1. Study suggests our trust in strangers is affected by their resemblance to previous acquaintances

    February 17, 2018 by Ashley

    From the New York University press release:

    Our trust in strangers is dependent on their resemblance to others we’ve previously known, finds a new study by a team of psychology researchers. Its results show that strangers resembling past individuals known to be trustworthy are trusted more; by contrast, those similar to others known to be untrustworthy are trusted less.

    The details of the research, conducted at New York University, are reported in the latest issue of the journal Proceedings of the National Academy of Sciences.

    “Our study reveals that strangers are distrusted even when they only minimally resemble someone previously associated with immoral behavior,” explains the work’s lead author, Oriel FeldmanHall, who led research as a post-doctoral fellow at NYU and who is now an assistant professor in Brown University’s Department of Cognitive, Linguistic, and Psychological Sciences. “Like Pavlov’s dog, who, despite being conditioned on a single bell, continues to salivate to bells that have similar tones, we use information about a person’s moral character, in this case whether they can be trusted, as a basic Pavlovian learning mechanism in order to make judgments about strangers.”

    “We make decisions about a stranger’s reputation without any direct or explicit information about them based on their similarity to others we’ve encountered, even when we’re unaware of this resemblance,” adds Elizabeth Phelps, a professor in NYU’s Department of Psychology and the paper’s senior author. “This shows our brains deploy a learning mechanism in which moral information encoded from past experiences guides future choices.”

    Scientists have a better grasp on how social decision-making unfolds in repeated one-on-one interactions. Less clear, however, is how our brain functions in making these same decisions when interacting with strangers.

    To explore this, the researchers conducted a series of experiments centering on a trust game in which participants make a series of decisions about their partners’ trustworthiness — in this case, deciding whether to entrust their money with three different players who were represented by facial images.

    Here, the subjects knew that any money they invested would be multiplied four times and that the other player could then either share the money back with the subject (reciprocate) or keep the money for himself (defect). Each player was highly trustworthy (reciprocated 93 percent of the time), somewhat trustworthy (reciprocated 60 percent of the time), or not at all trustworthy (reciprocated 7 percent of the time).

    In a second task, the same subjects were asked to select new partners for another game. However, unbeknownst to the subjects, the face of each potential new partner was morphed, to varying degrees, with one of the three original players so the new partners bore some physical resemblance to the previous ones.

    Even though the subjects were not consciously aware that the strangers (i.e., the new partners) resembled those they previously encountered, subjects consistently preferred to play with strangers who resembled the original player they previously learned was trustworthy and avoided playing with strangers resembling the earlier untrustworthy player. Moreover, these decisions to trust or distrust strangers uncovered an interesting and sophisticated gradient: trust steadily increased the more the stranger looked like the trustworthy partner from the previous experiment and steadily decreased the more the stranger looked like the untrustworthy one.

    In a subsequent experiment, the scientists examined the brain activity of the subjects as they made these decisions. Here they found that when deciding whether or not the strangers could be trusted, the subjects’ brains tapped the same neurological regions that were involved when learning about the partner in the first task, including the amygdala — a region that plays a large role in emotional learning. The greater the similarity in neural activity between initially learning about an untrustworthy player and deciding to trust a stranger, the more subjects refused to trust the stranger.

    This finding points to the highly adaptive nature of the brain as it shows we make moral assessments of strangers drawn from previous learning experiences.

    The study was supported by a grant from the National Institute of Aging (AG 039283), part of the National Institutes of Health.


  2. Study suggests mirror neuron activity predicts people’s decision-making in moral dilemmas

    January 13, 2018 by Ashley

    From the University of California – Los Angeles press release:

    It is wartime. You and your fellow refugees are hiding from enemy soldiers, when a baby begins to cry. You cover her mouth to block the sound. If you remove your hand, her crying will draw the attention of the soldiers, who will kill everyone. If you smother the child, you’ll save yourself and the others.

    If you were in that situation, which was dramatized in the final episode of the ’70s and ’80s TV series “M.A.S.H.,” what would you do?

    The results of a new UCLA study suggest that scientists could make a good guess based on how the brain responds when people watch someone else experience pain. The study found that those responses predict whether people will be inclined to avoid causing harm to others when facing moral dilemmas.

    “The findings give us a glimpse into what is the nature of morality,” said Dr. Marco Iacoboni, director of the Neuromodulation Lab at UCLA’s Ahmanson-Lovelace Brain Mapping Center and the study’s senior author. “This is a foundational question to understand ourselves, and to understand how the brain shapes our own nature.”

    In the study, which was published in Frontiers in Integrative Neuroscience, Iacoboni and colleagues analyzed mirror neurons, brain cells that respond equally when someone performs an action or simply watches someone else perform the same action. Mirror neurons play a vital role in how people learn through mimicry and feel empathy for others.

    When you wince while seeing someone experience pain — a phenomenon called “neural resonance” — mirror neurons are responsible.

    Iacoboni wondered if neural resonance might play a role in how people navigate complicated problems that require both conscious deliberation and consideration of another’s feelings.

    To find out, researchers showed 19 volunteers two videos: one of a hypodermic needle piercing a hand, and another of a hand being gently touched by a cotton swab. During both, the scientists used a functional MRI machine to measure activity in the volunteers’ brains.

    Researchers later asked the participants how they would behave in a variety of moral dilemmas, including the scenario involving the crying baby during wartime, the prospect of torturing another person to prevent a bomb from killing several other people and whether to harm research animals in order to cure AIDS.

    Participants also responded to scenarios in which causing harm would make the world worse — inflicting harm on another person in order to avoid two weeks of hard labor, for example — to gauge their willingness to cause harm for moral reasons and for less-noble motives.

    Iacoboni and his colleagues hypothesized that people who had greater neural resonance than the other participants while watching the hand-piercing video would also be less likely to choose to silence the baby in the hypothetical dilemma, and that proved to be true. Indeed, people with stronger activity in the inferior frontal cortex, a part of the brain essential for empathy and imitation, were less willing to cause direct harm, such as silencing the baby.

    But the researchers found no correlation between people’s brain activity and their willingness to hypothetically harm one person in the interest of the greater good — such as silencing the baby to save more lives. Those decisions are thought to stem from more cognitive, deliberative processes.

    The study confirms that genuine concern for others’ pain plays a causal role in moral dilemma judgments, Iacoboni said. In other words, a person’s refusal to silence the baby is due to concern for the baby, not just the person’s own discomfort in taking that action.

    Iacoboni’s next project will explore whether a person’s decision-making in moral dilemmas can be influenced by decreasing or enhancing activity in the areas of the brain that were targeted in the current study.

    “It would be fascinating to see if we can use brain stimulation to change complex moral decisions through impacting the amount of concern people experience for others’ pain,” Iacoboni said. “It could provide a new method for increasing concern for others’ well-being.”

    The research could point to a way to help people with mental disorders such as schizophrenia that make interpersonal communication difficult, Iacoboni said.

    The study’s first author is Leo Moore, a UCLA postdoctoral scholar in psychiatry and biobehavioral sciences. Paul Conway of Florida State University and the University of Cologne, Germany, is the paper’s other co-author.

    The study was supported by the National Institute of Mental Health, the Brain Mapping Medical Research Organization, the Brain Mapping Support Foundation, the Pierson-Lovelace Foundation, the Ahmanson Foundation, the William M. and Linda R. Dietel Philanthropic Fund at the Northern Piedmont Community Foundation, the Tamkin Foundation, the Jennifer Jones-Simon Foundation, the Capital Group Companies Charitable Foundation, the Robson family, and the Northstar Fund.


  3. Study suggests a good decision is not made in one go

    December 21, 2017 by Ashley

    From the Vrije Universiteit Amsterdam press release:

    The best decisions are made on the basis of the average of various estimates: this has been confirmed by the research of Dennie van Dolder and Martijn van den Assem, scientists at VU Amsterdam. Using data from Holland Casino promotional campaigns, they have researched whether it is true that when people make estimates, the average of their estimates is relatively close to reality. The results of the research are being published today in Nature Human Behaviour.

    During the last seven weeks of 2013, 2014 and 2015, Holland Casino visitors could participate in an estimation contest. The participant with the most accurate estimate of the number of pearls in a giant champagne glass won the tidy sum of €100,000. In total, no fewer than 1.2 million people participated over the three years. “For our research, we analysed the three enormous datasets of these promotional campaigns. The data showed that averaging all of the estimates yields significant accuracy gains,” says Van den Assem. “We also looked at the estimates of people who participated multiple times.”

    Wisdom of crowds

    More than a century ago, the famous British scientist Sir Francis Galton researched estimation contests that were very similar to the estimation contest at Holland Casino. At a cattle market, visitors could estimate the slaughter weight of an exhibited ox. Galton examined the estimates made by people and found that, surprisingly, the average estimate differed little from reality. The principle that averaging multiple estimates provides a relatively accurate outcome — often better than most underlying estimates and sometimes even better than all — has come to be known as the Wisdom of Crowds principle. It is an important principle because accurate estimates are crucial for making good decisions.

    Wisdom of inner crowds

    Also interesting and important is the analysis of the estimates from people who participated multiple times. Recently, researchers have suggested that it is also useful to average estimates that come from the same person. Van Dolder and Van den Assem believe that averages from the same person do indeed work, and that therefore ‘wisdom of inner crowds’ also exists.

    This is an attractive idea because it is often easier to make multiple estimates yourself than to involve various other people. For issues that require a high degree of specialised expertise and for private matters, decision-makers, in any case, have to rely on themselves to make the decision. Which holiday will you book? Will you stay with your partner or not? And will you or will you not move to a particular city? The research suggests that, to reach a good decision, it is better to think about it at different times of the day and with a few nights of sleep between each time.

    However, in comparison, the accuracy improves more dramatically when you take the average of estimates from different people: the average of a large number of estimates from the same person is hardly ever better than the average of two estimates from different people. Van Dolder: “For the quality of estimates, it is therefore better if two people are both engaged in the same two projects than when each focuses entirely on an individual project.”

    Two heads really are better than than one, and for good decision making, taking the average of the estimates of various people remains the best approach.


  4. Study suggests mindful yoga can reduce risky behaviors in troubled youth

    December 18, 2017 by Ashley

    From the University of Cincinnati press release:

    For some young people, dealing with life stressors like exposure to violence and family disruption often means turning to negative, risky behaviors — yet little is known about what can intervene to stop this cycle.

    But one long-term study by the University of Cincinnati looks at the link between stressful life events and an increase in substance abuse, risky sexual behaviors and delinquency in a diverse population of 18- to 24-year-old youths. The research also sheds light on distinct coping strategies that can lead to more positive outcomes.

    As part of a 10-year study looking at risk-taking and decision-making — or the lack thereof — Jacinda Dariotis, UC public health researcher, spent 12 months focusing on early life stressors as a predictor of risky sexual behavior, substance abuse and delinquency for more than 125 at-risk youths. Surprisingly, she found a small number of the youths were already engaging in constructive coping behaviors on their own that will have positive outcomes later in life.

    But what about the majority of troubled youth who cope by engaging in negative, risky and dangerous behaviors?

    Results from the most recent segment of Dariotis’ study were presented at the American Public Health Association conference in Atlanta, under the title,”Stress coping strategies as mediators: Toward a better understanding of sexual, substance and delinquency-related risk-taking among transition-aged youth.”

    The study revealed that in spite of early life stressors, positive coping behaviors, either learned or self-generated, can actually have a protective effect.

    “We found that many of these youths who had endured stressful life events and otherwise would have fallen into the risky behavior trap could actually have positive outcomes later in life because they chose to join in prosocial physical activities, yoga or mindfulness meditation,” says Dariotis.

    Risky outlets

    During the study, Dariotis looked at the disconnect between the youths who had intended to have positive influences in their lives but continually found themselves engaged in behaviors that had negative outcomes. She found a link between stressful life events and increased risky unprotected sex, violence and substance abuse.

    “We took a holistic approach, looking at these issues from a social and biological perspective,” says Dariotis, also director of UC’s College of Education, Criminal Justice and Human Services Evaluation Services Center. “In addition to question-and-answer information, we collected urine samples for drug use confirmation and testosterone levels early in the study to see how hormones played out in negative behaviors.”

    According to Dariotis, testosterone can be influential in dominance and aggressive behaviors, but if directed through prosocial behaviors like sports, yoga or healthy competition it can have very positive outcomes.

    “If you are the star on your sports team you are succeeding,” says Dariotis. “You can also be competitive academically where you succeed by competing with your peers.”

    It’s not that testosterone itself is all bad but it depends on how it is channeled, she adds.

    The right track

    Before joining UC as an associate professor of research, Dariotis spent the last decade at Johns Hopkins University gathering most of the data that includes neuroimaging and weekly questioning for hundreds of youth from all walks of life.

    “I’m particularly interested in teaching at-risk youths to regulate their thoughts, processes and emotions,” says Dariotis. “The neuroimaging allows us to see what’s activated in one’s brain while at rest or performing tasks to help us understand the intersection between hormones, brain structure and activity.”

    Dariotis found that at-risk youth who voluntarily spend their time reading books, playing sports or engaged in avoidance coping behaviors were twice as likely to avoid risky sexual behaviors or substance abuse. An example of avoidance coping behaviors, she says, is not thinking about a bad event that had occurred and instead, thinking about what could be better.

    Dariotis found youths who were unable to develop positive coping strategies were much more likely to turn to greater risk-taking behaviors that included unprotected sex or sex for money, substance abuse, violence and crime.

    Saving time, money and lives

    Participating in weekly mindful yoga intervention programs as part of the current study taught the youths how to take control of their breathing and their emotions and helped them develop healthier long-term coping skills.

    “These findings highlight the importance of implementing positive coping strategies for at-risk youth particularly for reducing illicit drug use and risky sexual behavior,” says Dariotis. “Mindfulness-based yoga programs designed to improve the ability to cope are needed at earlier ages in schools to help vulnerable youths channel their skills more effectively.”

    Given the relative low cost of such programs and easy adaptations to different populations and settings, Dariotis says the return on investment may be substantial especially if they can reduce arrests, repeat offenses and other negative outcomes for risk-taking youth.


  5. Study suggests babies can determine the value of a goal from how hard someone works to achieve it

    by Ashley

    From the Massachusetts Institute of Technology press release:

    Babies as young as 10 months can assess how much someone values a particular goal by observing how hard they are willing to work to achieve it, according to a new study from MIT and Harvard University.

    This ability requires integrating information about both the costs of obtaining a goal and the benefit gained by the person seeking it, suggesting that babies acquire very early an intuition about how people make decisions.

    “Infants are far from experiencing the world as a ‘blooming, buzzing confusion,'” says lead author Shari Liu, referring to a description by philosopher and psychologist William James about a baby’s first experience of the world. “They interpret people’s actions in terms of hidden variables, including the effort [people] expend in producing those actions, and also the value of the goals those actions achieve.”

    “This study is an important step in trying to understand the roots of common-sense understanding of other people’s actions. It shows quite strikingly that in some sense, the basic math that is at the heart of how economists think about rational choice is very intuitive to babies who don’t know math, don’t speak, and can barely understand a few words,” says Josh Tenenbaum, a professor in MIT’s Department of Brain and Cognitive Sciences, a core member of the joint MIT-Harvard Center for Brains, Minds and Machines (CBMM), and one of the paper’s authors.

    Tenenbaum helped to direct the research team along with Elizabeth Spelke, a professor of psychology at Harvard University and CBMM core member, in whose lab the research was conducted. Liu, the paper’s lead author, is a graduate student at Harvard. CBMM postdoc Tomer Ullman is also an author of the paper, which appears in the Nov. 23 online edition of Science.

    Calculating value

    Previous research has shown that adults and older children can infer someone’s motivations by observing how much effort that person exerts toward obtaining a goal.

    The Harvard/MIT team wanted to learn more about how and when this ability develops. Babies expect people to be consistent in their preferences and to be efficient in how they achieve their goals, previous studies have found. The question posed in this study was whether babies can combine what they know about a person’s goal and the effort required to obtain it, to calculate the value of that goal.

    To answer that question, the researchers showed 10-month-old infants animated videos in which an “agent,” a cartoon character shaped like a bouncing ball, tries to reach a certain goal (another cartoon character). In one of the videos, the agent has to leap over walls of varying height to reach the goal. First, the babies saw the agent jump over a low wall and then refuse to jump over a medium-height wall. Next, the agent jumped over the medium-height wall to reach a different goal, but refused to jump over a high wall to reach that goal.

    The babies were then shown a scene in which the agent could choose between the two goals, with no obstacles in the way. An adult or older child would assume the agent would choose the second goal, because the agent had worked harder to reach that goal in the video seen earlier. The researchers found that 10-month-olds also reached this conclusion: When the agent was shown choosing the first goal, infants looked at the scene longer, indicating that they were surprised by that outcome. (Length of looking time is commonly used to measure surprise in studies of infants.)

    The researchers found the same results when babies watched the agents perform the same set of actions with two different types of effort: climbing ramps of varying incline and jumping across gaps of varying width.

    “Across our experiments, we found that babies looked longer when the agent chose the thing it had exerted less effort for, showing that they infer the amount of value that agents place on goals from the amount of effort that they take toward these goals,” Liu says.

    The findings suggest that infants are able to calculate how much another person values something based on how much effort they put into getting it.

    “This paper is not the first to suggest that idea, but its novelty is that it shows this is true in much younger babies than anyone has seen. These are preverbal babies, who themselves are not actively doing very much, yet they appear to understand other people’s actions in this sophisticated, quantitative way,” says Tenenbaum, who is also affiliated with MIT’s Computer Science and Artificial Intelligence Laboratory.

    Studies of infants can reveal deep commonalities in the ways that we think throughout our lives, suggests Spelke. “Abstract, interrelated concepts like cost and value — concepts at the center both of our intuitive psychology and of utility theory in philosophy and economics — may originate in an early-emerging system by which infants understand other people’s actions,” she says.

    Modeling intelligence

    Over the past 10 years, scientists have developed computer models that come close to replicating how adults and older children incorporate different types of input to infer other people’s goals, intentions, and beliefs. For this study, the researchers built on that work, especially work by Julian Jara-Ettinger PhD ’16, who studied similar questions in preschool-age children. The researchers developed a computer model that can predict what 10-month-old babies would infer about an agent’s goals after observing the agent’s actions. This new model also posits an ability to calculate “work” (or total force applied over a distance) as a measure of the cost of actions, which the researchers believe babies are able to do on some intuitive level.

    “Babies of this age seem to understand basic ideas of Newtonian mechanics, before they can talk and before they can count,” Tenenbaum says. “They’re putting together an understanding of forces, including things like gravity, and they also have some understanding of the usefulness of a goal to another person.”

    Building this type of model is an important step toward developing artificial intelligence that replicates human behavior more accurately, the researchers say.

    “We have to recognize that we’re very far from building AI systems that have anything like the common sense even of a 10-month-old,” Tenenbaum says. “But if we can understand in engineering terms the intuitive theories that even these young infants seem to have, that hopefully would be the basis for building machines that have more human-like intelligence.”

    Still unanswered are the questions of exactly how and when these intuitive abilities arise in babies.

    “Do infants start with a completely blank slate, and somehow they’re able to build up this sophisticated machinery? Or do they start with some rudimentary understanding of goals and beliefs, and then build up the sophisticated machinery? Or is it all just built in?” Ullman says.

    The researchers hope that studies of even younger babies, perhaps as young as 3 months old, and computational models of learning intuitive theories that the team is also developing, may help to shed light on these questions.


  6. Study suggests neuron-pruning drug may nudge mice away from habit-driven behaviors when combined with retraining

    December 10, 2017 by Ashley

    From the Emory Health Sciences press release:

    A drug that stimulates neuron pruning can nudge mice away from habit-driven behaviors when combined with retraining, neuroscientists have found.

    The results were published online on November 30 by Nature Communications.

    The drug fasudil, approved in Japan for cerebral vasospasm and stroke, inhibits an enzyme that stabilizes cells’ internal skeletons. The researchers suggest that fasudil or similar compounds could be effective tools for facilitating the treatment of drug abuse and preventing relapse.

    A large fraction of the actions people perform each day come from habits, not from deliberate decision making. Going on auto-pilot can free up attention for new things, but it can also be detrimental, in the case of drug abuse and drug-seeking behavior, says lead author Shannon Gourley, PhD, assistant professor of pediatrics, psychiatry and behavioral sciences at Emory University School of Medicine and Yerkes National Primate Research Center.

    “Some habits are adaptive — for example, turning off a light when you exit a room — but others can be maladaptive, for example in the case of habitual drug use. We wanted to try to figure out a way to help ‘break’ habits, particularly those related to the highly-addictive drug cocaine,” says Gourley.

    Gourley and former graduate students Andrew Swanson, PhD and Lauren Depoy, PhD tested fasudil in situations where they had trained mice to poke their noses in two chambers, based on rewards of both food and cocaine. Then the researchers changed the rules of the game. The mice had to learn something new, in terms of where to poke their noses to get the reward.

    In particular, the mice could now only get a reward from one chamber instead of both. Fasudil helped the mice adjust and display “goal-directed” behavior, rather than their previous habit-based behavior.

    In addition, the researchers trained the mice to supply themselves a sweet cocaine solution. Then they changed the nature of that experience: the cocaine was paired with lithium chloride, which made the mice feel sick. Fasudil treatment nudged the mice to give themselves less cocaine afterwards, rather than continuing to respond habitually. The scientists envision this as modeling negative experiences associated with cocaine use in humans.

    “Humans may seek treatment due to the negative consequences of cocaine abuse, but many people still relapse. We’re trying to strengthen the goal of abstaining from drug taking,” says Gourley.

    The researchers conducted additional experiments that revealed that fasudil didn’t make cocaine itself less pleasurable, but was specifically modifying the habit process. Also, fasudil did not affect other forms of decision making.

    Un-learning of habits involves remodeling connections made by cells in the brain. In the mouse retraining experiments, the way that fasudil seems to work is that it promotes the pruning of dendritic spines. Dendritic spines are structures that help neurons communicate and embody the strength of connections between them.

    Fasudil inhibits Rho kinase, which stabilizes F-actin, a major component of cells’ internal skeletons. Thus, it loosens up cell structures. And in mice, fasudil appears to slightly reduce the density of dendritic spines in a region of the brain that is important for learning new behaviors.

    “In this context, we imagine that fasudil is optimizing signal-to-noise, so to speak, allowing this brain region to efficiently guide decision making,” says Gourley.

    When fasudil is given to the mice a day after training, no changes in spine density are seen, indicating that it must be paired with new learning to have that effect.

    Some caution is order, because overactive synaptic pruning is proposed to play roles in Alzheimer’s disease and schizophrenia. In their paper, the authors conclude:

    Pairing Rho kinase inhibitors with cognitive behavioral therapy in humans could be an effective pharmacological adjunct to reduce the rate of relapse… Given its favorable safety profile and our evidence that it can mitigate cocaine self-administration, fasudil is a strong candidate, with the caveats that we envision it administered as an adjunct to behavioral therapy and potentially during early phases of drug withdrawal.


  7. Study suggests stress can lead to risky decisions

    November 28, 2017 by Ashley

    From the Massachusetts Institute of Technology press release:

    Making decisions is not always easy, especially when choosing between two options that have both positive and negative elements, such as deciding between a job with a high salary but long hours, and a lower-paying job that allows for more leisure time.

    MIT neuroscientists have now discovered that making decisions in this type of situation, known as a cost-benefit conflict, is dramatically affected by chronic stress. In a study of mice, they found that stressed animals were far likelier to choose high-risk, high-payoff options.

    The researchers also found that impairments of a specific brain circuit underlie this abnormal decision making, and they showed that they could restore normal behavior by manipulating this circuit. If a method for tuning this circuit in humans were developed, it could help patients with disorders such as depression, addiction, and anxiety, which often feature poor decision-making.

    “One exciting thing is that by doing this very basic science, we found a microcircuit of neurons in the striatum that we could manipulate to reverse the effects of stress on this type of decision making. This to us is extremely promising, but we are aware that so far these experiments are in rats and mice,” says Ann Graybiel, an Institute Professor at MIT and member of the McGovern Institute for Brain Research.

    Graybiel is the senior author of the paper, which appears in Cell on Nov. 16. The paper’s lead author is Alexander Friedman, a McGovern Institute research scientist.

    Hard decisions

    In 2015, Graybiel, Friedman, and their colleagues first identified the brain circuit involved in decision making that involves cost-benefit conflict. The circuit begins in the medial prefrontal cortex, which is responsible for mood control, and extends into clusters of neurons called striosomes, which are located in the striatum, a region associated with habit formation, motivation, and reward reinforcement.

    In that study, the researchers trained rodents to run a maze in which they had to choose between one option that included highly concentrated chocolate milk, which they like, along with bright light, which they don’t, and an option with dimmer light but weaker chocolate milk. By inhibiting the connection between cortical neurons and striosomes, using a technique known as optogenetics, they found that they could transform the rodents’ preference for lower-risk, lower-payoff choices to a preference for bigger payoffs despite their bigger costs.

    In the new study, the researchers performed a similar experiment without optogenetic manipulations. Instead, they exposed the rodents to a short period of stress every day for two weeks.

    Before experiencing stress, normal rats and mice would choose to run toward the maze arm with dimmer light and weaker chocolate milk about half the time. The researchers gradually increased the concentration of chocolate milk found in the dimmer side, and as they did so, the animals began choosing that side more frequently.

    However, when chronically stressed rats and mice were put in the same situation, they continued to choose the bright light/better chocolate milk side even as the chocolate milk concentration greatly increased on the dimmer side. This was the same behavior the researchers saw in rodents that had the prefrontal cortex-striosome circuit disrupted optogenetically.

    “The result is that the animal ignores the high cost and chooses the high reward,” Friedman says.

    Circuit dynamics

    The researchers believe that this circuit integrates information about the good and bad aspects of possible choices, helping the brain to produce a decision. Normally, when the circuit is turned on, neurons of the prefrontal cortex activate certain neurons called high-firing interneurons, which then suppress striosome activity.

    When the animals are stressed, these circuit dynamics shift and the cortical neurons fire too late to inhibit the striosomes, which then become overexcited. This results in abnormal decision making.

    “Somehow this prior exposure to chronic stress controls the integration of good and bad,” Graybiel says. “It’s as though the animals had lost their ability to balance excitation and inhibition in order to settle on reasonable behavior.”

    Once this shift occurs, it remains in effect for months, the researchers found. However, they were able to restore normal decision making in the stressed mice by using optogenetics to stimulate the high-firing interneurons, thereby suppressing the striosomes. This suggests that the prefronto-striosome circuit remains intact following chronic stress and could potentially be susceptible to manipulations that would restore normal behavior in human patients whose disorders lead to abnormal decision making.

    “This state change could be reversible, and it’s possible in the future that you could target these interneurons and restore the excitation-inhibition balance,” Friedman says.


  8. How challenges change the way you think

    November 17, 2017 by Ashley

    From the Frontiers press release:

    Research published today in Frontiers in Behavioral Neuroscience shows that challenging situations make it harder to understand where you are and what’s happening around you. A team of researchers showed participants video clips of a positive, a negative and a neutral situation. After watching the challenging clips — whether positive or negative — the participants performed worse on tests measuring their unconscious ability to acquire information about where and when things happen. This suggests that challenging situations cause the brain to drop nuanced, context-based cognition in favor of reflexive action.

    Previous research suggests that long-term memories formed under stress lack the context and peripheral details encoded by the hippocampus, making false alarms and reflexive reactions more likely. These context details are necessary for situating yourself in space and time, so struggling to acquire them has implications for decision-making in the moment as well as in memory formation.

    The research team, led by Thomas Maran, Marco Furtner and Pierre Sachse, investigated the short-term effects of challenging experiences on acquiring these context details. The team also investigated whether experiences coded as positive produced the same response as those coded as negative.

    “We aimed to make this change measurable on a behavioral level, to draw conclusions on how behavior in everyday life and challenging situations is affected by variations in arousal,” Thomas Maran explains.

    The researchers predicted that study participants would be less able to acquire spatial and sequential context after watching challenging clips, and that their performance would worsen the same way faced with either a positive or a negative clip. To test this, they used clips of film footage used previously to elicit reactions in stress studies: one violent scene (which participants experienced as negative), one sex scene (which participants experienced as positive), and one neutral control scene.

    Immediately after watching the clips, two groups of participants performed tasks designed to test their ability to acquire either spatial or sequential context. Both the sex scene and violent scene disrupted participants’ ability to memorize where objects had been and notice patterns in two different tasks, compared to the neutral scene. This supports the hypothesis that challenging situations — positive or negative — cause the brain to drop nuanced, context-based cognition in favor of reflexive action.

    So if challenging situations decrease the ability to pick up on context cues, how does this happen? The researchers suggest that the answer may lie in the hippocampus region of the brain — although they caution that since no neurophysiological techniques were applied in this study, this can’t be proven. Since existing evidence supports the idea that the hippocampus is deeply involved in retrieving and reconstructing spatial and temporal details, downgrading this function when faced with a potentially dangerous situation could stop this context acquisition and achieve the effect seen in this behavioral study. Reflexive reactions are less complex and demanding, and might stop individuals from making decisions based on unreliable information from unpredictable surroundings.

    Changes in cognition during high arousal states play an important role in psychopathology,” Thomas Maran explains, outlining his hopes for the future use of this research. He considers that the evidence provided by this study may have important therapeutic and forensic applications. It also gives a better basis for understanding reactions to challenging situations — from witnessing a crime to fighting on a battlefield — and the changes in the brain that make those reactions happen.


  9. Modeling social interactions to improve collective decision-making

    November 16, 2017 by Ashley

    From the CNRS press release:

    How are we affected by other peoples’ opinions? To answer this question, scientists[1] at the CNRS, Inra and Université Toulouse 1 Capitole conducted a study in France and Japan, quantifying this impact on our decisions. They identified five behaviors common to both countries: a majority of subjects make a compromise between their opinion and that of others (59% of people in France), some hold to their opinion (29% in France), whereas others follow faithfully, amplify or contradict the information they receive. The study also shows how social information can help a group collectively improve its performance and the precision of its estimates. From this analysis, a model has been developed that reproduces the results of the study and predicts the performance of a group depending on the amount and quality of information exchanged between its members. The long-term goal would be to develop algorithms for decision-making support tools. The results of this study were published on November 6, 2017 in PNAS.

    The fast growth of digital technologies and content availability is making us interact more with others. Increasingly, social networks are becoming important sources of information that we choose to take account of or ignore. Many e-commerce sites make extensive use of review and scoring systems, which allow their customers to use the opinions of others to make their own choices. Without even considering false information, that is sometimes difficult to detect, we are each exposed to too much information to process it correctly every time.

    These observations call for the development of tools to help in collective decision-making, which could assist with processing information and making decisions in a group that uses social interactions. The group of researchers involved in the study focused on the impact of social information, i.e., the way that others affect what we do. Under what conditions can this social information increase the effectiveness of our collective decision-making?

    The experiments involved 186 people in France and 180 in Japan. Each participant had to estimate values, such as Gandhi’s age when he died, or the number of stars in our galaxy, and give a degree of confidence in their answer. After the first stage, the average of the previous participants’ responses — the social information-was given to them, and the subject had to reply again to give a final estimate. One of the unique features of this study is the introduction of virtual agents who were controlled by the researchers without the knowledge of the participants — and always gave the correct answer. These agents, whose number varied, therefore favorably influenced the social information sent to subjects.

    This work shows how social information leads the group to collectively improve its performance and the precision of its estimations. It can also accurately measure how sensitive subjects are to social information. The researchers identified five sensitivity profiles that are independent of cultural bias, because they are present in both countries. In France, an analysis of almost 11,000 responses shows that 29% of the people sampled hold to their opinion, 4% strictly follow the information given to them, and 59% find a compromise between their initial opinion and the social information. Thinking that the rest of the group has, the same way as they did, underestimated their initial response, 6% of people amplify the social information received. Finally, 2% end up contradicting their own estimation and that of the group, most often without being able to justify their decision. In addition, the further a participant’s personal feeling is from the social information received, the more sensitive this subject is to the information. In another more surprising result, the scientists have shown that the performance of a group may be improved by a limited quantity of incorrect information, which compensates for a human cognitive bias that underestimates quantities.

    Based on these experiments, a mathematical model has been developed. It faithfully reproduces the social information sensitivity mechanisms observed experimentally and predicts the impact of the amount and quality of information exchanged between the individuals in a group on their collective performance. A better understanding of the governing processes of how social information influences individual choices and collective information opens new perspectives. Personalized algorithms could be developed to anticipate the different types of answers according to the form of social information received. This could contribute to improving cooperation and collaboration on the scale of groups.

    Note:

    [1] The French laboratories involved in this study:

    The Centre de recherches sur la cognition animale (CNRS/Université Toulouse III — Paul Sabatier)

    The Laboratoire de physique théorique (CNRS/Université Toulouse III — Paul Sabatier)

    TSE Recherche (CNRS/Université Toulouse 1 Capitole/INRA/EHESS) a Toulouse school of economics laboratory


  10. Study suggests spending decisions are influenced by adaptation in neural circuits

    November 12, 2017 by Ashley

    From the Washington University School of Medicine press release:

    The British have a pithy way of describing people who dither over spending 20 cents more for premium ice cream but happily drop an extra $5,000 for a fancier house: penny wise and pound foolish.

    Now, a new study suggests that being penny wise and pound foolish is not so much a failure of judgment as it is a function of how our brains tally the value of objects that vary widely in worth.

    Researchers at Washington University School of Medicine in St. Louis have found that when monkeys are faced with a choice between two options, the firing of neurons activated in the brain adjusts to reflect the enormity of the decision. Such an approach would explain why the same person can see 20 cents as a lot one moment and $5,000 as a little the next, the researchers said.

    “Everybody recognizes this behavior, because everybody does it,” said senior author Camillo Padoa-Schioppa, PhD, an associate professor of neuroscience, of economics and of biomedical engineering. “This paper explains where those judgments originate. The same neural circuit underlies decisions that range from a few dollars to hundreds of thousands of dollars. We found that a system that adapts to the range of values ensures maximal payoff.”

    The study is available online in Nature Communications.

    While you are contemplating whether to order a scoop of vanilla or strawberry ice cream, a part of your brain just above the eyes is very busy. Brain scans have shown that blood flow to a brain area known as the orbitofrontal cortex increases as people weigh their options.

    Neurons in this part of the brain also become active when a monkey is faced with a choice. As the animal tries to decide between a sip of, say, apple juice or grape juice, two sets of neurons in its orbitofrontal cortex fire off electrical pulses. One set reflects how much the monkey wants apple juice; the other set corresponds to the animal’s interest in grape juice. The faster the neurons fire, the more highly the monkey values that option.

    A similar process likely occurs as people make decisions, the researchers said. But what happens to firing rates when a person stops thinking about ice cream and starts thinking about houses? A house might be hundreds of thousands of times more valuable than a cup of ice cream, but neurons cannot fire pulses 100,000 times faster. The speed at which they can fire maxes out at about 500 spikes per second.

    To find out how neurons cope with different values, Padoa-Schioppa and colleagues repeatedly gave monkeys a choice between two juices, offered in the range of 0 to 2 drops. After a break, the same two juices were offered in the range of 0 to 10 drops. The researchers recorded which neurons were active — and how quickly they were firing — as the monkeys made their choices.

    The researchers discovered that the neurons’ firing rates reset between the two sessions. In the first session the maximum firing rate corresponded to the option of two drops of juice, and in the second it corresponded to 10 drops of juice. In other words, the same change in how rapidly the neuron fired corresponded to a fine distinction in value when the range was narrow, and a coarse distinction when the range was broad.

    “As we adapt to large values, we lose some ability to consider smaller values,” Padoa-Schioppa said. “This is why salesmen try so hard to sell you upgrades when you’re buying a car. Spending $100 to add on a radio seems like no big deal if you’re already spending $20,000 on a car. But if you already have a car and you are thinking of spending $100 for a radio, suddenly it seems like a lot. They know that people don’t come back and buy the radio later.”

    While having adaptable neurons allows us effectively to shop for items ranging in value from groceries to cars to houses, it does introduce a theoretical quirk: It should be possible to change someone’s preferences simply by adjusting the range of each option. For example, by offering a large range of apple juice and a small range of grape juice, the researchers could make a drop of apple juice look less valuable than a drop of grape juice, convincing an apple-loving monkey to select grape juice instead.

    When they changed the ranges of the juices, however, the researchers found that the monkeys did not fall for it. Apple-loving monkeys continued to choose apple juice.

    The researchers concluded that making a choice between two juices is not a simple matter of comparing the firing rates of the apple-juice neurons to the firing rates of the grape-juice neurons. Instead, neurons pegged to each option feed into a neural circuit that processes the data and corrects for differences in scale.

    It’s a system optimized for making the best possible choice — the one that reflects true preferences over a vast range of values, even though some detail gets lost at the higher end.

    “It was a puzzle: How does the brain handle this enormous variability?” said Padoa-Schioppa. “We showed that a circuit that has adaptation and corrects for it ensures maximal payoff. And these findings have implications for understanding why people make the choices they do. There’s a good neurological reason for behavior that might seem illogical.”