Posts tagged neuroscience
Articles and news from the latest research reports.
Animals learn to fine-tune their sniffs
Animals use their noses to focus their sense of smell, much the same way that humans focus their eyes, new research at the University of Chicago shows.
A research team studying rats found that animals adjust their sense of smell through sniffing techniques that bring scents to receptors in different parts of the nose. The sniffing patterns changed according to what kind of substance the rats were attempting to detect.
The sense of smell is particularly important for many animals, as they need it to detect predators and to search out food. “Dogs, for instance, are quite dependent on their sense of smell,” said study author Leslie Kay, associate professor of psychology and director of the Institute for Mind & Biology at the University of Chicago. “But there are many chemicals in the smells they detect, so detecting the one that might be from a predator or an explosive, for instance, is a complex process.”
Kay was joined in writing the paper by Daniel Rojas-Líbano, a postdoctoral scholar at the University of Chile in Santiago, who received his PhD from UChicago in 2011. Rojas-Líbano, who did the work as a doctoral scholar, was the first author on the publication. Their results are published in an article, “Interplay Between Sniffing and Odorant Properties in the Rat,” in the current issue of the Journal of Neuroscience.
Unique protein bond enables learning and memory
Two proteins have a unique bond that enables brain receptors essential to learning and memory to not only get and stay where they’re needed, but to be hauled off when they aren’t, researchers say.
NMDA receptors increase the activity and communication of brain cells and are strategically placed, much like a welcome center, at the receiving end of the communication highway connecting two cells. They also are targets in brain-degenerating conditions such as Alzheimer’s and Parkinson’s.
In a true cradle-to-grave relationship, researchers have found the scaffolding protein, SAP102, which helps stabilize the receptor on the cell surface, binds with a subunit of the NMDA receptor called GluN2B at two sites, said Dr. Bo-Shiun Chen, neuroscientist at the Medical College of Georgia at Georgia Health Sciences University.
While one binding site is the norm, these proteins have one that’s stronger than the other. When it’s time for the normal receptor turnover, the stronger bond releases and the lesser one shuttles the receptor inside the cell for degradation or recycling.
“One binding site is involved in stabilizing the receptor on the cell surface and the other is important in removing the receptor. We think it’s a paradigm shift; we’ve never thought about the same scaffolding protein having two roles,” said Chen, corresponding author of the study in the journal Cell Reports.
Distinct developmental patterns identified in children with autism during their first three years
In the largest prospective study to date of children with early and later manifestation of autism spectrum disorders (ASD) compared to children without ASD, researchers found two distinct patterns of language, social and motor development in the children with ASD. Published in the journal Child Development, the study found that early in development, children who display early signs of ASD show greater initial delay across multiple aspects of development compared to children whose ASD symptoms emerge later. However at 36 months of age, the early differences between these groups are no longer obvious. By the third birthday, the level of impairment between these symptom onset groups of children with ASD is comparable. Additionally, researchers uncovered a preclinical phase of ASD in which the signs of delay are not easily detected with existing clinical tests.
Previous research by Kennedy Krieger Institute researchers found that approximately half of all children with ASD can be diagnosed around the first birthday, while the remaining half do not show diagnostic indicators until later. The current study builds upon these findings by further evaluating motor and language development in a wider age span of children diagnosed with ASD (6 to 36 months), and examining how development unfolds differently in each group.
“Regardless of diagnosis, the development of children with and without ASD appears similar at six months of age on clinical tests,” says Dr. Rebecca Landa, lead author and director of Kennedy Krieger’s Center for Autism and Related Disorders. “However, for those children who went on to develop autism, the earliest signs of atypical development were non-specific to autism, such as general communication or motor delay.”
Smoking and hyperactivity (ADHD) share common genetic risk factor
A variation of a particular gene may link the behaviours typical of childhood attention hyperactivity disorder, or ADHD for short, and those associated with smoking, suggests research published online in the Archives of Disease in Childhood (1, 2)
Childhood ADHD and subsequent smoking in adulthood frequently go hand in hand, say the authors, with people who have been diagnosed with ADHD more likely to start smoking early and to smoke twice as much as those without the condition.
The researchers focused on five variations in DNA sequences (single nucleotide polymorphisms or SNPs) in different genes that are strongly associated with different aspects of smoking behaviour, such as the number of cigarettes smoked every day, and taking up and quitting smoking.
More Than Good Vibes: Researchers Propose the Science Behind Mindfulness
Achieving mindfulness through meditation has helped people maintain a healthy mind by quelling negative emotions and thoughts, such as desire, anger and anxiety, and encouraging more positive dispositions such as compassion, empathy and forgiveness. Those who have reaped the benefits of mindfulness know that it works. But how exactly does it work?
Researchers at Brigham and Women’s Hospital (BWH) have proposed a new model that shifts how we think about mindfulness. Rather than describing mindfulness as a single dimension of cognition, the researchers demonstrate that mindfulness actually involves a broad framework of complex mechanisms in the brain.
In essence, they have laid out the science behind mindfulness.
This new model of mindfulness is published in the October 25, 2012 issue of Frontiers in Human Neuroscience. The model was recently presented to His Holiness The Dalai Lama in a private meeting, entitled “Mind and Life XXIV: Latest Findings in Contemplative Neuroscience.”
The endocannabinoid system in normal and pathological brain ageing
The role of endocannabinoids as inhibitory retrograde transmitters is now widely known and intensively studied. However, endocannabinoids also influence neuronal activity by exerting neuroprotective effects and regulating glial responses. This review centres around this less-studied area, focusing on the cellular and molecular mechanisms underlying the protective effect of the cannabinoid system in brain ageing. The progression of ageing is largely determined by the balance between detrimental, pro-ageing, largely stochastic processes, and the activity of the homeostatic defence system. Experimental evidence suggests that the cannabinoid system is part of the latter system. Cannabinoids as regulators of mitochondrial activity, as anti-oxidants and as modulators of clearance processes protect neurons on the molecular level. On the cellular level, the cannabinoid system regulates the expression of brain-derived neurotrophic factor and neurogenesis. Neuroinflammatory processes contributing to the progression of normal brain ageing and to the pathogenesis of neurodegenerative diseases are suppressed by cannabinoids, suggesting that they may also influence the ageing process on the system level. In good agreement with the hypothesized beneficial role of cannabinoid system activity against brain ageing, it was shown that animals lacking CB1 receptors show early onset of learning deficits associated with age-related histological and molecular changes. In preclinical models of neurodegenerative disorders, cannabinoids show beneficial effects, but the clinical evidence regarding their efficacy as therapeutic tools is either inconclusive or still missing.
The Brain An Electric Cure for the Mind
Why does shock therapy beat back depression? New experiments show how such a blunt treatment can have such positive effects.
Ian Reid, a psychiatrist at the Royal Cornhill Hospital in the Scottish city of Aberdeen, has treated people with severe depression for 25 years. “It’s a very nasty illness, depression,” he says. “I have worked with people who have cancer and depression, and more than one of them has said, ‘If I had to choose one of those two diseases, I’d go for the cancer.’ ”
When patients come to Royal Cornhill with major depression, they’re first treated with psychotherapy and antidepressants. Only about 40 percent respond to their first medication. Sometimes a different one will do the trick, but in Reid’s experience, about 10 to 20 percent of depressed people respond to no drug at all. In those cases, Reid regularly shifts to a third option. It’s officially called electroconvulsive therapy, or ECT—better known by its unofficial name, shock therapy.
Reid is an expert on ECT, and over the years he has received plenty of grief for it. “There are people on the Internet who describe me as a Nazi, as a barbarian,” he says. “And there’s one person who suggested I should get ECT so I know what I’m doing.”
Reid is not surprised by the reactions. For many people, the sum of their knowledge about ECT comes from the 1975 movie One Flew Over the Cuckoo’s Nest. Jack Nicholson plays Randle McMurphy, a criminal hoping to escape hard labor by spending his term in a mental institution. But McMurphy gets more than he bargained for, including a harrowing session of ECT. The hospital staff straps him down, puts a piece of rubber in his mouth so he won’t bite off his own tongue, and delivers a blast of electricity to his temples. He writhes in agony and then slumps back, his body limp.
That scene bears no resemblance to what Reid does for his patients. For one thing, he gives them anesthesia and muscle relaxants so they don’t experience any flailing. But most crucially, ECT works. “You can watch someone going from being unresponsive and soiling themselves to being completely transformed,” Reid says.
In Scotland, a country of 5 million, 400 people receive the treatment each year. And for about 75 percent of them, it brings relief. “ECT outperforms psychotherapeutic treatments and antidepressant drugs,” Reid notes. Yet its effectiveness is a mystery. “It doesn’t sound intuitive at all,” he admits. “Making someone have a seizure, giving them an electric shock, and making something as complex as depression better just seems crazy.”
How the brain controls our habits
Habits are behaviors wired so deeply in our brains that we perform them automatically. This allows you to follow the same route to work every day without thinking about it, liberating your brain to ponder other things, such as what to make for dinner.
However, the brain’s executive command center does not completely relinquish control of habitual behavior. A new study from MIT neuroscientists has found that a small region of the brain’s prefrontal cortex, where most thought and planning occurs, is responsible for moment-by-moment control of which habits are switched on at a given time.
“We’ve always thought — and I still do — that the value of a habit is you don’t have to think about it. It frees up your brain to do other things,” says Institute Professor Ann Graybiel, a member of the McGovern Institute for Brain Research at MIT. “However, it doesn’t free up all of it. There’s some piece of your cortex that’s still devoted to that control.”
The new study offers hope for those trying to kick bad habits, says Graybiel, senior author of the new study, which appears this week in the Proceedings of the National Academy of Sciences. It shows that though habits may be deeply ingrained, the brain’s planning centers can shut them off. It also raises the possibility of intervening in that brain region to treat people who suffer from disorders involving overly habitual behavior, such as obsessive-compulsive disorder.
Stay-at-home transcription factor saves axons
The old saw that local actions can have global consequences holds true for neurons, too. Selvaraj et al. show that a transcription factor remains in the axon to help prevent neurodegeneration.
In neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), neurons usually die in stages, with axons deteriorating first and the cells themselves perishing later. Axon degeneration may represent a turning point for patients, after which so much neuronal damage has accumulated that treatments won’t work. Researchers have tested several proteins for their ability to save axons. One of these molecules, ciliary neurotrophic factor (CNTF), rescues axons in rodents and extends their lives. But it caused severe side effects in patients during clinical trials. “Acting on the same pathway but farther downstream could be an ideal way to improve the situation for motor neuron disease” and possibly for other neurodegenerative diseases, says senior author Michael Sendtner.
To discover how CNTF works, Selvaraj et al. studied pmn mutant mice that mimic ALS. The researchers found that CNTF not only prevented the shrinkage of the rodents’ motor neurons, it also reduced the number of swellings along the axon that are markers of degeneration. Another sign that CNTF was beneficial was the movement of mitochondria, which continually shuttle back and forth along the axons of healthy motor neurons. In axons from pmn mice, stalled mitochondria were prevalent, but treatment with CNTF accelerated the organelles to normal speeds.
Sport Makes Middle-Aged People Smarter
High-intensity interval training makes middle-aged people not only healthier but smarter, showed a Montreal Heart Institute (MHI) study led by Dr. Anil Nigam of the MHI and University of Montreal, in collaboration with the Montreal Geriatric University Institute.
“We worked with six adults who all followed a four-month program of twice weekly interval training on stationary bicycles and twice weekly resistance training. Cognitive function, VO2max and brain oxygenation during exercise testing revealed that the participants’ cognitive functions had greatly improved thanks to the exercise,” Dr. Nigam said. VO2max is the maximum capacity of an individual’s body to transport and use oxygen during exercise. It impacts on the body’s ability to oxygenate the brain and is related to cognitive function.
“Our participants underwent a battery of cognitive, biological and physiological tests before the program began in order to determine their cognitive functions, body composition, cardiovascular risk, brain oxygenation during exercise and maximal aerobic capacity,” Dr. Nigam explained.
“After the program was finished, we discovered that their waist circumference and particularly their trunk fat mass had decreased. We also found that their VO2max, insulin sensitivity had increased significantly, in tandem with their score on the cognitive tests and the oxygenation signals in the brain during exercise,” Dr Nigam said. Insulin sensitivity is the ability of sugar to enter body tissue (mainly liver and muscle.)