint. Some prior studies using magnetic resonance imaging (MRI) have found small changes in brain volume after chemotherapy, but no definitive link has been found.
Instead of studying chemotherapy’s effect on the brain’s appearance, Dr. Lagos and colleagues set out to identify its effect on brain function. By using PET/CT, they were able to assess changes to the brain’s metabolism after chemotherapy.
"When we looked at the results, we were surprised at how obvious the changes were," Dr. Lagos said. "Chemo brain phenomenon is more than a feeling. It is not depression. It is a change in brain function observable on PET/CT brain imaging."
PET/CT results demonstrated statistically significant decreases in regional brain metabolism that were closely associated with symptoms of chemo brain phenomenon.
"The study shows that there are specific areas of the brain that use less energy following chemotherapy," Dr. Lagos said. "These brain areas are the ones known to be responsible for planning and prioritizing."
Dr. Lagos believes that PET/CT could be used to help facilitate clinical diagnosis and allow for earlier intervention.
Researchers Study Cry Acoustics of Infants to Determine Risk for Autism
Autism is a poorly understood family of related conditions. People with autism generally lack normal social interaction skills and engage in a variety of unusual and often characteristic behaviors, such as repetitive movements. While there is no specific medical treatment for autism, some success has been shown with early behavioral intervention.
Understanding the importance of early diagnosis, researchers at Women & Infants’Brown Center for the Study of Children at Riskin collaboration with researchers at University of Pittsburgh have been studying the cry acoustics of six-month-old infants. Their research has recently been published in Autism Research.
“Because we can measure various aspects of babies’ cries from the earliest days of life, it may be possible to use this technique to identify risk for neurological problems such as autism long before we can detect behavioral differences,” said Stephen J. Sheinkopf, PhD, lead researcher, psychologist at the Brown Center for the Study of Children at Risk, and assistant professor (research) in the Department of Psychiatry and Human Behavior at The Warren Alpert Medical School of Brown University.
The study examined ways in which infants at risk for autism produced cries as compared to the cries of low-risk infants. Recordings of babies’ cries were excerpted from vocal and video recordings of six-month-old infants at risk for autism spectrum disorder (ASD) and those with low risk. Infants were considered to be at risk if they had an older sibling with a confirmed ASD diagnosis.
Cries were categorized as either pain related or non-pain related based on observations of the videotapes. At-risk infants produced pain related cries with higher and more variable fundamental frequency (commonly referred to as “pitch”) as compared to low-risk infants. A small number of the at-risk infants were later diagnosed with an ASD at 36 months of age. The cries for these babies had among the highest fundamental frequency values and also differed in other acoustic characteristics.
“These findings demonstrate the potential of this approach for babies as young as six months of age,” said Dr. Sheinkopf.
(Photo: Thinkstock Source: Getty Images)
Researchers find reading uses the same brain regions regardless of language
A team of French and Taiwanese researchers has found evidence to indicate that people use the same regions of the brain when reading, regardless of which language is being read. In their paper published in the Proceedings of the National Academy of Sciences, they describe how fMRI brain scans made while people were reading revealed that there are very few differences in how the brain works as reading occurs.
The researchers note that previous research has suggested that different neural networks might be involved when people read text written in very different types of languages. French, for example, is an alphabetic language, whereas Chinese is logographic. Those of Roman origin are based on abstract concepts while Chinese characters are based on realistic depictions of handwriting strokes.
To learn more, the researchers ran fMRI scans on volunteers reading either Chinese or French material as their native language. The material presented was shown in various forms, e.g. normal, static, backwards or distorted. The researchers also employed priming, which is where words are flashed on a screen for such a short period of time as to be unknown to the reader. Priming has been found to influence the rate at which readers recognize words that are shown thereafter for a normal duration of time. The material written in French was presented as cursive rather than block printed letters.
In analyzing the results, the researchers found the differences in brain activity between the two groups as they read to be minimal. Those differences that were found, centered around a slight increase in the brain regions associated with processing the physical movements that had occurred in creating the characters, which in the brain is recognized as motor skills.
The researchers suggest that their results indicate that because reading is a relatively new process for the human brain, it likely evolved using previously existing neural network circuitry, which would explain why it appears the brain works in roughly the same way when reading, regardless of language.
Biking Restores Brain Connectivity in Parkinson’s
PROBLEM: It’s commonly known that Parkinson’s Disease is a chronic, progressive, disease of central nervous system that affects motor ability — its recognizable early stages are characterized by shakiness and difficulty walking. No cure exists, which is why back in 2003, the best Dr. Jay Alberts of the Cleveland Clinic Lerner Research Institute rode a tandem bicycle across Iowa with a Parkinson’s patient (to raise awareness). Unexpectedly, the patient showed improvements in her condition after the trip. In what now much be common lore at the Institute, Alberts attempted to explain the inexplicable by noticing that his own pace was faster than that of his partner, who was forced, by the cruel mechanics of tandem cycling, to pedal faster in order to keep up.
METHODOLOGY: Alberts and his colleagues used functional connectivity MRI to study the brains of 26 patients with Parkinson’s Disease before and after they engaged in an 8-week exercise program and then, as a follow-up, one month later. Three times a week, the patients worked out on stationary bicycles. The experimental group used a modified bike that, using an algorithm in the place of a super in-shape doctor, would measure their rate of exertion and use it as a basis to push them harder than they would otherwise choose.
RESULTS: What the researchers referred to as “forced rate activity,” others might feel is more accurately labeled “torture.” But when they calculated the brain activation of the patients forced to pedal past their comfort level, they found lasting increases in connectivity between two areas of the brain responsible for motor ability: the primary motor cortex and the posterior region of the thalamus.
CONCLUSION: Forced-rate bicycle exercise appears to be an effective therapy for Parkinson’s disease.
IMPLICATION: The treatment delivered dramatic results, and has the distinction of being inexpensive and accessible. Alberts contends that even those without access to their own algorithm for forced-rate activity may be able to see improvement by using an at-home stationary bike. The next step is to evaluate the possible effects of other forms of exercise, like swimming.
The full study was presented at the annual meeting of the Radiological Society of North America.
Auditory test predicts coma awakening
A coma patient’s chances of surviving and waking up could be predicted by changes in the brain’s ability to discriminate sounds, new research suggests.
Recovery from coma has been linked to auditory function before, but it wasn’t clear whether function depended on the time of assessment. Whereas previous studies tested patients several days or weeks after comas set in, a new study looks at the critical phase during the first 48 hours. At early stages, comatose brains can still distinguish between different sound patterns. How this ability progresses over time can predict whether a coma patient will survive and ultimately awaken, researchers report.
“It’s a very promising tool for prognosis,” says neurologist Mélanie Boly of the Belgian National Fund for Scientific Research, who was not involved with the study. “For the family, it’s very important to know if someone will recover or not.”
A team led by neuroscientist Marzia De Lucia of the University of Lausanne in Switzerland studied 30 coma patients who had experienced heart attacks that deprived their brains of oxygen. All the patients underwent therapeutic hypothermia, a standard treatment to minimize brain damage, in which their bodies were cooled to 33° Celsius for 24 hours.
De Lucia and colleagues played sounds for the patients and recorded their brain activity using scalp electrodes — once in hypothermic conditions during the first 24 hours of coma, and again a day later at normal body temperature. The sounds were a series of pure tones interspersed with sounds of different pitch, duration or location. The brain signals revealed how well patients could discriminate the sounds, compared with five healthy subjects.
After three months, the coma patients had either died or awoken. All the patients whose discrimination improved by the second day of testing survived and awoke from their comas. By contrast, many of those whose sound discrimination deteriorated by the second day did not survive. The results were reported online November 12 in Brain.
(Image credit: ANP)
Lack of nutrients and metabolic syndrome linked to different subtypes of depression
A low intake of folate and vitamin B12 increases the risk of melancholic depressive symptoms, according to a study among nearly 3,000 middle-aged and elderly Finnish subjects. On the other hand, non-melancholic depressive symptoms are associated with an increased risk for the metabolic syndrome. Based on these new observations, melancholic and non-melancholic depression may be separate depressive subtypes with different etiologies in terms of proinflammation and diet. The study was the first to look at these depressive sub-types separately.
"The findings have practical implications in the care of patients with depressive symptoms. For example, it may be wise to avoid medication causing weight gain among patients with non-melancholic depression, whereas melancholic depressive symptoms may call for a closer look at the quality of the patient’s diet," says Mr Jussi Seppälä, MD, Chief of the Department of Psychiatry of the Hospital District of Southern Savo.
Melancholic depression involves typical depressive symptoms, such as a depressed mood. Non-melancholic depression is characterized by other types of symptoms, such as low self-esteem and feelings of worry and anxiety.
Among subjects with the highest folate intake, the risk for melancholic depressive symptoms was almost 50 per cent lower than among those with the lowest intake. In addition, among those with the highest vitamin B12 levels, the risk for melancholic depressive symptoms was almost three times lower than among those with the lowest levels. Both findings are new. A similar association with non-melancholic depressive symptoms was not observed.
Another novel observation is that the risk for the metabolic syndrome was twofold among those with non-melancholic depressive symptoms, as compared to those with melancholic symptoms or those with no depressive symptoms.
Mr Seppälä’s doctoral thesis “Depressive symptoms, metabolic syndrome and diet" was published at the University of Eastern Finland. The study was conducted as part of the Finnish Type 2 Diabetes Prevention Programme. The findings were originally published in Journal of Affective Disorders.
Researchers find chemical ‘switches’ for neurodegenerative diseases
By using a model, researchers at the University of Montreal have identified and “switched off” a chemical chain that causes neurodegenerative diseases such as Huntington’s disease, amyotrophic lateral sclerosis and dementia. The findings could one day be of particular therapeutic benefit to Huntington’s disease patients. “We’ve identified a new way to protect neurons that express mutant huntingtin proteins,” explained Dr. Alex Parker of the University of Montreal’s Department of Pathology and Cell Biology and its affiliated CRCHUM Research Centre. A cardinal feature of Huntington’s disease – a fatal genetic disease that typically affects patients in midlife and causes progressive death of specific areas of the brain – is the aggregation of mutant huntingtin protein in cells. “Our model revealed that increasing another cell chemical called progranulin reduced the death of neurons by combating the accumulation of the mutant proteins. Furthermore, this approach may protect against neurodegenerative diseases other than Huntington’s disease.”
There is no cure for Huntingdon’s disease and current strategies show only modest benefits, and a component of the protein aggregates involved are also present in other degenerative diseases. “My team and I wondered if the proteins in question, TDP-43 and FUS, were just innocent bystanders or if they affected the toxicity caused by mutant huntingtin,” Dr. Parker said. To answer this question, Dr. Parker and University of Montreal doctoral student Arnaud Tauffenberger turned to a simple genetic model based on the expression of mutant huntingtin in the nervous system of the transparent roundworm C. elegans. A large number of human disease genes are conserved in worms, and C. elegans in particular enables researchers to rapidly conduct genetic analyses that would not be possible in mammals.
Dr. Parker’s team found that deleting the TDP-43 and FUS genes, which produce the proteins of the same name, reduced neurodegeneration caused by mutant huntingtin. They then confirmed their findings in the cell of a mammal cell, again by using models. The next step was then to determining how neuroprotection works. TDP-43 targets a chemical called progranulin, a protein linked to dementia. “We demonstrated that removing progranulin from either worms or cells enhanced huntingtin toxicity, but increasing progranulin reduced cell death in mammalian neurons. This points towards progranulin as a potent neuroprotective agent against mutant huntingtin neurodegeneration,” Dr. Parker said. The researchers will need to do further testing this in more complex biological models to determine if the same chemical switches work in all mammals. If they do, then progranulin treatment may slow disease onset or progression in Huntington’s disease patients.
(Source: eurekalert.org)
Metabolic Protein Launches Sugar Feast That Nurtures Brain Tumors
Researchers at The University of Texas MD Anderson Cancer Center have tracked down a cancer-promoting protein’s pathway into the cell nucleus and discovered how, once there, it fires up a glucose metabolism pathway on which brain tumors thrive.
They also found a vital spot along the protein’s journey that can be attacked with a type of drug not yet deployed against glioblastoma multiforme, the most common and lethal form of brain cancer. Published online by Nature Cell Biology, the paper further illuminates the importance of pyruvate kinase M2 (PKM2) in cancer development and progression.
"PKM2 is very active during infancy, when you want rapid cell growth, and eventually it turns off. Tumor cells turn PKM2 back on - it’s overexpressed in many types of cancer," said Zhimin Lu, M.D., Ph.D., the paper’s senior author and an associate professor in MD Anderson’s Department of Neuro-Oncology.
Lu and colleagues showed earlier this year that PKM2 in the nucleus also activates a variety of genes involved in cell division. The latest paper shows how it triggers aerobic glycolysis, processing glucose into energy, also known as the Warburg effect, upon which many types of solid tumors rely to survive and grow.
"PKM2 must get to the nucleus to activate genes involved in cell proliferation and the Warburg effect," Lu said. "If we can keep it out of the nucleus, we can block both of those cancer-promoting pathways. PKM2 could be an Achilles’ heel for cancer."
By pinpointing the complicated steps necessary for PKM2 to penetrate the nucleus, Lu and colleagues found a potentially druggable target that could keep the protein locked in the cell’s cytoplasm.
(Image Credit: Wikimedia Commons)
Risk Aversity Visible in the Brain
Some people live their lives by the motto “no risk - no fun!” and avoid hardly any risks. Others are clearly more cautious and focus primarily on safety when investing and for other business activities. Scientists from the University of Bonn in cooperation with colleagues from the University of Zurich studied the attitudes towards risk in a group of 56 subjects. They found that in people who preferred safety, certain regions of the brain show a higher level of activation when they are confronted with quite unforeseeable situations. In addition, they do not distinguish as clearly as risk takers whether a situation is more or less risky than expected. The results have just been published in the renowned “Journal of Neuroscience.”
"We were especially interested in the link between risk preferences and the brain regions processing this information," says Prof. Dr. Bernd Weber from the Center for Economics and Neuroscience (CENs) at the University of Bonn. First, the researchers tested a total of 56 subjects for their willingness to take risks. "In an economic game, the test subjects had a choice between a secured payout and a lottery," reports Sarah Rudorf from CENs, the study’s principal author. Those who showed a strong preference for the lottery in this test were categorized as risk takers. Others preferred the secured payout even if the lottery’s odds of winning were clearly better. They were put in the risk-averse group.
In risk-averse individuals, certain regions of the brain are activated more strongly
Then the test subjects played a card game in a brain scanner to study their risk perception. Cards carrying numbers from one to ten were shown on the video glasses in front of their eyes. Each time, two cards were randomly drawn. Before the subjects were shown the cards, they were asked to place bets on whether the second card would have a higher or a lower number than the first one. “The statistical probability for either case to occur is always the same: fifty-fifty,” says Prof. Weber. “This is important so that all subjects, whether they are risk takers or not, experience risky situations inside the scanner.” They were not able to assess their probability of winning their bet until they saw the first card. Here, the researchers found that in the subjects who tended to avoid risks, two specific regions of the brain were activated more strongly than in those who were willing to take risks. These areas are the ventral striatum and the insular cortex. The ventral striatum reacts both to the probability of winning, as well as to how well an individual can predict the outcome of the bet. The insular cortex is particularly sensitive to the risk a situation carries, and for whether it is higher or lower than anticipated.
Risk seekers adjust their strategy after lucky streaks
Sarah Rudorf summarized the results, “Individuals in whom these regions of the brain are activated at a higher level seem to perceive risks more clearly and assess them as more negative than those who are willing to take risks.” Risk-averse individuals seem to overestimate the con¬sequences of risk, and they did not distinguish as clearly between situations that turned out to be more or less risky than expected. In contrast, the test subjects who tended to take greater risks also focused their behavior more towards the wins and losses, and more clearly changed their strategy after negative situations.
Study is first to show the neurobiological mechanisms
"This study is the first to show the neurobiological mechanisms of how individual risk preferences determine risk perception," says Prof. Weber. "This also has effects on behavior in the areas of finance and health."
In a next step, the researchers want to study the consequences these results have on economic decisions such as in the stock market. “This might even allow improving the advising process for investors with regard to their individual risk behavior,” says Prof. Weber. And he considers health another important area. Smokers know that what they do is very dangerous, and yet they smoke. “If we learned more about smokers’ attitudes towards risk, we might be able to provide information for developing better anti-smoking campaigns.”
(Source: www3.uni-bonn.de)