Neuroscience

Some people live their lives by the motto “no risk - no fun!” and avoid hardly any risks. Others are clearly more cautious and focus primarily on safety when investing and for other business activities. Scientists from the University of Bonn in cooperation with colleagues from the University of Zurich studied the attitudes towards risk in a group of 56 subjects. They found that in people who preferred safety, certain regions of the brain show a higher level of activation when they are confronted with quite unforeseeable situations.  In addition, they do not distinguish as clearly as risk takers whether a situation is more or less risky than expected. The results have just been published in the renowned “Journal of Neuroscience.”

"We were especially interested in the link between risk preferences and the brain regions processing this information," says Prof. Dr. Bernd Weber from the Center for Economics and Neuroscience (CENs) at the University of Bonn. First, the researchers tested a total of 56 subjects for their willingness to take risks. "In an economic game, the test subjects had a choice between a secured payout and a lottery," reports Sarah Rudorf from CENs, the study’s principal author. Those who showed a strong preference for the lottery in this test were categorized as risk takers. Others preferred the secured payout even if the lottery’s odds of winning were clearly better. They were put in the risk-averse group.

In risk-averse individuals, certain regions of the brain are activated more strongly

Then the test subjects played a card game in a brain scanner to study their risk perception. Cards carrying numbers from one to ten were shown on the video glasses in front of their eyes. Each time, two cards were randomly drawn. Before the subjects were shown the cards, they were asked to place bets on whether the second card would have a higher or a lower number than the first one. “The statistical probability for either case to occur is always the same: fifty-fifty,” says Prof. Weber. “This is important so that all subjects, whether they are risk takers or not,  experience risky situations inside the scanner.” They were not able to assess their probability of winning their bet until they saw the first card. Here, the researchers found that in the subjects who tended to avoid risks, two specific regions of the brain were activated more strongly than in those who were willing to take risks. These areas are the ventral striatum and the insular cortex. The ventral striatum reacts both to the probability of winning, as well as to how well an individual can predict the outcome of the bet. The insular cortex is particularly sensitive to the risk a situation carries, and for whether it is higher or lower than anticipated.

Risk seekers adjust their strategy after lucky streaks

Sarah Rudorf summarized the results, “Individuals in whom these regions of the brain are activated at a higher level seem to perceive risks more clearly and assess them as more negative than those who are willing to take risks.” Risk-averse individuals seem to overestimate the con¬sequences of risk, and they did not distinguish as clearly between situations that turned out to be more or less risky than expected. In contrast, the test subjects who tended to take greater risks also focused their behavior more towards the wins and losses, and more clearly changed their strategy after negative situations.

Study is first to show the neurobiological mechanisms

"This study is the first to show the neurobiological mechanisms of how individual risk preferences determine risk perception," says Prof. Weber. "This also has effects on behavior in the areas of finance and health."
In a next step, the researchers want to study the consequences these results have on economic decisions such as in the stock market. “This might even allow improving the advising process for investors with regard to their individual risk behavior,” says Prof. Weber. And he considers health another important area. Smokers know that what they do is very dangerous, and yet they smoke. “If we learned more about smokers’ attitudes towards risk, we might be able to provide information for developing better anti-smoking campaigns.”

Drinking during pregnancy can have a severe, adverse effect on the central nervous systems of children after birth, researchers from Poland have discovered.

The study, which was presented Sunday at the annual meeting of the Radiological Society of North America (RSNA), looked at 200 children who were exposed to alcohol during their fetal stage, as well as 30 other kids whose mothers did not drink while pregnant or during lactation.

The researchers used a trio of different MRI techniques in order to study the brain development of both groups of subjects. First, they used standard MRI scans to observe the size and shape of the corpus callosum, which is a group of nerve fibers that oversees communication between the two halves of the brain.

Fetal alcohol exposure is believed to be one of the primary causes of impaired development of the corpus callosum, and sure enough, the MRI scans revealed those who had been exposed to alcohol had “statistically significant thinning of the corpus callosum… compared with the other group,” the RSNA said in a statement.

They also used diffusion weighted imaging (DWI) to study six areas of the central nervous system in both groups. The DWI technique maps the diffusion of water in the brain and can be more successful in detecting tissue abnormalities than regular MRI scans, the researchers explained.

Again, children who had been exposed to alcohol “exhibited statistically significant increases in diffusion on DWI” than their counterparts — an indication there had been damage to the brain tissue, or the presence of neurological disorders, according to Dr Andrzej Urbanik, chair of the Department of Radiology at Jagiellonian University.

Finally, they used proton (hydrogen) magnetic resonance spectroscopy (HMRS) to study the metabolism in the youngsters’ brains. The results uncovered “a high degree of metabolic changes that were specific for particular locations within the brain,” according to Dr. Urbanik.

The RSNA, citing US Centers for Disease Control and Prevention (CDC) statistics, reports as many as 1.5 out of every 1,000 children born alive suffer from fetal alcohol syndrome, and the costs of treating those victims tops $4 billion annually in America alone.

Researchers at Yale University have found that neural receptors in a fly’s antenna are able to communicate with one another despite a lack of synaptic connections. They suggest in their paper published in the journal Nature that the communication between the neurons occurs via electrical signals transported by shared fluids.

Suspecting that the fluid filled hairs in the antennas of the fly, Drosophila melanogaster, called sensilla, might possess a property known as ephaptic coupling, where nerve cells communicate without a direct link, the researchers tested the abilities of several fly specimens in their lab. The first focused on two receptors located in the sensilla responsible for detecting fruity methyl hexanoate and banana-scented 2-heptanone, respectively. When exposed to methyl hexonate, they found that only the first receptor fired. If heptanone were suddenly introduced however, the first receptor ceased firing immediately as the second commenced indicating that some form of communication between the two was occurring. They found that the reverse worked as well. To rule out possible modes of communication, the researchers conducted the same experiment with flies that had their synapses disabled via drugs and with others that had had their antennas physically cut off. Both showed the same results indicating that the communication was not direct but was localized.

In another experiment the researchers blocked a neuron in a sensilla responsible for detecting vinegar which was situated next to a neuron responsible for detecting carbon dioxide (for avoidance). When placed in a maze with two arms that smelled of carbon dioxide and one of vinegar, the fly headed for the vinegar scented arm, showing that the vinegar disabled neuron was still able to communicate with its carbon dioxide detecting partner.

The researchers suggest such an ability in flies might help in figuring out which path to take when encountering an environment filled with many different options. They also suggest that neuron pairs in the sensilla might be communicating with one another via electrical signals. When one detects what it’s supposed to detect, it sends a small charge into the fluid in which it and other neurons reside. That charge may then cause other neurons in the vicinity to go silent.

Researchers from McGill University and the University of Montreal have identified a crucial link between protein synthesis and autism spectrum disorders (ASD), which can bolster new therapeutic avenues. Regulation of protein synthesis, also termed mRNA translation, is the process by which cells manufacture proteins.

This mechanism is involved in all aspects of cell and organism function.  A new study in mice has found that abnormally high synthesis of a group of neuronal proteins called neuroligins results in symptoms similar to those diagnosed in ASD. The study also reveals that autism-like behaviors can be rectified in adult mice with compounds inhibiting protein synthesis, or with gene-therapy targeting neuroligins. Their results are published in the journal Nature.

Autism spectrum disorders (ASD) encompass a wide array of neurodevelopmental diseases that affect three areas of behaviour: social interactions, communication and repetitive interests or behaviors. According to the U.S.-based Centers for Disease Control and Prevention, 1 in 88 children suffer from ASD, and the disorder is reported to occur in all racial, ethnic, and socioeconomic groups. ASDs are almost five times more common among boys (1 in 54) than among girls (1 in 252).

“My lab is dedicated to elucidating the role of dysregulated protein synthesis in cancer etiology. However, our team was surprised to discover that similar mechanisms may be implicated in the development of ASD”, explained Prof. Nahum Sonenberg, from McGill’s Dept. of Biochemistry, Faculty of Medicine, and the Goodman Cancer Research Centre. “We used a mouse model in which a key gene controlling initiation of protein synthesis was deleted. In these mice, production of neuroligins was increased. Neuroligins are important for the formation and regulation of connections known as synapses between neuronal cells in the brain and essential for the maintenance of the balance in the transmission of information from neuron to neuron.”

“Since the discovery of neuroligin mutations in individuals with ASD in 2003, the precise molecular mechanisms implicated remain unknown,” said Christos Gkogkas, a postdoctoral fellow at McGill and lead author. “Our work is the first to link translational control of neuroligins with altered synaptic function and autism-like behaviors in mice. The key is that we achieved reversal of ASD-like symptoms in adult mice. Firstly, we used compounds, which were previously developed for cancer treatment, to reduce protein synthesis. Secondly, we used non-replicating viruses as vehicles to put a break on exaggerated synthesis of neuroligins.”

Computer modeling played an important role in this research. “By using a new sophisticated computer algorithm that we specially developed to answer Dr. Sonenberg’s questions, we identified the unique structures of mRNAs of the neuroligins that could be responsible for their specific regulation,” explained Prof. François Major, of the University of Montreal’s Institute for Research in Immunology and Cancer and Department of Computer Science.

The researchers found that dysregulated synthesis of neuroligins augments synaptic activity, resulting in an imbalance between excitation and inhibition in single brain cells, opening up exciting new avenues for research that may unlock the secrets of autism.

“The autistic behaviours in mice were prevented by selectively reducing the synthesis of one type of neuroligin and reversing the changes in synaptic excitation in cells,” explained Prof. Jean-Claude Lacaille at the University of Montreal’s Groupe de Recherche sur le Système Nerveux Central and Department of Physiology. “In short, we manipulated mechanisms in brain cells and observed how they influence the behaviour of the animal.” The researchers were also able to reverse changes in inhibition and augment autistic behaviors by manipulating a second neuroligin. “The fact that the balance can be affected suggests that there could be a potential for pharmacological intervention by targeting these mechanisms,” Lacaille concluded.