ScienceDaily (Apr. 9, 2009) — By doing a set of vigorous visual exercises on a computer every day for several months, patients who had gone partially blind as a result of suffering a stroke were able to regain some vision, according to scientists who published their results in the April 1 issue of the Journal of Neuroscience.
Such rigorous visual retraining is not common for people who suffer blindness after a stroke. That’s in contrast to other consequences of stroke, such as speech or movement difficulties, where rehabilitation is common and successful.
“We were very surprised when we saw the results from our first patients,” said Krystel Huxlin, Ph.D., the neuroscientist and associate professor who led the study of seven patients at the University of Rochester Eye Institute. “This is a type of brain damage that clinicians and scientists have long believed you simply can’t recover from. It’s devastating, and patients are usually sent home to somehow deal with it the best they can.”
The results are a cause for hope for patients with vision damage from stroke or other causes, said Huxlin. The work also shows a remarkable capacity for “plasticity” in damaged, adult brains. It shows that the brain can change a great deal in older adults and that some brain regions are capable of covering for other areas that have been damaged.
Huxlin studied seven people who had suffered a stroke that damaged an area of the brain known as the primary visual cortex or V1, which serves as the gateway to the rest of the brain for all the visual information that comes through our eyes. V1 passes visual information along to dozens of other brain areas, which process and make sense of the information, ultimately allowing us to see.
Patients with damage to the primary visual cortex have severely impaired vision – they typically have a difficult or impossible time reading, driving, or getting out to do ordinary chores like grocery shopping. Patients may walk into walls, oftentimes cannot navigate stores without bumping into goods or other people, and they may be completely unaware of cars on the road coming toward them from the left or right.
Depending on where in the brain the stroke occurred, most patients will be blind in one-quarter to one-half of their normal field of view. Everything right or left of center, depending on the side of the stroke, might be gray or dark, for instance.
Friday, April 10, 2009
Neuroscientists Demonstrate The Link Between Brainwave Activity and Visual Perception
ScienceDaily (Apr. 9, 2009) — Can we always see what is in front of us? According to Dr. Tony Ro, a Professor of Psychology and Cognitive Neuroscience at The City College of New York (CCNY), the answer is “no.” New research published in The Journal of Neuroscience by Professor Ro and colleagues from the University of Illinois demonstrates that the brain cannot detect images when brainwave activity is in a trough.
“We may have our eyes open, but we sometimes miss seeing things,” Professor Ro said. “When the brain is in a state of readiness, you see; when it is not, you don’t see.”
Brainwave activity has peaks and troughs that can occur around 10 times a second, he explained. In their research, Professor Ro and his colleagues demonstrated how the phase of the brainwave or alpha wave can reliably predict visual detection.
Subjects were shown a faint image of a dot on a computer screen and asked to indicate whether they saw the image by pushing a button. Subsequently, the dot was masked making it more difficult to see. “We tried to see whether there was variability in people’s ability to see the image,” he said. “When we presented the dots with masks sometimes people saw it and sometimes they didn’t.”
The research has potential applications in improving safety. For example, automobile accidents often occur because drivers miss seeing something, even if for a split second, he explained.
“With brain sensors we might be able to know when people will actually miss seeing something. By being able to predict whether or not someone will see something, we should be able to implement better ways of delivering information to people to ensure that they will detect it. This might then enhance safety, reduce errors, and prevent mishaps that frequently occur because people fail to see something that is right in front of them.”
Professor Ro said future research will investigate what occurs when images are flashed by a strobe light at intervals to match these brainwave frequencies
“We may have our eyes open, but we sometimes miss seeing things,” Professor Ro said. “When the brain is in a state of readiness, you see; when it is not, you don’t see.”
Brainwave activity has peaks and troughs that can occur around 10 times a second, he explained. In their research, Professor Ro and his colleagues demonstrated how the phase of the brainwave or alpha wave can reliably predict visual detection.
Subjects were shown a faint image of a dot on a computer screen and asked to indicate whether they saw the image by pushing a button. Subsequently, the dot was masked making it more difficult to see. “We tried to see whether there was variability in people’s ability to see the image,” he said. “When we presented the dots with masks sometimes people saw it and sometimes they didn’t.”
The research has potential applications in improving safety. For example, automobile accidents often occur because drivers miss seeing something, even if for a split second, he explained.
“With brain sensors we might be able to know when people will actually miss seeing something. By being able to predict whether or not someone will see something, we should be able to implement better ways of delivering information to people to ensure that they will detect it. This might then enhance safety, reduce errors, and prevent mishaps that frequently occur because people fail to see something that is right in front of them.”
Professor Ro said future research will investigate what occurs when images are flashed by a strobe light at intervals to match these brainwave frequencies
Sunday, April 5, 2009
Blood Test For Head Injuries Gains Momentum
Science News
Blood Test For Brain Injuries Gains Momentum
ScienceDaily (Apr. 2, 2009) —
A blood test that can help predict the seriousness of a head injury and detect the status of the blood-brain barrier is a step closer to reality, according to two recently published studies involving University of Rochester Medical Center researchers.
News stories about tragic head injuries – from the death of actress Natasha Richardson to brain-injured Iraq war soldiers and young athletes – certainly underscore the need for a simpler, faster, accurate screening tool, said brain injury expert Jeffrey Bazarian, M.D., M.P.H., associate professor of Emergency Medicine, Neurology and Neurosurgery at URMC, and a co-author on both studies.
The S-100B blood test recently cleared a significant hurdle when a panel of national experts, including Bazarian, agreed for the first time that it could be a useful tool for patients with a mild injury, allowing them to safely avoid a CT scan.
Previous studies have shown the S-100B serum protein biomarker to increase rapidly after an injury. If measured within four hours of the injury, the S-100B test accurately predicts which head injury patients will have a traumatic abnormality such as hemorrhage or skull fracture on a head CT scan. It takes about 20 minutes to get results and could spare many patients unnecessary radiation exposure.
Physicians at six Emergency Departments in upstate New York, including the ED at Strong Memorial Hospital in Rochester, this year will continue to study the accuracy of the test among 1,500 patients. Scientists plan to use the data to apply for U.S. Food and Drug Administration approval.
"The S-100B blood test is an important part of the tool set we need to improve our treatment of patients with brain injuries," Bazarian said. "It's not the ultimate diagnostic test, but it may make things easier for patients, and it will help doctors sort through difficult clinical decisions."
The test is used routinely in 16 European countries as a screening device. If a person falls and gets a head injury in Munich, Germany, during Oktoberfest, for example, a neurosurgeon is on duty within 500 meters of the beer tent, ready to administer the blood test, Bazarian said.
But in the United States, the current, accepted standard screening tool for head injuries is still the CT scan, which shows bleeding in the brain but does not detect more subtle injury to the brain's neurons, which can result in lasting neurological defects. In fact, 95 percent of CT scans look normal for patients with a relatively mild but potentially life-altering injury, Bazarian said.
There are more than 1 million emergency visits annually for traumatic brain injury (TBI) in the U.S. The majority of these visits are for mild injuries, primarily the result of falls and motor vehicle crashes. The challenge for doctors is to identify which of these patients has an acute, traumatic intracranial injury, something that is not always evident, and which patients can be observed and sent home.
Widespread use of the blood test could result in a 30 percent reduction of CT scans, according to the report by the national panel of brain experts, which published updated clinical guidelines in the December 2008 Annals of Emergency Medicine, and the April 2009 Journal of Emergency Nursing.
Bazarian and colleague Brian J. Blyth, M.D., assistant professor of Emergency Medicine at URMC, additionally found that the S-100B test can relay critical information about how the blood-brain barrier (BBB) is functioning after a head injury. Blyth was the first author on this study, reported electronically March 3, 2009, in the Journal of Neurotrauma.
In the context of head injuries, the BBB acts like a gate between the brain tissue and peripheral circulation. The gate often opens after injury, but not always. Knowing the status of the BBB helps doctors to decide if medications given to repair damage will actually reach the brain. The time between injury and irreversible brain swelling is short – and many drug studies have failed to find a therapy that leverages this time frame and works as designed.
Before the S-100B blood test, the best way to know if the BBB was open was to perform an invasive procedure called a ventriculostomy. (Doctors insert a catheter through the skull and into the brain, withdrawal fluid, and compare the concentration of albumin protein in the cerebrospinal fluid to the concentration in the blood.)
In a pilot study of 20 patients, however, Blyth found that serum S-100B concentrations could accurately predict the function of the blood-brain barrier 12 hours after injury, eliminating the need for the invasive procedure.
The study compared levels of S-100B proteins to the CSF-serum albumin quotient (Qa), the gold standard measurement signaling a brain injury. Researchers compared nine people with a known severe head injury, to 11 people who suffered from non-traumatic headaches.
Blyth and Bazarian believe the research may impact future drug studies. "The disability and death rates from brain injuries have not improved much in the past 20 years," Blyth said. "Many clinical trials for new medications have failed, probably because it was difficult to know if the blood-brain barrier was open and the drugs were reaching its target. Our study shows that any diagnostic test for brain injury should incorporate a way to measure the status of the blood-brain barrier into its design."
Blood Test For Brain Injuries Gains Momentum
ScienceDaily (Apr. 2, 2009) —
A blood test that can help predict the seriousness of a head injury and detect the status of the blood-brain barrier is a step closer to reality, according to two recently published studies involving University of Rochester Medical Center researchers.
News stories about tragic head injuries – from the death of actress Natasha Richardson to brain-injured Iraq war soldiers and young athletes – certainly underscore the need for a simpler, faster, accurate screening tool, said brain injury expert Jeffrey Bazarian, M.D., M.P.H., associate professor of Emergency Medicine, Neurology and Neurosurgery at URMC, and a co-author on both studies.
The S-100B blood test recently cleared a significant hurdle when a panel of national experts, including Bazarian, agreed for the first time that it could be a useful tool for patients with a mild injury, allowing them to safely avoid a CT scan.
Previous studies have shown the S-100B serum protein biomarker to increase rapidly after an injury. If measured within four hours of the injury, the S-100B test accurately predicts which head injury patients will have a traumatic abnormality such as hemorrhage or skull fracture on a head CT scan. It takes about 20 minutes to get results and could spare many patients unnecessary radiation exposure.
Physicians at six Emergency Departments in upstate New York, including the ED at Strong Memorial Hospital in Rochester, this year will continue to study the accuracy of the test among 1,500 patients. Scientists plan to use the data to apply for U.S. Food and Drug Administration approval.
"The S-100B blood test is an important part of the tool set we need to improve our treatment of patients with brain injuries," Bazarian said. "It's not the ultimate diagnostic test, but it may make things easier for patients, and it will help doctors sort through difficult clinical decisions."
The test is used routinely in 16 European countries as a screening device. If a person falls and gets a head injury in Munich, Germany, during Oktoberfest, for example, a neurosurgeon is on duty within 500 meters of the beer tent, ready to administer the blood test, Bazarian said.
But in the United States, the current, accepted standard screening tool for head injuries is still the CT scan, which shows bleeding in the brain but does not detect more subtle injury to the brain's neurons, which can result in lasting neurological defects. In fact, 95 percent of CT scans look normal for patients with a relatively mild but potentially life-altering injury, Bazarian said.
There are more than 1 million emergency visits annually for traumatic brain injury (TBI) in the U.S. The majority of these visits are for mild injuries, primarily the result of falls and motor vehicle crashes. The challenge for doctors is to identify which of these patients has an acute, traumatic intracranial injury, something that is not always evident, and which patients can be observed and sent home.
Widespread use of the blood test could result in a 30 percent reduction of CT scans, according to the report by the national panel of brain experts, which published updated clinical guidelines in the December 2008 Annals of Emergency Medicine, and the April 2009 Journal of Emergency Nursing.
Bazarian and colleague Brian J. Blyth, M.D., assistant professor of Emergency Medicine at URMC, additionally found that the S-100B test can relay critical information about how the blood-brain barrier (BBB) is functioning after a head injury. Blyth was the first author on this study, reported electronically March 3, 2009, in the Journal of Neurotrauma.
In the context of head injuries, the BBB acts like a gate between the brain tissue and peripheral circulation. The gate often opens after injury, but not always. Knowing the status of the BBB helps doctors to decide if medications given to repair damage will actually reach the brain. The time between injury and irreversible brain swelling is short – and many drug studies have failed to find a therapy that leverages this time frame and works as designed.
Before the S-100B blood test, the best way to know if the BBB was open was to perform an invasive procedure called a ventriculostomy. (Doctors insert a catheter through the skull and into the brain, withdrawal fluid, and compare the concentration of albumin protein in the cerebrospinal fluid to the concentration in the blood.)
In a pilot study of 20 patients, however, Blyth found that serum S-100B concentrations could accurately predict the function of the blood-brain barrier 12 hours after injury, eliminating the need for the invasive procedure.
The study compared levels of S-100B proteins to the CSF-serum albumin quotient (Qa), the gold standard measurement signaling a brain injury. Researchers compared nine people with a known severe head injury, to 11 people who suffered from non-traumatic headaches.
Blyth and Bazarian believe the research may impact future drug studies. "The disability and death rates from brain injuries have not improved much in the past 20 years," Blyth said. "Many clinical trials for new medications have failed, probably because it was difficult to know if the blood-brain barrier was open and the drugs were reaching its target. Our study shows that any diagnostic test for brain injury should incorporate a way to measure the status of the blood-brain barrier into its design."
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