Posts tagged neuroscience
Articles and news from the latest research reports.
The iPod in the head: How the brain processes musical hallucinations
A woman with an “iPod in her head” has helped scientists at Newcastle University and University College London identify the areas of the brain that are affected when patients experience a rare condition called musical hallucinations.
Sufferers persistently perceive music, as if they were hearing it with their ears, when no music is actually being played. Initially they often mistake the experience for actual music playing and while musical hallucinations can occasionally be a symptom of a neurological or psychiatric disorder, it is usually caused by hearing loss in people who are in normal physical and mental health.
Dr Sukhbinder Kumar from the Institute of Neuroscience at Newcastle University, lead author of the paper published in Cortex said: “We found that a network of brain areas, that are usually involved in processing of melodies and retrieval of memory of music, were particularly active during hallucinations of music in the absence of any sound or music being played externally.”
Nearly one in ten people suffer from tinnitus which is technically an auditory hallucination, in which tones or buzzing noises are heard following hearing loss. However in a small number of people with hearing loss these hallucinations take the form of music, but until now the brain mechanisms underlying this process were poorly understood.
This study by researchers at Newcastle University and University College London and funded by the Wellcome Trust has looked in depth at one sufferer of the condition and pinpointed the regions of the brain involved in producing the hallucinations. These findings could lead to a better understanding of the condition and possibly treatments in the future.
Musical hallucination
Sylvia, 69, a maths teacher who is also a musician with perfect pitch, started to go deaf about 20 years ago after a viral infection. Then about eleven years later she experienced a sudden acute hearing loss and severe tinnitus and her musical hallucinations developed after this. Due to her musical knowledge Sylvia was able to notate what she was hearing.
Initially the condition was irritating and affected Sylvia’s sleep, but she learnt to live with it. “I did everything I could to get rid of them but they persisted, always in a minor key and therefore a bit depressing,” she said.
“Eventually the number of notes increased until they seemed to be parts of tunes. One day I recognized something and, once I had done so, more and more phrases from classical music appeared in my brain.”
Among the pieces of music that Sylvia was hearing in her hallucinations was Gilbert and Sullivan’s HMS Pinafore, as well as music by Bach. Amazingly Sylvia found that by playing music herself, she was able to alter the music in her hallucinations.
“I can change the hallucination playing in my head to the music I am practising. This is particularly the case with the music of Bach - the hallucination will pause and then a whole page will start to play in my head, gradually curtailing itself until just a phrase remains and is repeated. That might then repeat a thousand times a day. It is as if I have my own internal ipod.”
Sylvia’s experience is fairly typical, though the condition occurs just as often in non-musicians, and sometimes starts abruptly rather than slowly developing as in her case.
How we hear
As Sylvia’s hallucinations could be manipulated by playing an external piece of music that allowed the researchers to understand what was happening in her brain during hallucinations. They first identified pieces of music that suppressed her hallucinations and these pieces were then played to her while her brain activity was being monitored using magnetoencephalography MEG), which measures magnetic fields around the scalp as the brain processes information.
During normal perception of music what we actually ‘hear’ is a complex interplay of the sound entering the ear and our brain’s interpretations and predictions. Normally the strength and quality of the input from the ear is so high that it dominates what we actually perceive however the brain fills in the gaps when the ears do not provide enough input.
“With hearing loss, as in Sylvia’s case, the signal from the ear becomes weak and noisy, like a poorly-tuned radio. The brain’s predictive mechanisms therefore have to work very hard to make sense of what we are hearing. What we have found is that these processes sometimes end up running away with themselves to cause hallucinations,” said author Dr William Sedley also of Newcastle University.
Dr Kumar added: “This also explains why listening to an external piece of music suppresses hallucinations. When external music is playing the signal entering her brain is much stronger and more reliable, which constrains the aberrant communication going on in the brain areas during hallucinations.”
This new understanding of musical hallucinations may provide better treatment in the future as Newcastle University’s Professor Tim Griffiths, professor of Cognitive Neurology who lead the study explained: “It might be possible to disrupt the abnormal communication between the brain areas using brain stimulation, or to use pharmacological treatments to disrupt chemical transmitters that drive communication between them.
“Better hearing aids also appear to help suppress hallucinations, so we would advise people experiencing musical hallucinations to seek medical attention, if for nothing more than to ensure they have the best available hearing aids.”
Dr John Williams, Head of Neuroscience and Mental Health at the Wellcome Trust, says: “This case is extremely fascinating, but the condition is relatively rare. However, it is unusual cases such as this that can give us profound insights into how the brain works and, one hopes, lead to potential new treatments to improve the patient’s life.”
Brain structure, function predict future memory performance in children, adolescents
Assessing structural and functional changes in the brain may predict future memory performance in healthy children and adolescents, according to a study appearing January 29 in The Journal of Neuroscience. The findings shed new light on cognitive development and suggest MRI and other tools may one day help identify children at risk for developmental challenges earlier than current testing methods allow.
Working memory capacity — the ability to hold onto information for a short period of time — is one of the strongest predictors of future achievements in math and reading. While previous studies showed that MRI could predict current working memory performance in children, scientists were unsure if MRI could predict their future cognitive capacity.
In the current study, Henrik Ullman, Rita Almeida, PhD, and Torkel Klingberg, MD, PhD, at the Karolinska Institutet in Sweden evaluated the cognitive abilities of a group of healthy children and adolescents and measured each child’s brain structure and function using MRI. Based on the MRI data collected during this initial testing, the researchers found they could predict the children’s working memory performance two years later, a prediction that was not possible using the cognitive tests.
“Our results suggest that future cognitive development can be predicted from anatomical and functional information offered by MRI above and beyond that currently achieved by cognitive tests,” said Ullman, the lead author of the study. “This has wide implications for understanding the neural mechanisms of cognitive development.”
The scientists recruited 62 children and adolescents between the ages of 6 and 20 years to the lab, where they completed working memory and reasoning tests. They also received multiple MRI scans to assess brain structure and changes in brain activity as they performed a working memory task. Two years later, the group returned to the lab to perform the same cognitive tests.
Using a statistical model, the researchers evaluated whether MRI data obtained during the initial tests correlated with the children’s working memory performance during the follow-up visit. They found that while brain activity in the frontal cortex correlated with children’s working memory at the time of the initial tests, activity in the basal ganglia and thalamus predicted how well children scored on the working memory tests two years later.
“This study is another contribution to the growing body of neuroimaging research that yields insights into unraveling present and predicting future cognitive capacity in development,” said Judy Illes, PhD, a neuroethicist at the University of British Columbia. “However, the appreciation of this important new knowledge is simpler than its application to everyday life. How a child performs today and tomorrow relies on multiple positive and negative life events that cannot be assessed by today’s technology alone.”
(Source: alphagalileo.org)
What makes us human? Unique brain area linked to higher cognitive powers
Oxford University researchers have identified an area of the human brain that appears unlike anything in the brains of some of our closest relatives.
The brain area pinpointed is known to be intimately involved in some of the most advanced planning and decision-making processes that we think of as being especially human.
'We tend to think that being able to plan into the future, be flexible in our approach and learn from others are things that are particularly impressive about humans. We've identified an area of the brain that appears to be uniquely human and is likely to have something to do with these cognitive powers,' says senior researcher Professor Matthew Rushworth of Oxford University's Department of Experimental Psychology.
MRI imaging of 25 adult volunteers was used to identify key components in the ventrolateral frontal cortex area of the human brain, and how these components were connected up with other brain areas. The results were then compared to equivalent MRI data from 25 macaque monkeys.
Study Examines the Development of Children’s Prelife Reasoning
Most people, regardless of race, religion or culture, believe they are immortal. That is, people believe that part of themselves–some indelible core, soul or essence–will transcend the body’s death and live forever. But what is this essence? Why do we believe it survives? And why is this belief so unshakable?
A new Boston University study led by postdoctoral fellow Natalie Emmons and published in the January 16, 2014 online edition of Child Development sheds light on these profound questions by examining children’s ideas about “prelife,” the time before conception. By interviewing 283 children from two distinct cultures in Ecuador, Emmons’s research suggests that our bias toward immortality is a part of human intuition that naturally emerges early in life. And the part of us that is eternal, we believe, is not our skills or ability to reason, but rather our hopes, desires and emotions. We are, in fact, what we feel.
Emmons’ study fits into a growing body of work examining the cognitive roots of religion. Although religion is a dominant force across cultures, science has made little headway in examining whether religious belief–such as the human tendency to believe in a creator–may actually be hard-wired into our brains.
“This work shows that it’s possible for science to study religious belief,” said Deborah Kelemen, an Associate Professor of Psychology at Boston University and co-author of the paper. “At the same time, it helps us understand some universal aspects of human cognition and the structure of the mind.”
Most studies on immortality or “eternalist” beliefs have focused on people’s views of the afterlife. Studies have found that both children and adults believe that bodily needs, such as hunger and thirst, end when people die, but mental capacities, such as thinking or feeling sad, continue in some form. But these afterlife studies leave one critical question unanswered: where do these beliefs come from? Researchers have long suspected that people develop ideas about the afterlife through cultural exposure, like television or movies, or through religious instruction. But perhaps, thought Emmons, these ideas of immortality actually emerge from our intuition. Just as children learn to talk without formal instruction, maybe they also intuit that part of their mind could exist apart from their body.
Emmons tackled this question by focusing on “prelife,” the period before conception, since few cultures have beliefs or views on the subject. “By focusing on prelife, we could see if culture causes these beliefs to appear, or if they appear spontaneously,” said Emmons.
“I think it’s a brilliant idea,” said Paul Bloom, a Professor of Psychology and Cognitive Science at Yale who was not involved with the study. “One persistent belief is that children learn these ideas through school or church. That’s what makes the prelife research so cool. It’s a very clever way to get at children’s beliefs on a topic where they aren’t given answers ahead of time.”
Emmons interviewed children from an indigenous Shuar village in the Amazon Basin of Ecuador. She chose the group because they have no cultural prelife beliefs, and she suspected that indigenous children, who have regular exposure to birth and death through hunting and farming, would have a more rational, biologically-based view of the time before they were conceived. For comparison, she also interviewed children from an urban area near Quito, Ecuador. Most of the urban children were Roman Catholic, a religion that teaches that life begins only at conception. If cultural influences were paramount, reasoned Emmons, both urban and indigenous children should reject the idea of life before birth.
Emmons showed the children drawings of a baby, a young woman, and the same woman while pregnant, then asked a series of questions about the child’s abilities, thoughts and emotions during each period: as babies, in the womb, and before conception.
The results were surprising. Both groups gave remarkably similar answers, despite their radically different cultures. The children reasoned that their bodies didn’t exist before birth, and that they didn’t have the ability to think or remember. However, both groups also said that their emotions and desires existed before they were born. For example, while children generally reported that they didn’t have eyes and couldn’t see things before birth, they often reported being happy that they would soon meet their mother, or sad that they were apart from their family.
“They didn’t even realize they were contradicting themselves,” said Emmons. “Even kids who had biological knowledge about reproduction still seemed to think that they had existed in some sort of eternal form. And that form really seemed to be about emotions and desires.”
Why would humans have evolved this seemingly universal belief in the eternal existence of our emotions? Emmons said that this human trait might be a by-product of our highly developed social reasoning. “We’re really good at figuring out what people are thinking, what their emotions are, what their desires are,” she said. We tend to see people as the sum of their mental states, and desires and emotions may be particularly helpful when predicting their behavior. Because this ability is so useful and so powerful, it flows over into other parts of our thinking. We sometimes see connections where potentially none exist, we hope there’s a master plan for the universe, we see purpose when there is none, and we imagine that a soul survives without a body.
These ideas, while nonscientific, are natural and deep-seated. “I study these things for a living but even find myself defaulting to them. I know that my mind is a product of my brain but I still like to think of myself as something independent of my body,” said Emmons.
“We have the ability to reflect and reason scientifically, and we have the ability to reason based on our gut and intuition,” she added. “And depending on the situation, one may be more useful than the other.”
Visual System Can Retain Plasticity, Even After Extended Early Blindness
Image: Fotolia
Deprivation of vision during critical periods of childhood development has long been thought to result in irreversible vision loss. Now, researchers from the Schepens Eye Research Institute/Massachusetts Eye and Ear, Harvard Medical School (HMS) and Massachusetts Institute of Technology (MIT) have challenged that theory by studying a unique population of pediatric patients who were blind during these critical periods before removal of bilateral cataracts. The researchers found improvement after sight onset in contrast sensitivity tests, which measure basic visual function and have well-understood neural underpinnings. Their results show that the human visual system can retain plasticity beyond critical periods, even after early and extended blindness. Their findings were recently published in the Proceedings of the National Advancement of Science (PNAS) Early Edition.
Expanding our view of vision
Every time you open your eyes, visual information flows into your brain, which interprets what you’re seeing. Now, for the first time, MIT neuroscientists have noninvasively mapped this flow of information in the human brain with unique accuracy, using a novel brain-scanning technique.
This technique, which combines two existing technologies, allows researchers to identify precisely both the location and timing of human brain activity. Using this new approach, the MIT researchers scanned individuals’ brains as they looked at different images and were able to pinpoint, to the millisecond, when the brain recognizes and categorizes an object, and where these processes occur.
“This method gives you a visualization of ‘when’ and ‘where’ at the same time. It’s a window into processes happening at the millisecond and millimeter scale,” says Aude Oliva, a principal research scientist in MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL).
Oliva is the senior author of a paper describing the findings in the Jan. 26 issue of Nature Neuroscience. Lead author of the paper is CSAIL postdoc Radoslaw Cichy. Dimitrios Pantazis, a research scientist at MIT’s McGovern Institute for Brain Research, is also an author of the paper.
Natural plant compound prevents Alzheimer’s disease in mice
A chemical that’s found in fruits and vegetables from strawberries to cucumbers appears to stop memory loss that accompanies Alzheimer’s disease in mice, scientists at the Salk Institute for Biological Studies have discovered. In experiments on mice that normally develop Alzheimer’s symptoms less than a year after birth, a daily dose of the compound—a flavonol called fisetin—prevented the progressive memory and learning impairments. The drug, however, did not alter the formation of amyloid plaques in the brain, accumulations of proteins which are commonly blamed for Alzheimer’s disease. The new finding suggests a way to treat Alzheimer’s symptoms independently of targeting amyloid plaques.
"We had already shown that in normal animals, fisetin can improve memory," says Pamela Maher, a senior staff scientist in Salk’s Cellular Neurobiology Laboratory who led the new study. "What we showed here is that it also can have an effect on animals prone to Alzheimer’s."
More than a decade ago, Maher discovered that fisetin helps protect neurons in the brain from the effects of aging. She and her colleagues have since—in both isolated cell cultures and mouse studies—probed how the compound has both antioxidant and anti-inflammatory effects on cells in the brain. Most recently, they found that fisetin turns on a cellular pathway known to be involved in memory.
"What we realized is that fisetin has a number of properties that we thought might be beneficial when it comes to Alzheimer’s," says Maher.
So Maher—who works with Dave Schubert, the head of the Cellular Neurobiology Lab—turned to a strain of mice that have mutations in two genes linked to Alzheimer’s disease. The researchers took a subset of these mice and, when they were only three months old, began adding fisetin to their food. As the mice aged, the researchers tested their memory and learning skills with water mazes. By nine months of age, mice that hadn’t received fisetin began performing more poorly in the mazes. Mice that had gotten a daily dose of the compound, however, performed as well as normal mice, at both nine months and a year old.
"Even as the disease would have been progressing, the fisetin was able to continue preventing symptoms," Maher says.
In collaboration with scientists at the University of California, San Diego, Maher’s team next tested the levels of different molecules in the brains of mice that had received doses of fisetin and those that hadn’t. In mice with Alzheimer’s symptoms, they found, pathways involved in cellular inflammation were turned on. In the animals that had taken fisetin, those pathways were dampened and anti-inflammatory molecules were present instead. One protein in particular—known as p35—was blocked from being cleaved into a shorter version when fisetin was taken. The shortened version of p35 is known to turn on and off many other molecular pathways. The results were published December 17, 2013, in the journal Aging Cell.
Studies on isolated tissue had hinted that fisetin might also decrease the number of amyloid plaques in Alzheimer’s affected brains. However, that observation didn’t hold up in the mice studies. “Fisetin didn’t affect the plaques,” says Maher. “It seems to act on other pathways that haven’t been seriously investigated in the past as therapeutic targets.”
Next, Maher’s team hopes to understand more of the molecular details on how fisetin affects memory, including whether there are targets other than p35.
"It may be that compounds like this that have more than one target are most effective at treating Alzheimer’s disease," says Maher, "because it’s a complex disease where there are a lot of things going wrong."
They also aim to develop new studies to look at how the timing of fisetin doses affect its influence on Alzheimer’s.
"The model that we used here was a preventive model," explains Maher. "We started the mice on the drugs before they had any memory loss. But obviously human patients don’t go to the doctor until they are already having memory problems." So the next step in moving the discovery toward the clinic, she says, is to test whether fisetin can reverse declines in memory once they have already appeared.
(Source: salk.edu)
Quality of white matter in the brain is crucial for adding and multiplying
‘Grey’ cells process information in the brain and are connected via neural pathways, the tracts through which signals are transferred.
"Neural pathways are comparable to a bundle of cables. These cables are surrounded by an isolating sheath: myelin, or ‘white matter’. The thicker the isolating sheath and the more cables there are, the more white matter. And the more white matter, the faster the signals are transferred," explains educational neuroscientist Bert de Smedt.
While the correlation between arithmetic and white matter tracts linking certain brain regions is known, very little research has been done to test this correlation in normally-developing children. Nor has previous research teased out differences in neuroactivity when carrying out different arithmetic operations, e.g., adding, subtracting, multiplying and dividing.
In this study, the researchers had 25 children solve a series of different arithmetic operations while undergoing a brain scan. They then compared the quality of the children’s white matter tracts with their arithmetic test performance.
"We found that a better quality of the arcuate fasciculus anterior – a white matter tract that connects brain regions often used for arithmetic – corresponds to better performance in adding and multiplying, while there is no correlation for subtracting and dividing.”
“A possible explanation for this is that this white matter bundle is involved in rote memorization, whereas when we subtract and divide, such memorization plays less of a role. When subtracting and dividing we are more likely to use intermediary steps to calculate the solution, even as adults.”
Nursery rhymes
These findings also add insight into the link between reading and arithmetic, explains Professor De Smedt: “Reading proficiency and arithmetic proficiency often go hand-in-hand. The white matter tract that we studied also plays an important role in reading: when we learn to read, we have to memorize the correspondence between particular letters and the sound they represent. It is likely that a similar process occurs for addition and multiplication. Just think of the notorious times-table drills we all memorized as schoolchildren; it is almost like learning a nursery rhyme. Some of us can even auto-recall these sums.”
"This also might explain why we often see arithmetic problems in children with dyslexia. Likewise, children with dyscalculia often have trouble reading," says Professor De Smedt.
The researchers now aim to explore how these results relate to children with impairments such as dyscalculia or head trauma. In a next step, the team will also investigate how white matter tracts can be strengthened through extra arithmetic training.
Groundbreaking Research Explores Link Between Traumatic Brain Injury and Sleep
It has long been believed that a person with a concussion should stay awake or not sleep for more than a few hours at a time.
But there appears to be no medical evidence to support that idea, according to a study regarding the relationship between traumatic brain injury, also known as TBI, and sleepiness conducted by scientists at Barrow Neurological Institute at Phoenix Children’s Hospital and the University of Arizona College of Medicine – Phoenix.
"This translational research study lays the foundation for understanding the immediate impact of brain injury on a person’s physiology. In this case, substantial post-traumatic sleep occurred regardless of injury timing or severity," said Jonathan Lifshitz, director of the Translational Neurotrauma Program at Barrow Neurological Institute at Phoenix Children’s Hospital and an associate professor at the UA College of Medicine – Phoenix. "These studies explore sleep as an immediate response to TBI."
Traumatic brain injury is a major cause of death and disability throughout the world with little pharmacological treatment for the individuals who suffer from lifelong problems associated with TBI. Clinical studies have provided evidence to support the claim that brain injury contributes to chronic sleep disturbances as well as excessive daytime sleepiness. Clinical observations have reported excessive sleepiness immediately following traumatic brain injury. However; there is a lack of experimental evidence to support or refute the benefit of sleep following a brain injury.
"We know that some individuals after a traumatic brain injury become excessively sleepy and some cannot sleep at all. It is not well understood why this occurs as mechanisms of injury, and locations of injury are not always consistent between clinical phenotypes of normal sleep, hypersomnia and insomnia," said Matthew Troester, a neurologist and sleep specialist at Phoenix Children’s Hospital and a clinical assistant professor at the UA College of Medicine – Phoenix.
Lifshiz and his associates are breaking new ground with descriptions of sleep in the acute – or immediately after injury – state, where little is known clinically, Troester added.
"They demonstrate that the subjects slept immediately and similarly post-injury no matter the severity of the injury or time of day the injury occurred. This tells us that the brain is reacting to the injury in a very specific manner – not something we always see clinically – and, ultimately, this may help us better understand what the role of sleep is in brain injury" such as being restorative, protective or merely a consequence of the injury, he said. "It is an exciting beginning."
This initial study is phase one of the Post-Traumatic Sleep Study. Phase two is in the works. The research will look to provide medical evidence for sleeping after a concussion.
(Source: uanews.org)
How does the brain create sequences?
When you learn how to play the piano, first you have to learn notes, scales and chords and only then will you be able to play a piece of music. The same principle applies to speech and to reading, where instead of scales you have to learn the alphabet and the rules of grammar.
But how do separate small elements come together to become a unique and meaningful sequence?
It has been shown that a specific area of the brain, the basal ganglia, is implicated in a mechanism called chunking, which allows the brain to efficiently organise memories and actions. Until now little was known about how this mechanism is implemented in the brain.
In an article published today (Jan 26th) in Nature Neuroscience, neuroscientist Rui Costa, and his postdoctoral fellow, Fatuel Tecuapetla, both working at the Champalimaud Neuroscience Programme (CNP) in Lisbon, Portugal, and Xin Jin, an investigator at the Salk Institute, in San Diego, USA, reveal that neurons in the basal ganglia can signal the concatenation of individual elements into a behavioural sequence.
"We trained mice to perform gradually faster sequences of lever presses, similar to a person who is learning to play a piano piece at an increasingly fast pace." explains Rui Costa. "By recording the neural activity in the basal ganglia during this task we found neurons that seem to treat a whole sequence of actions as a single behaviour."
The basal ganglia encompass two major pathways, the direct and the indirect pathways. The authors found that although activity in these pathways was similar during the initiation of movement, it was rather different during the execution of a behavioural sequence.
"The basal ganglia and these pathways are absolutely crucial for the execution of actions. These circuits are affected in neural disorders, such as Parkinson or Huntington’s disease, in which learning of action sequences is impaired", adds Xin Jin.
The work published in this article “is just the beginning of the story”, says Rui Costa. The Neurobiology of Action laboratory at the CNP, a group of around 20 researchers headed by Rui Costa, will continue to study the functional organisation of the basal ganglia during learning and execution of action sequences. Earlier this year, Rui Costa was awarded a 2 million euro Consolidation Grant by the European Research Council to study the mechanism of Chunking.
(Source: eurekalert.org)