Thursday, April 30, 2009

Features of Einstein's brain.

Clips from Michael Balter's recent report:

The first anatomical study of Einstein's brain was published in 1999, by a team led by Sandra Witelson, a neurobiologist at McMaster University in Hamilton, Canada..Witelson's team found that Einstein's parietal lobes--which are implicated in mathematical, visual, and spatial cognition--were 15% wider than normal parietal lobes...One parameter that did not explain Einstein's mental prowess, however, was the size of his brain: At 1230 grams, it fell at the low end of average for modern humans. Now Dean Falk, an anthropologist at Florida State University in Tallahassee...claims to have identified a number of previously unrecognized unusual features in Einstein's brain. They include a pronounced knoblike structure in the part of the motor cortex that controls the left hand; in other studies, similar "knobs" have been associated with musical ability. (Einstein had played the violin avidly since childhood.)

Like Witelson's team, Falk found that Einstein's parietal lobes were larger; comparing the photographs of Einstein's brain with a second previously published set of 58 control brains, Falk also identified a very rare pattern of grooves and ridges in the parietal regions of both sides of the brain that she speculates might somehow be related to Einstein's superior ability to conceptualize physics problems. Indeed, during his lifetime, Einstein often claimed that he thought in images and sensations rather than in words. Falk speculates that Einstein's talent as "a synthetic thinker" may have arisen from the unusual anatomy of his parietal cortex.

Juicing up your brain

"Every era has its defining drug. Neuroenhancers are perfectly suited for our efficiency-obsessed, BlackBerry-equipped office culture." Margaret Talbot writes an interesting article on the underground world of performance enhancing drugs in the New Yorker, covering benefits and pitfalls. Given that chemicals enhancing our sex life and beauty are commonly taken, it is not surprising that there is growing use of drugs enhancing our smarts.

Wednesday, April 29, 2009

The emerging bottom-up world order?

Two interesting articles on the kind of world order (or disorder) that is likely to emerge in the 21st century. David Brooks notes that:

We face a series of decentralized, transnational threats: jihadi terrorism, a global financial crisis, global warming, energy scarcity, nuclear proliferation and...possible health pandemics like swine flu...Do we build centralized global institutions that are strong enough to respond to transnational threats? Or do we rely on diverse and decentralized communities and nation-states?..The response to swine flu suggests that a decentralized approach is best. This crisis is only days old, yet we’ve already seen a bottom-up, highly aggressive response.

First, the decentralized approach is much faster. Mexico responded unilaterally and aggressively to close schools and cancel events. The U.S. has responded with astonishing speed, considering there are still few illnesses and just one hospitalization...Second, the decentralized approach is more credible. It is a fact of human nature that in times of crisis, people like to feel protected by one of their own. They will only trust people who share their historical experience, who understand their cultural assumptions about disease and the threat of outsiders and who have the legitimacy to make brutal choices...Finally, the decentralized approach has coped reasonably well with uncertainty. It is clear from the response, so far, that there is an informal network of scientists who have met over the years and come to certain shared understandings about things like quarantining and rates of infection.

A single global response would produce a uniform approach. A decentralized response fosters experimentation...The correct response to these dynamic, decentralized, emergent problems is to create dynamic, decentralized, emergent authorities: chains of local officials, state agencies, national governments and international bodies that are as flexible as the problem itself.
Kakutani reviews "The Age of the Unthinkable" by J. C. Ramo. Ramo argues:
that today’s complex, interconnected, globalized world requires policy makers willing to toss out old assumptions (about cause and effect, deterrence and defense, nation states and balances of power) and embrace creative new approaches...The central image that Mr. Ramo uses to evoke what he calls this “age of surprise” is Per Bak’s sand pile — that is, a sand pile described some two decades ago by the Danish-American physicist Per Bak, who argued that if grains of sand were dropped on a pile one at a time, the pile, at some point, would enter a critical state in which another grain of sand could cause a large avalanche — or nothing at all. It’s a hypothesis that shows that a small event can have momentous consequences and that seemingly stable systems can behave in highly unpredictable ways...It’s also a hypothesis that Mr. Ramo employs as a metaphor for a complex world in which changes — in politics, ecosystems or financial markets — take place not in smooth, linear progressions but as sequences of fast, sometimes catastrophic events.

So how should leaders cope with the sand-pile world? How can they learn to “ride the earthquake” and protect their countries from the worst fallout of such tremors? Mr. Ramo suggests that they must learn to build resilient societies with strong immune systems: instead of undertaking the impossible task of trying to prepare for every possible contingency, they ought to focus on things like national health care, construction of a better transport infrastructure and investment in education...leaders should develop ways of looking at problems that focus more on context than on reductive answers. And he talks about people learning to become gardeners instead of architects, of embracing Eastern ideas of indirection instead of Western patterns of confrontation, of seeing “threats as systems, not objects.”

Born to be Good

I have just thoroughly enjoyed a reading of Dacher Keltner's book "Born to be Good." Keltner, a former student of Paul Ekman, starts with Darwin's acute observations on human emotions, describes Ekman's pioneering work on innate human facial communication, and then proceeds through chapters on embarassment, smiling, laughing, teasing, touching, compassion and awe. He documents work of his own and others that demonstrates evolved stereotyped facial and body movement patterns characteristic of each of these behaviors. The video is a brief promo of the book.

The quest for compassion

Greg Miller writes (PDF here) on the establishment of a new institute at Stanford University for the scientific study of compassion.

Tuesday, April 28, 2009

Enlightenment therapy?

I found myself disappointed by what at first appeared to be a promising article in this past Sunday’s NY Times magazine: “Enlightenment Therapy” by Chip Brown. It relates the interaction of a 63-year old professor who renounced a tenured professorship in philosophy to become a Zen Buddhist monk 35 years ago and a psychotherapist who has published a series of books on psychotherapy and Buddhism. A detailed account of the professor’s childhood traumas, and their effect on his adult life, is given, but it seems a pity that the article is almost completely lacking in any broader reference to other religious figures and psychiatrists (Alan Wallace and Mark Epstein come to mind) who have been very influential in integrating Buddhist and Psychoanalytic insights. Even more puzzling is the absence of reference to discoveries in cognitive neuroscience that validate the insights of both traditions (noted by integrative writers such as philosopher Thomas Metzinger and trade writer Alan Nisker).

Econophysics - a model that explains the crash

I thought I would pass on this report by Cho, slightly edited, on a model that shows leverage to be the root of the current financial turmoil:

During the 1990s, physicists flocked to Wall Street and other financial hubs, eager to turn their analytical skills and phenomenological mindset to the problem of making a killing. Now that the world's stock markets are in retreat, they've turned to explaining why markets crash. According to one new analysis, leverage—the practice by hedge funds and other investors of borrowing money to buy investments—is the root of many nettlesome properties of financial markets that classical economics cannot explain, including a propensity to crash.

Given that in the buildup to the recent global economic meltdown hedge funds had been leveraging their deals by ratios of 30-to-1 (that is, borrowing $30 for every $1 of their own that they put in), it may seem obvious that massive leverage leads to trouble. But Stefan Thurner, an econophysicist and director of the complex systems research group at the Medical University of Vienna, Austria, and colleagues say their model shows that many of the distinctive statistical properties of financial markets emerge together as rates of leverage climb.

Financial markets behave in ways that... classical economic theory cannot explain. Classical economics assumes that the fluctuations in stock prices conform to a so-called Gaussian distribution—a bell curve that gives little probability to large swings. In reality, the distribution has "fat tails" that make big changes more likely, and the shapes of those tails conform to a mathematical formula known as a power law. Classical economics assumes that the fluctuations are uncorrelated from one moment to the next, whereas big swings in prices tend to come together in the so-called clustering of volatility.

To try to explain those characteristics, over the past 5 years Thurner and colleagues have developed an "agent-based model" of a market. In such a computer model, virtual agents of various types interact according to certain rules, like robots playing a game. The researchers included hedge funds that could borrow to make their investments; banks to loan the money; "noise investors" who, like day traders, simply react to the market and have no other insight into the value of assets; and general investors who played the role of, for example, state pension funds.

The model contains more than a dozen adjustable parameters. However, Thurner and colleagues found that the maximum level of leverage exerts a curious, unifying effect. If they forbade leverage, the market behaved largely as classical economics would predict. But as they increased the maximum leverage, the characteristics of real markets emerged together. "We can explain the fat tails, the right [power law], the clustering of volatility, all this," Thurner says. And when the leverage limit climbed to levels of 5-to-1 and beyond, the market became unstable and hedge funds went bust much more often.

Thurner, who managed a hedge fund that tanked, says that limiting leverage should help prevent crashes. He admits, however, that he would not have embraced that idea when the market was still going strong.

Monday, April 27, 2009

Childhood poverty, chronic stress, and adult working memory

Sobering observations from Evans and Schaumberg presented in an open access article in PNAS:

The income–achievement gap is a formidable societal problem, but little is known about either neurocognitive or biological mechanisms that might account for income-related deficits in academic achievement. We show that childhood poverty is inversely related to working memory in young adults. Furthermore, this prospective relationship is mediated by elevated chronic stress during childhood. Chronic stress is measured by allostatic load, a biological marker of cumulative wear and tear on the body that is caused by the mobilization of multiple physiological systems in response to chronic environmental demands.

Failure to find effect of estrogen or testosterone on economic behavior.

Zethraeus et al.(open access) obtain a result that is contrary to expectations generated by previous studies:

Existing correlative evidence suggests that sex hormones may affect economic behavior such as risk taking and reciprocal fairness. To test this hypothesis we conducted a double-blind randomized study. Two-hundred healthy postmenopausal women aged 50–65 years were randomly allocated to 4 weeks of treatment with estrogen, testosterone, or placebo. At the end of the treatment period, the subjects participated in a series of economic experiments that measure altruism, reciprocal fairness, trust, trustworthiness, and risk attitudes. There was no significant effect of estrogen or testosterone on any of the studied behaviors.

Saturday, April 25, 2009

The sapient paradox

Merlin Donald has written a series of fascinating books on the emergence of modern humans, one of which I used extensively as a reference in my "Biology of Mind" book. He now reviews a special issue of the Proceedings of the Royal Society devoted to a conference at the Univ. of Cambridge titled ‘Archaeology meets neuroscience’. His review (PDF here) is well worth reading.

A major link between archaeology and neuroscience is provided by cognitive science, which has a foot in both camps. Some aspects of cognition, such as literacy, mathematics and music are obviously cultural in origin. Others, such as attention, perception and action stem directly from the design of the central nervous system. These two influences, brain and culture, work together in forming human cognition, and cognitive scientists find themselves in the position of having to explain many of the higher cognitive capabilities of human beings in terms of hybrid brain-culture mechanisms. Evolutionary models are one important way of ordering the evidence on hybrid mechanisms, and epigenetic factors may prove to be paramount in this process.

The ‘sapient paradox’ refers to a puzzle that has been a thorn in the side of prehistory researchers for some time. There seems to have been a long — in fact, inordinately long — delay between the emergence of anatomically modern humans and our later cultural flowering. Both genetic and archaeological evidence converge on the conclusion that the ‘speciation’ phase of sapient humans occurred in Africa at least 70 000–100 000 years BP, and possibly earlier, and all modern humans are descended from those original populations...a later period, extending from 10 000 years ago to the present, is referred to as the ‘tectonic’ phase. This has been a period of greatly accelerated change, stepping relatively quickly through several different levels of social and material culture, including the domestication of plants and animals, sedentary societies, cities and advanced metallurgy. It has culminated in many recent changes, giving us dramatic innovations, such as skyscrapers, atomic energy and the internet. The paradox is that there was a gap of well over 50 000 years between the speciation and tectonic phases. The acceleration of recent cultural change is especially puzzling when viewed in the light of the hundreds of thousands of years it took our ancestors to master fire, stone tool making and coordinated seasonal hunting.
Merlin's review succinctly summarizes the views of conference contributors on these issues.

Risk and reward processing in different prefrontal areas

More information from Bechara and collaborators on how decisions are parceled out within the prefrontal cortex:

Making a risky decision is a complex process that involves evaluation of both the value of the options and the associated risk level. Yet the neural processes underlying these processes have not so far been clearly identified. Using functional magnetic resonance imaging and a task that simulates risky decisions, we found that the dorsal region of the medial prefrontal cortex (MPFC) was activated whenever a risky decision was made, but the degree of this activity across subjects was negatively correlated with their risk preference. In contrast, the ventral MPFC was parametrically modulated by the received gain/loss, and the activation in this region was positively correlated with an individual's risk preference. These results extend existing neurological evidence by showing that the dorsal and ventral MPFC convey different decision signals (i.e., aversion to uncertainty vs. approach to rewarding outcomes), where the relative strengths of these signals determine behavioral decisions involving risk and uncertainty.

Friday, April 24, 2009

Can evolution explain how minds work?

Some clips from an essay in Nature Magazine by Bolhuis and Wynne:

....biologists have tended to assume that species with shared ancestry will have similar cognitive abilities, and that the evolutionary history of traits can be used to reveal how we and other animals perform certain mental tasks. A closer analysis suggests things aren't so simple.

...Over the past two decades, researchers have reported that chimpanzees can empathize with other members of their species, and that they reconcile and even console each other after conflicts. Monkeys and apes have been credited with a sense of fairness and aversion to inequity and, in the case of apes, an awareness of the mental states of others — in other words, a theory of mind. A closer look at many of these studies reveals, however, that appropriate control conditions have often been lacking, and simpler explanations overlooked in a flurry of anthropomorphic overinterpretation. For instance, capuchin monkeys were thought to have a sense of fairness because they reject a slice of cucumber if they see another monkey in an adjacent cage, performing the same task, rewarded with a more-sought-after grape. Researchers interpreted a monkey's refusal to eat the cucumber as evidence of 'inequity aversion' prompted by seeing another monkey being more generously rewarded. Yet, closer analysis has revealed that a monkey will still refuse cucumber when a grape is placed in a nearby empty cage. This suggests that the monkeys simply reject lesser rewards when better ones are available.

...Laboratory studies of a number of species performing a wide range of tasks indicate that different species may have arrived at similar solutions to cognitive problems because they have experienced similar selection pressures, not because they are closely related. In other words, evolutionary convergence may be more important than common descent in accounting for similar cognitive outcomes in different animal groups.

...For example, we now know that birds are capable of feats that match or even exceed those reported in monkeys and apes. Rooks, for example, rub their bills together after one of them has been involved in a confrontation with another bird. Equivalent stroking and embracing in chimpanzees would be labelled 'consolation'. The self-directed pecking that magpies show when they are put in front of a mirror after a mark has been placed on their body is similar to the reactions seen in apes given the same treatment. In magpies, this behaviour has been interpreted as evidence for some degree of self-recognition. But in apes, the same behaviour has been thought to indicate a deeper level of self-consciousness. Caledonian crows outperform monkeys in their ability to retrieve food from a trap tube — from which food can be accessed only at one end. The crows can also work out how to use one tool to obtain a second with which they can retrieve food, a skill that monkeys and apes struggle to master.

...Researchers have tried for decades to teach apes some form of language, be it by using visual symbols or gestures. But linguists generally agree that the resulting efforts made by chimps and bonobos don't qualify as language. One of the prerequisites for language is being able to imitate sounds that are created by someone else. Our primate cousins show no inclination to do this. Yet many parrots and songbirds are striking vocal mimics. Furthermore, the way that they learn to sing is not unlike how human infants learn to speak. Both children and the chicks of parrots and songbirds learn many of their vocalizations during a sensitive period early in life. They also undergo a transitional period during which their attempts to speak or sing increasingly come to resemble those of adults. Recent studies even suggest that starlings can identify certain syntactic features of sound patterns that non-human primates miss.

The appearance of similar abilities in distantly related species, but not necessarily in closely related ones, illustrates that cognitive traits cannot be neatly arranged on an evolutionary scale of relatedness.

Cortical thinning in people with familial risk for major depression

From Peterson et al:

The brain disturbances that place a person at risk for developing depression are unknown. We imaged the brains of 131 individuals, ages 6 to 54 years, who were biological descendants (children or grandchildren) of individuals identified as having either moderate to severe, recurrent, and functionally debilitating depression or as having no lifetime history of depression. We compared cortical thickness across high- and low-risk groups, detecting large expanses of cortical thinning across the lateral surface of the right cerebral hemisphere in persons at high risk. Thinning correlated with measures of current symptom severity, inattention, and visual memory for social and emotional stimuli. Mediator analyses indicated that cortical thickness mediated the associations of familial risk with inattention, visual memory, and clinical symptoms. These findings suggest that cortical thinning in the right hemisphere produces disturbances in arousal, attention, and memory for social stimuli, which in turn may increase the risk of developing depressive illness.

Thursday, April 23, 2009

The Green Brain

I would recommend reading Jon Gertner's article "Why isn't the Brain Green?" (In the same issue of the New York Times Magazine, Paul Bloom's article is also worth a look). I give just a few clips below, in which Gertner writes on the psychology of environmentalism, starting by noting a meeting at the Center for Research on Environmental Decisions.

A branch of behavioral research situated at the intersection of psychology and economics, decision science focuses on the mental proces­ses that shape our choices, behaviors and attitudes. The field’s origins grew mostly out of the work, beginning in the 1970s, of Daniel Kahneman and Amos Tversky, two psychologists whose experiments have demonstrated that people can behave unexpectedly when confronted with simple choices. We have many automatic biases — we’re more averse to losses than we are interested in gains, for instance — and we make repeated errors in judgment based on our tendency to use shorthand rules to solve problems. We can also be extremely susceptible to how questions are posed. Would you undergo surgery if it had a 20 percent mortality rate? What if it had an 80 percent survival rate? It’s the same procedure, of course, but in various experiments, responses from patients can differ markedly.

...where nearly all dollars for climate investigation are directed toward physical or biological projects, the notion that vital environmental solutions will be attained through social-science research — instead of improved climate models or innovative technologies — is an aggressively insurgent view.
But in fact,
...climate change is anthropogenic...More or less, people have agreed on that. That means it’s caused by human behavior. That’s not to say that engineering solutions aren’t important. But if it’s caused by human behavior, then the solution probably also lies in changing human behavior.

...Cognitive psychologists now broadly accept that we have different systems for processing risks. One system works analytically, often involving a careful consideration of costs and benefits. The other experiences risk as a feeling: a primitive and urgent reaction to danger, usually based on a personal experience, that can prove invaluable when (for example) we wake at night to the smell of smoke.

There are some unfortunate implications here. In analytical mode, we are not always adept at long-term thinking; experiments have shown a frequent dislike for delayed benefits, so we undervalue promised future outcomes. (Given a choice, we usually take $10 now as opposed to, say, $20 two years from now.) Environmentally speaking, this means we are far less likely to make lifestyle changes in order to ensure a safer future climate. Letting emotions determine how we assess risk presents its own problems. Almost certainly, we underestimate the danger of rising sea levels or epic droughts or other events that we’ve never experienced and seem far away in time and place.

...we have a “finite pool of worry,” which means we’re unable to maintain our fear of climate change when a different problem — a plunging stock market, a personal emergency — comes along. We simply move one fear into the worry bin and one fear out. And even if we could remain persistently concerned about a warmer world? We have a “single-action bias.” Prompted by a distressing emotional signal, we buy a more efficient furnace or insulate our attic or vote for a green candidate — a single action that effectively diminishes global warming as a motivating factor.

...Increasing personal evidence of global warming and its potentially devastating consequences can be counted on to be an extremely effective teacher and motivator...emotional and experiential feelings of risk are superb drivers of action. Unfortunately, such lessons may arrive too late for corrective action.

Music and the brain - rhythm and pleasure

Two PNAS articles I have been meaning to mention deal with an apparently innate sense of rhythm in infants, and how pleasing music activates brain regions implicated in reward. First, an open access article from Winkler et al on infants:

To shed light on how humans can learn to understand music, we need to discover what the perceptual capabilities with which infants are born. Beat induction, the detection of a regular pulse in an auditory signal, is considered a fundamental human trait that, arguably, played a decisive role in the origin of music. Theorists are divided on the issue whether this ability is innate or learned. We show that newborn infants develop expectation for the onset of rhythmic cycles (the downbeat), even when it is not marked by stress or other distinguishing spectral features. Omitting the downbeat elicits brain activity associated with violating sensory expectations. Thus, our results strongly support the view that beat perception is innate.
Also, Blood and Zatorre on brain imaging during experiencing pleasurable music:
We used positron emission tomography to study neural mechanisms underlying intensely pleasant emotional responses to music. Cerebral blood flow changes were measured in response to subject-selected music that elicited the highly pleasurable experience of “shivers-down-the-spine” or “chills.” Subjective reports of chills were accompanied by changes in heart rate, electromyogram, and respiration. As intensity of these chills increased, cerebral blood flow increases and decreases were observed in brain regions thought to be involved in reward/motivation, emotion, and arousal, including ventral striatum, midbrain, amygdala, orbitofrontal cortex, and ventral medial prefrontal cortex. These brain structures are known to be active in response to other euphoria-inducing stimuli, such as food, sex, and drugs of abuse. This finding links music with biologically relevant, survival-related stimuli via their common recruitment of brain circuitry involved in pleasure and reward.

Wednesday, April 22, 2009

A bird that follows human eye movements.

Interesting observations from von Bayern and Emery. They offered food to hand-raised jackdaws. The birds took longer to nab a proffered nibble if the food was the subject of a stranger's stare, and they seemed to be watching the eyes rather than the direction of the head (see variations of head and eye attitudes, pictured). In a separate experiment, the birds needed moving, rather than static, eye signals from a familiar person to understand communication about the location of hidden food. They speculate that jackdaws evolved this eye-following ability to interact with one another. However, they add that the birds followed by the study have spent their whole lives with humans.:

Humans communicate their intentions and disposition using their eyes, whereas the communicative function of eyes in animals is less clear. Many species show aversive reactions to eyes, and several species gain information from conspecifics' gaze direction by automatically co-orienting with them. However, most species show little sensitivity to more subtle indicators of attention than head orientation and have difficulties using such cues in a cooperative context. Recently, some species have been found responsive to gaze direction in competitive situations. We investigated the sensitivity of jackdaws, pair-bonded social corvids that exhibit an analogous eye morphology to humans, to subtle attentional and communicative cues in two contexts and paradigms. In a conflict paradigm, we measured the birds' latency to retrieve food in front of an unfamiliar or familiar human, depending on the state and orientation of their eyes toward food. In a cooperative paradigm, we tested whether the jackdaws used familiar human's attentional or communicative cues to locate hidden food. Jackdaws were sensitive to human attentional states in the conflict situation but only responded to communicative cues in the cooperative situation. These findings may be the result of a natural tendency to attend to conspecifics' eyes or the effect of intense human contact during socialization.

Chimps exchange meat for sex

Evolutionary origin of the upscale date at Ruths' Chris Steakhouse meant to impress your girlfriend? From Gomes and Boesch:

Humans and chimpanzees are unusual among primates in that they frequently perform group hunts of mammalian prey and share meat with conspecifics. Especially interesting are cases in which males give meat to unrelated females. The meat-for-sex hypothesis aims at explaining these cases by proposing that males and females exchange meat for sex, which would result in males increasing their mating success and females increasing their caloric intake without suffering the energetic costs and potential risk of injury related to hunting. Although chimpanzees have been shown to share meat extensively with females, there has not been much direct evidence in this species to support the meat-for-sex hypothesis. Here we show that female wild chimpanzees copulate more frequently with those males who, over a period of 22 months, share meat with them. We excluded other alternative hypotheses to exchanging meat for sex, by statistically controlling for rank of the male, age, rank and gregariousness of the female, association patterns of each male-female dyad and meat begging frequency of each female. Although males were more likely to share meat with estrous than anestrous females given their proportional representation in hunting parties, the relationship between mating success and sharing meat remained significant after excluding from the analysis sharing episodes with estrous females. These results strongly suggest that wild chimpanzees exchange meat for sex, and do so on a long-term basis. Similar studies on humans will determine if the direct nutritional benefits that women receive from hunters in foraging societies could also be driving the relationship between reproductive success and good hunting skills.

Tuesday, April 21, 2009

Link between brain anatomy, personality, and the placebo analgesic response

As a companion to today's first post, on motivation, a note that Schweinhardt et al. provide some interesting correlations between personality traits related to dopaminergic neurotransmission (novelty seeking, harm avoidance (inversely related), behavioral drive, fun seeking, and reward responsiveness.), size of the mesolimbic reward system, and the effectiveness of the placebo effect:

The anticipation of clinical benefit, a crucial component of placebo analgesia, has been suggested to be a special case of reward anticipation. Since reward processing is closely linked to the ventral striatum and the neurotransmitter dopamine, we examined the relationships between brain gray matter, placebo analgesic response, and personality traits associated with dopaminergic neurotransmission. We report that dopamine-related traits predict a substantial portion of the pain relief an individual gains from a sham treatment. Voxel-based morphometry of magnetic resonance images shows that the magnitude of placebo analgesia is related to gray matter density (GMD) in several brain regions, including the ventral striatum, insula, and prefrontal cortex. Similarly, GMD in ventral striatum and prefrontal cortex is related to dopamine-related personality traits. Our findings highlight the relationship between placebo and reward and potentially offer ways of identifying subjects who are likely to show large placebo analgesic responses.


The shoplifting "high"

I pass on this tidbit from the random samples section of science magazine:

For compulsive shoplifters, covertly pinching a lipstick or a blouse brings a rush "similar to a cocaine or heroin high," says Jon Grant, a psychiatrist at the University of Minnesota School of Medicine in Minneapolis. That's why some psychiatrists prescribe naltrexone, a drug used to treat addicts, for the problem.

Naltrexone blocks the same brain receptors used by opioids, but there's little published evidence about its effectiveness in treating kleptomania. Now, in the April issue of Biological Psychiatry, Grant and colleagues report the first placebo-controlled trial of any drug against the disorder.

Subjects were 25 kleptomaniacs aged 17 to 65, 18 of them women. Almost all had been arrested for shoplifting at least once. For 8 weeks, half were given naltrexone daily and the rest a placebo. "Two-thirds of those on naltrexone had complete remission of their symptoms," says Grant. Psychiatrist Samuel Chamberlain of the University of Cambridge in the U.K. says the results "suggest that the brain circuits involved in compulsive stealing overlap with those involved in addictions more broadly." Grant hopes to get funding for a larger study.

Monday, April 20, 2009

The power of positive thinking.

Following up on experiments I mentioned in a previous post in 2006, Cohen et al. provide an example of how recursive positive feedback cycles can generate a self-perpetuating pattern of behavior. They performed a multiyear field experiment in which three cohorts of 7th-grade students were given seemingly gentle interventions--a brief writing assignment on personal values--several times throughout their 7th- and 8th-grade school years. Poorly performing African American students who had been assigned to write about self-affirmation displayed significantly smaller declines in their grades than those who had written about someone else's values; the intervention had no effect on the grade trends of highly performing African American or European American students. The intervention appeared to help to prevent the poorly performing group from falling into a cycle of negativity. Their abstract:

A subtle intervention to lessen minority students' psychological threat related to being negatively stereotyped in school was tested in an experiment conducted three times with three independent cohorts (N = 133, 149, and 134). The intervention, a series of brief but structured writing assignments focusing students on a self-affirming value, reduced the racial achievement gap. Over 2 years, the grade point average (GPA) of African Americans was, on average, raised by 0.24 grade points. Low-achieving African Americans were particularly benefited. Their GPA improved, on average, 0.41 points, and their rate of remediation or grade repetition was less (5% versus 18%). Additionally, treated students' self-perceptions showed long-term benefits. Findings suggest that because initial psychological states and performance determine later outcomes by providing a baseline and initial trajectory for a recursive process, apparently small but early alterations in trajectory can have long-term effects. Implications for psychological theory and educational practice are discussed.

Automatically extracting group membership from faces.

Rule et al. show that everyone has 'Gaydar'. Information on sexual orientation is automatically extracted from faces, even though this has not been considered to be a property akin to the primary categories of sex, age, or race of a person. This suggest that the automaticity of person categorization associated with perceptually salient groups may extend to categories with less obvious visual markers. Edited clips from their paper:

Individuals quickly and accurately categorize others into groups; indeed, for groups with salient perceptual markers (e.g., sex, age, race), category activation is deemed to be an unavoidable consequence of the person-perception process. But what about social groups with less obvious physical cues, do they also trigger automatic person categorization? Recent data hint that this may, indeed, be the case. Take, for example, male sexual orientation. Although the cues to male sexual orientation are ostensibly ambiguous (yielding categorization accuracy of approximately 60–70% against a chance guessing rate of 50%), differences between gay and straight men can be judged significantly better than chance following very brief (50 ms) exposure to a target and can modulate incidental memory for previously encountered faces.

To explore the possibility that information pertaining to male sexual orientation may be extracted automatically from faces (like sex, age, and race) we employed a lexical decision task in which participants responded to gay and straight verbal associates ( after the presentation of facial primes. A subset of 20 head shots of gay (n= 10) and straight (n= 10) men were randomly selected from a previously validated, standardized set of photographs obtained from Internet dating sites. The targets self-identified as either gay or straight and did not differ systematically along dimensions such as facial attractiveness. Pretesting showed that the faces were categorized with accuracy better than chance. Ten words relating to gay stereotypes (e.g., fabulous, rainbow) and 10 words relating to straight stereotypes (e.g., rough, football) were selected based on pretests. For the purpose of the lexical decision task, 20 nonword letter strings were constructed from these stereotype-related items.

The basic result was that exposure to faces of members of a perceptually ambiguous group slightly facilitated access to associated stereotypic material.

Friday, April 17, 2009

Science by machine....

Two rather amazing papers in Science on automating scientific discovery describe a computer program that can sift raw and imperfect data to uncover fundamental laws of nature and a robot that can not only devise a hypothesis but can also run and analyze experiments to test the hypothesis. One wonders how soon old-fashioned bench scientists like myself will become obsolete.

Schmidt and Lipson use genetic programming that starts with random guesses at a solution and then employs an evolution-inspired algorithm to shuffle and change pieces of the equations until it finds a solution that works. They demonstrate their approach:

...by automatically searching motion-tracking data captured from various physical systems, ranging from simple harmonic oscillators to chaotic double-pendula. Without any prior knowledge about physics, kinematics, or geometry, the algorithm discovered Hamiltonians, Lagrangians, and other laws of geometric and momentum conservation. The discovery rate accelerated as laws found for simpler systems were used to bootstrap explanations for more complex systems, gradually uncovering the "alphabet" used to describe those systems.
King et al. constructed a robot scientist named Adam that used artificial intelligence to come up with a hypothesis about genes in baker’s yeast and the enzymes produced by the genes. It then designed and ran experiments to test its hypothesis. Using the results, it revised its hypothesis and ran more experiments before arriving at its conclusions. From their abstract:
Adam has autonomously generated functional genomics hypotheses about the yeast Saccharomyces cerevisiae and experimentally tested these hypotheses by using laboratory automation. We have confirmed Adam's conclusions through manual experiments. To describe Adam's research, we have developed an ontology and logical language. The resulting formalization involves over 10,000 different research units in a nested treelike structure, 10 levels deep, that relates the 6.6 million biomass measurements to their logical description. This formalization describes how a machine contributed to scientific knowledge.

Pride

Benedict Carey summarizes work showing that that pride, in ways that are not obvious, is centrally important not just for surviving physical danger but for thriving in difficult social circumstances. A few edited clips:

As with the laid-off lawyer, who’s commuting in every day after getting dressed up — to his Starbucks, networks, and meets with colleagues...The fine art of keeping up appearances may seem shallow and deceitful, the very embodiment of denial... but to the extent that it sustains good habits and reflects personal pride, this kind of play-acting can be an extremely effective social strategy, especially in uncertain times.

...the expressions associated with pride in Western society — most commonly a slight smile and head tilt, with hands on the hips or raised high — are nearly identical across cultures. Children first experience pride about age 2 ½, studies suggest, and recognize it by age 4...It’s not a simple matter of imitation, analyses of spontaneous responses to winning or losing a judo match during the 2004 Olympic and Paralympic games found that expressions of pride after a victory were similar for athletes from 37 nations, including for 53 blind competitors, many of them blind from birth...people tend to associate an expression of pride with high status — even when they know that the person wearing it is low on the ladder. In one study, participants impulsively assigned higher status to a prideful water boy than to a team captain who looked ashamed.

A feeling of pride, when it’s convincing, acts something like an emotional magnet.(See my March 24 post). Participants in experiments who have had their sense of pride artificially and unconsciously manipulated are perceived by other participants as more dominant and likable.

...wearing a sad or happy face can have a top-down effect on how a person feels: Smile and you may feel fleetingly happier. The same most likely is true for an expression of pride...Pride, in short, begets perseverance. All of which may explain why, when the repo man is at the door, people so often remind themselves that they still have theirs, and that it’s worth something. Because they do, and because it is...However much pride may go before a fall, it may be far more useful after one.

Thursday, April 16, 2009

Sleeping to reset overstimulated brain connections

Here are a few slightly edited clips from Greg Miller's review of two papers and fragments of the paper abstracts. In fruit flies, as surely will also be shown for us humans, sleep is needed for brain connections (synapses) to let go of all the garbage they have accumulated during the day:

Cirelli, Tononi, and postdoc Giorgio Gilestro report that depriving flies of sleep, either by periodically shaking the vials they call home or by forcing individual male flies to cohabitate with an unwelcome stranger (a male from another fly strain), resulted in higher levels of several synaptic proteins throughout the brain. Levels of these proteins, which included components of the transmitting and receiving sides of the synapse as well as proteins involved in neurotransmitter release, declined after flies had a chance to sleep. This pattern held up even when flies slept at odd hours, confirming that the proteins fluctuate with the sleep-wake cycle, not the time of day...The decrease of synaptic markers during sleep was progressive, and sleep was necessary for their decline. Thus, sleep may be involved in maintaining synaptic homeostasis altered by waking activities.

Donlea et al. find that disrupting any one of three genes, including period, an integral component of the circadian clock, prevents flies from sleeping longer after a socially stimulating day. Restoring the genes in just 16 so-called ventral lateral neurons--out of some 200,000 neurons in the fly brain--is enough to restore increased sleep after social enrichment...The circadian clock tells animals when to sleep, but the duration of sleep depends on how long they've been awake and what they've done during that time...the same social experiences that increase the need for sleep also increase the number of synapses between lateral ventral neurons and their partners in the brainstem. After sleep, synapse numbers had declined
However,
...it's unlikely that downscaling happens only during sleep or that synaptic strengthening is limited to waking hours. Human and rodent studies have suggested that sleep may be important for consolidating newly formed memories, a process that's widely assumed to depend on strengthening synapses.

Cognitive gains in bilingual infants

Interesting work from Kovács and Mehler. Infants exposed to two languages demonstrate a domain-general enhancement of their cognitive control system well before the onset of speech:

Children exposed to bilingual input typically learn 2 languages without obvious difficulties. However, it is unclear how preverbal infants cope with the inconsistent input and how bilingualism affects early development. In 3 eye-tracking studies we show that 7-month-old infants, raised with 2 languages from birth, display improved cognitive control abilities compared with matched monolinguals. Whereas both monolinguals and bilinguals learned to respond to a speech or visual cue to anticipate a reward on one side of a screen, only bilinguals succeeded in redirecting their anticipatory looks when the cue began signaling the reward on the opposite side. Bilingual infants rapidly suppressed their looks to the first location and learned the new response. These findings show that processing representations from 2 languages leads to a domain-general enhancement of the cognitive control system well before the onset of speech.

Wednesday, April 15, 2009

Illusory control

Interesting observations from Fast et al. on why the powerful often seem to exhibit hubristic overconfidence:

Three experiments demonstrated that the experience of power leads to an illusion of personal control. Regardless of whether power was experientially primed (Experiments 1 and 3) or manipulated through roles (manager vs. subordinate; Experiment 2), it led to perceived control over outcomes that were beyond the reach of the power holder. Furthermore, this illusory control mediated the influence of power on several self-enhancement and approach-related outcomes reported in the power literature, including optimism (Experiment 2), self-esteem (Experiment 3), and action orientation (Experiment 3). These results demonstrate the theoretical importance of perceived control as a generative cause of and driving force behind many of power's far-reaching effects. A fourth experiment ruled out an alternative explanation: that positive mood, rather than illusory control, is at the root of power's effects.
Here is a bit more detail from the article (slightly edited) on the procedures that produced the predicted results:
Experiment 1 manipulated power by asking participants to recall an experience with high power, an experience with low power, or an event unrelated to power. Illusory control was measured using a classic die-rolling paradigm in which participants are offered a reward for predicting the outcome of a roll and are given a choice of rolling the die themselves or having another person roll the die for them. Choosing to roll the die reflects an illusory sense of control; it indicates that the actor believes he or she can personally influence the outcome of the random roll and, thus, increase the odds of obtaining the reward. We predicted that participants in the high-power condition would be more likely than those in the other two conditions to choose to roll the die.

Experiment 2 tested whether illusory control mediates the established relationship between power and optimism. We manipulated power by instructing participants that they would be matched with a partner and play the role of either a manager or a worker. Before completing any tasks associated with their roles, participants were asked to complete a separate study that was unrelated to their power role and assessed perceived control and optimism.

Experiment 3 tested whether illusory control mediates power's effects on self-esteem and action orientation. We used a context for action—voting in a national election—that is particularly important given that democracies are based on active citizen involvement and are largely shaped by voter mobilization and turnout. Power was manipulated with the same experiential prime used in Experiment 1. We compared the high-power condition with a baseline condition in order to demonstrate that the effects observed in Study 2 were driven by the experience of power and not by powerlessness. After the power manipulation, participants completed measures of sense of control, self-esteem, and action orientation. We predicted that those imbued with a sense of power would demonstrate illusory control, which would mediate power-induced increases in self-esteem and action orientation.

In summary...power led to perceived control over outcomes that were uncontrollable or unrelated to the power. Power predicted perceived control over a chance event (Experiment 1), over outcomes in domains that were unrelated to the source of power (Experiment 2), and over future outcomes that were virtually impossible for any one individual to control (e.g., performance of the national economy, national election results; Experiment 3). Furthermore, this inflated sense of control mediated power's positive effects on optimism (Experiment 2), self-esteem (Experiment 3), and action orientation (Experiment 3).

Social motives for syntax.

Enfield offers a review of Tomasello's new book "Origins of Human Communication." Some clips:

One dominant philosophy, grounded in the work of linguist Noam Chomsky, sees language as primarily an instrument of thought, not action. On this view, the key event in the evolution of language was a mutation resulting in an organlike faculty in the human mind, with selective advantage in the realm of reasoning. This faculty happened also to be useful for generating complex communicative behavior, though perhaps in the same way that a foot happens to be good for playing soccer: it did not evolve under the selective pressure of that function.

Tomasello sees language as a means for doing things, not a device for processing or merely externalizing thoughts....to communicate is to act on others in the social realm. For language to have this function presumes not only a conspecific with a comprehending mind but also a willingness to cooperate...Requests form one of three classes of social action...The others are informing-helping (e.g., when one person points to keys that another just dropped) and sharing (e.g., when two people's attitudes toward a third person align in the course of a gossip session). He summarizes research showing that all three social motives are fully evident in the communicative behavior of prelinguistic infants and all but absent among our closest relatives, the great apes. Humans have a special combination of cooperative instincts, prosocial motives, high-level intention attribution, and moral propensities. Tomasello contends that without this unique psychological wherewithal in the domain of social cognition, language as we know it could never have evolved.

Tomasello's work represents a long-standing and now rapidly growing view that language is not restricted to abstract structures of grammatical patterning but includes gestures and other bodily movements of the kinds that typically accompany speech... Gestures, he argues, are necessary for the development of language in both phylogeny and ontogeny...9-month-olds use gestures for multiple, often sophisticated social functions, including the three basic social motives. These favorable conclusions on the social cognitive sophistication of human infants contrast with the findings on primates.

Gestures lack the highly structured complexity of grammar: How to get from one to the other? ...Tomasello's solution is an ingenious linking of requesting, informing, and sharing with three distinct levels of complexity in the grammatical possibilities that any language will furnish. He dubs these "simple syntax" (strongly dependent on immediate context), "serious syntax" (for making unambiguous reference across contexts), and "fancy syntax" (for organizing long and complex narratives). But this is essentially as far as his links to grammar go, promissory notes notwithstanding. Precisely because the author is a linguist, this omission is a missed opportunity to complete the argument, to connect the dots that lead from basic social actions ultimately to the radically varying, historically developed complex linguistic systems that are found around the world.

Tuesday, April 14, 2009

Social isolation enhances neuroinflammatory response to stroke.

Karelina et al. give more detail on how social isolation can alter the expression of the interleukin molecules that regulate inflammation:

Social isolation has dramatic long-term physiological and psychological consequences; however, the mechanisms by which social isolation influences disease outcome are largely unknown. The purpose of the present study was to investigate the effects of social isolation on neuronal damage, neuroinflammation, and functional outcome after focal cerebral ischemia. Male mice were socially isolated (housed individually) or pair housed with an ovariectomized female before induction of stroke, via transient intraluminal middle cerebral artery occlusion (MCAO), or SHAM surgery. In these experiments, peri-ischemic social isolation decreases poststroke survival rate and exacerbates infarct size and edema development. The social influence on ischemic damage is accompanied by an altered neuroinflammatory response; specifically, central interleukin-6 (IL-6) signaling is down-regulated, whereas peripheral IL-6 is up-regulated, in isolated relative to socially housed mice. In addition, intracerebroventricular injection of an IL-6 neutralizing antibody (10 ng) eliminates social housing differences in measures of ischemic outcome. Taken together, these data suggest that central IL-6 is an important mediator of social influences on stroke outcome.

Sinning Saints and Saintly Sinners

From Sachdeva et al (The first two experiments measured altruistic behavior as a donation amount pledged by participants. The third experiments used a cooperative decision-making task in an environmental context to assess whether people would show moral cleansing and licensing when they were asked to cooperate with others for the good of the environment.):

The question of why people are motivated to act altruistically has been an important one for centuries, and across various disciplines. Drawing on previous research on moral regulation, we propose a framework suggesting that moral (or immoral) behavior can result from an internal balancing of moral self-worth and the cost inherent in altruistic behavior. In a first experiment, participants were asked to write a self-relevant story containing words referring to either positive or negative traits. Participants who wrote a story referring to the positive traits donated one fifth as much as those who wrote a story referring to the negative traits. In the second experiment, we showed that this effect was due specifically to a change in the self-concept. Finally, in experiment 3, we replicated these findings and extended them to cooperative behavior in environmental decision making. We suggest that affirming a moral identity leads people to feel licensed to act immorally. However, when moral identity is threatened, moral behavior is a means to regain some lost self-worth.

Monday, April 13, 2009

Seeing is remembering

A fascinating article from Harrison and Tong on how we hold fine details in our working memory by a top down mechanism in which frontal working memory areas apparently instruct early visual areas (V1-V4) at the rear of our cortex to retain information about visual features held in working memory :

Visual working memory provides an essential link between perception and higher cognitive functions, allowing for the active maintenance of information about stimuli no longer in view. Research suggests that sustained activity in higher-order prefrontal, parietal, inferotemporal and lateral occipital areas supports visual maintenance, and may account for the limited capacity of working memory to hold up to 3–4 items. Because higher-order areas lack the visual selectivity of early sensory areas, it has remained unclear how observers can remember specific visual features, such as the precise orientation of a grating, with minimal decay in performance over delays of many seconds. One proposal is that sensory areas serve to maintain fine-tuned feature information, but early visual areas show little to no sustained activity over prolonged delays. Here we show that orientations held in working memory can be decoded from activity patterns in the human visual cortex, even when overall levels of activity are low. Using functional magnetic resonance imaging and pattern classification methods, we found that activity patterns in visual areas V1–V4 could predict which of two oriented gratings was held in memory with mean accuracy levels upwards of 80%, even in participants whose activity fell to baseline levels after a prolonged delay. These orientation-selective activity patterns were sustained throughout the delay period, evident in individual visual areas, and similar to the responses evoked by unattended, task-irrelevant gratings. Our results demonstrate that early visual areas can retain specific information about visual features held in working memory, over periods of many seconds when no physical stimulus is present.

The 100 year old neuroscientist

Nature does a brief review of the life of Rita Levi-Montalcini, the first Nobel Laureate to reach their 100th birthday. It makes a fascinating read. I was just getting into neuroscience in the late 1950's when she, along with others, discovered NGF (nerve growth factor). Things were very competitive, a number of priority disputes arose, there were accusations of dishonest behavior. (My own bit of gossip from the sidelines: a colleague of mine at the time sent a letter to her describing in detail some of his recent experimental results, then told me that three verbatim paragraphs from his letter appeared in Levi-Montalcini's next paper, which claimed priority for the discoveries.) Here is a striking clip about her more recent, and laudable, efforts.

...on the morning of 18 November 2006, she had the attention of the entire Italian government. A senator for life, Levi-Montalcini held the deciding vote on a budget backed by the government of Romano Prodi, which held a parliamentary majority of just one.

A few days earlier, Levi-Montalcini had said she would withdraw her support for the budget unless the government reversed a last-minute decision to sacrifice science funds. It was Levi-Montalcini versus Prodi — and Levi-Montalcini won. On the morning of the vote, immaculately turned out as always, she walked regally on the arm of an usher to her seat in the Italian senate and cast her vote. At one stroke, she secured the budget, won a battle for Italian science and snubbed Francesco Storace, leader of the Right party and part of the opposition coalition. A few weeks earlier, Storace had caused a national scandal by announcing his intention to send crutches to Levi-Montalcini's home — symbolic of her both being a crutch to an ailing government, he said, and her age, which he considered too old to be allowed to vote.

Levi-Montalcini didn't consider herself too old then, when she was 97 years old, and she certainly doesn't now when, on 22 April, she will become the first Nobel laureate to reach the age of 100. Italy — and quite possibly the world — has never seen a scientist quite like her.

Friday, April 10, 2009

Family Tree

Check out this site. The artist has photographed father/son, mother/daughter, and even father/daughter and mother/son individually, sized and printed the photos at the same proportions, then torn and glued them together to make one portrait. (click to enlarge).

Sites for abstract versus concrete actions in frontal lobes.

By observing behavioral deficits of lesion patients Badre et al. find that there is a hierarchical organization of cognitive control, with rostral (towards top of head) areas of the frontal lobes being required for decisions about more abstract actions and lower caudal areas (towards spinal column or tail) being required for decisions about more concrete actions.

Cognitive control permits us to make decisions about abstract actions, such as whether to e-mail versus call a friend, and to select the concrete motor programs required to produce those actions, based on our goals and knowledge. The frontal lobes are necessary for cognitive control at all levels of abstraction. Recent neuroimaging data have motivated the hypothesis that the frontal lobes are organized hierarchically, such that control is supported in progressively caudal regions as decisions are made at more concrete levels of action. We found that frontal damage impaired action decisions at a level of abstraction that was dependent on lesion location (rostral lesions affected more abstract tasks, whereas caudal lesions affected more concrete tasks), in addition to impairing tasks requiring more, but not less, abstract action control. Moreover, two adjacent regions were distinguished on the basis of the level of control, consistent with previous functional magnetic resonance imaging results. These results provide direct evidence for a rostro-caudal hierarchical organization of the frontal lobes.

Thursday, April 09, 2009

Neural mechanism of first impressions.

From Schiller et al:

Evaluating social others requires processing complex information. Nevertheless, we can rapidly form an opinion of an individual during an initial encounter. Moreover, people can vary in these opinions, even though the same information is provided. We investigated the brain mechanisms that give rise to the impressions that are formed on meeting a new person. Neuroimaging revealed that responses in the amygdala and the posterior cingulate cortex (PCC) were stronger while encoding social information that was consistent, relative to inconsistent, with subsequent evaluations. In addition, these responses scaled parametrically with the strength of evaluations. These findings provide evidence for encoding differences on the basis of subsequent evaluations, suggesting that the amygdala and PCC are important for forming first impressions.

Figure. (Click to enlarge) a - Functional regions of interest (ROIs) were identified by contrasting faces with person-descriptive sentences versus face-alone presentations. The dmPFC and left amygdala are denoted by yellow circle on the statistical activation map. b - To examine whether these ROIs show differential neural response to information that is relevant versus irrelevant to later evaluations, we extracted the BOLD response from each of these regions and compared the mean percentage BOLD signal change during the presentation of evaluation-relevant versus evaluation-irrelevant person-descriptive sentences. The differential score was calculated by subtracting evaluation-irrelevant from evaluation-relevant responses, so positive scores correspond to stronger responses to the evaluation-relevant information. A significant differential responding was shown by the PCC and the amygdala, but not by the dmPFC.


Thinking like a trader reduces your loss aversion.

Sokol-Hessnera et al (open access). note that a cognitive regulation strategy can reduce loss aversion:

Research on emotion regulation has focused upon observers' ability to regulate their emotional reaction to stimuli such as affective pictures, but many other aspects of our affective experience are also potentially amenable to intentional cognitive regulation. In the domain of decision-making, recent work has demonstrated a role for emotions in choice, although such work has generally remained agnostic about the specific role of emotion. Combining psychologically-derived cognitive strategies, physiological measurements of arousal, and an economic model of behavior, this study examined changes in choices (specifically, loss aversion) and physiological correlates of behavior as the result of an intentional cognitive regulation strategy. Participants were on average more aroused per dollar to losses relative to gains, as measured with skin conductance response, and the difference in arousal to losses versus gains correlated with behavioral loss aversion across subjects. These results suggest a specific role for arousal responses in loss aversion. Most importantly, the intentional cognitive regulation strategy, which emphasized “perspective-taking,” uniquely reduced both behavioral loss aversion and arousal to losses relative to gains, largely by influencing arousal to losses. Our results confirm previous research demonstrating loss aversion while providing new evidence characterizing individual differences and arousal correlates and illustrating the effectiveness of intentional regulation strategies in reducing loss aversion both behaviorally and physiologically.

Wednesday, April 08, 2009

Fetal ethanol exposure increases ethanol intake of offspring

More sobering information on how maternal patterns of drug use, can be passed on to offspring, presumably by means of epigenetic chemosensory mechanisms.

Human epidemiologic studies reveal that fetal ethanol exposure is highly predictive of adolescent ethanol avidity and abuse. Little is known about how fetal exposure produces these effects. It is hypothesized that fetal ethanol exposure results in stimulus-induced chemosensory plasticity. Here, we asked whether gestational ethanol exposure increases postnatal ethanol avidity in rats by altering its taste and odor. Experimental rats were exposed to ethanol in utero via the dam's diet, whereas control rats were either pair-fed an iso-caloric diet or given food ad libitum. We found that fetal ethanol exposure increased the taste-mediated acceptability of both ethanol and quinine hydrochloride (bitter), but not sucrose (sweet). Importantly, a significant proportion of the increased ethanol acceptability could be attributed directly to the attenuated aversion to ethanol's quinine-like taste quality. Fetal ethanol exposure also enhanced ethanol intake and the behavioral response to ethanol odor. Notably, the elevated intake of ethanol was also causally linked to the enhanced odor response. Our results demonstrate that fetal exposure specifically increases ethanol avidity by, in part, making it taste and smell better. More generally, they establish an epigenetic chemosensory mechanism by which maternal patterns of drug use can be transferred to offspring. Given that many licit (e.g., tobacco products) and illicit (e.g., marijuana) drugs have noteworthy chemosensory components, our findings have broad implications for the relationship between maternal patterns of drug use, child development, and postnatal vulnerability.

Visual neglect overcome by pleasant music

Soto et al. make the fascinating observation that positive emotions can overcome the neglect of part of the visual field that can result from brain lesions:

During the past 20 years there has been much research into the factors that modulate awareness of contralesional information in neurological patients with visual neglect or extinction. However, the potential role of the individual's emotional state in modulating awareness has been largely overlooked. In the current study, we induced a pleasant and positive affective response in patients with chronic visual neglect by allowing them to listen to their pleasant preferred music. We report that the patients showed enhanced visual awareness when tasks were performed under preferred music conditions relative to when tasks were performed either with unpreferred music or in silence. These results were also replicated when positive affect was induced before neglect was tested. Functional MRI data showed enhanced activity in the orbitofrontal cortex and the cingulate gyrus associated with emotional responses when tasks were performed with preferred music relative to unpreferred music. Improved awareness of contralesional (left) targets with preferred music was also associated with a strong functional coupling between emotional areas and attentional brain regions in spared areas of the parietal cortex and early visual areas of the right hemisphere. These findings suggest that positive affect, generated by preferred music, can decrease visual neglect by increasing attentional resources. We discuss the possible roles of arousal and mood in generating these effects.

Tuesday, April 07, 2009

The end of moral philosophy

Again I am amazed at how well David Brooks keeps up with contemporary psychology and brain science, picking up on the recent upsurge in research on the good stuff in human nature like our evolved affiliative emotions. Check out this Op-Ed piece.

Another Twitter parody...

I couldn't resist passing this on:

Medial prefrontal cortex exhibits money illusion

My Feb. 23 post noted work showing, yet again, that we can be lured into making decisions by numbers that seem bigger than they really are. We apparently go with numerical values rather than real economic values. Weber et al. look at brain activity at accompanies the money illusion:

Behavioral economists have proposed that money illusion, which is a deviation from rationality in which individuals engage in nominal evaluation, can explain a wide range of important economic and social phenomena. This proposition stands in sharp contrast to the standard economic assumption of rationality that requires individuals to judge the value of money only on the basis of the bundle of goods that it can buy—its real value—and not on the basis of the actual amount of currency—its nominal value. We used fMRI to investigate whether the brain's reward circuitry exhibits money illusion. Subjects received prizes in 2 different experimental conditions that were identical in real economic terms, but differed in nominal terms. Thus, in the absence of money illusion there should be no differences in activation in reward-related brain areas. In contrast, we found that areas of the ventromedial prefrontal cortex (vmPFC), which have been previously associated with the processing of anticipatory and experienced rewards, and the valuation of goods, exhibited money illusion. We also found that the amount of money illusion exhibited by the vmPFC was correlated with the amount of money illusion exhibited in the evaluation of economic transactions.

Delayed brain development in humans compared with other primates

A prevailing view is that the appearance of many human-specific features during development has been made possible by a slowing down of the process, particularly in the brain (developmental retardation, or neoteny). Somel et al. prove the point by looking at gene expression in humans and other primates during development:

In development, timing is of the utmost importance, and the timing of developmental processes often changes as organisms evolve. In human evolution, developmental retardation, or neoteny, has been proposed as a possible mechanism that contributed to the rise of many human-specific features, including an increase in brain size and the emergence of human-specific cognitive traits. We analyzed mRNA expression in the prefrontal cortex of humans, chimpanzees, and rhesus macaques to determine whether human-specific neotenic changes are present at the gene expression level. We show that the brain transcriptome is dramatically remodeled during postnatal development and that developmental changes in the human brain are indeed delayed relative to other primates. This delay is not uniform across the human transcriptome but affects a specific subset of genes that play a potential role in neural development.

Monday, April 06, 2009

MindBlog is on the road again.

This is the time of year when I leave Fort Lauderdale with my new one year old children, shown in the photographs, to drive first to Austin Texas for a visit with my son and his wife, and then on to my home in Madison Wisconsin. (The photos show Marvin and Melvin checking out their carrier, then in the carrier on top of the car, but in fact they are given free range while in the car ). The posts in the queue this week for Tuesday through Friday are mainly passing on abstracts that I have found interesting, with an occasional figure.


The surprising power of neighborly advice.

I did a series of posts in June, 2006 abstracting Dan Gilberts book "Stumbling on Happiness." (You can use the blog search box to find them by entering the word "stumbling.") His main suggestion for knowing how you might actually feel emotionally about a desired future situation was simply to ask someone who has been there (become a successful doctor, actor, writer, etc.) Following in this vein, his group has recently obtained a very simple result concerning how people predict their future emotional reactions. Their abstract, following by some text:

Two experiments revealed that (i) people can more accurately predict their affective reactions to a future event when they know how a neighbor in their social network reacted to the event than when they know about the event itself and (ii) people do not believe this. Undergraduates made more accurate predictions about their affective reactions to a 5-minute speed date (n = 25) and to a peer evaluation (n = 88) when they knew only how another undergraduate had reacted to these events than when they had information about the events themselves. Both participants and independent judges mistakenly believed that predictions based on information about the event would be more accurate than predictions based on information about how another person had reacted to it.
Some context from the text of the article:
People make systematic errors when attempting to predict their affective reactions to future events...to overestimate how unhappy they will be after receiving bad test results, becoming disabled, or being denied a promotion, and to overestimate how happy they will be after winning a prize, initiating a romantic relationship, or taking revenge against those who have harmed them. Research suggests that the main reason people mispredict their affective reactions to future events is that they imagine those events inaccurately.

The 17th century writer François de La Rochefoucauld suggested that rather than mentally simulating a future event, people should consult those who have experienced it. "Before we set our hearts too much upon anything," he wrote, "let us first examine how happy those are who already possess it" . La Rochefoucauld was essentially suggesting that forecasters should use other people as surrogates for themselves, and the advantages of his "surrogation strategy" are clear: Because surrogation does not rely on mental simulation, it is immune to the many errors that inaccurate simulations produce.

The disadvantages of surrogation are also clear: Individuals differ, and thus, one person's affective reaction is almost certainly an imperfect predictor of another's. But there are at least two reasons to suspect that affective reactions are not as different as people may believe. First, affective reactions are produced in large part by physiological mechanisms that are evolutionarily ancient, which is why people the world over have very different beliefs and opinions but very similar affective reactions to a wide range of stimuli, preferring warm to cold, satiety to hunger, friends to enemies, winning to losing, and so on.
Their summary and conclusions:
In two experiments, participants more accurately predicted their affective reactions to a future event when they knew how a neighbor in their social network had reacted to it than when they knew about the event itself. Women made more accurate predictions about how much they would enjoy a date with a man when they knew how much another woman in their social network enjoyed dating the man than when they read the man's personal profile and saw his photograph. Men and women made more accurate predictions about how they would feel after being evaluated by a peer when they knew how another person in their social network had felt after being evaluated than when they previewed the evaluation itself. Although surrogation trumped simulation, both participants and independent judges had precisely the opposite intuition. By a wide margin, they believed that simulation was more likely than surrogation to produce accurate affective forecasts.

Two points are worthy of note. First, surrogation is by definition superior to simulation when individual differences are relatively small and simulations errors are relatively large, and it is inferior to simulation when the opposite is true. Although there is no way to know which of these is more typical in everyday life, the situations we studied—dating and peer-evaluation—are by no means exotic.

Second, although our experiments demonstrate the power of surrogation, they also suggest that people may not normally take advantage of this power. Our participants mistakenly believed that simulation was the superior strategy even after it had failed them, which suggests that people may be reluctant to engage in surrogation if they have the opportunity to do otherwise...it seems likely that in everyday life, La Rochefoucauld's advice—like the advice of good neighbors—is more often than not ignored. When we want to know our emotional futures, it is difficult to believe that a neighbor's experience can provide greater insight than our own best guess.