Posts tagged brain
Articles and news from the latest research reports.
Animals, including dogs, dolphins, monkeys and man, follow gaze. What mediates this bias towards the eyes? One hypothesis is that primates possess a distinct neural module that is uniquely tuned for the eyes of others. An alternative explanation is that configural face processing drives fixations to the middle of peoples’ faces, which is where the eyes happen to be located. We distinguish between these two accounts. Observers were presented with images of people, non-human creatures with eyes in the middle of their faces (`humanoids’) or creatures with eyes positioned elsewhere (`monsters’). There was a profound and significant bias towards looking early and often at the eyes of humans and humanoids and also, critically, at the eyes of monsters. These findings demonstrate that the eyes, and not the middle of the head, are being targeted by the oculomotor system.
How does the brain measure time?
(Image: bzztbomb)
Researchers at the University of Minnesota’s Center for Magnetic Resonance Research (CMRR) have found a small population of neurons that is involved in measuring time, which is a process that has traditionally been difficult to study in the lab.
In the study, which is published October 30 in the open access journal PLOS Biology, the researchers developed a task in which monkeys could only rely on their internal sense of the passage of time. Their task design eliminated all external cues which could have served as “clocks”.
The monkeys were trained to move their eyes consistently at regular time intervals without any external cues or immediate expectation of reward. Researchers found that despite the lack of sensory information, the monkeys were remarkably precise and consistent in their timed behaviors. This consistency could be explained by activity in a specific region of the brain called the lateral intraparietal area (LIP). Interestingly, the researchers found that LIP activity during their task was different from activity in previous studies that had failed to eliminate external cues or expectation of reward.
"In contrast to previous studies that observed a build-up of activity associated with the passage of time, we found that LIP activity decreased at a constant rate between timed movements," said lead researcher Geoffrey Ghose, Ph.D., associate professor of neuroscience at the University of Minnesota. "Importantly, the animals’ timing varied after these neurons were more, or less, active. It’s as if the activity of these neurons was serving as an internal hourglass."
By developing a model to help explain the differences in timing signals they see relative to previous studies, their study also suggests that there is no “central clock” in the brain that is relied upon for all tasks involving timing. Instead, it appears as though each of the brain’s circuits responsible for different actions are capable of independently producing an accurate timing signal.
One important direction for future research is to explore how such precise timing signals arise as a consequence of practice and learning, and whether, when the signals are altered, there are clear effects on behavior.
(Source: medicalxpress.com)
Empathy represses analytic thought, and vice versa
New research shows a simple reason why even the most intelligent, complex brains can be taken by a swindler’s story – one that upon a second look offers clues it was false.
When the brain fires up the network of neurons that allows us to empathize, it suppresses the network used for analysis, a pivotal study led by a Case Western Reserve University researcher shows.
How could a CEO be so blind to the public relations fiasco his cost-cutting decision has made?
When the analytic network is engaged, our ability to appreciate the human cost of our action is repressed.
At rest, our brains cycle between the social and analytical networks. But when presented with a task, healthy adults engage the appropriate neural pathway, the researchers found.
The study shows for the first time that we have a built-in neural constraint on our ability to be both empathetic and analytic at the same time
The work suggests that established theories about two competing networks within the brain must be revised. More, it provides insights into the operation of a healthy mind versus those of the mentally ill or developmentally disabled.
“This is the cognitive structure we’ve evolved,” said Anthony Jack, an assistant professor of cognitive science at Case Western Reserve and lead author of the new study. “Empathetic and analytic thinking are, at least to some extent, mutually exclusive in the brain.”
The research is published in the current online issue of NeuroImage.
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.”
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.”