Stroke Patients Benefit From New Brain And Motor Skills Research

Bioengineers have taken a small step toward improving physical recovery in stroke patients by showing that a key feature of how limb motion is encoded in the nervous system plays a crucial role in how new motor skills are learned.

Published in a recent issue of Neuron, a Harvard-based study about the neural learning elements responsible for motor learning may help scientists design rehabilitation protocols in which motor adaptation occurs more readily, potentially allowing for a more rapid recovery.

Neuroscientists have long understood that the brain's primary motor cortex and the body's low-level peripheral stretch sensors encode information about the position and velocity of limb motion in a positively-correlated manner rather than as independent variables.

"While this correlation between the brain's encoding of the position and the velocity of motion is well-known, its potential importance and practical use has been unclear until now," says coauthor Maurice A. Smith, Assistant Professor of Bioengineering at the Harvard School of Engineering and Applied Sciences (SEAS) and the Center for Brain Science in the Faculty of Arts and Sciences.

Smith and colleagues showed that the correlated neural tuning to position and velocity is also present in the neural learning elements responsible for motor learning. Moreover, this correlated drive can explain key features of the motor adaptation process.

To study and record motor adaptation, the researchers had subjects grasp a robotic arm. The device was programmed to simulate novel physical dynamics as subjects made reaching motions. In addition, the team used a newly developed measurement technique called an "error-clamp" to tease apart the resulting data.

The method measures motor output during learning, allowing learning-related changes in motor output over the course of a movement to be dissociated from feedback adjustments that correct motor errors that happen simultaneously.

"Conceptually, this error-clamp is analogous to a voltage-clamp, commonly used in electrophysiology to measure how ions move through a neuron's membrane when it fires," explains lead author Gary C. Sing, a graduate student at SEAS. "The general idea is that devising an experimental method to clamp and control the key variable in an experiment can allow for greater insight into the underlying physiology."

Analysis of the data extracted by the error-clamp technique led to the creation of a computational model that identifies a set of vectors that characterize the principal components of motor adaptation in the state space of physical motion. While such analysis is commonplace in systems engineering -- for example, in evaluating how a bridge might react to high winds or earthquakes -- the method has only been recently applied to how motor output evolves.

"We observed that the initial stages of motor learning are often quick but non-specific, whereas later stages of learning are slower and more precise," says Sing. "Further, we saw that some physical patterns of movement are learned more quickly than others."

By understanding what types of motor adaptations are easier to learn, the researchers hope to design rehabilitation activities that will encourage patients to use an affected limb more.

"In stroke rehabilitation, patients who make a greater effort to use their impaired limbs can achieve better outcomes," says Smith. "However, there is often a vicious cycle, as a patient is far less likely to use an impaired limb if his or her other limb is fine. This pattern slows recovery and leads to greater impairment of the affected limb."

Smith and his colleagues are beginning studies with stroke patients to determine whether training them with such optimized patterns will, in fact, improve their rate of motor learning and speed up recovery.
More broadly, untangling the algorithms the brain uses for motor learning could help improve a wide range of neural and muscular rehabilitation programs. The researchers also anticipate that such findings could be one day be adapted for enhancing the brain/machine interfaces increasingly used for those with amputated limbs.

Sources:  Harvard University and "Primitives for Motor Adaptation Reflect Correlated Neural Tuning to Position and Velocity"

For Exercise, Kids Do As Parents Say Not As They Do

According to a new study, there is no direct link between parents' own level of physical activity, and how much their child may exercise. In fact, parents' perceptions of their children's athleticism are what have a direct impact on the children's activity.

The study by Oregon State University researchers Stewart Trost and Paul Loprinzi, published in the journal Preventive Medicine, studied 268 children ages 2 to 5 in early childhood education centers in Queensland, Australia. Of these children, 156 parents or caregivers were surveyed on their parental practices, behaviors related to physical activity and demographic information.

What they found is that parents' level of physical activity is not directly associated with their children, but instead that the direct link was between parental support and a child's level of physical activity.

"Active parents may be more likely to have active children because they encourage that behavior through the use of support systems and opportunities for physical activity, but there is no statistical evidence that a child is active simply because they see that their parents exercise," Trost said.

Trost, who is director of the Obesity Prevention Research Core at the new Hallie Ford Center for Healthy Children and Families at OSU, is an international expert on the issue of childhood obesity.

His study found that parents who think their children have some sort of athletic ability were much more likely than other parents to provide instrumental and emotional support for young children to be physically active.

"I think this underscores the need for parents to provide emotional support, as well as opportunities for activity," Trost said. "Regardless of whether a child is athletic or is perceived to be physically gifted, all children need opportunities and encouragement of physical activity."

However, Trost said parental support of physical activity did not translate to a child's behavior once they were not in the home and were in a childcare setting. He said this adds to the body of research showing that both parents as well as childcare providers must provide support for physical activity.

Sources:  Oregon State University and Parental influences on physical activity behavior in preschool children, Preventive Medicine

For Rock Climbers, Endurance Is Key To Performance

The maximum time an athlete is able to continue climbing to exhaustion may be the only determinant of his/her performance. A new European study, led by researchers from the University of Granada, the objective of which is to help trainers and climbers design training programmes for this type of sport, shows this to be the case.


Until now, performance indicators for climbing have been low body fat percentage and grip strength. Furthermore, existing research was based on the comparison of amateur and expert climbers. Now, a new study carried out with 16 high-level climbers breaks with this approach and reveals that the time it takes for an athlete to become exhausted is the only indicator of his/her performance.

Vanesa España Romero was the first author of the work and is a researcher at the University of Granada.

The study, published in the European Journal of Applied Physiology, analyses the physiological parameters that determine performance in this sport at its highest level. The participants, eight women with an average rating of 7a (the scale of difficulty of a climbing route is graded from 5 to 9, with sub-grades of a, b and c) and eight men with an average rating of 8a, were divided into an "expert group" and an "elite group."

The researchers assessed the climbers with body composition tests (weight, height, body mass index, body fat %, bone mineral density, and bone mineral content), kinanthropometry (length of arms, hands and fingers, bone mineral density and bone mineral content of the forearm), and physical fitness tests (flexibility, strength of the upper and lower body and aerobic capacity measured at a climbing centre).

The results show there to be no significant differences between expert and elite climbers in any of the tests performed, except in climbing time to exhaustion and in bone mineral density, both of which were higher in the elite group. "Therefore, the maximum climbing time to exhaustion of an athlete is the sole determinant of performance," the researcher confirms.

Sport climbing began as a form of traditional climbing in the mid 80s, and is now a sport in its own right. The International Federation of Sport Climbing is currently requesting its inclusion as an Olympic sport.

The increase in the number of climbers and the proliferation of climbing centres and competitions have contributed to its interest in recent years, although there is limited scientific literature on climbing effort.

The most important research relates to energy consumption (ergospirometry, heart rate and lactic acid blood concentrations), the designation of maximum strength and local muscular resistance of climbers (dynamometry and electromyography), and to establishing anthropometric characteristics.

According to experts, a fundamental characteristic of sport climbing is its "vertical dimension," making it unique given its postural organisation in space, and from a physiological point of view, the effect a gravitational load has on movements.

In short, to complete a climb successfully, athletes should maintain their effort for as long as possible to improve their chances of reaching the ultimate goal.

Sources: FECYT - Spanish Foundation for Science and Technology and Climbing time to exhaustion is a determinant of climbing performance in high-level sport climbers. European Journal of Applied Physiology.

Virtual Reality Lab Proves How Fly Balls Are Caught

While baseball fans still rank "The Catch" by Willie Mays in the 1954 World Series as one of the greatest baseball moments of all times, scientists see the feat as more of a puzzle: How does an outfielder get to the right place at the right time to catch a fly ball?


Thousands of fans (and hundreds of thousands of YouTube viewers) saw Mays turn his back on a fly ball, race to the center field fence and catch the ball over his shoulder, seemingly a precise prediction of a fly ball's path that led his team to victory. According to a recent article in the Journal of Vision ("Catching Flyballs in Virtual Reality: A Critical Test of the Outfielder Problem"), the "outfielder problem" represents the definitive question of visual-motor control. How does the brain use visual information to guide action?

To test three theories that might explain an outfielder's ability to catch a fly ball, researcher Philip Fink, PhD, from Massey University in New Zealand and Patrick Foo, PhD, from the University of North Carolina at Ashville programmed Brown University's virtual reality lab, the VENLab, to produce realistic balls and simulate catches. The team then lobbed virtual fly balls to a dozen experienced ball players.

"The three existing theories all predict the same thing: successful catches with very similar behavior," said Brown researcher William Warren, PhD. "We realized that we could pull them apart by using virtual reality to create physically impossible fly ball trajectories."

Warren said their results support the idea that the ball players do not necessarily predict a ball's landing point based on the first part of its flight, a theory described as trajectory prediction. "Rather than predicting the landing point, the fielder might continuously track the visual motion of the ball, letting it lead him to the right place at the right time," Warren said.

Because the researchers were able to use the virtual reality lab to perturb the balls' vertical motion in ways that would not happen in reality, they were able to isolate different characteristics of each theory. The subjects tended to adjust their forward-backward movements depending on the perceived elevation angle of the incoming ball, and separately move from side to side to keep the ball at a constant bearing, consistent with the theory of optical acceleration cancellation (OAC). The third theory, linear optical trajectory (LOT), predicted that the outfielder will run in a direction that makes the visual image of the ball appear to travel in a straight line, adjusting both forward-backward and side-to-side movements together.

Fink said these results focus on the visual information a ball player receives, and that future studies could bring in other variables, such as the effect of the batter's movements or sound.
"As a first step we chose to concentrate on what seemed likely to be the most important factor," Fink said. "Fielders might also use information such as the batter's swing or the sound of the bat hitting the ball to help guide their movements."

Sources:  Catching fly balls in virtual reality: A critical test of the outfielder problem and Association for Research in Vision and Ophthalmology

Boomer Brains Need Exercise

Moderate physical activity performed in midlife or later appears to be associated with a reduced risk of mild cognitive impairment, whereas a six-month high-intensity aerobic exercise program may improve cognitive function in individuals who already have the condition, according to two reports in the January issue of Archives of Neurology.

Mild cognitive impairment is an intermediate state between the normal thinking, learning and memory changes that occur with age and dementia, according to background information in one of the articles. Each year, 10 percent to 15 percent of individuals with mild cognitive impairment will develop dementia, as compared with 1 percent to 2 percent of the general population. Previous studies in animals and humans have suggested that exercise may improve cognitive function.

In one article, Laura D. Baker, Ph.D., of the University of Washington and Veterans Affairs Puget Sound Health Care System, Seattle, and colleagues report the results of a randomized, controlled clinical trial involving 33 adults with mild cognitive impairment (17 women, average age 70). A group of 23 were randomly assigned to an aerobic exercise group and exercised at high intensity levels under the supervision of a trainer for 45 to 60 minutes per day, four days per week. The control group of 10 individuals performed supervised stretching exercises according to the same schedule but kept their heart rate low. Fitness testing, body fat analysis, blood tests of metabolic markers and cognitive functions were assessed before, during and after the six-month trial.

A total of 29 participants completed the study. Overall, the patients in the high-intensity aerobic exercise group experienced improved cognitive function compared with those in the control group. These effects were more pronounced in women than in men, despite similar increases in fitness. The sex differences may be related to the metabolic effects of exercise, as changes to the body's use and production of insulin, glucose and the stress hormone cortisol differed in men and women.

"Aerobic exercise is a cost-effective practice that is associated with numerous physical benefits. The results of this study suggest that exercise also provides a cognitive benefit for some adults with mild cognitive impairment," the authors conclude. "Six months of a behavioral intervention involving regular intervals of increased heart rate was sufficient to improve cognitive performance for an at-risk group without the cost and adverse effects associated with most pharmaceutical therapies."

In another report, Yonas E. Geda, M.D., M.Sc., and colleagues at Mayo Clinic, Rochester, Minn., studied 1,324 individuals without dementia who were part of the Mayo Clinic Study of Aging. Participants completed a physical exercise questionnaire between 2006 and 2008. They were then assessed by an expert consensus panel, who classified each as having normal cognition or mild cognitive impairment.

A total of 198 participants (median or midpoint age, 83 years) were determined to have mild cognitive impairment and 1,126 (median age 80) had normal cognition. Those who reported performing moderate exercise—such as brisk walking, aerobics, yoga, strength training or swimming—during midlife or late life were less likely to have mild cognitive impairment. Midlife moderate exercise was associated with 39 percent reduction in the odds of developing the condition, and moderate exercise in late life was associated with a 32 percent reduction. The findings were consistent among men and women.

Light exercise (such as bowling, slow dancing or golfing with a cart) or vigorous exercise (including jogging, skiing and racquetball) were not independently associated with reduced risk for mild cognitive impairment.

Physical exercise may protect against mild cognitive impairment via the production of nerve-protecting compounds, greater blood flow to the brain, improved development and survival of neurons and the decreased risk of heart and blood vessel diseases, the authors note. "A second possibility is that physical exercise may be a marker for a healthy lifestyle," they write. "A subject who engages in regular physical exercise may also show the same type of discipline in dietary habits, accident prevention, adherence to preventive intervention, compliance with medical care and similar health-promoting behaviors."

Future study is needed to confirm whether exercise is associated with the decreased risk of mild cognitive impairment and provide additional information on cause and effect relationships, they conclude.

Sources:  JAMA and Archives Journals, Physical Exercise, Aging, and Mild Cognitive Impairment: A Population-Based Study  and Effects of Aerobic Exercise on Mild Cognitive Impairment: A Controlled Trial.

Bodily Benefits Of A Big Butt

If you’re prone to worrying whether your ‘butt looks big in this’, particularly after the holidays, you can take comfort that there may be health benefits.

Oxford University scientists – who have looked at all the evidence on the health effects of storing more fat on the hips, thighs and bum, rather than around the waist – show that having a ‘pear shape’ is not just less bad for you than an ‘apple shape’, but actively protects against diabetes and heart disease.

The team from the Oxford Centre for Diabetes, Endocrinology, and Metabolism (OCDEM) have published their summary of the latest research in the International Journal of Obesity today.

‘The idea that body fat distribution is important to health has been known for some time,’ says Dr Konstantinos Manolopoulos, one of the paper’s authors along with Dr Fredrik Karpe and Professor Keith Frayn.

‘However, it is only very recently that thigh fat and a larger hip circumference have been shown to promote health, that lower body fat is protective by itself.’

He adds: ‘This protective effect is independent of weight. However, if you put on weight, thigh circumference will increase but your waist circumference will also increase, which over-rides the protective effect.’

‘Control of body weight is still the best way to stay healthy, and the advice remains the same: it is important to eat less and exercise more.’

The Oxford researchers explain that the body uses its fat tissues to store energy in the form of fatty acids, which can be released when needed, for example after heavy exercise or a period of starvation. Both tummy and thigh fat handle this process, but fat around the waist is much more active in storing and releasing fatty acids in response to need throughout the day. Thigh fat is used for much longer term storage.

More waist or abdominal fat tends to lead to more fatty acids floating around the body where it can get deposited in other organs like the liver and muscle, and cause harm. This is associated with conditions like diabetes, insulin resistance and heart disease.

Thigh fat on the other hand, traps the fatty acids long term, so they can’t get deposited and cause harm.

'Thigh fat and a larger hip circumference have been shown to promote health, and lower body fat is protective by itself,' said Manolopoulos.

The scientists also review evidence that abdominal fat and thigh fat release different levels of hormones. Waist fat is known to release molecules called pro-inflammatory cytokines, and inflammation is a process linked to diabetes and heart disease.

Thigh fat might also secrete more beneficial hormones like leptin and adiponectin, Dr Manolopoulos says, although this is unclear at the moment.

Dr Manolopoulos says the typical difference in male and female body shapes, with men more likely to have fat around the waist and women have more fat on their thighs and hips, neatly illustrates the health effects of different body shapes.

‘If you looked at a man and woman of the same weight and aged around 40, they would have different weight distributions, and it would be the man that was at higher risk of diabetes and heart disease,’ he says.

‘However, when women go through menopause, as well as changes in their hormones they tend to see a change in body shape. They lose body fat and move to a more ‘male’ fat distribution. They then have the same risk of heart disease and diabetes as men.’

It may be possible to use these findings in the future to reduce people’s health risks but that is a long way off, cautions Dr Manolopoulos.

‘We don’t really know how the body decides where to store fat. At the moment we need to understand more about the mechanisms the body uses. Only then will we be able to take the next step and try to influence this.’

‘In principle, this should be possible. There is a class of anti-diabetic drugs that is known to redistribute fat in the body from internal organs to fat stored subcutaneously under the skin. This improves symptoms in diabetes,’ he says.

The team at OCDEM, funded by the Wellcome Trust, is working to understand the way the body stores and turns over fat. They recently pinpointed two genes that are associated with differences in people’s body fat distribution and may be important during embryo development.

‘They are weak effects, but this is just a beginning,’ says Dr Karpe, one of the research group heads. ‘Obesity is a big problem, but it may be that the characteristics of that obesity are more important.’

Source: University of Oxford   and "Gluteofemoral body fat as a determinant of metabolic health"

Barefoot Is Better

Knee osteoarthritis (OA) accounts for more disability in the elderly than any other disease. Running, although it has proven cardiovascular and other health benefits, can increase stresses on the joints of the leg. In a study published in the December 2009 issue of PM&R: The journal of injury, function and rehabilitation, researchers compared the effects on knee, hip and ankle joint motions of running barefoot versus running in modern running shoes. They concluded that running shoes exerted more stress on these joints compared to running barefoot or walking in high-heeled shoes.


Sixty-eight healthy young adult runners (37 women), who run in typical, currently available running shoes, were selected from the general population. None had any history of musculoskeletal injury and each ran at least 15 miles per week. A running shoe, selected for its neutral classification and design characteristics typical of most running footwear, was provided to all runners. Using a treadmill and a motion analysis system, each subject was observed running barefoot and with shoes. Data were collected at each runner's comfortable running pace after a warm-up period.

The researchers observed increased joint torques at the hip, knee and ankle with running shoes compared with running barefoot. Disproportionately large increases were observed in the hip internal rotation torque and in the knee flexion and knee varus torques. An average 54% increase in the hip internal rotation torque, a 36% increase in knee flexion torque, and a 38% increase in knee varus torque were measured when running in running shoes compared with barefoot.
 
These findings confirm that while the typical construction of modern-day running shoes provides good support and protection of the foot itself, one negative effect is the increased stress on each of the 3 lower extremity joints. These increases are likely caused in large part by an elevated heel and increased material under the medial arch, both characteristic of today's running shoes.

Writing in the article, lead author D. Casey Kerrigan, MD, JKM Technologies LLC, Charlottesville, VA, and co-investigators state, "Remarkably, the effect of running shoes on knee joint torques during running (36%-38% increase) that the authors observed here is even greater than the effect that was reported earlier of high-heeled shoes during walking (20%-26% increase). Considering that lower extremity joint loading is of a significantly greater magnitude during running than is experienced during walking, the current findings indeed represent substantial biomechanical changes."

Dr. Kerrigan concludes, "Reducing joint torques with footwear completely to that of barefoot running, while providing meaningful footwear functions, especially compliance, should be the goal of new footwear designs."

Source: Elsevier Health Sciences  "The Effect of Running Shoes on Lower Extremity Joint Torques" by D. Casey Kerrigan, MD, Jason R. Franz, MS, Geoffrey S. Keenan, MD, Jay Dicharry, MPT, Ugo Della Croce, PhD, and Robert P. Wilder, MD. It appears in PM&R: The journal of injury, function and rehabilitation, Volume 1, Issue 12 (December 2009), published by Elsevier. The article has been made freely available and may be accessed at: http://www.pmrjournal.org/article/S1934-1482(09)01367-7/fulltext

How Nerves Affect Soccer Penalty Kicks

Research by the University of Exeter shows for the first time the effect of anxiety on a soccer player's eye movements while taking a penalty.

The study shows that when penalty takers are anxious they are more likely to look at and focus on the centrally positioned goalkeeper. Due to the tight coordination between gaze control and motor control, shots also tend to centralise, making them easier to save. The research is now published in the December 2009 edition of the Journal of Sport and Exercise Psychology.

The researchers attribute this change in eye movements and focus to anxiety. Author Greg Wood, a PhD student in the University of Exeter’s School of Sport and Health Sciences said: “During a highly stressful situation, we are more likely to be distracted by any threatening stimuli and focus on them, rather than the task in hand. Therefore, in a stressful penalty shootout, a footballer’s attention is likely to be directed towards the goalkeeper as opposed to the optimal scoring zones (just inside the post). This disrupts the aiming of the shot and increases the likelihood of subsequently hitting the shot towards the goalkeeper, making it easier to save.”

For their study, the researchers focused on 14 members of the University of Exeter football team. They asked the players to perform two series of penalty shots. First, they were simply asked to do their best to score. The researchers made the second series more stressful and more akin to a penalty shoot-out. The players were told that the results would be recorded and shared with the other players and there would be a £50 prize for the best penalty taker.

The players wore special glasses which enabled the researchers to record precise eye movements and analyse the focus of each footballer’s gaze and the amount of time spent looking at different locations in the goal.

The results showed that when anxious, the footballers looked at the goalkeeper significantly earlier and for longer. This change in eye behaviour made players more likely to shoot towards the centre of the goal, making it easier for the keeper to save. The researchers believe that by being made aware of the impact of anxiety on eye movements, and the affect this has on the accuracy of a player’s shot, coaches could address this through training.

Greg Wood continues: “Research shows that the optimum strategy for penalty takers to use is to pick a spot and shoot to it, ignoring the goalkeeper in the process. Training this strategy is likely to build on the tight coordination between eye movements and subsequent actions, making for more accurate shooting. The idea that you cannot recreate the anxiety a penalty taker feels during a shootout is no excuse for not practicing. Do you think other elite performers don’t practice basic aiming shots in darts, snooker or golf for the same reasons? These skills need to be ingrained so they are robust under pressure”.

Source: University of Exeter: Anxiety, Attentional Control, and Performance Impairment in Penalty Kicks.

Ending The Myth Of The Dumb Jock

In the first study to demonstrate a clear positive association between adolescent fitness and adult cognitive performance, Nancy Pedersen of the University of Southern California and colleagues in Sweden find that better cardiovascular health among teenage boys correlates to higher scores on a range of intelligence tests – and more education and income later in life.

"During early adolescence and adulthood, the central nervous system displays considerable plasticity," said Pedersen, research professor of psychology at the USC College of Letters, Arts & Sciences. "Yet, the effect of exercise on cognition remains poorly understood."

Pedersen, lead author Maria Åberg of the University of Gothenburg and the research team looked at data for all 1.2 million Swedish men born between 1950 and 1976 who enlisted for mandatory military service at the age of 18.

In every measure of cognitive functioning they analyzed – from verbal ability to logical performance to geometric perception to mechanical skills – average test scores increased according to aerobic fitness.

However, scores on intelligence tests did not increase along with muscle strength, the researchers found.

"Positive associations with intelligence scores were restricted to cardiovascular fitness, not muscular strength," Pedersen explained, "supporting the notion that aerobic exercise improved cognition through the circulatory system influencing brain plasticity."

The results of the study – in the current issue of PNAS Early Edition – also show the importance of getting healthier between the ages of 15 and 18 while the brain is still changing.

Boys who improved their cardiovascular health between ages 15 to 18 exhibited significantly greater intelligence scores than those who became less healthy over the same time period. Over a longer term, boys who were most fit at the age of 18 were more likely to go to college than their less fit counterparts.

"Direct causality cannot be established. However, the fact that we demonstrated associations between cognition and cardiovascular fitness but not muscle strength . . . and the longitudinal prediction by cardiovascular fitness on subsequent academic achievement, speak in favor of a cardiovascular effect on brain function," Pedersen said.

In their sample, the researchers looked at 260,000 full-sibling pairs, 3,000 sets of twins, and more than 1,400 sets of identical twins. Having relatives enabled the research team to evaluate whether the results might reflect shared family environments or genetic influences.

Even among identical twin pairs, the link between cardiovascular health and intelligence remained strong, according to the study. Thus, the results are not a reflection of genetic influences on cardiovascular health and intelligence. Rather, the twin results give further support to the likelihood that there is indeed a causal relationship, Pedersen explained.

"The results provide scientific support for educational policies to maintain or increase physical education in school curricula," Pedersen said. "Physical exercise should be an important instrument for public health initiatives to optimize cognitive performance, as well as disease prevention at the society level."

Source: University of Southern California