The Brain on Stress: Vulnerability and Plasticity of the Prefrontal Cortex over the Life Course

The prefrontal cortex (PFC) is involved in working memory and self-regulatory and goal-directed behaviors and displays remarkable structural and functional plasticity over the life course. Neural circuitry, molecular profiles, and neurochemistry can be changed by experiences, which influence behavior as well as neuroendocrine and autonomic function. Such effects have a particular impact during infancy and in adolescence. Behavioral stress affects both the structure and function of PFC, though such effects are not necessarily permanent, as young animals show remarkable neuronal resilience if the stress is discontinued. During aging, neurons within the PFC become less resilient to stress. There are also sex differences in the PFC response to stressors. While such stress and sex hormone-related alterations occur in regions mediating the highest levels of cognitive function and self-regulatory control, the fact that they are not necessarily permanent has implications for future behavior-based therapies that harness neural plasticity for recovery.

Robot mom would beat robot butler in popularity contest

If you tickle a robot, it may not laugh, but you may still consider it humanlike — depending on its role in your life, reports an international group of researchers.

Designers and engineers assign robots specific roles, such as servant, caregiver, assistant or playmate. Researchers found that people expressed more positive feelings toward a robot that would take care of them than toward a robot that needed care.

"For robot designers, this means greater emphasis on role assignments to robots,” said S. Shyam Sundar, Distinguished Professor of Communications at Penn State and co-director of University’s Media Effects Research Laboratory. “How the robot is presented to users can send important signals to users about its helpfulness and intelligence, which can have consequences for how it is received by end users.”

To determine how human perception of a robot changed based on its role, researchers observed 60 interactions between college students and Nao, a social robot developed by Aldebaran Robotics, a French company specializing in humanoid robots.

Each interaction could go one of two ways. The human could help Nao calibrate its eyes, or Nao could examine the human’s eyes like a concerned eye doctor and make suggestions to improve vision.

Participants then filled out a questionnaire about their feelings toward Nao. Researchers used these answers to calculate the robot’s perceived benefit and social presence in both scenarios. They published their results in the current issue of Computers in Human Behavior.

"When (humans) perceive greater benefit from the robot, they are more satisfied in their relationship with it, and even trust it more," Sundar said. "In addition, we found that when the robot cares for you, it seems to have greater social presence."

A robot with a strong social presence behaves and interacts like an authentic human, according to Ki Joon Kim, doctoral candidate in the department of interaction science, Sungkyunkwan University, Korea, and lead author of the journal article.

The research team found that when participants perceived a strong social presence, they considered the caregiving robot smarter than the robot in the alternate scenario. Participants were also more likely to attribute human qualities to the caregiving robot.

"Social presence is particularly important in human-robot interactions and areas of artificial intelligence because the ultimate goal of designing and interacting with social robots is to provide users with strong feelings of socialness,” said Kim.

The next immediate goal is to confirm these experimental findings in real-life situations where caretaker robots are already working. Examining how other robot roles influence human perception toward them is also important.

"We have just finished collecting data at a local retirement village in State College with the Homemate robot which we brought in from Korea,” said Sundar. “In that study, we are examining differences in user reactions to a robot that is an assistant versus one that is framed as a companion.”

Exposure to Stress Even Before Conception Causes Genetic Changes to Offspring

A female’s exposure to distress even before she conceives causes changes in the expression of a gene linked to the stress mechanism in the body — in the ovum and later in the brains of the offspring from when they are born, according to a new study on rats conducted by the University of Haifa.

“The systemic similarity in many instances between us and mice raises questions about the transgenerational influences in humans as well, for example, the effects of the Second Lebanon War or the security situation in the South on the children of those who went through those difficult experiences,” the researchers said. “If until now we saw evidence only of behavioral effects, now we’ve found proof of effects at the genetic level.”

In previous studies in Prof. Micah Leshem’s lab, it was found that exposing rats to stress before they had even conceived (and even at their “teen” stage) influences the behavior of their offspring. This study, conducted in the lab of Dr. Inna Gaisler-Salomon by PhD student Hiba Zaidan, in cooperation with Prof. Leshem, the researchers sought to examine whether there was an influence on genetic expression.

In the study, which was recently published in the journal Biological Psychiatry, the researchers focused on the gene known as CRF-1, a gene linked to the body’s stress-control system that expresses itself in many places in the brain under stress.

The researchers took female rats that were 45 days old, which is parallel to human adolescence. Some of the rats were exposed to “minor” stress, which included changes in temperature and daily routine for seven days, and compared them to a control group that was not exposed to stress at all. The rats were mated and conceived two weeks later.

In the first part of the study, the researchers examined the ova of the rats that were exposed to stress even before they conceived, and they found that at that stage there was enhanced expression of the CRF-1 gene. For the second part, the researchers examined the brains of newborn rats immediately after birth, before the mother could have any influence on them, and found that even at the neonatal stage, there was enhanced expression of the CRF-1 gene in the brains of the rats born to mothers who had been exposed to stress.

During the third stage, the researchers exposed the offspring – both those whose mothers had been exposed to stress and those whose mothers were not – to stress when they reached adulthood. It emerged that the expression of CRF-1 among the offspring was dependent on three factors: The sex of the offspring, the stress undergone by the mother and the stress to which the offspring were exposed. The female rats whose mothers had been exposed to stress and who themselves underwent a “stressful” behavioral test showed higher levels of CRF-1 than other groups.

“This is the first time that we showed that the genetic response to stress in rats is linked to the experiences their mothers underwent long before they even got pregnant with them,” the researchers said. “We are learning more and more about intergenerational genetic transfer and in light of the findings, and in light of the fact that in today’s reality many women are exposed to stress even before they get pregnant, it’s important to research the degree to which such phenomenon take place in humans.”

(Image: iStockphoto)

Are Thoughts of Death Conducive to Humor?

A New Study Shows an Increase in Humorous Creativity when Individuals are Primed with Thoughts of Death.

Humor is an intrinsic part of human experience. It plays a role in every aspect of human existence, from day-to-day conversation to television shows. Yet little research has been conducted to date on the psychological function of humor. In human psychology, awareness of the impermanence of life is just as prevalent as humor. According to the Terror Management Theory, knowledge of one’s own impermanence creates potentially disruptive existential anxiety, which the individual brings under control with two coping mechanisms, or anxiety buffers: rigid adherence to dominant cultural values, and self-esteem bolstering.

A new article by Christopher R. Long of Ouachita Baptist University and Dara Greenwood of Vassar College is titled Joking in the Face of Death: A Terror Management Approach to Humor Production. Appearing in the journal HUMOR, it documents research on whether the activation of thoughts concerning death influences one’s ability to creatively generate humor. As humor is useful on a fundamental level for a variety of purposes, including psychological defense against anxiety, the authors hypothesized that the activation of thoughts concerning death could facilitate the production of humor.

For their study, Long and Greenwood subdivided 117 students into four experimental groups. These groups were confronted with the topics of pain and death while completing various tasks. Two of the test groups were exposed unconsciously to words flashed for 33 milliseconds on a computer while they completed tasks – the first to the word “pain,” the second to the word “death.” The remaining two groups were prompted in a writing task to express emotions concerning either their own death or a painful visit to the dentist. Afterward, all four groups were instructed to supply a caption to a cartoon from The New Yorker.

These cartoon captions were presented to an independent jury who knew nothing about the experiment. The captions written by individuals who were subconsciously primed with the word death were clearly voted as funnier by the jury. By contrast, the exact opposite result was obtained for the students who consciously wrote about death: their captions were seen as less humorous.

Based on this experiment, the researchers conclude that humor helps the individual to tolerate latent anxiety that may otherwise be destabilizing. In this connection, they point to previous studies indicating that humor is an integral component of resilience.

In light of the finding that the activation of conscious thoughts concerning death impaired the creative generation of humor, Long and Greenwood highlight the need for additional research, not only to explore the effectiveness of humor as a coping mechanism under various circumstances, but also to identify its emotional, cognitive, and/or social benefits under conditions of adversity.

How the brain creates the ‘buzz’ that helps ideas spread

How do ideas spread? What messages will go viral on social media, and can this be predicted?

UCLA psychologists have taken a significant step toward answering these questions, identifying for the first time the brain regions associated with the successful spread of ideas, often called “buzz.”

The research has a broad range of implications, the study authors say, and could lead to more effective public health campaigns, more persuasive advertisements and better ways for teachers to communicate with students.

"Our study suggests that people are regularly attuned to how the things they’re seeing will be useful and interesting, not just to themselves but to other people," said the study’s senior author, Matthew Lieberman, a UCLA professor of psychology and of psychiatry and biobehavioral sciences and author of the forthcoming book "Social: Why Our Brains Are Wired to Connect." "We always seem to be on the lookout for who else will find this helpful, amusing or interesting, and our brain data are showing evidence of that. At the first encounter with information, people are already using the brain network involved in thinking about how this can be interesting to other people. We’re wired to want to share information with other people. I think that is a profound statement about the social nature of our minds."

The study findings are published in the online edition of the journal Psychological Science, with print publication to follow later this summer.

"Before this study, we didn’t know what brain regions were associated with ideas that become contagious, and we didn’t know what regions were associated with being an effective communicator of ideas," said lead author Emily Falk, who conducted the research as a UCLA doctoral student in Lieberman’s lab and is currently a faculty member at the University of Pennsylvania’s Annenberg School for Communication. "Now we have mapped the brain regions associated with ideas that are likely to be contagious and are associated with being a good ‘idea salesperson.’ In the future, we would like to be able to use these brain maps to forecast what ideas are likely to be successful and who is likely to be effective at spreading them."

In the first part of the study, 19 UCLA students (average age 21), underwent functional magnetic resonance imaging (fMRI) brain scans at UCLA’s Ahmanson–Lovelace Brain Mapping Center as they saw and heard information about 24 potential television pilot ideas. Among the fictitious pilots — which were presented by a separate group of students — were a show about former beauty-queen mothers who want their daughters to follow in their footsteps; a Spanish soap opera about a young woman and her relationships; a reality show in which contestants travel to countries with harsh environments; a program about teenage vampires and werewolves; and a show about best friends and rivals in a crime family.

The students exposed to these TV pilot ideas were asked to envision themselves as television studio interns who would decide whether or not they would recommend each idea to their “producers.” These students made videotaped assessments of each pilot.

Another group of 79 UCLA undergraduates (average age 21) was asked to act as the “producers.” These students watched the interns’ videos assessments of the pilots and then made their own ratings about the pilot ideas based on those assessments.

Lieberman and Falk wanted to learn which brain regions were activated when the interns were first exposed to information they would later pass on to others.

"We’re constantly being exposed to information on Facebook, Twitter and so on," said Lieberman. "Some of it we pass on, and a lot of it we don’t. Is there something that happens in the moment we first see it — maybe before we even realize we might pass it on — that is different for those things that we will pass on successfully versus those that we won’t?"

It turns out, there is. The psychologists found that the interns who were especially good at persuading the producers showed significantly more activation in a brain region known as the temporoparietal junction, or TPJ, at the time they were first exposed to the pilot ideas they would later recommend. They had more activation in this region than the interns who were less persuasive and more activation than they themselves had when exposed to pilot ideas they didn’t like. The psychologists call this the “salesperson effect.”

"It was the only region in the brain that showed this effect," Lieberman said. One might have thought brain regions associated with memory would show more activation, but that was not the case, he said.

"We wanted to explore what differentiates ideas that bomb from ideas that go viral," Falk said. "We found that increased activity in the TPJ was associated with an increased ability to convince others to get on board with their favorite ideas. Nobody had looked before at which brain regions are associated with the successful spread of ideas. You might expect people to be most enthusiastic and opinionated about ideas that they themselves are excited about, but our research suggests that’s not the whole story. Thinking about what appeals to others may be even more important."

The TPJ, located on the outer surface of the brain, is part of what is known as the brain’s “mentalizing network,” which is involved in thinking about what other people think and feel. The network also includes the dorsomedial prefrontal cortex, located in the middle of the brain.

"When we read fiction or watch a movie, we’re entering the minds of the characters — that’s mentalizing," Lieberman said. "As soon as you hear a good joke, you think, ‘Who can I tell this to and who can’t I tell?’ Making this judgment will activate these two brain regions. If we’re playing poker and I’m trying to figure out if you’re bluffing, that’s going to invoke this network. And when I see someone on Capitol Hill testifying and I’m thinking whether they are lying or telling the truth, that’s going to invoke these two brain regions.

"Good ideas turn on the mentalizing system," he said. "They make us want to tell other people."

The interns who showed more activity in their mentalizing system when they saw the pilots they intended to recommend were then more successful in convincing the producers to also recommend those pilots, the psychologists found.

"As I’m looking at an idea, I might be thinking about what other people are likely to value, and that might make me a better idea salesperson later," Falk said.

By further studying the neural activity in these brain regions to see what information and ideas activate these regions more, psychologists potentially could predict which advertisements are most likely to spread and go viral and which will be most effective, Lieberman and Falk said.

Such knowledge could also benefit public health campaigns aimed at everything from reducing risky behaviors among teenagers to combating cancer, smoking and obesity.

"The explosion of new communication technologies, combined with novel analytic tools, promises to dramatically expand our understanding of how ideas spread," Falk said. "We’re laying basic science foundations to addressimportant public health questions that are difficult to answer otherwise — about what makes campaigns successful and how we can improve their impact."

As we may like particular radio DJs who play music we enjoy, the Internet has led us to act as “information DJs” who share things that we think will be of interest to people in our networks, Lieberman said.

"What is new about our study is the finding that the mentalizing network is involved when I read something and decide who else might be interested in it," he said. "This is similar to what an advertiser has to do. It’s not enough to have a product that people should like."

With Parents’ Help, Preschoolers Can Learn to Pay Attention

To Preserve Memory Into Old Age, Keep Your Brain Active!

A new study from Rush University Medical Center in Chicago claims reading and writing may preserve memory into old age. By keeping your brain active, says study author Robert S. Wilson, PhD, you’re able to slow the rate at which your memory decreases in later years.

This is not the first time researchers have arrived at such a conclusion, of course. Previous studies have also found keeping the brain active by reading, writing, completing crossword puzzles and more can essentially exercise the brain and keep it limber far into old age. One study also concluded that keeping television consumption to a minimal amount may also boost brain power over the years. Wilson’s study was recently published in the journal Neurology.

“Our study suggests that exercising your brain by taking part in activities such as these across a person’s lifetime, from childhood through old age, is important for brain health in old age,” said Wilson in a statement.

For his study, Wilson gathered nearly 300 people around the age of 80. He then gave them tests which were designed to measure both their memory and cognition each year until they passed away at an average age of 89. The same participants also answered questions about their past, such as whether they read books, did any writing, or engaged in any other mentally stimulating activities. The volunteers answered these questions for every part of their life, from childhood to adolescence, middle age and beyond.

When the participants passed away, their brains were then examined at an autopsy as Wilson’s team looked for physical evidence of dementia, such as lesions in the brain, tangles or plaques. After examining the brains of these volunteers and compiling the data from the questionnaires, Wilson’s team found those who had kept their minds active throughout their lives had a slower rate of memory decline than those who did not often participate in mentally challenging activities. Based on the amount of plaques and tangles in the brains, keeping your brain active is responsible for a 15 percent differential in memory decline.

The study also found the rate of memory decline was reduced by 32 percent in people who kept their brains active late in life. Those who were not mentally active had it much worse; their memories declined 48 percent faster than their actively reading and writing peers.

“Based on this, we shouldn’t underestimate the effects of everyday activities, such as reading and writing, on our children, ourselves and our parents or grandparents,” said Wilson.

And this news is hardly surprising. Doctors, teachers and parents have been admonishing children to turn off the television and pick up a book for years. There is no shortage of studies to back up their claims. A 2009 study, for example, found people who keep their brains active saw a 30 to 50 percent decrease in risk of developing memory loss. This study, conducted by doctors at the Mayo Clinic in Rochester, Minnesota observed people between the ages of 70 and 89 with and without diagnosed memory loss.

Those who were likely to read magazines or engage in other social activities were 40 percent less likely to develop memory loss than homebodies who did not read. Furthermore, those who spent less than seven hours a day watching television were 50 percent less likely to develop memory loss than those who planted themselves in front of the tube for long stretches of time.

Teens’ Self-Consciousness Linked With Specific Brain, Physiological Responses

Teenagers are famously self-conscious, acutely aware and concerned about what their peers think of them. A new study reveals that this self-consciousness is linked with specific physiological and brain responses that seem to emerge in adolescence.

“Our study identifies adolescence as a unique period of the lifespan in which self-conscious emotion, physiological reactivity, and activity in specific brain areas converge and peak in response to being evaluated by others,” says psychological scientist and lead researcher Leah Somerville of Harvard University.

The findings, published in Psychological Science, a journal of the Association for Psychological Science, suggest that teens’ sensitivity to social evaluation might be explained by shifts in physiological and brain function during adolescence, in addition to the numerous sociocultural changes that take place during the teen years.

Somerville and colleagues wanted to investigate whether just being looked at — a minimal social-evaluation situation — might register with greater importance, arousal, and intensity for adolescents than for either children or adults. The researchers hypothesized that late-developing regions of the brain, such as the medial prefrontal cortex (MPFC), could play a unique role in the way teens monitor these types of social evaluative contexts.

The researchers had 69 participants, ranging in age from 8 to almost 23 years old, come to the lab and complete measures that gauged emotional, physiological, and neural responses to social evaluation.

They told the participants that they would be testing a new video camera embedded in the head coil of a functional MRI scanner. The participants watched a screen indicating whether the camera was “off,” “warming up,” or “on”, and were told that a same-sex peer of about the same age would be watching the video feed and would be able to see them when the camera was on. In reality, there was no camera in the MRI machine.

The consistency and strength of the resulting data took the researchers by surprise:

“We were concerned about whether simply being looked at was a strong enough ‘social evaluation’ to evoke emotional, physiological and neural responses,” says Somerville. “Our findings suggest that being watched, and to some extent anticipating being watched, were sufficient to elicit self-conscious emotional responses at each level of measurement.”

Specifically, participants’ self-reported embarrassment, physiological arousal, and MPFC activation showed reactivity to social evaluation that seemed to converge and peak during adolescence.

Adolescent participants also showed increased functional connectivity between the MPFC and striatum, an area of the brain that mediates motivated behaviors and actions. Somerville and colleagues speculate that the MPFC-striatum pathway may be a route by which social evaluative contexts influence behavior. The link may provide an initial clue as to why teens often engage in riskier behaviors when they’re with their peers.

Why Do We Yawn and Why Is It Contagious?

Snakes and fish do it. Cats and dogs do it. Even human babies do it inside the womb. And maybe after seeing the picture above, you’re doing it now: yawning.

Yawning appears to be ubiquitous within the animal kingdom. But despite being such a widespread feature, scientists still can’t explain why yawning happens, or why for social mammals, like humans and their closest relatives, it’s contagious.

As yawning experts themselves will admit, the behavior isn’t exactly the hottest research topic in the field. Nevertheless, they are getting closer to the answer to these questions. An oft-used explanation for why we yawn goes like this: when we open wide, we suck in oxygen-rich air. The oxygen enters our bloodstream and helps to wake us up when we’re falling asleep at our desks.

Sounds believable, right? Unfortunately, this explanation is actually a myth, says Steven Platek, a psychology professor at Georgia Gwinnett College. So far, there’s no evidence that yawning affects levels of oxygen in the bloodstream, blood pressure or heart rate.

The real function of yawning, according to one hypothesis, could lie in the human body’s most complex system: the brain.

Yawning—a stretching of the jaw, gaping of the mouth and long deep inhalation, followed by a shallow exhalation—may serve as a thermoregulatory mechanism, says Andrew Gallup, a psychology professor at SUNY College at Oneonta. In other words, it’s kind of like a radiator. In a 2007 study, Gallup found that holding hot or cold packs to the forehead influenced how often people yawned when they saw videos of others doing it. When participants held a warm pack to their forehead, they yawned 41 percent of the time. When they held a cold pack, the incidence of yawning dropped to 9 percent.

The human brain takes up 40 percent of the body’s metabolic energy, which means it tends to heat up more than other organ systems. When we yawn, that big gulp of air travels through to our upper nasal and oral cavities. The mucus membranes there are covered with tons of blood vessels that project almost directly up to the forebrain. When we stretch our jaws, we increase the rate of blood flow to the skull, Gallup says. And as we inhale at the same time, the air changes the temperature of that blood flow, bringing cooler blood to the brains.

In studies of mice, an increase in brain temperature was found to precede yawning. Once the tiny rodents opened wide and inhaled, the temperature decreased. “That’s pretty much the nail in the coffin as far as the function of yawning being a brain cooling mechanism, as opposed to a mechanism for increasing oxygen in the blood,” says Platek.

Yawning as a thermoregulatory system mechanism could explain why we seem to yawn most often when it’s almost bedtime or right as we wake up. “Before we fall asleep, our brain and body temperatures are at their highest point during the course of our circadian rhythm,” Gallup says. As we fall asleep, these temperatures steadily decline, aided in part by yawning. But, he added, “Once we wake up, our brain and body temperatures are rising more rapidly than at any other point during the day.” Cue more yawns as we stumble toward the coffee machine. On average, we yawn about eight times a day, Gallup says.

Scientists haven’t yet pinpointed the reason we often feel refreshed after a hearty morning yawn. Platek suspects it’s because our brains function more efficiently once they’re cooled down, making us more alert as result.

A biological need to keep our brains cool may have trickled into early humans and other primates’ social networks. “If I see a yawn, that might automatically cue an instinctual behavior that if so-and-so’s brain is heating up, that means I’m in close enough vicinity, I may need to regulate my neural processes,” Platek says. This subconscious copycat behavior could improve individuals’ alertness, improving their chances of survival as a group.

Mimicry is likely at the heart of why yawning is contagious. This is because yawning may be a product of a quality inherent in social animals: empathy. In humans, it’s the ability to understand and feel another individual’s emotions. The way we do that is by stirring a given emotion in ourselves, says Matthew Campbell, a researcher at the Yerkes National Primate Research Center at Emory University. When we see someone smile or frown, we imitate them to feel happiness or sadness. We catch yawns for the same reasons—we see a yawn, so we yawn. “It isn’t a deliberate attempt to empathize with you,” Campbell says. “It’s just a byproduct of how our bodies and brains work.”

Platek says that yawning is contagious in about 60 to 70 percent of people—that is, if people see photos or footage of or read about yawning, the majority will spontaneously do the same. He has found that this phenomenon occurs most often in individuals who score high on measures of empathic understanding. Using functional magnetic resonance imaging (fMRI) scans, he found that areas of the brain activated during contagious yawning, the posterior cingulate and precuneus, are involved in processing the our own and others’ emotions. “My capacity to put myself in your shoes and understand your situation is a predictor for my susceptibility to contagiously yawn,” he says.

Contagious yawning has been observed in humans’ closest relatives, chimpanzees and bonobos, animals that are also characterized by their social natures. This begs a corollary question: is their capacity to contagiously yawn further evidence of the ability of chimps and bonobos to feel empathy?

Along with being contagious, yawning is highly suggestible, meaning that for English speakers, the word “yawn” is a representation of the action, a symbol that we’ve learned to create meaning. When we hear, read or think about the word or the action itself, that symbol becomes “activated” in the brain. “If you get enough stimulation to trip the switch, so to speak, you yawn,” Campbell says. “It doesn’t happen every time, but it builds up and at some point, you get enough activation in the brain and you yawn.”