OWLS PROVIDES CLUES ON HOW HUMANS FOCUS ATTENTION
From the FMS Global News Desk of Jeanne Hambleton Embargoed: 11-Sep-2014 Source: Johns Hopkins University Citations Neuron, online-Sep-11-2014;
Newswise — Imagine a quarterback on the gridiron getting ready to pass the ball to a receiver. Suddenly, in charges a growling linebacker aiming to take him down. At what point does the quarterback abandon the throw and trigger evasive maneuvers?
A 1-pound owl might have some answers.
A Johns Hopkins University neuroscientist who works with barn owls is publishing his study about attention that reveals the rules and mechanisms for how the brain makes such decisions.
Shreesh Mysore, lead author of the paper to be published online Sept. 11 in the journal Neuron, and an assistant professor in the university’s Department of Psychological and Brain Sciences, said the scenarios represent two options: the “top-down” control of attention in which you choose what to focus on, and “bottom-up” control of attention in which physical stimuli in the world capture your attention by virtue of their properties.
It is competition among options – focus on the wide receiver or dodge the linebacker – that determines in a sliver of a second which situation requires immediate attention.
Mysore completed his research while he was a postdoctoral scholar at Stanford University. Eric Knudsen, a professor at the Stanford School of Medicine, is a senior author of the study. Mysore says the findings from this research provide insights into how the brain might choose what to focus on.
“The idea is that there is constant interplay and competition between these two kinds of influences,” said Mysore. “At any given moment, your brain has to pick from a vast variety of information, both top-down and bottom-up, and the brain runs a competition and picks a winner. To anthropomorphize this process, the brain basically says, ‘At this instant, I’m going to select this location in the world to direct my attention.’”
Learning more about how attention is controlled can help in the future treatment of such disorders as attention deficit disorder, autism and schizophrenia. As for barn owls, their acute hearing and laser-like gaze make them great test cases in research exploring spatial attention.
Using a visual projector and a pair of specialized earphones, the owls were presented with a series of computer-controlled images of dots and noise bursts. Electrodes just thicker than an average human hair were inserted into a portion of the owls’ brain called the optic tectum.
The tectum is a key hub in the midbrain of all vertebrate animals and is important for the control of spatial attention. Cells in different layers of the tectum have different jobs, with the surface layers being more vision-dominated, and the deeper layers processing information from multiple senses and driving body movement. All layers contain a map-like representation of the outside world.
After determining that brain cells in the tectum fired when the images and sounds appeared, the researchers then used two stimuli to measure which was more likely to dominate in the brain’s representation of the world.
“If you want to measure competition, you have to have things that are competing against each other,” said Mysore.
“So we used two stimuli, either two images or an image and a sound. Because objects with stronger physical properties tend to capture your attention behaviorally, we were looking for some signature of a ‘switch’ in the brain’s activity when one stimulus became just stronger than the other.”
This physical strength of a stimulus, called salience, was varied in their experiments by having visual dots loom at different speeds or by changing the loudness of sounds. An abrupt, switch-like change in the activity of tectal neurons is what they found when the owls were exposed to just these bottom-up or sensory stimuli, consistent with a previous study by Mysore.
“With these results as a basis, we went after the main goal of this study, which was to examine how top-down information influences competition and selection,” he said.
In an interesting twist, the study’s authors controlled where the owls intended to apply their focus. By delivering a tiny amount of current to a specific part of a region in the forebrain of owls called the gaze field, they essentially caused the animal to “want to” pay attention to a specific location in the world.
The authors found that this intention to pay attention to one particular stimulus had a powerful effect in that it nearly tripled the ability of the brain to determine which among all competing stimuli was the strongest. This ability could potentially make the animal that much better at correctly deciding which information is the most important at any instant.
In addition, using a computer model of the neurons in the tectum, they were able to provide an explanation for how top-down information may fine-tune the ability of the brain to make decisions about where to pay attention.
Mysore said that while much is known about how the brain processes sensory information, not as much is understood about how the brain performs stimulus competition to decide where to focus. This study provides important clues.
“One of my longstanding interests is to understand how specific circuits in the brain produce specific behaviors,” he said. “My hope is that by understanding neural computations and circuits underlying behavior in normal animals, we will be able to contribute meaningfully to the understanding of what has gone awry in disease states. This, to me, is one of the best approaches to developing effective therapeutics for psychiatric.”
CAN YOUR BLOOD TYPE AFFECT YOUR MEMORY?
From FMS Global News Desk of Jeanne Hambleton Embargoed: 10-Sep-2014 Source: American Academy of Neurology (AAN) Citations Neurology
Newswise — MINNEAPOLIS – 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.
The study was supported by the National Institute of Neurological Disorders and Stroke, National Institutes of Health, U.S. Department of Health and Human Services and National Heart, Lung, and Blood Institute.
The American Academy of Neurology, an association of 28,000 neurologists and neuroscience professionals, is dedicated to promoting the highest quality patient-centered neurologic care. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as Alzheimer’s disease, stroke, migraine, multiple sclerosis, brain injury, Parkinson’s disease and epilepsy.
YOGIC BREATHING SHOWS PROMISE IN REDUCING SYMPTOMS OF POST-TRAUMATIC STRESS DISORDER
From the FMS Global News Desk of Jeanne Hambleton Released: 11-Sep-2014
Source: University of Wisconsin-Madison Citations Journal of Traumatic Stress
Newswise — MADISON, Wis. — One of the greatest casualties of war is its lasting effect on the minds of soldiers. This presents a daunting public health problem: More than 20 percent of veterans returning from the wars in Iraq and Afghanistan have post-traumatic stress disorder, according to a 2012 report by RAND Corp.
A new study from the Center for Investigating Healthy Minds at the Waisman Center of the University of Wisconsin-Madison offers hope for those suffering from the disorder. Researchers there have shown that a breathing-based meditation practice called Sudarshan Kriya Yoga can be an effective treatment for PTSD.
Individuals with PTSD suffer from intrusive memories, heightened anxiety, and personality changes. The hallmark of the disorder is hyperarousal, which can be defined as overreacting to innocuous stimuli, and is often described as feeling “jumpy,” or easily startled and constantly on guard.
Hyperarousal is one aspect of the autonomic nervous system, the system that controls the beating of the heart and other body functions, and governs one’s ability to respond to his or her environment. Scientists believe hyperarousal is at the core of PTSD and the driving force behind some of its symptoms.
Standard treatment interventions for PTSD offer mixed results. Some individuals are prescribed antidepressants and do well while others do not; others are treated with psychotherapy and still experience residual affects of the disorder.
Sudarshan Kriya Yoga is a practice of controlled breathing that directly affects the autonomic nervous system. While the practice has proven effective in balancing the autonomic nervous system and reducing symptoms of PTSD in tsunami survivors, it has not been well studied until now.
The CIHM team was interested in Sudarshan Yoga because of its focus on manipulating the breath, and how that in turn may have consequences for the autonomic nervous system and specifically, hyperarousal. Theirs is the first randomized, controlled, longitudinal study to show that the practice of controlled breathing can benefit people with PTSD.
“This was a preliminary attempt to begin to gather some information on whether this practice of yogic breathing actually reduces symptoms of PTSD,” says Richard J. Davidson, founder of CIHM and one of the authors of the study.
“Secondly, we wanted to find out whether the reduction in symptoms was associated with biological measures that may be important in hyperarousal.”
These tests included measuring eye-blink startle magnitude and respiration rates in response to stimuli such as a noise burst in the laboratory. Respiration is one of the functions controlled by the autonomic nervous system; the eye-blink startle rate is an involuntary response that can be used to measure one component of hyperarousal. These two measurements reflect aspects of mental health because they affect how an individual regulates emotion.
The CIHM study included 21 soldiers: an active group of 11 and a control group of 10. Those who received the one-week training in yogic breathing showed lower anxiety, reduced respiration rates and fewer PTSD symptoms.
Davidson would like to further the research by including more participants, with the end goal of enabling physicians to prescribe treatment based on the cognitive and emotional style of the individual patient.
“A clinician could use a ‘tool box’ of psychological assessments to determine the cognitive and emotional style of the patient, and thereby determine a treatment that would be most effective for that individual,” he says.
“Right now, a large fraction of individuals who are given any one type of therapy are not improving on that therapy. The only way we can improve that is if we determine which kinds of people will benefit most from different types of treatments.”
That assessment is critical. At least 22 veterans take their own lives every day, according to the U.S. Department of Veterans Affairs. Because Sudarshan Kriya Yoga has already been shown to increase optimism in college students, and reduce stress and anxiety in people suffering from depression, it may be an effective way to decrease suffering and, quite possibly, the incidence of suicide among veterans.
The study, published in the Journal of Traumatic Stress, was funded by a grant from the Disabled Veterans of America Charitable Service Trust and individual donors.
Back Wednesday. Jeanne