Neuroscience

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It’s Not Just Amyloid: White Matter Hyperintensities and Alzheimer’s Disease New findings by Columbia researchers suggest that along with amyloid deposits, white matter hyperintensities (WMHs) may be a second necessary factor for the development of Alzheimer’s disease. Most current approaches to Alzheimer’s disease focus on the accumulation of amyloid plaque in the brain. The researchers at the Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, led by Adam M. Brickman, PhD, assistant professor of neuropsychology, examined the additional contribution of small-vessel cerebrovascular disease, which they visualized as white matter hyperintensities (WMHs). The study included 20 subjects with clinically defined Alzheimer’s disease, 59 subjects with mild cognitive impairment, and 21 normal control subjects. Using data from the Alzheimer’s Disease Neuroimaging Initiative public database, the researchers found that amyloid and WHMs were equally associated with an Alzheimer’s diagnosis. Amyloid and WMHs were also equally predictive of which subjects with mildcognitive impairment would go on to develop Alzheimer’s. Among those with significant amyloid, WMHs were more prevalent in those with Alzheimer’s than in normal control subjects. Because the risk factors for WMHs—which are mainly vascular—can be controlled, the findings suggest potential ways to prevent the development of Alzheimer’s in those with amyloid deposits. “White Matter Hyperintensities and Cerebral Amyloidosis” was published online in JAMA Neurology.

It’s Not Just Amyloid: White Matter Hyperintensities and Alzheimer’s Disease

New findings by Columbia researchers suggest that along with amyloid deposits, white matter hyperintensities (WMHs) may be a second necessary factor for the development of Alzheimer’s disease.

Most current approaches to Alzheimer’s disease focus on the accumulation of amyloid plaque in the brain. The researchers at the Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, led by Adam M. Brickman, PhD, assistant professor of neuropsychology, examined the additional contribution of small-vessel cerebrovascular disease, which they visualized as white matter hyperintensities (WMHs).

The study included 20 subjects with clinically defined Alzheimer’s disease, 59 subjects with mild cognitive impairment, and 21 normal control subjects. Using data from the Alzheimer’s Disease Neuroimaging Initiative public database, the researchers found that amyloid and WHMs were equally associated with an Alzheimer’s diagnosis. Amyloid and WMHs were also equally predictive of which subjects with mildcognitive impairment would go on to develop Alzheimer’s. Among those with significant amyloid, WMHs were more prevalent in those with Alzheimer’s than in normal control subjects.

Because the risk factors for WMHs—which are mainly vascular—can be controlled, the findings suggest potential ways to prevent the development of Alzheimer’s in those with amyloid deposits.

“White Matter Hyperintensities and Cerebral Amyloidosis” was published online in JAMA Neurology.

Filed under alzheimer's disease dementia cognitive decline amyloid plaque white matter hyperintensities neuroscience science

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New study shows how seals sleep with only half their brain at a time A new study led by an international team of biologists has identified some of the brain chemicals that allow seals to sleep with half of their brain at a time. The study was published this month in the Journal of Neuroscience and was headed by scientists at UCLA and the University of Toronto. It identified the chemical cues that allow the seal brain to remain half awake and asleep. Findings from this study may explain the biological mechanisms that enable the brain to remain alert during waking hours and go off-line during sleep. “Seals do something biologically amazing — they sleep with half their brain at a time. The left side of their brain can sleep while the right side stays awake. Seals sleep this way while they’re in water, but they sleep like humans while on land. Our research may explain how this unique biological phenomenon happens” said Professor John Peever of the University of Toronto. The study’s first author, University of Toronto PhD student Jennifer Lapierre, made this discovery by measuring how different chemicals change in the sleeping and waking sides of the brain. She found that acetylcholine – an important brain chemical – was at low levels on the sleeping side of the brain but at high levels on the waking side. This finding suggests that acetylcholine may drive brain alertness on the side that is awake. But, the study also showed that another important brain chemical – serotonin – was present at the equal levels on both sides of the brain whether the seals were awake or asleep. This was a surprising finding because scientist long thought that serotonin was a chemical that causes brain arousal. These findings have possible human health implications because “about 40% of North Americans suffer from sleep problems and understanding which brain chemicals function to keep us awake or asleep is a major scientific advance. It could help solve the mystery of how and why we sleep” says the study’s senior author Jerome Siegel of UCLA’s Brain Research Institute. (Image: AFP)

New study shows how seals sleep with only half their brain at a time

A new study led by an international team of biologists has identified some of the brain chemicals that allow seals to sleep with half of their brain at a time.

The study was published this month in the Journal of Neuroscience and was headed by scientists at UCLA and the University of Toronto. It identified the chemical cues that allow the seal brain to remain half awake and asleep. Findings from this study may explain the biological mechanisms that enable the brain to remain alert during waking hours and go off-line during sleep.

“Seals do something biologically amazing — they sleep with half their brain at a time. The left side of their brain can sleep while the right side stays awake. Seals sleep this way while they’re in water, but they sleep like humans while on land. Our research may explain how this unique biological phenomenon happens” said Professor John Peever of the University of Toronto.

The study’s first author, University of Toronto PhD student Jennifer Lapierre, made this discovery by measuring how different chemicals change in the sleeping and waking sides of the brain. She found that acetylcholine – an important brain chemical – was at low levels on the sleeping side of the brain but at high levels on the waking side. This finding suggests that acetylcholine may drive brain alertness on the side that is awake.

But, the study also showed that another important brain chemical – serotonin – was present at the equal levels on both sides of the brain whether the seals were awake or asleep. This was a surprising finding because scientist long thought that serotonin was a chemical that causes brain arousal.

These findings have possible human health implications because “about 40% of North Americans suffer from sleep problems and understanding which brain chemicals function to keep us awake or asleep is a major scientific advance. It could help solve the mystery of how and why we sleep” says the study’s senior author Jerome Siegel of UCLA’s Brain Research Institute.

(Image: AFP)

Filed under seals sleep sleep problems brain serotonin neuroscience science

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Researchers develop tool for reading the minds of mice If you want to read a mouse’s mind, it takes some fluorescent protein and a tiny microscope implanted in the rodent’s head. Stanford scientists have demonstrated a technique for observing hundreds of neurons firing in the brain of a live mouse, in real time, and have linked that activity to long-term information storage. The unprecedented work could provide a useful tool for studying new therapies for neurodegenerative diseases such as Alzheimer’s. The researchers first used a gene therapy approach to cause the mouse’s neurons to express a green fluorescent protein that was engineered to be sensitive to the presence of calcium ions. When a neuron fires, the cell naturally floods with calcium ions. Calcium stimulates the protein, causing the entire cell to fluoresce bright green. A tiny microscope implanted just above the mouse’s hippocampus – a part of the brain that is critical for spatial and episodic memory – captures the light of roughly 700 neurons. The microscope is connected to a camera chip, which sends a digital version of the image to a computer screen. The computer then displays near real-time video of the mouse’s brain activity as a mouse runs around a small enclosure, which the researchers call an arena. The neuronal firings look like tiny green fireworks, randomly bursting against a black background, but the scientists have deciphered clear patterns in the chaos. "We can literally figure out where the mouse is in the arena by looking at these lights," said Mark Schnitzer, an associate professor of biology and of applied physics and the senior author on the paper, recently published in the journal Nature Neuroscience. When a mouse is scratching at the wall in a certain area of the arena, a specific neuron will fire and flash green. When the mouse scampers to a different area, the light from the first neuron fades and a new cell sparks up. "The hippocampus is very sensitive to where the animal is in its environment, and different cells respond to different parts of the arena," Schnitzer said. "Imagine walking around your office. Some of the neurons in your hippocampus light up when you’re near your desk, and others fire when you’re near your chair. This is how your brain makes a representative map of a space." The group has found that a mouse’s neurons fire in the same patterns even when a month has passed between experiments. “The ability to come back and observe the same cells is very important for studying progressive brain diseases,” Schnitzer said.

Researchers develop tool for reading the minds of mice

If you want to read a mouse’s mind, it takes some fluorescent protein and a tiny microscope implanted in the rodent’s head.

Stanford scientists have demonstrated a technique for observing hundreds of neurons firing in the brain of a live mouse, in real time, and have linked that activity to long-term information storage. The unprecedented work could provide a useful tool for studying new therapies for neurodegenerative diseases such as Alzheimer’s.

The researchers first used a gene therapy approach to cause the mouse’s neurons to express a green fluorescent protein that was engineered to be sensitive to the presence of calcium ions. When a neuron fires, the cell naturally floods with calcium ions. Calcium stimulates the protein, causing the entire cell to fluoresce bright green.

A tiny microscope implanted just above the mouse’s hippocampus – a part of the brain that is critical for spatial and episodic memory – captures the light of roughly 700 neurons. The microscope is connected to a camera chip, which sends a digital version of the image to a computer screen.

The computer then displays near real-time video of the mouse’s brain activity as a mouse runs around a small enclosure, which the researchers call an arena.

The neuronal firings look like tiny green fireworks, randomly bursting against a black background, but the scientists have deciphered clear patterns in the chaos.

"We can literally figure out where the mouse is in the arena by looking at these lights," said Mark Schnitzer, an associate professor of biology and of applied physics and the senior author on the paper, recently published in the journal Nature Neuroscience.

When a mouse is scratching at the wall in a certain area of the arena, a specific neuron will fire and flash green. When the mouse scampers to a different area, the light from the first neuron fades and a new cell sparks up.

"The hippocampus is very sensitive to where the animal is in its environment, and different cells respond to different parts of the arena," Schnitzer said. "Imagine walking around your office. Some of the neurons in your hippocampus light up when you’re near your desk, and others fire when you’re near your chair. This is how your brain makes a representative map of a space."

The group has found that a mouse’s neurons fire in the same patterns even when a month has passed between experiments. “The ability to come back and observe the same cells is very important for studying progressive brain diseases,” Schnitzer said.

Filed under alzheimer's disease hippocampus brain activity episodic memory neurons neuroscience science

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We know when we’re being lazy thinkers New study shows that human thinkers are conscious cognitive misers Are we intellectually lazy? Yes we are, but we do know when we take the easy way out, according to a new study by Wim De Neys and colleagues, from the CNRS in France. Contrary to what psychologists believe, we are aware that we occasionally answer easier questions rather than the more complex ones we were asked, and we are also less confident about our answers when we do. The work is published online in Springer’s journal Psychonomic Bulletin & Review. Research to date on human thinking suggests that our judgment is often biased because we are intellectually lazy, or so-called cognitive misers. We intuitively substitute hard questions for easier ones. What is less clear is whether or not we realize that we are doing this and notice our mistake. Using an adaptation of the standard ‘bat-and-ball’ problem, the researchers explored this phenomenon. The typical ‘bat-and-ball’ problem is as follows: a bat and ball together cost $1.10. The bat costs $1 more than the ball. How much does the ball cost? The intuitive answer that immediately springs to mind is 10 cents. However, the correct response is 5 cents. The authors developed a control version of this problem, without the relative statement that triggers the substitution of a hard question for an easier one: A magazine and a banana together cost $2.90. The magazine costs $2. How much does the banana cost?A total of 248 French university students were asked to solve each version of the problem. Once they had written down their answers, they were asked to indicate how confident they were that their answer was correct. Only 21 percent of the participants managed to solve the standard problem (bat/ball) correctly. In contrast, the control version (magazine/banana) was solved correctly by 98 percent of the participants. In addition, those who gave the wrong answer to the standard problem were much less confident of their answer to the standard problem than they were of their answer to the control version. In other words, they were not completely oblivious to the questionable nature of their wrong answer. The key reason seems to be that reasoners tend to minimize cognitive effort and stick to intuitive processing. The authors comment: “Although we might be cognitive misers, we are not happy fools who blindly answer erroneous questions without realizing it.” Indeed, although people appear to unconsciously substitute hard questions for easier ones, in reality, they are less foolish than psychologists might believe because they do know they are doing it.

We know when we’re being lazy thinkers

New study shows that human thinkers are conscious cognitive misers

Are we intellectually lazy? Yes we are, but we do know when we take the easy way out, according to a new study by Wim De Neys and colleagues, from the CNRS in France. Contrary to what psychologists believe, we are aware that we occasionally answer easier questions rather than the more complex ones we were asked, and we are also less confident about our answers when we do. The work is published online in Springer’s journal Psychonomic Bulletin & Review.

Research to date on human thinking suggests that our judgment is often biased because we are intellectually lazy, or so-called cognitive misers. We intuitively substitute hard questions for easier ones. What is less clear is whether or not we realize that we are doing this and notice our mistake.

Using an adaptation of the standard ‘bat-and-ball’ problem, the researchers explored this phenomenon. The typical ‘bat-and-ball’ problem is as follows: a bat and ball together cost $1.10. The bat costs $1 more than the ball. How much does the ball cost? The intuitive answer that immediately springs to mind is 10 cents. However, the correct response is 5 cents.

The authors developed a control version of this problem, without the relative statement that triggers the substitution of a hard question for an easier one: A magazine and a banana together cost $2.90. The magazine costs $2. How much does the banana cost?A total of 248 French university students were asked to solve each version of the problem. Once they had written down their answers, they were asked to indicate how confident they were that their answer was correct.

Only 21 percent of the participants managed to solve the standard problem (bat/ball) correctly. In contrast, the control version (magazine/banana) was solved correctly by 98 percent of the participants. In addition, those who gave the wrong answer to the standard problem were much less confident of their answer to the standard problem than they were of their answer to the control version. In other words, they were not completely oblivious to the questionable nature of their wrong answer. The key reason seems to be that reasoners tend to minimize cognitive effort and stick to intuitive processing.

The authors comment: “Although we might be cognitive misers, we are not happy fools who blindly answer erroneous questions without realizing it.”

Indeed, although people appear to unconsciously substitute hard questions for easier ones, in reality, they are less foolish than psychologists might believe because they do know they are doing it.

Filed under thinking cognitive misers consciousness psychology neuroscience science

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Is there a link between childhood obesity and ADHD, learning disabilities?

A University of Illinois study has established a possible link between high-fat diets and such childhood brain-based conditions as attention deficit hyperactivity disorder (ADHD) and memory-dependent learning disabilities.

“We found that a high-fat diet rapidly affected dopamine metabolism in the brains of juvenile mice, triggering anxious behaviors and learning deficiencies. Interestingly, when methylphenidate (Ritalin) was administered, the learning and memory problems went away,” said Gregory Freund, a professor in the U of I College of Medicine and a member of the university’s Division of Nutritional Sciences.

The research was published in Psychoneuroendocrinology.

Freund said that altered dopamine signaling in the brain is common to both ADHD and the overweight or obese state. “And an increase in the number of dopamine metabolites is associated with anxiety behaviors in children,” he added.

Intrigued by the recent upsurge in both child obesity and adverse childhood psychological conditions, including impulsivity, depression, and ADHD, Freund’s team examined the short-term effects of a high-fat (60% calories from fat) versus a low-fat (10% calories from fat) diet on the behavior of two groups of four-week-old mice. A typical Western diet contains from 35 to 45 percent fat, he said.

“After only one week of the high-fat diet, even before we were able to see any weight gain, the behavior of the mice in the first group began to change,” he said.

Evidence of anxiety included increased burrowing and wheel running as well a reluctance to explore open spaces. The mice also developed learning and memory deficits, including decreased ability to negotiate a maze and impaired object recognition.

Switching mice from a high-fat to a low-fat diet restored memory in one week, he noted.

In mice that continued on the high-fat diet, impaired object recognition remained three weeks after the onset of symptoms. But Freund knows from other studies that brain biochemistry normalizes after 10 weeks as the body appears to compensate for the diet. At that point, brain dopamine has returned to normal, and mice have become obese and developed diabetes.

“Although the mice grow out of these anxious behaviors and learning deficiencies, the study suggests to me that a high-fat diet could trigger anxiety and memory disorders in a child who is genetically or environmentally susceptible to them,” he said.

Because the animals adapt to the high-fat fare, the scientists also hypothesized that abruptly removing fat from the diet might negatively affect anxiety, learning, and memory.

The researchers had expected that the high-fat diet would stimulate inflammation, which is associated with obesity, but they saw no evidence of an inflammatory response in the brain after one or three weeks on the high-fat regimen.

Instead, they saw evidence that a high-fat diet initiates chemical responses that are similar to the ones seen in addiction, with dopamine, the chemical important to the addict’s pleasurable experiences, increasing in the brain.

(Source: news.aces.illinois.edu)

Filed under brain obesity ADHD dopamine learning learning disabilities neuroscience science

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“Simplified” brain lets the iCub robot learn language The iCub humanoid robot on which the team directed by Peter Ford Dominey, CNRS Director of Research at Inserm Unit 846 known as the “Institut pour les cellules souches et cerveau de Lyon” [Lyon Institute for Stem Cell and Brain Research] (Inserm, CNRS, Université Claude Bernard Lyon 1) has been working for many years will now be able to understand what is being said to it and even anticipate the end of a sentence. This technological prowess was made possible by the development of a “simplified artificial brain” that reproduces certain types of so-called “recurrent” connections observed in the human brain. The artificial brain system enables the robot to learn, and subsequently understand, new sentences containing a new grammatical structure. It can link two sentences together and even predict how a sentence will end before it is uttered. This research has been published in the Plos One journal.

“Simplified” brain lets the iCub robot learn language

The iCub humanoid robot on which the team directed by Peter Ford Dominey, CNRS Director of Research at Inserm Unit 846 known as the “Institut pour les cellules souches et cerveau de Lyon” [Lyon Institute for Stem Cell and Brain Research] (Inserm, CNRS, Université Claude Bernard Lyon 1) has been working for many years will now be able to understand what is being said to it and even anticipate the end of a sentence. This technological prowess was made possible by the development of a “simplified artificial brain” that reproduces certain types of so-called “recurrent” connections observed in the human brain. The artificial brain system enables the robot to learn, and subsequently understand, new sentences containing a new grammatical structure. It can link two sentences together and even predict how a sentence will end before it is uttered. This research has been published in the Plos One journal.

Filed under robots robotics humanoids iCub language language processing neural networks ANN neuroscience science

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Language Protein Differs in Males, Females Male rat pups have more of a specific brain protein associated with language development than females, according to a study published February 20 in The Journal of Neuroscience. The study also found sex differences in the brain protein in a small group of children. The findings may shed light on sex differences in communication in animals and language acquisition in people. Sex differences in early language acquisition and development in children are well documented — on average, girls tend to speak earlier and with greater complexity than boys of the same age. However, scientists continue to debate the origin and significance of such differences. Previous studies showed the Foxp2 protein plays an important role in speech and language development in humans and vocal communication in birds and other mammals. In the current study, J. Michael Bowers, PhD, Margaret McCarthy, PhD, and colleagues at the University of Maryland School of Medicine examined whether sex differences in the expression of the Foxp2 protein in the developing brain might underlie communication differences between the sexes. The researchers analyzed the levels of Foxp2 protein in the brains of four-day-old female and male rats and compared the ultrasonic distress calls made by the animals when separated from their mothers and siblings. Compared with females, males had more of the protein in brain areas associated with cognition, emotion, and vocalization. They also made more noise than females — producing nearly double the total vocalizations over the five-minute separation period — and were preferentially retrieved and returned to the nest first by the mother. When the researchers reduced levels of the Foxp2 protein in the male pups and increased it in female pups, they reversed the sex difference in the distress calls, causing males to sound like females and the females like males. This change led the mother to reverse her behavior as well, preferentially retrieving the females over the males. “This study is one of the first to report a sex difference in the expression of a language-associated protein in humans or animals,” McCarthy said. “The findings raise the possibility that sex differences in brain and behavior are more pervasive and established earlier than previously appreciated.” The researchers extended their findings to humans in a preliminary study of Foxp2 protein in a small group of children. Unlike the rats, in which Foxp2 protein was elevated in males, they found that in humans, the girls had more of the Foxp2 protein in the cortex — a brain region associated with language — than age-matched boys. “At first glance, one might conclude that the findings in rats don’t generalize to humans, but the higher levels of Foxp2 expression are found in the more communicative sex in each species,” noted Cheryl Sisk, who studies sex differences at Michigan State University and was not involved with the study.

Language Protein Differs in Males, Females

Male rat pups have more of a specific brain protein associated with language development than females, according to a study published February 20 in The Journal of Neuroscience. The study also found sex differences in the brain protein in a small group of children. The findings may shed light on sex differences in communication in animals and language acquisition in people.

Sex differences in early language acquisition and development in children are well documented — on average, girls tend to speak earlier and with greater complexity than boys of the same age. However, scientists continue to debate the origin and significance of such differences. Previous studies showed the Foxp2 protein plays an important role in speech and language development in humans and vocal communication in birds and other mammals.

In the current study, J. Michael Bowers, PhD, Margaret McCarthy, PhD, and colleagues at the University of Maryland School of Medicine examined whether sex differences in the expression of the Foxp2 protein in the developing brain might underlie communication differences between the sexes.

The researchers analyzed the levels of Foxp2 protein in the brains of four-day-old female and male rats and compared the ultrasonic distress calls made by the animals when separated from their mothers and siblings. Compared with females, males had more of the protein in brain areas associated with cognition, emotion, and vocalization. They also made more noise than females — producing nearly double the total vocalizations over the five-minute separation period — and were preferentially retrieved and returned to the nest first by the mother.

When the researchers reduced levels of the Foxp2 protein in the male pups and increased it in female pups, they reversed the sex difference in the distress calls, causing males to sound like females and the females like males. This change led the mother to reverse her behavior as well, preferentially retrieving the females over the males.

“This study is one of the first to report a sex difference in the expression of a language-associated protein in humans or animals,” McCarthy said. “The findings raise the possibility that sex differences in brain and behavior are more pervasive and established earlier than previously appreciated.”

The researchers extended their findings to humans in a preliminary study of Foxp2 protein in a small group of children. Unlike the rats, in which Foxp2 protein was elevated in males, they found that in humans, the girls had more of the Foxp2 protein in the cortex — a brain region associated with language — than age-matched boys.

“At first glance, one might conclude that the findings in rats don’t generalize to humans, but the higher levels of Foxp2 expression are found in the more communicative sex in each species,” noted Cheryl Sisk, who studies sex differences at Michigan State University and was not involved with the study.

Filed under language development brain protein sex differences vocal communication vocalization neuroscience science

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Researchers discover a biological marker of dyslexia Though learning to read proceeds smoothly for most children, as many as one in 10 is estimated to suffer from dyslexia, a constellation of impairments unrelated to intelligence, hearing or vision that make learning to read a struggle. Now, Northwestern University researchers report they have found a biological mechanism that appears to play an important role in the reading process. "We discovered a systematic relationship between reading ability and the consistency with which the brain encodes sounds," says Nina Kraus, Hugh Knowles Professor of Neurobiology, Physiology and Communication. "Unstable Representation of Sound: A Biological Marker of Dyslexia," co-authored by Jane Hornickel, will appear in the Feb. 20 issue of The Journal of Neuroscience. Recording the automatic brain wave responses of 100 school-aged children to speech sounds, the Northwestern researchers found that the very best readers encoded the sound most consistently while the poorest readers encoded it with the greatest inconsistency. Presumably, the brain’s response to sound stabilizes when children learn to successfully connect sounds with their meanings. Happily biology is not destiny. In prior work in Northwestern’s Auditory Neuroscience Laboratory, Kraus and her colleagues found that the inconsistency with which the poorest readers encode sound could be “fixed” through training. In that study, children with reading impairments were fitted for a year with assistive listening devices that transmitted their teacher’s voice directly into their ears. After a year, the children showed improvement not only in reading but also in the consistency with which their brains encoded speech sounds, particularly consonants. "Use of the devices focused youngsters’ brains on the "meaningful" sounds coming from their teacher, diminishing other, extraneous distractions," said Kraus. "After a year of use, the students had honed their auditory systems and no longer required the assistive devices to keep their reading and encoding advantage." People rarely have difficulty encoding vowel sounds, which are relatively simple and long, according to Kraus. It is consonant sounds — sounds which are shorter and more acoustically complex — that are most likely to be incorrectly categorized by the brain. "Understanding the biological mechanisms of reading puts us in a better position to both understand how normal reading works and to ameliorate it where it goes awry," says Kraus. "Our results suggest that good readers profit from a stable neural representation of sound, and that children with inconsistent neural responses are likely at a disadvantage when learning to read," Kraus adds. "The good news is that response consistency can be improved with auditory training." Decades of research from laboratories worldwide have shown that reading ability is associated with auditory skills, including auditory memory and attention, the ability to rhyme sounds and the ability to categorize rapidly occurring sounds. (Image: Michael Pettigrew)

Researchers discover a biological marker of dyslexia

Though learning to read proceeds smoothly for most children, as many as one in 10 is estimated to suffer from dyslexia, a constellation of impairments unrelated to intelligence, hearing or vision that make learning to read a struggle. Now, Northwestern University researchers report they have found a biological mechanism that appears to play an important role in the reading process.

"We discovered a systematic relationship between reading ability and the consistency with which the brain encodes sounds," says Nina Kraus, Hugh Knowles Professor of Neurobiology, Physiology and Communication. "Unstable Representation of Sound: A Biological Marker of Dyslexia," co-authored by Jane Hornickel, will appear in the Feb. 20 issue of The Journal of Neuroscience.

Recording the automatic brain wave responses of 100 school-aged children to speech sounds, the Northwestern researchers found that the very best readers encoded the sound most consistently while the poorest readers encoded it with the greatest inconsistency. Presumably, the brain’s response to sound stabilizes when children learn to successfully connect sounds with their meanings.

Happily biology is not destiny. In prior work in Northwestern’s Auditory Neuroscience Laboratory, Kraus and her colleagues found that the inconsistency with which the poorest readers encode sound could be “fixed” through training.

In that study, children with reading impairments were fitted for a year with assistive listening devices that transmitted their teacher’s voice directly into their ears. After a year, the children showed improvement not only in reading but also in the consistency with which their brains encoded speech sounds, particularly consonants.

"Use of the devices focused youngsters’ brains on the "meaningful" sounds coming from their teacher, diminishing other, extraneous distractions," said Kraus. "After a year of use, the students had honed their auditory systems and no longer required the assistive devices to keep their reading and encoding advantage."

People rarely have difficulty encoding vowel sounds, which are relatively simple and long, according to Kraus. It is consonant sounds — sounds which are shorter and more acoustically complex — that are most likely to be incorrectly categorized by the brain.

"Understanding the biological mechanisms of reading puts us in a better position to both understand how normal reading works and to ameliorate it where it goes awry," says Kraus.

"Our results suggest that good readers profit from a stable neural representation of sound, and that children with inconsistent neural responses are likely at a disadvantage when learning to read," Kraus adds. "The good news is that response consistency can be improved with auditory training."

Decades of research from laboratories worldwide have shown that reading ability is associated with auditory skills, including auditory memory and attention, the ability to rhyme sounds and the ability to categorize rapidly occurring sounds.

(Image: Michael Pettigrew)

Filed under dyslexia brainwaves biological marker reading ability neuroscience science

78 notes

New therapy uses electricity to cancel out Parkinson tremors A new therapy could help suppress tremors in people with Parkinson’s disease, an Oxford University study suggests. The technique – called transcranial alternating current stimulation or TACS – cancels out the brain signal causing the tremors by applying a small, safe electric current across electrodes on the outside of a patient’s head. The preliminary study, conducted with 15 people with Parkinson’s disease at Oxford’s John Radcliffe Hospital, is published in the journal Current Biology. The researchers showed a 50 per cent reduction in resting tremors among the patients. Physical tremors are a significant and debilitating symptom of Parkinson’s disease, but do not respond well to existing drug treatments. Tremors can be successfully treated with deep brain stimulation, a technique that involves surgery to insert electrodes deep into the brain itself to deliver electrical impulses. But this invasive therapy is expensive and carries some health risks, including bleeding in to the brain, which means it is not suitable for all patients. In TACS in contrast, the electrode pads are placed on the outside of the patient’s head, so it does not carry the risks associated with deep brain stimulation. Professor Peter Brown of the Nuffield Department of Clinical Neurosciences, who led the study, said: ‘Tremors experienced by Parkinson’s sufferers can be devastating and any therapy that can suppress or reduce those tremors significantly improves quality of life for patients. 'We are very hopeful this research may, in time, lead to a therapy that is both successful and carries reduced medical risks. We have proved the principle, now we have to optimise it and adapt it so it is able to be used in patients. Often that is the hardest part.'

New therapy uses electricity to cancel out Parkinson tremors

A new therapy could help suppress tremors in people with Parkinson’s disease, an Oxford University study suggests.

The technique – called transcranial alternating current stimulation or TACS – cancels out the brain signal causing the tremors by applying a small, safe electric current across electrodes on the outside of a patient’s head.

The preliminary study, conducted with 15 people with Parkinson’s disease at Oxford’s John Radcliffe Hospital, is published in the journal Current Biology. The researchers showed a 50 per cent reduction in resting tremors among the patients.

Physical tremors are a significant and debilitating symptom of Parkinson’s disease, but do not respond well to existing drug treatments.

Tremors can be successfully treated with deep brain stimulation, a technique that involves surgery to insert electrodes deep into the brain itself to deliver electrical impulses. But this invasive therapy is expensive and carries some health risks, including bleeding in to the brain, which means it is not suitable for all patients.

In TACS in contrast, the electrode pads are placed on the outside of the patient’s head, so it does not carry the risks associated with deep brain stimulation.

Professor Peter Brown of the Nuffield Department of Clinical Neurosciences, who led the study, said: ‘Tremors experienced by Parkinson’s sufferers can be devastating and any therapy that can suppress or reduce those tremors significantly improves quality of life for patients.

'We are very hopeful this research may, in time, lead to a therapy that is both successful and carries reduced medical risks. We have proved the principle, now we have to optimise it and adapt it so it is able to be used in patients. Often that is the hardest part.'

Filed under parkinson's disease tremors TACS electric current neuroscience science

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