Scholarship & Creative Work
Brain-training to improve memory boosts fluid intelligence
"Considering the fundamental importance of fluid intelligence in everyday life and its predictive power for a large variety of intellectual tasks and professional success, we believe that our findings may be highly relevant to applications in education," psychology researchers Susanne Jaeggi and Martin Buschkuehl say.
The research appears in the current Proceedings of the National Academy of Sciences (PNAS).
Many psychologists believe general intelligence can be separated into "fluid" and "crystalline" components. Fluid intelligence considered one of the most important factors in learning applies to all problems while crystallized intelligence consists of skills useful for specific tasks.
"Working memory and fluid intelligence both seem to rely on similar neural networks," Jaeggi says. "Our study does not permit us to know how long the training-gain persists. Longitudinal studies will be required to address that issue."
Many psychologists previously believed the only way to increase fluid intelligence was through direct practice of the tests themselves, rather than by training. But the new findings show that multiple efforts designed to improve memory skills similarly improve fluid intelligence.
After initially giving a standard test for fluid intelligence, the researchers gave subjects a series of training exercises designed to improve working memory.
The training was given to four groups, who repeated the exercises for eight, 12, 17 or 19 days. After the training, researchers re-tested the subjects' fluid intelligence.
Although the performance of untrained controls improved slightly, the trained subjects showed a significant performance improvement, which increased with training.
"The more training, the more improvement in fluid intelligence," Jaeggi says.
The researchers suggest that the training exercises strengthened multiple "executive processes" in the brain that function in problem-solving, noting that fluid intelligence is usually seen as "robust against influences of education and socialization, and it is commonly seen as having a strong hereditary component."
Asthma inhaler misuse common among anti-social teens
"Our findings indicate that inhaler misuse for the purposes of becoming intoxicated is both widespread and may justifiably be regarded as a form of substance abuse in many cases," says Brian Perron, an assistant professor in the School of Social Work and study's lead author.
Perron co-authored the study with Matthew Howard, a professor at the University of North Carolina.
The researchers conducted a survey assessing substance use, psychiatric symptoms and anti-social behaviors among 723 adolescents in 32 residential treatment facilities. About 27 percent of youths who had been prescribed an inhaler used it excessively. In addition, one-third of all youths in the sample had used an asthma inhaler without a prescription.
Asthma inhaler misusers were more psychiatrically distressed and prone to suicidal thoughts and attempts than youths who did not misuse their inhalers to get high, the study shows.
Many inhaler abusers reported positive feelings of euphoria, relaxation and increased confidence during or immediately following inhaler use. Adverse reactions noted included feeling more dizzy, headaches, rapid heartbeat, anxiety, irritability and confusion.
Bionic boot measures ankle movement, spring in step
Scientists using a bionic boot found that while walking, the ankle does about three times the work for the same amount of energy compared to isolated muscles. In other words, the spring in a person's step is real and helps efficient movement.
While much has been done measuring the efficiency of individual muscles, this is the first known study to measure the energy efficiency of a body part such as the ankle, says Daniel Ferris, associate professor with the Division of Kinesiology and lead researcher on the project.
The results suggest manufacturers should rethink prosthesis design so the ankle part can do more of the work, said Ferris, who also holds an appointment in the Department of Biomedical Engineering. It also sheds light on why rehabilitation and mobility are so exhausting for people with unhealthy ankles or neurologic problems.
Greg Sawicki, a graduate student working with Ferris and now at Brown University, built a bionic ankle equipped with fake muscles that mimic real muscle activity in the ankle.
Healthy subjects wore two of the boots, which were attached to the nervous system by electrodes. Sawicki measured the amount of oxygen consumed when walking with or without the boot and compared the two. Muscles use oxygen when they burn fuel, which means the more oxygen used the more energy expended, Ferris says.
"The ankle is incredibly efficient at working so the amount of energy you burn with the ankle is much lower than what would be predicted with just isolated muscle studies," Ferris says.
Researchers suspect this is largely because the Achilles tendon is so long and compliant, and able to store and return energy during the stride cycle.
Amputees and people with neurologic disorders don't have the "bounce" of the stored energy in the ankle, Ferris says.
"For amputees, we need to come up with a better way for them to have a powered push off at the ankle," he says.
The next step is to build a bionic hip and measure its efficiency during walking.
New insights emerge into cause of diabetes
Researchers have new clues to what goes awry at the cellular level in Type 2 diabetes.
Their results, published in the Journal of the American Chemical Society (JACS), challenge conventional views of how the disease is initiated and may lead to development of drugs to treat aging-related diseases, as well as diabetes.
One of the most striking hallmarks of Type 2 diabetes is the presence of clumped protein fibers called amyloids in the insulin-producing cells of the pancreas. Previous research has suggested that amyloid formation somehow damages the membranes surrounding those cells, killing the cells and precipitating diabetes.
But Associate Professor of Chemistry and Biophysics Ayyalusamy Ramamoorthy and co-workers show in the new study that membrane damage can occur independently of amyloid formation and that the protein involved, known as Islet Amyloid Polypeptide Protein (IAPP), has separate regions responsible for amyloid formation and membrane disruption.
By breaking off one end of the protein and testing the resulting fragment's properties, the U-M group learned that the fragment can disrupt membranes and cause cell death as effectively as the full-length protein, without forming amyloids.
Then, comparing the human form of the IAPP with the rat version, which does not cause cell death, the researchers found that a difference of a single amino acid (protein building block) accounts for the toxicity. In conjunction with chemistry and pharmacology professor Robert T. Kennedy, Ramamoorthy is now studying the protein in living cells and obtaining the same results as with the model cell membranes used in the recent JACS paper.
Although IAPP is believed to contribute to the development of Type 2 diabetes, drugs to suppress the role of IAPP in diabetes have not yet been developed, mainly because the molecular mechanism by which IAPP becomes toxic has been a mystery.
Next, the researchers plan to use atomic-level molecular imaging solid-state NMR techniques to make nanoscopic movies to further elucidate the causes of Type 2 diabetes. In addition, they plan to explore how changes in cell membrane molecules with age contribute to the development of aging-related diseases.
Ramamoorthy collaborated on the project with postdoctoral fellow Jeffrey Brender; graduate students Edgar Lee and Marchello Cavitt; biological chemistry and biophysics professor Ari Gafni; and physics and biophysics professor Duncan Steel.
Bioartificial kidney improves survival of patients with acute renal failure
Another promising clinical trial for the bioartificial kidney is offering researchers even more hope that within the next few years the device will be available to save lives of patients with acute renal failure.
The latest U-M Health System-led study reveals that short-term replacement of renal cell function using the renal tubule assist device, or RAD the living cell cartridge that is key to the function of the bioartificial kidney significantly reduces mortality risk and speeds recovery of kidney function for patients with acute renal failure resulting from acute kidney injury.
"Our study results are encouraging, and they raise expectations that our new approach may yield a better treatment for life-threatening acute renal failure, for which a high mortality rate has remained unchanged despite years of advances in conventional therapies," says lead study author Dr. H. David Humes, professor of internal medicine at the Medical School. "Even more promising, the nature of our new approach using living cells as therapeutic agents argues for the feasibility of developing whole classes of new cell-based and tissue engineered therapies."
Humes and his colleagues began developing the bioartificial more than a decade ago, and today the RAD is being developed for future commercial applications under license to Nephrion, a U-M biotechnology spinout company.
The bioartificial kidney includes a cartridge that filters the blood as in traditional kidney dialysis. That cartridge is connected to a renal tubule assist device, which is made of hollow fibers lined with a type of kidney cell called renal proximal tubule cells. These cells are intended to reclaim vital electrolytes, salt, glucose and water, as well as control production of immune system molecules called cytokines, which the body needs to fight infection.
Conventional kidney dialysis machines remove these important components of blood plasma, along with toxic waste products, and cannot provide the immune regulation function of living cells. Traditional therapy for patients with acute or chronic renal failure involves dialysis or kidney transplant, both of which have limitations.
Iron supplements might harm infants who have enough
A study suggests that extra iron for infants who don't need it might delay development results that fuel the debate over optimal iron supplement levels and could have huge implications for the baby formula and food industry.
"Our results for 25 years of research show problems with lack of iron. For us to find this result is a big deal, it's really unexpected," says Dr. Betsy Lozoff, research professor at the Center for Human Growth and Development, and the study's principal investigator.
U.S. infant formulas typically come fortified with 12 mg/L of iron to prevent iron-deficiency anemia. Europe generally uses a lower amount. In infants, iron-deficiency anemia is associated with poorer development, and during pregnancy it contributes to anemia in mothers, contributing to premature birth, low birth weight and other complications.
"I thought that behavior and development would be better with the 12 mg formula," says Lozoff, also professor of pediatrics in the Department of Pediatrics and Communicable Diseases at the Medical School and C.S. Mott Children's Hospital.
The study of 494 Chilean children showed that those who received iron fortified formula in infancy at the 12 mg used in the U.S. lagged behind those who received low-iron formula in cognitive and visual-motor development by age 10 years.
Lozoff notes that not many infants in Chile had high hemoglobin levels at the time since there was no iron-fortification program for infants and that more than 5 percent of U.S. infants might have high hemoglobin levels in early infancy.
Iron deficiency occurs because babies grow so quickly they often outgrow the amount of iron they are born with. Breast milk is thought to contain the iron a baby needs for 4-6 months, Lozoff says. Other important sources of iron for infants include iron-fortified infant formulas and cereals, iron drops and meat.
The paper, "Poorer developmental outcome at 10 years with 12 mg/L iron-fortified formula in infancy," was to be presented May 5 at the Pediatric Academic Societies annual meeting in Honolulu.
Substance abuse services, job training helps homeless maintain shelter
A new U-M report indicates homeless individuals and families need subsidized housing in conjunction with health care and job training to remain permanently housed.
In addition, state lawmakers can reduce homelessness by implementing policies that target specific groups of displaced people, says Robin Phinney, a graduate research assistant at the Gerald R. Ford School of Public Policy.
"Communities are struggling to develop effective homeless programs to keep individuals from cycling in and out of homelessness," says Phinney, who co-authored an analysis of housing and service arrangements for the homeless.
Elisabeth Gerber, a professor of public policy, and graduate student Sarah Haradon also collaborated on the policy report published by the Center for Local, State and Urban Policy at the Ford School.
U-M researchers analyzed policy reports and literature to help communities evaluate and reform the system that cares for homeless persons. The researchers looked at the relationship between housing and service arrangements for different segments of the homeless population, such as disabled (which includes mental illness and substance abuse), domestic violence victims and adults in homeless families.
Some cities are investing in affordable residential units, which often have access to treatment for mental illness or substance abuse, rather than opening additional shelters.
"Services in the absence of housing support are generally not enough to prevent repeat episodes of homelessness," the report states.
Phinney says housing and services provided by emergency or transitional shelter are often not enough to lead to successful outcomes for this population. Permanent housing offering supportive services can assist people with mental illness or substance abuse.
To review the report, go to www.closup.umich.edu.
Physicist confines plasma components in a trap
A U-M professor has taken a step toward simulating a type of matter found in the crusts of neutron stars, in the cores of gas giant planets, and in exotic plasmas thought to be present in the earliest universe.
Physics professor Georg Raithel trapped both the electronic and ionic components of a cold plasma using electric and strong magnetic fields. Raithel confined clouds of negatively charged electrons and positively charged rubidium ions in what's called a nested Penning trap.
"What we observed for the first time is two charged clouds oscillating in the trapping volume," Raithel says. "They were dense enough to affect each other's oscillation patterns due to electrostatic interactions, and that's how we could tell they were both there."
Forming two clouds a positive and a negative is an important step toward creating a neutral, strongly coupled plasma, found in nature in hard to get to astrophysical places, Raithel says.
In a strongly coupled plasma, the particles behave more like they would in a liquid, interacting with each other more strongly than would particles in a regular plasma.
This result could pave the way for trapping antimatter, Raithel says. Scientists only know they've created antimatter after it explodes out of existence. If they were able to trap it, they could learn more about it. And this is also a step toward simulating a quark-gluon plasma, which is a type of plasma created by heavy ion collisions. Quark-gluon plasma is often considered a fifth state of matter that scientists believe was present just after the Big Bang.
To achieve this confinement, Raithel first traps rubidium atoms in their ground state with magnets that generate a strong, precise field with a slightly weaker dimple in the middle, where the atoms get stuck. The atoms cool down in the divot due to scattering of infra-red laser light, which creates friction that Raithel calls "optical molasses." That traps the atoms.
Raithel next creates a plasma by exciting the trapped atoms with blue lasers. This causes electrons to break free, leaving negatively charged electrons and positive rubidium ions.
Additional electrodes generate an electric field that works with the strong magnetic field to keep the plasma components from escaping.
"This experiment shows that we generated electron and ion numbers high enough to get correlated motions. To get to a two-component strongly coupled plasma, we need still higher numbers of particles," Raithel says.
The paper, "Trapping and evolution dynamics of ultracold two-component plasmas," appears in the current edition of Physical Review Letters.