Posts tagged psychology
Articles and news from the latest research reports.
The stalked eyes of mantis shrimp species that live in shallow water can have up to 16 kinds of photoreceptor cells, 12 of which are specialized for different colors. People make do with four kinds, three of which pick up colors.
Hanne Thoen of the University of Queensland in Brisbane, Australia, tested the color vision of mantis shrimp by training them to scoot out of their burrows toward a pair of optical fibers and punch at the one glowing a particular color. As she narrowed the color gap between the two fibers, she could tell when the animals no longer discerned a difference.
So far, Thoen has tested her mantis shrimp on six target colors ranging from a 425-nanometer purple to a 628-nanometer red. If the animals perform just as poorly at distinguishing colors in other wavelengths, then mantis shrimp may be using some unknown system of color perception.
People and other animals studied so far distinguish colors through brainpower by interpreting competing activity in different kinds of light-receptor cells. Instead of doing such fancy brainwork, mantis shrimp may just rely on what a particular specialized cell responds to strongly. Wavelengths that tickle the purple-sensitive cells may be just plain purple regardless of whether they’re more toward the blue or the ultraviolet.
Unlocking a major secret of the brain
McGill researchers uncover crucial link between hippocampus and prefrontal cortex
A clue to understanding certain cognitive and mental disorders may involve two parts of the brain which were previously thought to have independent functions, according to a McGill University team of researchers led by Prof. Yogita Chudasama, of the Laboratory of Brain and Behavior, Department of Psychology. The McGill team discovered a critical interaction between two prominent brain areas: the hippocampus, a well-known memory structure made famous by Dr. Brenda Milner’s patient H.M., and the prefrontal cortex, which is involved in decision-making and inhibiting inappropriate behaviours.
“We had always thought that the hippocampus and the prefrontal cortex functioned independently,” says Prof. Chudasama. “Our latest study provides the first indication that that is not the case.”
The team’s finding, just published in the Journal of Neuroscience, reveals a critical interaction between these two brain areas and the control of behavior, and may advance the treatment of some cognitive and mental disorders including schizophrenia, and depression. The interaction between the hippocampus and the prefrontal cortex shows that brain circuits function not just as specific parts of the brain, but are linked together and work as a system.
“Although the prefrontal cortex has long been known to be the driving force that steers our behavior, pushing us to make good decisions and withhold improper actions, it turns out that it can’t do this unless it interacts with the hippocampus,” added Prof. Chudasama. “We found that when we prevented these two structures from communicating with each other, like humans with compulsive disorders, rats persisted with behaviours that were not good for them; they didn’t correct their errant behaviours and could not control their natural urges.
The ability to control impulsive urges or inhibit our actions allows us to interact normally in personal or social situations, and this type of behaviour depends on the normal interaction of the hippocampus and the prefrontal cortex. This result provides a means for understanding the neural basis for social and cognitive deficits in disorders of brain and behaviour, such as those with frontotemporal dementia”, concludes Prof. Chudasama.
To find out how mice use their high-resolution ganglion, a team from Harvard attached a tiny camera to a rat volunteer and then watched to see what sorts of things it focused on. Next, they played the video back directly onto the retinas of several test mice while simultaneously monitoring neural cell activity. In so doing, they found that the high-resolution cells sat mostly quiet, doing nothing.
When silhouettes of birds were projected overhead, the waiting ended as the ganglia sprang into action, interpreting every movement. This shows, the researchers say, that the high-resolution neuron groups in mice retinas serve not as interpreters of everyday life, but as highly specific predator detectors. More specifically they found the nerves reacted when the birds were in their center of view, meaning close and ready to snatch them up. Sadly, they also found that the nerves quit firing once the birds came close enough, indicating the mice were doomed.
Genetics of Obsessive-Compulsive Disorder Narrowed Down
The first genome-wide searches for the genes responsible for Tourette syndrome and obsessive-compulsive disorder have uncovered a few clues to the underpinnings of both disorders.
Tourette syndrome is a neurological disorder characterized by muscle and vocal tics such as eye blinking, throat clearing and uttering taboo words or phrases. Tourette’s often co-occurs with obsessive-compulsive disorder (OCD), a mental illness marked by repetitive behaviors and anxiety-producing intrusive thoughts.
Neither Tourette syndrome nor OCD are simple enough to be traced to a single gene, but two new studies detailed today (Aug. 14) in the journal Molecular Psychiatry find several locations on the human chromosome that may contribute to the conditions.
A DNA molecule.
CREDIT: Giovanni Cancemi | Shutterstock
"Both disorders clearly have a complex underlying genetic architecture, and these two studies lay the foundation for understanding the underlying genetic etiology of Tourette syndrome and OCD," said Jeremiah Scharf, a neurologist at Massachusetts General Hospital in Boston, who worked on both projects.
Genetics of Tourette Syndrome
In the Tourette syndrome study, Scharf and his colleagues compared the genomes of more than 1,200 people with the disorder with the genomes of nearly 5,000 healthy individuals. They conducted what’s called a genome-wide association study, scanning hundreds of thousands of genetic variants from across the genomes to see if any were more common in the people with the disorder.
They found that no single genetic signal was significantly different between the two genomes, meaning that the researchers could not rule out random chance as the reason for any given difference. But among the top genetic variations, the researchers found an unusually high number that influence levels of gene expression in the frontal lobe of the brain — a region important in both Tourette syndrome and OCD, Scharf said.
One intriguing gene that varied the most between Tourette- and non-Tourette genomes was called COL27A1, a gene that encodes a collagen protein found in cartilage. The same gene is also active in the cerebellum, a brain region important for motor control during development. More research will be necessary to find what link, if any, COL27A1 has to Tourette syndrome, Scharf said.
The architecture of OCD
In a separate study, the scientists carried out the same analysis on healthy genomes as well as about 1,500 people with obsessive-compulsive disorder. Again, no one gene rose to the top as a definitive OCD gene, but the results revealed a good candidate near a gene called BTBD3, which is involved in multiple cellular functions. BTBD3 is very active in the brain during childhood and adolescent development, when OCD often first appears. It’s also related to a gene called BTBD9, which has been linked to Tourette syndrome in the past.
This first genome-wide pass is bound to turn up some false positives, Scharf said, so researchers will now need to home in on the intriguing genes in larger samples of people. They are also merging the two studies to look for genetic linkages that might explain why Tourette syndrome and OCD so frequently co-occur.
"The important thing this study does is that it really brings Tourette syndrome and OCD into the company of a number of other psychiatric diseases, which people have studied using genome-wide association," Scharf said, citing autism, schizophrenia and bipolar disorder as examples. “Now that we have these data for Tourette syndrome and OCD, we can work with investigators who are studying those other diseases to try to see what we can learn about what variants are shared between different neurodevelopment disorders.”
Source: Live Science
A young autistic boy has found his outlet in making science videos. Jordan Hilkowitz was diagnosed with autism when he was just 18 months old, he didn’t begin to speak until he was 5. His mother Stacey remembers the heartbreak she experienced as she watched her young son bang his head against the wall out of frustration at not being able to communicate.
It was his babysitter’s idea for Jordan to start making science videos. He’d always had an interest in science, and she felt that this could be an outlet for him to communicate to a larger audience. Larger indeed! Jordan’s channel, Doctor Mad Science, has received over 2.4 million views to date – and he’s become a local celebrity for his scientific knowhow.
(Source: blogs.scientificamerican.com)
Palaeontologists from the University of Zurich have “rediscovered” a skull bone that was thought to have been lost during the course of evolution for many mammals.
Mammals’ skulls are composed of around 20 bones — fewer than those of fish, reptiles and birds. This is because when mammals evolved from reptile-like vertebrates 320 million years ago, the skull structure simplified. Some bones were lost in the process, particularly some of the skull roof bones. The interparietal is one such bone, but it has perplexed researchers since it had survived in some mammals, such as horses and cats (and 2.8 percent of humans) but not in others.
The interparietal is clearly discernible in the embryo, but fuses with other bones beyond recognition shortly afterwards. As a result it’s often been missed. However, new imaging techniques have been able to detect its presence in all mammals.
The scent of love: Decomposition and male sex pheromones
A team of researchers, led by Christian von Hoermann from Ulm University, Germany, filled olfactometers with different volatile scents and recorded which scents female hide beetles were attracted to. The scents used were pig cadaver, collected at different stages of decay, male pheromone gland extract, synthetic pheromones, and a control, pentane (an organic solvent which was used to extract the other odours).
The females ignored both the control and synthetic pheromone. In fact they pretty much ignored everything apart from the odour of piglet in the dry remains stage, as long as it was enhanced by male pheromones.
Christian von Hoermann explained, “Although cadaver odour alone is not sufficient to attract two to three week-old virgin female hide beetles, it is enough to attract newly emerged males.” Release of pheromones by these males appears to signal the cadaver as an appropriate site for feeding, mating and egg laying. Evolution seems to have ensured that hide beetle females only respond to a mate (or a food source for their larvae) when the other is also present, so that they can optimise the chances of their offspring’s survival.
In a new study, scientists at the Wisconsin Institute for Discovery (WID) at UW-Madison develop a computational approach to determine whether individuals behave predictably. With data from previous fights, the team looked at how much memory individuals in the group would need to make predictions themselves. The analysis proposes a novel estimate of “cognitive burden,” or the minimal amount of information an organism needs to remember to make a prediction.
The research draws from a concept called “sparse coding,” or the brain’s tendency to use fewer visual details and a small number of neurons to stow an image or scene. Previous studies support the idea that neurons in the brain react to a few large details such as the lines, edges and orientations within images rather than many smaller details.
"So what you get is a model where you have to remember fewer things but you still get very high predictive power — that’s what we’re interested in," says Bryan Daniels, a WID researcher who led the study.
Levels of sleep problems in the developing world are approaching those seen in developed nations, linked to an increase in problems like depression and anxiety.
According to the first ever pan-African and Asian analysis of sleep problems, led by Warwick Medical School at the University of Warwick, an estimated 150 million adults are suffering from sleep-related problems across the developing world.
The results are published in a study in the journal Sleep.
Source: The University of Warwick
According to new research, meerkats enhance their intelligence through nine different social and asocial mechanisms. What really makes these animals stand out is their intelligent coordinated behaviour, which rivals that of chimps, baboons, dolphins and even humans in its complexity and efficiency.
A team led by William Hoppitt of the University of St. Andrews presented wild meerkats with a novel foraging task to investigate the animal’s learning mechanisms. ‘The model deals with the rate at which individuals interact with the task, solve the task once they are interacting with it, or give up on the task when they are manipulating it,’ said Hoppitt.
They found that the meerkats engaged in a wide variety of social and asocial behaviours to learn to solve the task, and that in general the social factors helped draw the meerkats into the task, while the asocial processes helped them actually solve the task.
The model may also be more broadly applicable and can be used to investigate the relationship between social learning mechanisms and so-called ‘behavioural traditions’ that together can constitute a culture.