Posts tagged neuroscience
Articles and news from the latest research reports.
Speech processing while unconscious: Sleep inhibits action but not preparation and meaning
In a team effort between the Medical Research Council Cognition and Brain Sciences Unit (Cambridge, UK) and the Laboratory of Cognitive and Psycholinguistics Sciences, Ecole Normale Superiore (Paris), part of what we are capable of while sleeping has been unravelled.
People were asked to classify words belonging to one of two categories – animals or objects – by pressing buttons with the left or the right hand, and continued to do so until they have fallen asleep. Their brain activity indicated that they were able to decode the meaning of the words and intended to act but the unconscious state during sleep prevented them from responding (no movement of the fingers).
This result indicates that once a rule (animals press left/objects press right) is established during wakefulness it can still be implemented even during sleep. This means that the decoding networks in the brain process the spoken words and that information (if it is an animal or an object for instance) is passed to a motor plan signaling the intention and subsequent action. During sleep that action is inhibited (we do not purposefully move during sleep) but this study has found that the meaning extraction and subsequent action preparation remained but was slower and lasted longer.
To confirm this result a second study tested whether people could classify word or nonwords (like boat or foat). A similar pattern emerged, showing appropriate brain preparation activity for left or right button presses even if responses were inhibited by the sleep mechanisms.
New Study Examines Impact of Violent Media on the Brain
With the longstanding debate over whether violent movies cause real world violence as a backstop, a study published today in PLOS One found that each person’s reaction to violent images depends on that individual’s brain circuitry, and on how aggressive they were to begin with.
The study, which was led by researchers at the Icahn School of Medicine at Mount Sinai and the NIH Intramural Program, featured brain scans which revealed that both watching and not watching violent images caused different brain activity in people with different aggression levels. The findings may have implications for intervention programs that seek to reduce aggressive behavior starting in childhood.
“Our aim was to investigate what is going on in the brains of people when they watch violent movies,” said lead investigator Nelly Alia-Klein, PhD, Associate Professor of Neuroscience and Psychiatry at the Friedman Brain Institute and Icahn School of Medicine at Mount Sinai. “We hypothesized that if people have aggressive traits to begin with, they will process violent media in a very different way as compared to non-aggressive people, a theory supported by these findings.”
After answering a questionnaire, a group of 54 men were split by the research team into two groups—one with individuals possessing aggressive traits, including a history of physical assault, and a second group without these tendencies. The participants’ brains were then scanned as they watched a succession of violent scenes (shootings and street fights) on day one, emotional, but non-violent scenes (people interacting during a natural disaster) on day two, and nothing on day three.
The scans measured the subjects’ brain metabolic activity, a marker of brain function. Participants also had their blood pressure taken every 5 minutes, and were asked how they were feeling at 15 minute intervals.
Investigators discovered that during mind wandering, when no movies were presented, the participants with aggressive traits had unusually high brain activity in a network of regions that are known to be active when not doing anything in particular. This suggests that participants with aggressive traits have a different brain function map than non-aggressive participants, researchers said.
Interestingly, while watching scenes from violent movies, the aggressive group had less brain activity than the non-aggressive group in the orbitofrontal cortex, a brain region associated by past studies with emotion-related decision making and self-control. The aggressive subjects described feeling more inspired and determined and less upset or nervous than non-aggressive participants when watching violent (day 1) versus just emotional (day 2) media. In line with these responses, while watching the violent media, aggressive participants’ blood pressure went down progressively with time while the non-aggressive participants experienced a rise in blood pressure.
“How an individual responds to their environment depends on the brain of the beholder,” said Dr. Alia-Klein. “Aggression is a trait that develops together with the nervous system over time starting from childhood; patterns of behavior become solidified and the nervous system prepares to continue the behavior patterns into adulthood when they become increasingly coached in personality. This could be at the root of the differences in people who are aggressive and not aggressive, and how media motivates them to do certain things. Hopefully these results will give educators an opportunity to identify children with aggressive traits and teach them to be more aware of how aggressive material activates them specifically.”
Study Finds Air Pollution Harmful to Young Brains
Pollution in many cities threatens the brain development in children.
Findings by University of Montana Professor Dr. Lilian Calderón-Garcidueñas, MA, MD, Ph.D., and her team of researchers reveal that children living in megacities are at increased risk for brain inflammation and neurodegenerative changes, including Alzheimer’s or Parkinson’s disease.
Calderón-Garcidueñas’ findings are detailed in a paper titled “Air pollution and children: Neural and tight junction antibodies and combustion metals, the role of barrier breakdown and brain immunity in neurodegeneration,” which can be found online at http://iospress.metapress.com/content/xx6582688105j48h/.
The study found when air particulate matter and their components such as metals are inhaled or swallowed, they pass through damaged barriers, including respiratory, gastrointestinal and the blood-brain barriers and can result in long-lasting harmful effects.
Calderón-Garcidueñas and her team compared 58 serum and cerebrospinal fluid samples from a control group living in a low-pollution city and matched them by age, gender, socioeconomic status, education and education levels achieved by their parents to 81 children living in Mexico City.
The results found that the children living in Mexico City had significantly higher serum and cerebrospinal fluid levels of autoantibodies against key tight-junction and neural proteins, as well as combustion-related metals.
“We asked why a clinically healthy kid is making autoantibodies against their own brain components,” Calderón-Garcidueñas said. “That is indicative of damage to barriers that keep antigens and neurotoxins away from the brain. Brain autoantibodies are one of the features in the brains of people who have neuroinflammatory diseases like multiple sclerosis.”
The issue is important and relevant for one reason, she explained. The breakdown of the blood-brain barrier and the presence of autoantibodies to important brain proteins will contribute to the neuroinflammation observed in urban children and raises the question of what role air pollution plays in a 400 percent increase of MS cases in Mexico City, making it one of the main diagnoses for neurology referrals.
Calderón-Garcidueñas points out that there is a need for a longitudinal follow-up study to determine if there is a relationship between the cognition deficits and brain MRI alterations previously reported in Mexico City children, and their autoimmune responses. But what is clear is that the kids are suffering from immune dysregulation.
Once there is a breakdown in the blood-brain barrier, not only will particulate matter enter the body but it also opens the door to harmful neurotoxins, bacteria and viruses.
“The barriers are there for a reason,” she explains. “They are there to protect you, but once they are broken the expected results are not good.”
The results of constant exposure to air pollution and the constant damage to all barriers eventually result in significant consequences later in life. She explains that the autoimmune responses are potentially contributing to the neuroinflammatory and Alzheimer’s and Parkinson’s pathology they are observing in young urban children.
While the study focused on children living in Mexico City, others living in cities where there are alarming levels of air pollution such as Los Angeles, Philadelphia-Wilmington, New York City, Salt Lake City, Chicago, Tokyo, Mumbai, New Delhi or Shanghai, among others, also face major health risks. In the U.S. alone, 200 million people live in areas where pollutants such as ozone and fine particulate matter exceed the standards.
“Investing in defining the central nervous system pathology associated with exposure to air pollutants in children is of pressing importance for public health,” Calderón-Garcidueñas said.
The full article is scheduled to be published in Volume 43, Issue 3 of the Journal of Alzheimer’s Disease and will appear online at http://www.j-alz.com in December with a 2015 copyright.
(Source: news.umt.edu)
Study provides more evidence that sleep apnea is hurting your brain
Employing a measure rarely used in sleep apnea studies, researchers at the UCLA School of Nursing have uncovered evidence of what may be damaging the brain in people with the sleep disorder — weaker brain blood flow.
(Image caption: This brain scan shows that the brain blood flow in a subject with obstructive sleep apnea (left) is markedly lower compared to a subject without the sleep disorder. Credit: UCLA)
In the study, published Aug. 28 in the peer-reviewed journal PLOS ONE, researchers measured blood flow in the brain using a non-invasive MRI procedure: the global blood volume and oxygen dependent (BOLD) signal. This method is usually used to observe brain activity. Because previous research showed that poor regulation of blood in the brain might be a problem for people with sleep apnea, the researchers used the whole-brain BOLD signal to look at blood flow in individuals with and without obstructive sleep apnea (OSA).
“We know there is injury to the brain from sleep apnea, and we also know that the heart has problems pumping blood to the body, and potentially also to the brain,” said Paul Macey, associate dean for Information Technology and Innovations at the UCLA School of Nursing and lead researcher for the study. “By using this method, we were able to show changes in the amount of oxygenated blood across the whole brain, which could be one cause of the damage we see in people with sleep apnea.”
Obstructive sleep apnea is a serious disorder that occurs when a person’s breathing is repeatedly interrupted during sleep, hundreds of times a night. Each time breathing stops, the oxygen level in the blood drops, which damages many cells in the body. If left untreated, it can lead to high blood pressure, stroke, heart failure, diabetes, depression and other serious health problems. Approximately 10 percent of adults struggle with obstructive sleep apnea, which is accompanied by symptoms of brain dysfunction, including extreme daytime sleepiness, depression and anxiety, and memory problems.
In this study, men and women — both with and without obstructive sleep apnea had their BOLD signals measured during three physical tasks while they were awake:
- The Valsalva maneuver: participants forcefully breathe out through a very small tube, which raises the pressure in the chest.
- A hand-grip challenge: participants squeeze hard with their hand.
- A cold pressor challenge: A participants’s right foot is put in icy water for a minute.
“When we looked at the results, we didn’t see much difference between the participants with and without OSA in the Valsalva maneuver,” said Macey. “But for the hand-grip and cold-pressor challenges, people with OSA saw a much weaker brain blood flow response.”
The researchers believe that the reason there were differences in the sleep apnea patients during the hand-grip and cold pressor challenge was because the signals from the nerves in the arms and legs had to be processed through the high brain areas controlling sensation and muscle movement, which was slower due to the brain injury. On the other hand, the changes from the Valsalva are mainly driven by blood pressure signaling in the chest, and do not need the sensory or muscle-controlling parts of the brain.
“This study brings us closer to understanding what causes the problems in the brain of people with sleep apnea,” concluded Macey.
The study also found the problem is greater in women with sleep apnea, which may explain the worse apnea-related outcomes in females than males. Studies recently published by the UCLA School of Nursing have shown that brain injury from sleep apnea is much worse in women than men.
The researchers are now looking at whether treatment for obstructive sleep apnea can reverse the damaging effects.
(Source: newsroom.ucla.edu)
Device to help people with Parkinson’s disease communicate better now available
SpeechVive Inc. announced Wednesday (Sept. 10) the commercial launch of the SpeechVive device intended to help people with a soft voice due to Parkinson’s disease speak more loudly and communicate more effectively.
The device is now available to try as a demo through the National Parkinson’s Disease Foundation’s Centers of Excellence prior to purchasing. People who suffer from a soft voice due to Parkinson’s disease can make an appointment at any of these centers: the Muhammad Ali Parkinson Center at Barrow Neurological Institute in Phoenix; the University of Florida, Gainesville, Florida; University of North Carolina, Chapel Hill, North Carolina; Struthers Parkinson’s Center, Minneapolis, Minnesota; and Baylor College of Medicine, Waco, Texas.
"We are providing demo units and training at no cost to as many of the National Parkinson’s Centers of Excellence as are interested in offering SpeechVive in conjunction with or as an alternative to speech therapy," said Steve Mogensen, president and CEO of SpeechVive. "We also are offering the SpeechVive units and training to professionals at Veterans Administration Medical Centers across the country. The first VAMC to offer SpeechVive is in Cincinnati, Ohio."
The SpeechVive device also is available to try at the M.D. Steer Speech and Hearing Clinic at Purdue University in West Lafayette, Indiana.
The technology was developed over the past decade by Jessica Huber, associate professor in Purdue’s Department of Speech, Language and Hearing Sciences and licensed through the Purdue Office of Technology Commercialization. The focus of Huber’s research is the development and testing of behavioral treatments to improve communication and quality of life in older adults and people with degenerative motor diseases.
SpeechVive reduces the speech impairments associated with Parkinson’s disease, which cause people with the disease to speak in a hushed, whispery voice and to have mumbled speech. People with Parkinson’s disease are commonly affected in their ability to communicate effectively.
"The clinical data we have collected over the past four years demonstrates that SpeechVive is effective in 90 percent of the people using the device," Huber said. "I am proud of the improvements in communication and quality of life demonstrated in our clinical studies. I look forward to seeing the device on the market so that more people with Parkinson’s disease will have access to it."
More than 1.5 million people in the United States are diagnosed with Parkinson’s disease, and it is one of the most common degenerative neurological diseases. About 89 percent of those with the disease have voice-related change affecting how loudly they speak, and at least 45 percent have speech-related change affecting how clearly they speak.
Neuroscientists decode brain maps to discover how we take aim
Serena Williams won her third consecutive US Open title a few days ago, thanks to reasons including obvious ones like physical strength and endurance. But how much did her brain and its egocentric and allocentric functions help the American tennis star retain the cup?
Quite significantly, according to York University neuroscience researchers whose recent study shows that different regions of the brain help to visually locate objects relative to one’s own body (self-centred or egocentric) and those relative to external visual landmarks (world-centred or allocentric).
“The current study shows how the brain encodes allocentric and egocentric space in different ways during activities that involve manual aiming,” explains Distinguished Research Professor Doug Crawford, in the Department of Psychology. “Take tennis for example. Allocentric brain areas could help aim the ball toward the opponent’s weak side of play, whereas the egocentric areas would make sure your muscles return the serve in the right direction.”
The study finding will help healthcare providers to develop therapeutic treatment for patients with brain damage in these two areas, according to the neuroscientists at York Centre for Vision Research.
“As a neurologist, I am excited by the finding because it provides clues for doctors and therapists how they might design different therapeutic approaches,” says Ying Chen, lead researcher and PhD candidate in the School of Kinesiology and Health Science.
The study, Allocentric versus Egocentric Representation of Remembered Reach Targets in Human Cortex, published in the Journal of Neuroscience, was conducted using the state-of-the-art fMRI scanner at York U’s Sherman Health Science Research Centre. A dozen participants were tested using the scanner, which Chen modified to distinguish brain areas relating to these two functions.
The participants were given three different tasks to complete when viewing remembered visual targets: egocentric reach (remembering absolute target location), allocentric reach (remembering target location relative to a visual landmark) and a nonspatial control, colour report (reporting color of target).
When participants remembered egocentric targets’ locations, areas in the upper occipital lobe (at the back of the brain) encoded visual direction. In contrast, lower areas of the occipital and temporal lobes encoded object direction relative to other visual landmarks. In both cases, the parietal and frontal cortex (near the top of the brain) coded reach direction during the movement.
(Image caption: Example axial sections of a three-dimensional MPF map (A) obtained from a 63-year old woman with SPMS disease course and results of brain tissue segmentation (B-D). Segmentation masks corresponding to white matter (WM) (B), gray matter (GM) (C), and lesi)
MRI Shows Gray Matter Myelin Loss Strongly Related to MS Disability
People with multiple sclerosis (MS) lose myelin in the gray matter of their brains and the loss is closely correlated with the severity of the disease, according to a new magnetic resonance imaging (MRI) study. Researchers said the findings could have important applications in clinical trials and treatment monitoring. The study appears online in the journal Radiology.
Loss of myelin, the fatty protective sheath around nerve fibers, is a characteristic of MS, an inflammatory disease of the central nervous system that can lead to a variety of serious neurological symptoms and disability. MS is typically considered a disease of the brain’s signal-conducting white matter, where myelin is most abundant, but myelin is also present in smaller amounts in gray matter, the brain’s information processing center that is made up primarily of nerve cell bodies. Though the myelin content in gray matter is small, it is still extremely important to proper function, as it enables protection of thin nerve fibers connecting neighboring areas of the brain cortex, according to Vasily L. Yarnykh, Ph.D., associate professor in the Department of Radiology at University of Washington in Seattle.
“The fact that MS patients lose myelin not only in white but also in gray matter has been proven by earlier post-mortem pathological studies,” he said. “However, the clinical significance of the myelin loss, or demyelination, in gray matter has not been established because of the absence of appropriate imaging methods.”
To learn more about associations between MS and demyelination in both white and gray matter, Dr. Yarnykh and colleagues used a refined MRI technique that provides information on the content of biological macromolecules – molecules present in tissues and composed of a large number of atoms, such as proteins, lipids and carbohydrates. The new method, known as macromolecular proton fraction (MPF) mapping, has been hampered in the past because of the length of time required for data collection, but improvements now allow much faster generation of whole-brain maps that reflect the macromolecular content in tissues.
“The method utilizes a standard MRI scanner and doesn’t require any special hardware—only some software modifications,” Dr. Yarnykh said. “MPF mapping allows quantitative assessment of microscopic demyelination in brain tissues that look normal on clinical images, and is the only existing method able to evaluate the myelin content in gray matter.”
The researchers looked at 30 MS patients, including 18 with relapsing-remitting MS (RRMS), the most common type of MS initially diagnosed, and 12 with the more advanced type of disease known as secondary progressive MS (SPMS). Fourteen healthy control participants were also included in the study. Each participant underwent MRI on a 3-Tesla imager, and the researchers reconstructed 3-D whole-brain MPF maps to look at normal-appearing white matter, gray matter and MS lesions. The researchers further compared the results of their imaging technique with clinical tests characterizing neurological dysfunction in MS patients.
The results showed that MPF was significantly lower in both white and gray matter in RRMS patients compared with healthy controls, and was also significantly reduced in both normal-appearing brain tissues and lesions of SPMS patients compared to RRMS patients with the largest relative decrease in gray matter. MPF in brain tissues of MS patients significantly correlated with clinical disability and the strongest associations were found for gray matter.
“The major finding of the study is that the loss of myelin in gray matter caused by MS in its relative amount is comparable to or even larger than that in white matter,” said Dr. Yarnykh. “Furthermore, gray matter demyelination is much more advanced in patients with secondary-progressive MS, and it is very strongly related to patients’ disability. As such, we believe that information about gray matter myelin damage in MS is of primary clinical relevance.”
The improved technique has potentially important applications for MS treatments targeted to protect and restore myelin.
“First, this method may provide an objective measure of the disease progression and treatment success in clinical trials,” Dr. Yarnykh said. “And second, assessment of both gray and white matter damage with this method may become an individual patient management tool in the future.”
Dr. Yarnykh and colleagues are currently conducting additional research on the new method with the support of the National Multiple Sclerosis Society and the National Institutes of Health.
“This study was done on the participants at a single point in time,” he said. “Now we want to compare MS patients with control participants to see how myelin content will evolve over time. We further plan to extend our method to the spinal cord imaging and test whether the combined assessment of demyelination in the brain and spinal cord could better explain disability progression as compared to brain demyelination alone.”
MS researchers find role for working memory in cognitive reserve
Kessler Foundation scientists have shown that working memory may be an underlying mechanism of cognitive reserve in multiple sclerosis (MS). This finding informs the relationships between working memory, intellectual enrichment (the proxy measure for cognitive reserve) and long-term memory in this population. “Working memory mediates the relationship between intellectual enrichment and long-term memory in multiple sclerosis: An exploratory analysis of cognitive reserve” was published online ahead of print by the Journal of the International Neuropsychological Society on July 14. The authors are Joshua Sandry, PhD, and research scientist James F. Sumowski, PhD, of Neuropsychological & Neuroscience Research at Kessler Foundation. Dr. Sandry is a postdoctoral fellow funded by a grant from the National MS Society.
Cognitive symptoms, including deficits in long-term memory, are known to affect approximately half of individuals with MS. This study was conducted in 70 patients with MS, who were evaluated for intellectual enrichment, verbal long-term memory, and working memory capacity. “We found that working memory capacity explained the relationship between intellectual enrichment and long-term memory in this population,” said Dr Sandry. “This suggests that interventions targeted at working memory in people with MS may help build cognitive reserve to protect against decline in long-term memory.”
(Source: kesslerfoundation.org)
Association between sunshine and suicide examined in study
Lower rates of suicide are associated with more daily sunshine in the prior 14 to 60 days.
Light interacts with brain serotonin systems and possibly influences serotonin-related behaviors. Those behaviors, such as mood and impulsiveness, can play a role in suicide.
The authors examined the relationship between suicide and the duration of sunshine after mathematically removing seasonal variations in sunshine and suicide numbers. They analyzed data on 69,462 officially confirmed suicides in Austria between January 1970 and May 2010. Hours of sunshine per day were calculated from 86 representative meteorological stations.
There was a positive correlation between the number of suicides and hours of daily sunshine on the day of the suicide and up to 10 days before that seemed to facilitate suicide, while sunshine 14 to 60 days prior appeared to have a negative correlation and was associated with reduced suicides. The correlation between daily sunshine hours and suicide rates was seen largely among women, while negative correlations between the two were mainly found among men.
"Owing to the correlative nature of the data, it is impossible to directly attribute the increase in suicide to sunshine during the 10 days prior to the suicide event. … Further research is warranted to determine which patients with severe episodes of depression are more susceptible to the suicide-triggering effects of sunshine."
(Image: Shutterstock)
Can Your Blood Type Affect Your Memory?
People with blood type AB may be more likely to develop memory loss in later years than people with other blood types, according to a study published in the September 10, 2014, online issue of Neurology®, the medical journal of the American Academy of Neurology.
AB is the least common blood type, found in about 4 percent of the U.S. population. The study found that people with AB blood were 82 percent more likely to develop the thinking and memory problems that can lead to dementia than people with other blood types. Previous studies have shown that people with type O blood have a lower risk of heart disease and stroke, factors that can increase the risk of memory loss and dementia.
The study was part of a larger study (the REasons for Geographic And Racial Differences in Stroke, or REGARDS Study) of more than 30,000 people followed for an average of 3.4 years. In those who had no memory or thinking problems at the beginning, the study identified 495 participants who developed thinking and memory problems, or cognitive impairment, during the study. They were compared to 587 people with no cognitive problems.
People with AB blood type made up 6 percent of the group who developed cognitive impairment, which is higher than the 4 percent found in the population.
“Our study looks at blood type and risk of cognitive impairment, but several studies have shown that factors such as high blood pressure, high cholesterol and diabetes increase the risk of cognitive impairment and dementia,” said study author Mary Cushman, MD, MSc, of the University of Vermont College of Medicine in Burlington. “Blood type is also related to other vascular conditions like stroke, so the findings highlight the connections between vascular issues and brain health. More research is needed to confirm these results.”
Researchers also looked at blood levels of factor VIII, a protein that helps blood to clot. High levels of factor VIII are related to higher risk of cognitive impairment and dementia. People in this study with higher levels of factor VIII were 24 percent more likely to develop thinking and memory problems than people with lower levels of the protein. People with AB blood had a higher average level of factor VIII than people with other blood types.