Status and the Brain

Social hierarchy is a fact of life for many animals. Navigating social hierarchy requires understanding one’s own status relative to others and behaving accordingly, while achieving higher status may call upon cunning and strategic thinking. The neural mechanisms mediating social status have become increasingly well understood in invertebrates and model organisms like fish and mice but until recently have remained more opaque in humans and other primates. In a new study in this issue, Noonan and colleagues explore the neural correlates of social rank in macaques. Using both structural and functional brain imaging, they found neural changes associated with individual monkeys’ social status, including alterations in the amygdala, hypothalamus, and brainstem—areas previously implicated in dominance-related behavior in other vertebrates. A separate but related network in the temporal and prefrontal cortex appears to mediate more cognitive aspects of strategic social behavior. These findings begin to delineate the neural circuits that enable us to navigate our own social worlds. A major remaining challenge is identifying how these networks contribute functionally to our social lives, which may open new avenues for developing innovative treatments for social disorders.

Full Article

Brain mechanism underlying the recognition of hand gestures develops even when blind

Does a distinctive mechanism work in the brain of congenitally blind individuals when understanding and learning others’ gestures? Or does the same mechanism as with sighted individuals work? Japanese researchers figured out that activated brain regions of congenitally blind individuals and activated brain regions of sighted individuals share common regions when recognizing human hand gestures. They indicated that a region of the neural network that recognizes others’ hand gestures is formed in the same way even without visual information. The findings are discussed in The Journal of Neuroscience.

Our brain mechanism perceives human bodies from inanimate objects and shows a particular response. A part of a region of the “visual cortex” that processes visual information supports this mechanism. Since visual information is largely used in perception, this is reasonable, however, for perception using haptic information and also for the recognition of one’s own gestures, it has been recently learned that the same brain region is activated. It came to be considered that there is a mechanism that is formed regardless of the sensory modalities and recognizes human bodies.

Blind and sighted individuals participated in the study of the research group of Assistant Professor Ryo Kitada of the National Institute for Physiological Sciences, National Institutes of Natural Sciences. With their eyes closed, they were instructed to touch plastic casts of hands, teapots, and toy cars and identify the shape. As it turned out, sighted individuals and blind individuals could make an identification with the same accuracy. Through measuring the activated brain region using functional magnetic resonance imaging (fMRI), for plastic casts of hands and not for teapots or toy cars, the research group was able to pinpoint a common activated brain region regardless of visual experience. On another front, it also revealed a region showing signs of activity that is dependent on the duration of the visual experience and it was also learned that this region functions as a supplement when recognizing hand gestures.

As Assistant Professor Ryo Kitada notes, “Many individuals are active in many parts of the society even with the loss of their sight as a child. Developmental psychology has been advancing its doctrine based on sighted individuals. I wish this finding will help us grasp how blind individuals understand and learn about others and be seen as an important step in supporting the development of social skills for blind individuals.”

2-D or 3-D? That is the Question

The increased visual realism of 3-D films is believed to offer viewers a more vivid and lifelike experience—more thrilling and intense than 2-D because it more closely approximates real life. However, psychology researchers at the University of Utah, among those who use film clips routinely in the lab to study patients’ emotional conditions, have found that there is no significant difference between the two formats. The results were published recently in PLOS ONE.

The study aimed to validate the effectiveness of 3-D film, a newer technology, as compared to 2-D film that is currently widely used as a research tool. Film clips are used in psychological and neuroscience studies as a standardized method for assessing emotional development. Because it is less invasive than other methods, it is especially useful when studying the emotional responses of young people for whom emotional well-being is critical to healthy development.

Author Sheila Crowell, assistant professor of psychology at the U, says that results of the large and tightly controlled study also suggest that as an entertainment medium, 3-D may not provide a different experience from 2-D, insofar as evoking emotional responses go.

“We set out to learn whether technological advances like 3-D enhance the study of emotion, especially for young patients who are routinely exposed to high-tech devices and mediums in their daily lives,” says Crowell. “Both 2-D and 3-D are equally effective at eliciting emotional responses, which also may mean that the expense involved in producing 3-D films is not creating much more than novelty. Further studies are of course warranted, but our findings should be encouraging to researchers who cannot now afford 3-D technologies.”

How the study was conducted

Researchers looked at several measures of emotional state in 408 subjects, including palm sweat, breathing and cardiovascular responses, such as heart rate. These measures are commonly used to gauge emotional responses.

Four film clips were chosen because each prompted one discrete emotion intensely and in context without viewing the entire film. Study participants viewed a 3-D and 2-D clip of approximately five minutes of each film: “My Bloody Valentine” (fear), “Despicable Me” (amusement), “Tangled” (sadness) and “The Polar Express” (thrill or excitement). Participants were randomized to view the films in a design that balanced the pairs of films watched, in which format, and order of presentation. The complex configurations allowed the researchers to compare not only emotional responses, but effects of format and viewing order on the results.

Taken as a whole, the results showed few significant differences between physiological reactions to the films. When accounting for the large number of statistical tests, only one difference was seen between the formats—the number of electrodermal responses (palm sweat) during a thrilling scene from “The Polar Express” 3-D clip. The researchers believe that could be because the 3-D content of the film is of especially high quality, with more and a larger variety of 3-D effects than the others.

Supporting the overall finding is that participants’ individual differences in anxiety, inability to control emotional responses or “thrill seeking” did not alter the psychological or physiological responses to 3-D viewing. In other words, personality differences did not change the results: 2-D is still equally effective for emotion elicitation. According to Crowell, “this could be good news for people who would rather not wear 3-D glasses or pay the extra money to see these types of films.”

The Yin and Yang of Overcoming Cocaine Addiction

Yaoying Ma says that biology, by nature, has a yin and a yang—a push and a pull.

Addiction, particularly relapse, she finds, is no exception.

Ma is a research associate in the lab of Yan Dong, assistant professor of neuroscience in the University of Pittsburgh’s Kenneth P. Dietrich School of Arts and Sciences. She is the lead author of a paper published online today in the journal Neuron that posits that it may be possible to ramp up an intrinsic anti-addiction response as a means to fight cocaine relapse and keep the wolves of relapse at bay.

This paper is the first to establish the existence of a brain circuitry that resists a relapse of cocaine use through a naturally occurring neural remodeling with “silent synapses.”

The work is a follow-up on a recent study conducted by Dong and his colleagues, which was published in Nature Neuroscience last November. The team used rat models to examine the effects of cocaine self-administration and withdrawal on nerve cells in the nucleus accumbens, a small region in the brain that is commonly associated with reward, emotion, motivation, and addiction. Specifically, they investigated the roles of synapses—the structures at the ends of nerve cells that relay signals.

The team reported in its Nature Neuroscience study that when a rat uses cocaine, some immature synapses are generated, which are called “silent synapses” because they are semifunctional and send few signals under normal physiological conditions. After that rat stops using cocaine, these “silent synapses” go through a maturation phase and acquire their full function to send signals. Once they can send signals, the synapses will send craving signals for cocaine if the rat is exposed to cues previously associated with the drug.

The current Neuron paper shows that there’s another side of “silent synapse” remodeling. Silent synapses that are generated in a specific cortical projection to the nucleus accumbens by cocaine exposure become “unsilenced” after cocaine withdrawal, resulting in a profound remodeling of this cortical projection. Additional experiments show that silent synapse-based remodeling of this cortical projection decreases cocaine craving. Importantly, this anti-relapse circuitry remodeling is induced by cocaine exposure itself, suggesting that our body has its own way to fight addiction.

Dong, the paper’s senior author, says that the pro-relapse response is predominant after cocaine exposure. But since the anti-relapse response exists inside the brain, it could possibly be clinically tweaked to achieve therapeutic benefits.

Ma notes that this finding “may provide insight into ways to manipulate this yin-yang balance and hopefully provide new neurobiological targets for interventions designed to decrease relapse.”

“The story won’t stop here,” Ma adds. “Our ongoing study is exploring some unusual but simple ways to beef up the endogenous anti-relapse mechanism.”

(Image: PA)

New research offers help for spinal cord patients

In a study on rats, researchers at the University of Copenhagen have discovered the cause of the involuntary muscle contractions which patients with severe spinal cord injuries frequently suffer. The findings have just been published in the Journal of Neuroscience and, in the long run, can pave the way for new treatment methods.

Three thousand Danish patients suffer from severe spinal cord injuries after being involved in traffic accidents or accidents at work. An injury to the spinal cord is a catastrophe for the individual, and often results in complete or partial paralysis of the person’s arms and legs. Despite the paralysis, several patients experience problems with involuntary muscle contractions or spasms which impair the patient’s quality of life.

The movements are due to the neurotransmitter serotonin, which normally plays a crucial role in relation to our voluntary control of movements by reinforcing the level of activity in the motor neurones when they have to activate the muscles to an extraordinary degree. Research shows that a group of cells in the spinal cord start supplying serotonin in an uncontrolled way following an injury, and this knocks the motor system out of control.

“We now have a qualified idea of why the serotonin level goes out of control, and we have documented that a special serotonin-producing enzyme plays a key role. By targeting the specific enzyme, in the long term we will be able to devise new methods of treatment when we are trying to impact functions in the nervous system,” says associate professor and neurophysiologist Jacob Wienecke.

The prospects of the study are interesting for both spinal cord patients and patients suffering from Parkinson’s disease.

Emergency response kicks in

The enzyme aromatic L-amino acid decarboxylase (AADC) plays an important role in the production of the neurotransmitter serotonin:

“In the first few days after an injury to the spinal cord, we can see there is a very rapid regulation of AADC which results in the uncontrolled production of serotonin. It is our guess that this is the spinal cord’s emergency response trying to boost the enzyme’s capacity,” says Jacob Wienecke.

According to the researchers, it may be the same emergency response which causes the involuntary movements – dyskinesia – that are also experienced by patients with Parkinson’s disease. However, for Parkinson’s patients, it is the dopamine system which is affected, but the enzyme which activates the emergency response is the same.

“It is an interesting perspective, which will hopefully focus efforts on targeting drugs specifically at the AADC cells. Perhaps in the future we can regulate the undesired neural activity in this way so that the unnecessary ‘disturbance on the line’ disappears for the affected patients,” says Jacob Wienecke.

Existing treatment puts a damper on learning

Existing forms of treatment for spinal cord patients currently involve, for example, using the drug baclofen, which suppresses neural activity, and thereby the motor neurones which cause the involuntary movements. The problem with baclofen though is that it impacts motor learning – and thus the patients’ rehabilitation. However, there is still a long way to go. Developing new drugs is a protracted process, and the way is paved with obstacles. Injuries to the spinal column are extremely complex, and primarily result in interruptions to the signalling between the brain and the body.

“Finding a solution to the problem is no easy task. However, a lot suggests that regulating serotonin production more precisely could mitigate undesirable spasms while also supporting the rehabilitation of controlled movements. So far, the study has been carried out on rats, but we have reason to believe that the same mechanisms apply in humans,” says Jacob Wienecke in conclusion.

Reacting to Personal Setbacks: Do You Bounce Back or Give Up?

Sometimes when people get upsetting news – such as a failing exam grade or a negative job review – they decide instantly to do better the next time. In other situations that are equally disappointing, the same people may feel inclined to just give up.

How can similar setbacks produce such different reactions? It may come down to how much control we feel we have over what happened, according to new research from Rutgers University-Newark. The study, published in the journal Neuron, also finds that when these setbacks occur, the level of control we perceive may even determine which of two distinct parts of the brain will handle the crisis.

“Think of the student who failed an exam,” says Jamil Bhanji, a postdoctoral fellow at Rutgers and one of the study’s co-authors. “They might feel they wouldn’t have failed if they had studied harder, studied differently – something under their control.” That student, Bhanji says, resolves to try new study habits and work hard toward acing the next exam. Functional magnetic resonance imaging (fMRI) used in the study showed activity in a part of the brain called the ventral striatum – which has been shown to guide goals based on prior experiences.

A different student might have failed the same test, but believes it happened because the questions were unfair or the professor was mean, things that he could not control. The negative emotions produced by this uncontrollable setback may cause the student to drop the course.

Overcoming those negative emotions and refocusing on doing well in the class may require a more complicated thought process. In cases like this, fMRI revealed that activity in the ventromedial prefrontal cortex (vmPFC), a part of the brain that regulates emotions in more flexible ways, is necessary to promote persistence.

Mauricio Delgado, an associate professor of psychology at Rutgers’ Newark College of Arts and Sciences and the study’s other co-author, says people whose jobs include delivering bad news should pay attention to these results, because their actions might influence how the news is received.

“You may deliver the news to the student – no sugar coating, here’s your setback,” says Delgado. “But then you make an offer – ‘would you like to review those study habits with me? I’d be happy to do it.’ This puts the student in a situation where they may experience control and be more likely to improve the next time.” This approach, Delgado says, may be far more constructive than curtly delivering a bad grade.

Bhanji says lessons from the study may even guide certain people toward giving up too soon on careers where they could do well. “We wonder why there are fewer women and minorities in the sciences, for example,” he explains. “Maybe in cases like that it’s fair to say there are things we can do to promote reactions to negative feedback that encourage persistence.”

That is not to say everyone should persist. “There are times,” Delgado adds, “when you should not be persistent with your goals. That’s where the striatal system in the brain, which can be a source of more habitual responses, may be a detriment. You keep thinking ‘I can do it, I can do it.’ But maybe you shouldn’t do it. During these times, interpreting the setback more flexibly, via the vmPFC, may be more helpful.”

As research continues, adds Bhanji, important areas to explore will include “figuring out when it’s worth continuing to keep trying and when it’s not.”