Posts tagged science
Articles and news from the latest research reports.
Neuroscientists find Broca’s area is really two subunits, each with its own function
A century and a half ago, French physician Pierre Paul Broca found that patients with damage to part of the brain’s frontal lobe were unable to speak more than a few words. Later dubbed Broca’s area, this region is believed to be critical for speech production and some aspects of language comprehension.
However, in recent years neuroscientists have observed activity in Broca’s area when people perform cognitive tasks that have nothing to do with language, such as solving math problems or holding information in working memory. Those findings have stimulated debate over whether Broca’s area is specific to language or plays a more general role in cognition.
A new study from MIT may help resolve this longstanding question. The researchers, led by Nancy Kanwisher, the Walter A. Rosenblith Professor of Cognitive Neuroscience, found that Broca’s area actually consists of two distinct subunits. One of these focuses selectively on language processing, while the other is part of a brainwide network that appears to act as a central processing unit for general cognitive functions.
"I think we’ve shown pretty convincingly that there are two distinct bits that we should not be treating as a single region, and perhaps we shouldn’t even be talking about ‘Broca’s area’ because it’s not a functional unit," says Evelina Fedorenko, a research scientist in Kanwisher’s lab and lead author of the new study, which recently appeared in the journal Current Biology.
How Neuroscience is Changing the Talking Cure
What’s the Latest Development?
A new book which attempts to reconcile psychoanalysis with neuroscience may have practical implications in the treatment of neurological disorders such as Alzheimer’s and PTSD. Catherine Malabou’s What Should We Do With Our Brain? argues that “we have failed to understand ourselves because we have failed to acknowledge recent scientific discoveries, particularly ‘plasticity,’ or the brain’s ability to change.” Through the course of the argument, Malabou updates psychotherapy’s concept of clinical treatment by recognizing that mental wounds do not come from a buried subconscious but from events that befall us in the real world.
What’s the Big Idea?
Malabou references clinical trials with patients who have acquired neurological disorders (rather than being born with them) and finds that patients do not identify with a stable psyche—the sort required by traditional psychological investigation. Rather, patients experience themselves as a different person, one with whom they are unfamiliar. “The old onion of the psyche, with its layers upon layers of meaning, is simply not there to peel apart in analysis; rather, it has been replaced by a new self, which requires a different clinical approach.”
Status affects how readily people return smiles, research reveals
If you smile at your boss and she smiles back, beware. It could be a sign that she does not think too highly of you, according to a study.
People who feel powerful are more likely to mimic the smiles of those they perceive as low status, according to research presented at the annual Society for Neuroscience conference in New Orleans. They are less likely, however, to return the smiles of people they consider of higher status than themselves. And when people are not feeling particularly powerful, they return everyone’s smiles almost equally.
Mimicking other people’s behaviour is an important mechanism of bonding in group situations, according to Evan Carr from the department of psychology at the University of California in San Diego, who led the study. “Mimicry has been shown to help build relationships, and both power and status seem to affect how we unconsciously employ this strategy,” he said.
Power, he said, referred to someone’s internal feeling of being able to take control of others, whereas status was a more externally defined quality. “It’s more to do with perceived reverence or some type of social hierarchy,” said Carr.
Link Between Smoking And Cataracts Discovered
Cigarettes have already been linked to a plethora of different diseases and adverse health conditions, and now a new study has found that the smoking could also increase the risk of developing cataracts in some individuals.
Dr. Juan Ye of the Zhejiang University Institute of Ophthalmology and colleagues conducted a meta-analysis, reviewing a dozen cohorts and eight case-control studies from five continents (Africa, Asia, Australia, Europe and North America) to determine smoking’s impact on the development of age-related cataracts, the leading cause of vision loss and blindness in the world.
They looked at the occurrence of age-related cataract in individuals who had smoked cigarettes versus those who had never lit up. They also looked at the differences between former and current smokers, as well as each of the three different types of cataract that can develop in older individuals, the Association for Research and Vision in Ophthalmology (ARVO) explained in an October 12 press release.
“The results showed that every individual that ever smoked cigarettes was associated with an increased risk of age-related cataract, with a higher risk of incidence in current smokers,” they said, adding that “former and current smokers showed a positive association with two of the subtypes: nuclear cataract, when the clouding is in the central nucleus of the eye, and subscapular cataract, when the clouding is in the rear of the lens capsule.”
The study did not find a link between smoking and cortical cataract, a type of cataract in which the cortex of the lens is affected by cloudiness. Their findings have been published in the journal Investigative Ophthalmology & Visual Science (IOVS).
“Although cataracts can be removed surgically to restore sight, many people remain blind from cataracts due to inadequate surgical services and high surgery expenses,” Ye said. “Identifying modifiable risk factors for cataracts may help establish preventive measures and reduce the financial as well as clinical burden caused by the disease.”
“We think our analysis may inspire more high-quality epidemiological studies” the study author added. “Our analysis shows that association between smoking and the risk of age-related cataract differ by subtypes, suggesting that pathophysiologic processes may differ in the different cataract types.”
(Source: redorbit.com)
Does motherhood dampen cocaine’s effects?
Mother rats respond much differently to cocaine than female rats that have never given birth, according to new University of Michigan research that looks at both behavior and brain chemistry.
The findings may help lay the groundwork for more tailored human addiction treatment, based on scientific understanding of how gender, hormones and life experience impact drug use.
In an oral presentation at the Society for Neuroscience meeting, U-M researcher Jennifer Cummings, Ph.D., summarized findings from experiments with rats at the Molecular and Behavioral Neuroscience Institute, part of the U-M Medical School. She worked with Jill Becker, Ph.D., of the U-M Department of Psychology.
They identified clear differences in how intensely the “pleasure centers” in the mother rats’ brains reacted to the drug, compared with non-mothers. Mother rats’ brains released less of a chemical called dopamine, which helps cause the “high” from cocaine.
They also found an interaction with stress: mother rats that were exposed to periods of increased stress weren’t willing to work as hard to get a dose of cocaine, compared with rats that had never given birth or mother rats that weren’t exposed to the stress – even though the stressed mother rats showed an increased tendency to use cocaine when it was easy to get.
Taken together, the findings suggest that the experience of becoming a mother alters a female’s overall response to cocaine – adding complexity to the issue of how best to treat addiction.
“While we have not yet identified a mechanism to explain these differences, they do suggest that the reward system and brain circuitry affected by cocaine is changed with maternal experience,” says Cummings, a research investigator at MBNI and former postdoctoral fellow in Becker’s laboratory. “The next step is to determine how factors such as hormone changes in pregnancy and early motherhood, and the experience of caring for offspring, might be differentially contributing to this response.”
Plaque Build-Up in Your Brain May Be More Harmful Than Having Alzheimer’s Gene
A new study shows that having a high amount of beta amyloid or “plaques” in the brain associated with Alzheimer’s disease may cause steeper memory decline in mentally healthy older people than does having the APOE ɛ4 allele, also associated with the disease. The study is published in the October 16, 2012, print issue of Neurology®, the medical journal of the American Academy of Neurology.
“Our results show that plaques may be a more important factor in determining which people are at greater risk for cognitive impairment or other memory diseases such as Alzheimer’s disease,” said study author Yen Ying Lim, MPsych, with the University of Melbourne in Victoria, Australia. “Unfortunately, testing for the APOE genotype is easier and much less costly than conducting amyloid imaging.”
Image credit: PASIEKA/SCIENCE PHOTO LIBRARY
New study shows that even your fat cells need sleep
In a study that challenges the long-held notion that the primary function of sleep is to give rest to the brain, researchers have found that not getting enough shut-eye has a harmful impact on fat cells, reducing by 30 percent their ability to respond to insulin, a hormone that regulates energy.
Sleep deprivation has long been associated with impaired brain function, causing decreased alertness and reduced cognitive ability. The latest finding—published by University of Chicago Medicine researchers in the Oct. 16 issue of the Annals of Internal Medicine—is the first description of a molecular mechanism directly connecting sleep loss to the disruption of energy regulation in humans, a process that can lead over time to weight gain, diabetes and other health problems. The study suggests that sleep’s role in energy metabolism is at least as important as it is in brain function.
"We found that fat cells need sleep to function properly," said study author Matthew Brady, PhD, associate professor of medicine and vice-chair of the Committee on Molecular Metabolism and Nutrition at the University of Chicago.
A tool to quantify consciousness?
Assessing consciousness may seem like the ultimate exercise in subjectivity, but some researchers are moving closer to what they call an objective measure.
The goal is to provide clearer information for families with loved ones living in vegetative or minimally conscious states — conditions that are often caused by brain trauma or cardiac arrest.
“We really need to find a way to be able to measure consciousness reliably,” says Melanie Boly, a postdoctoral fellow at the Belgian National Fund for Research in Liege, Belgium. “For the family, this changes everything,” says Boly, who presented her team’s research on 14 October at the Society for Neuroscience meeting in New Orleans, Louisiana.
Vegetative patients make only reflexive movements and appear insensitive to their surroundings, while minimally conscious patients can make some purposeful movements and even feel pain. Clinically, the differences between these patients can be difficult even for experienced physicians to discern. But legally, the differences are clear.
In 2011, the UK court system denied a family’s request to end life support for their daughter after additional tests revised her initial diagnosis from ‘vegetative’ to ‘minimally conscious’.
To derive a numerical measure of consciousness, Boly and her colleagues pulsed subjects’ heads with a brief electromagnetic wave, then measured neural responses using electrodes stuck to the scalp.
In 32 healthy, awake people, the electromagnetic impulse sent complex patterns of electrical activity reverberating throughout the brain. In healthy sleeping people, or people under general anaesthesia, the brain displayed shorter, simpler responses that stayed closer to the site of the initial stimulation. The researchers quantified these differences in a measure of response complexity.
In six patients diagnosed as vegetative, the electromagnetic pulse elicited responses with complexity indices similar to those in sleeping or anaesthetized healthy subjects. Twelve minimally conscious patients showed slightly more complex responses. And two ‘locked-in’ patients — people who are fully conscious but unable to move or communicate — showed complexity indices similar to healthy, awake subjects.
Boly and her colleagues have previously noted some of these differences across patient groups but with poor reliability for individual patients. With the complexity index, which combines several aspects of the brain’s response, she says, “this is the first time we really have a measure that works at a single-subject level.”
“It’s not going to supplant a clinical assessment,” says Nicholas Schiff, a neurologist at the Weill Cornell Medical College in New York. But he says the complexity index could become a valuable tool for adding some certainty to the subjective process of evaluating patient consciousness.
“I personally would welcome a test that could provide us with objective measurements,” says David Okonkwo, clinical director of the Brain Trauma Research Center at the University of Pittsburgh in Pennsylvania. However, he said much more testing is needed to tell whether the complexity index meets that standard.
“We need more patients,” agrees Boly, “but it’s extremely promising.”
(Source: blogs.nature.com)
New merciful treatment method for children with brain tumours
Children who undergo brain radiation therapy run a significant risk of suffering from permanent neurocognitive adverse effects. These adverse effects are due to the fact that the radiation often encounters healthy tissue. This reduces the formation of new cells, particularly in the hippocampus – the part of the brain involved in memory and learning.
Researchers at the University of Gothenburg’s Sahlgrenska Academy have used a model study to test newer radiation therapy techniques which could reduce these harmful adverse effects. The researchers based their study on a number of paediatric patients who had undergone conventional radiation treatment for medulloblastoma, a form of brain tumour that almost exclusively affects children, and simulated treatment plans using proton therapy techniques and newer photon therapy techniques.
Each treatment plan was personalised by physician Malin Blomstrand, physicist Patrik Brodin and their colleagues. The results show that the risk of neurocognitive adverse effects can be reduced significantly using the new radiation treatment techniques, particularly proton therapy.
“This could mean a better quality of life for children who are forced to undergo brain radiation therapy,” says Malin Blomstrand.
A Future Without Seizures
Five-year-old Nathan Kalina of Naperville will enter kindergarten this fall after spending the summer in day camp: playing games, enjoying field trips, and romping in the pool. He loves playing with action figures and acting out scenes from his favorite movies.
The scene two years ago was very different. After getting a few reports from daycare about unexplained falls, Nathan’s parents started to notice him having minor seizures. His mother, Megan, wasn’t too concerned at first; both she and her father had had childhood seizures and recovered from them without incident. Then came Nathan’s first tonic-clonic seizure (formerly known as a “grand mal” seizure), a major event involving his whole brain and body. A trip to a local emergency room for basic tests led to an electroencephalogram a few days later. All the while Nathan was having more seizures, large and small.
"We went from zero to crazy in a matter of days," Megan said.
Medication helped some. Nathan’s father David, a teacher in the Naperville schools, devoted his summer to adjusting Nathan’s regimen. But in the fall, the seizures ramped up again. One specialist suggested a high-fat ketogenic diet, which has been shown to help some children with epilepsy — but it didn’t help Nathan. “Feeding a 4-year-old picky eater on meat, cheese and cream was hard on us and started making him sick,” Megan said.