Friday, November 28, 2008

What happy people don't do.

Rabin notes the work of John Robinson, who finds that:

Although people who describe themselves as happy enjoy watching television, it turns out to be the single activity they engage in less often than unhappy people.

The study relied primarily on the responses of 45,000 Americans collected over 35 years by the University of Chicago’s General Social Survey, and on published “time diary” studies recording the daily activities of participants.

“We looked at 8 to 10 activities that happy people engage in, and for each one, the people who did the activities more — visiting others, going to church, all those things — were more happy,” Dr. Robinson said. “TV was the one activity that showed a negative relationship. Unhappy people did it more, and happy people did it less.”

Slow Blogging....

From an article by Sharon Otterman:

The practice is inspired by the slow food movement, which says that fast food is destroying local traditions and healthy eating habits. Slow food advocates, like the chef Alice Waters of Chez Panisse in Berkeley, Calif., believe that food should be local, organic and seasonal...A Slow Blog Manifesto, written in 2006 by Todd Sieling, a technology consultant from Vancouver, British Columbia, laid out the movement’s tenets. “Slow Blogging is a rejection of immediacy,” he wrote. “It is an affirmation that not all things worth reading are written quickly.” ...Some slow bloggers like to push the envelope of their readers’ attention even further. Academics post lengthy pieces about literature and teaching styles, while techies experiment to see how infrequently they can post before readers desert them.

This approach is a deliberate smack at the popular group blogs like Huffington Post, the Daily Beast, Valleywag and boingboing, which can crank out as many as 50 items a day. On those sites, readers flood in and advertisers sign on. Spin and snark abound. Earnest descriptions of the first frost of the season are nowhere to be found.

Andrew Sullivan, perhaps the world’s best-read political blogger, talked about the burnout factor in an article in November’s Atlantic magazine called “Why I Blog.” He said in an interview posted on the magazine’s Web site that during the election, his readers became so addicted to his stream of posts that he sometimes set his blog to post automatically so he could go to lunch. When he took two days off to make sense of “the whole Sarah Palin thing,” his audience flipped, thinking he was dead or silenced.

“You can’t stop,” Mr. Sullivan said in the online interview. “The readers act as if you’ve cut off their oxygen supply, and they just flap around like a goldfish out of water until you plop them back in.”

Thursday, November 27, 2008

The Wall Street Bonus degrades rather than enhancing performance.

Dan Ariely, a professor of behavioral economics at Duke, reports interesting work showing that people perform better on tasks requiring cognitive skills when they are not offered huge rewards. Social pressure has the same effect that money has. It motivates people, especially when the tasks at hand require only effort and no skill. But it can provide stress, too, and at some point that stress overwhelms the motivating influence.

Contempt and disgust - sexual differences in brain responses

Aleman and Swart use fMRI measurements to note (slightly edited clip from the abstract) that:

Men display stronger brain activation than women to facial expressions of contempt in the medial frontal gyrus, inferior frontal gyrus, and superior temporal gyrus. Conversely, women showed stronger neural responses than men to facial expressions of disgust. The effect of stimulus sex differed for men versus women. Specifically, women showed stronger responses to male contemptuous faces (as compared to female expressions) in the insula and middle frontal gyrus. Contempt has been conceptualized as signaling perceived moral violations of social hierarchy, whereas disgust would signal violations of physical purity.
They suggest that the results indicate a neural basis for sex differences in moral sensitivity regarding hierarchy on the one hand and physical purity on the other.

Wednesday, November 26, 2008

Reading the drug side-effects label can make you sick.

An interesting article from the Wall Street Journal on the nocebo effect, which I have mentioned before, the opposite of the placebo effect. Numerous studies report that negative side effects of a medical condition or drug treatment are reported to occur more frequently by those who are aware of them than by those who are not.

Another herbal miracle drug fails to pan out....

The largest clinical trial to date finds no effect of ginkgo biloba on slowing memory loss or dementia in Alzheimer's.

Tuesday, November 25, 2008

Reversal of fear in the human brain

Schiller et al. do work on learned fear responses and their reversal:

Fear learning is a rapid and persistent process that promotes defense against threats and reduces the need to relearn about danger. However, it is also important to flexibly readjust fear behavior when circumstances change. Indeed, a failure to adjust to changing conditions may contribute to anxiety disorders. A central, yet neglected aspect of fear modulation is the ability to flexibly shift fear responses from one stimulus to another if a once-threatening stimulus becomes safe or a once-safe stimulus becomes threatening. In these situations, the inhibition of fear and the development of fear reactions co-occur but are directed at different targets, requiring accurate responding under continuous stress. To date, research on fear modulation has focused mainly on the shift from fear to safety by using paradigms such as extinction, resulting in a reduction of fear. The aim of the present study was to track the dynamic shifts from fear to safety and from safety to fear when these transitions occur simultaneously. We used functional neuroimaging in conjunction with a fear-conditioning reversal paradigm. Our results reveal a unique dissociation within the ventromedial prefrontal cortex between a safe stimulus that previously predicted danger and a "naive" safe stimulus. We show that amygdala and striatal responses tracked the fear-predictive stimuli, flexibly flipping their responses from one predictive stimulus to another. Moreover, prediction errors associated with reversal learning correlated with striatal activation. These results elucidate how fear is readjusted to appropriately track environmental changes, and the brain mechanisms underlying the flexible control of fear.


Figure: Striatum and amygdala BOLD responses throughout the discrimination and reversal task. A, Mean differential striatal (left and right caudate) and amygdala percent BOLD signal change in the different phases of the task. The differential responding is calculated as [face A – face B]. Positive scores correspond to stronger responses to face A, which was paired with the shock during acquisition (CS+). Negative scores correspond to stronger responses to face B, which was paired with the shock during reversal (new CS+). These BOLD responses were extracted from the CS+ greater than CS– in early acquisition contrast. B, Striatal activation is denoted by yellow circle. C, Left amygdala activation is denoted by yellow circle.

How we learn to value others

Behrens et al. use a combination of computational and neuroimaging techniques to address a key question in social neuroscience: how we learn to value some individuals more than others. The work demonstrates that demonstrates that social valuation is achieved using the same mechanisms that underlie the reward-based learning — that is, by associative learning. Their abstract:

Our decisions are guided by information learnt from our environment. This information may come via personal experiences of reward, but also from the behaviour of social partners. Social learning is widely held to be distinct from other forms of learning in its mechanism and neural implementation; it is often assumed to compete with simpler mechanisms, such as reward-based associative learning, to drive behaviour. Recently, neural signals have been observed during social exchange reminiscent of signals seen in studies of associative learning. Here we demonstrate that social information may be acquired using the same associative processes assumed to underlie reward-based learning. We find that key computational variables for learning in the social and reward domains are processed in a similar fashion, but in parallel neural processing streams. Two neighbouring divisions of the anterior cingulate cortex were central to learning about social and reward-based information, and for determining the extent to which each source of information guides behaviour. When making a decision, however, the information learnt using these parallel streams was combined within ventromedial prefrontal cortex. These findings suggest that human social valuation can be realized by means of the same associative processes previously established for learning other, simpler, features of the environment.

Monday, November 24, 2008

Potential flaws in unconscious bias tests

An interesting article by John Tierney notes controversy over the way researchers have been using split-second reactions on a computer test (the Implicit Association Test, or I.A.T.) to diagnose an epidemic of racial bias. Critic Hart Blanton notes:

One can decrease racial bias scores on the I.A.T. by simply exposing people to pictures of African-Americans enjoying a picnic...Yet respondents who take this test on the Web are given feedback suggesting that some enduring quality is being assessed...People receiving feedback about their ‘strong’ racial biases are encouraged in sensitivity workshops to confront these tendencies as some ugly reality that has meaning in their daily lives. But unbeknownst to respondents who take this test, the labels given to them were chosen by a small group of people who simply looked at a distribution of test scores and decided what terms seemed about right. This is not how science is done.
However,
In a new a meta-analysis of more than 100 studies, Dr. Greenwald, Dr. Banaji (two of the leading I.A.T. researchers) and fellow psychologists conclude that scores on I.A.T. reliably predict people’s behavior and attitudes, and that the test is a better predictor of interracial behavior than self-description. Their critics reach a different conclusion after reanalyzing the data in some of those studies, which they say are inconsistent and sometimes demonstrate the reverse of what has been reported. They have suggested addressing the scientific dispute over bias — and the researchers’ arguments about the legal implications for affirmative-action policies — by having the two sides join in an “adversarial collaboration.”

One critic, Philip Tetlock, a psychologist at the University of California, Berkeley, said he had found prominent research groups and scholars willing to mediate joint experiments. But so far nothing has happened — and each side blames the other. Dr. Greenwald says he tried proposing a joint experiment to Dr. Tetlock only to have it rejected. Dr. Tetlock says that he tried a counterproposal and offered to work out a compromise, but that the I.A.T. researchers had refused two invitations to sit down with independent mediators.

After all the mutual invective in the I.A.T. debate, maybe it’s unrealistic to expect the two sides to collaborate. But these social scientists are supposed to be experts in overcoming bias and promoting social harmony. If they can’t figure out how to get along with their own colleagues, how seriously should we take their advice for everyone else?

Cultural specificity in amygdala response to fear faces

From Chiao et al. :

The human amygdala robustly activates to fear faces. Heightened response to fear faces is thought to reflect the amygdala's adaptive function as an early warning mechanism. Although culture shapes several facets of emotional and social experience, including how fear is perceived and expressed to others, very little is known about how culture influences neural responses to fear stimuli. Here we show that the bilateral amygdala response to fear faces is modulated by culture. We used functional magnetic resonance imaging to measure amygdala response to fear and nonfear faces in two distinct cultures. Native Japanese in Japan and Caucasians in the United States showed greater amygdala activation to fear expressed by members of their own cultural group. This finding provides novel and surprising evidence of cultural tuning in an automatic neural response.

Friday, November 21, 2008

The innovative brain

Lawrence et al. present preliminary neurocognitive data from matched groups of entrepreneurs and managerial controls that suggests that entrepreneurs represent an example of highly adaptive risk-taking behavior, with positive functional outcomes in the context of stressful economic decision-making. They suggest this 'functional impulsivity' may have evolutionary value as a means of seizing opportunities in a rapidly changing environment. Their neurocognitive tests distinguished the involvement of distinct processes in risky and risk-free decision-making. Referred to as 'hot' and 'cold' processes, these appear to be localized to distinct regions of the brain's frontal lobes. Risk-taking performance in the entrepreneurs was accompanied by elevated scores on personality impulsiveness measures and superior cognitive-flexibility performance. They conclude that entrepreneurs and managers do equally well when asked to perform cold decision-making tasks, but differences emerge in the context of risky or emotional decisions.

The pattern of performance seen on a gambling task in entrepreneurs reflects a behavioral index of risk-seeking or risk tolerance. Greater rewards (as well as greater losses) are available for those who bet more. If these impulsive risk-taking traits can be beneficial, can they be taught or otherwise imparted to the potential entrepreneur? What does it take to make an entrepreneur — is it an inherited, inbuilt characteristic, or is it acquired, and if so, can it be acquired by anyone? These cognitive processes are intimately linked to brain neurochemistry, particularly to the neurotransmitter dopamine. Using single-dose psychostimulants to manipulate dopamine levels, we have seen modulation of risky decision-making on this task9. Therefore, it might be possible to enhance entrepreneurship pharmacologically.

Alexithymia

I just learned a new word: Alexithymia, the inability to express feelings with words, or more generally deficiency in understanding, processing, or describing emotions. The condition is associated with less activation of the anterior cingulate cortex, involved in cognitive and emotional processing. Gu et al. show that the trait is also associated with less efficient voluntary control.

Thursday, November 20, 2008

Mozart's Symphony No. 40 in G minor - a new version

I just have to pass this on (from Andrews Sullivan's blog):

Towards a Moral Neuropolitics

Gary Olson writes an article on the neuroscience of empathy and mirror neuron systems, arguing that the morality that leads to progressive political possibilities is grounded in biology.

Making your tennis racquet part of your brain's body representation

Interesting work from Fourkas et al. in Cerebral Cortex:

Specific physical or mental practice may induce short- and long-term neuroplastic changes in the motor system and cause tools to become part of one's own body representation. Athletes who use tools as part of their practice may be an excellent model for assessing the neural correlates of possible bodily representation changes that are specific to extensive practice. We used single-pulse transcranial magnetic stimulation to measure corticospinal excitability in forearm and hand muscles of expert tennis players and novices while they mentally practiced a tennis forehand, table tennis forehand, and a golf drive. The muscles of expert tennis players showed increased corticospinal facilitation during motor imagery of tennis but not golf or table tennis. Novices, although athletes, were not modulated across sports. Subjective reports indicated that only in the tennis imagery condition did experts differ from novices in the ability to form proprioceptive images and to consider the tool as an extension of the hand. Neurophysiological and subjective data converge to suggest a key role of long-term experience in modulating sensorimotor body representations during mental simulation of sports.

Wednesday, November 19, 2008

Why do intelligent people live longer?

Ian Deary offers an interesting essay in Nature. Here are some clips:

Scores from cognitive-ability tests (intelligence tests or IQ tests) have validity that is almost unequalled in psychology. A general cognitive-ability factor emerges from measures of diverse mental tasks, something that hundreds of data sets since 1904 have replicated. People's rankings on intelligence tests show high stability across almost the whole lifespan, are substantially heritable and are associated with important life outcomes — including educational achievements, occupational success and morbidity and mortality. More thumping confirmatory studies of the link between intelligence and mortality have appeared...One of these contains nearly a million Swedish men tested at around age 19 during military induction and followed for almost 20 years. It shows a clear association: as intelligence test scores go up the scale, so too does the likelihood of survival over those two decades...Intelligence can predict mortality more strongly than body mass index, total cholesterol, blood pressure or blood glucose, and at a similar level to smoking4. But the reasons for this are still mysterious.

The field has focused on four non-exclusive possibilities for the link between intelligence and death. First, what occurs to many people as an obvious pathway of explanation, is that intelligence is associated with more education, and thereafter with more professional occupations that might place the person in healthier environments. Statistical adjustment for education and adult social class can make the association between early-life intelligence and mortality lessen or disappear. But not always.

Second, people with higher intelligence might engage in more healthy behaviours. Evidence is accruing that people with higher intelligence in early life are more likely to have better diets, take more exercise, avoid accidents, give up smoking, engage in less binge drinking and put on less weight in adulthood. But this too doesn't seem to be the whole story.

Third, mental test scores from early life might act as a record of insults to the brain that have occurred before that date. These insults — perinatal events, or the result of illnesses, accidents or deprivations before the mental testing — might be the fundamental cause behind both intelligence test scores and mortality risk. So far, little evidence supports this.

Fourth, mental test scores obtained in youth might be an indicator of a well-put-together system. It is hypothesized that a well-wired body is more able to respond effectively to environmental insults. This 'system integrity' idea has a parallel in the field of ageing, where some data suggest that bodily and cognitive functions age in concert. Some supporting evidence comes from the finding that simple reaction speed — the time taken to press a button when a stimulus appears — can displace intelligence test scores as an even better predictor of mortality risk.

There is also a search for other, non-cognitive psychological characteristics that are associated with living longer. For example, it seems that, independently of any association with intelligence, being more dependable or conscientious in childhood is also significantly protective to health. Children who scored in the top 50% of the population for intelligence and dependability were in one study more than twice as likely to survive to their late sixties as children scoring in the bottom half for both.

Religion and visual attention

Colzato et al. report a quirky study in PLoS ONE: "Losing the Big Picture: How Religion May Control Visual Attention"

Despite the abundance of evidence that human perception is penetrated by beliefs and expectations, scientific research so far has entirely neglected the possible impact of religious background on attention. Here we show that Dutch Calvinists and atheists, brought up in the same country and culture and controlled for race, intelligence, sex, and age, differ with respect to the way they attend to and process the global and local features of complex visual stimuli: Calvinists attend less to global aspects of perceived events, which fits with the idea that people's attentional processing style reflects possible biases rewarded by their religious belief system.

Tuesday, November 18, 2008

The way we age

I find myself returning again and again to a New Yorker article by Atul Gawande, "The Way We Age Now." (PDF here). It was the subject of a May 2007 post which included a few clips from the article. His descriptions of the natural processes that underlie changes in teeth, hair, skin, bones, muscles, joints, etc during agin are the most concise and clear that I have read.

Massive reorganization of visual cortex at the level of dendritic spines..

Keck et al. do elegant experiments to directly observe spine replacement in individual apical dendritic tufts of layer-5 pyramidal neurons, replacement that correlates with functional recovery over a period of months after lesioning the retinal input:

The cerebral cortex has the ability to adapt to altered sensory inputs. In the visual cortex, a small lesion to the retina causes the deprived cortical region to become responsive to adjacent parts of the visual field. This extensive topographic remapping is assumed to be mediated by the rewiring of intracortical connections, but the dynamics of this reorganization process remain unknown. We used repeated intrinsic signal and two-photon imaging to monitor functional and structural alterations in adult mouse visual cortex over a period of months following a retinal lesion. The rate at which dendritic spines were lost and gained increased threefold after a small retinal lesion, leading to an almost complete replacement of spines in the deafferented cortex within 2 months. Because this massive remodeling of synaptic structures did not occur when all visual input was removed, it likely reflects the activity-dependent establishment of new cortical circuits that serve the recovery of visual responses.

Monday, November 17, 2008

A novel theory of mental disorders

Benedict Carey writes a useful article on a radical new theory for explaining the psychotic spectrum:

...that an evolutionary tug of war between genes from the father’s sperm and the mother’s egg can, in effect, tip brain development in one of two ways. A strong bias toward the father pushes a developing brain along the autistic spectrum, toward a fascination with objects, patterns, mechanical systems, at the expense of social development. A bias toward the mother moves the growing brain along what the researchers call the psychotic spectrum, toward hypersensitivity to mood, their own and others’. This, according to the theory, increases a child’s risk of developing schizophrenia later on, as well as mood problems like bipolar disorder and depression.

In short: autism and schizophrenia represent opposite ends of a spectrum that includes most, if not all, psychiatric and developmental brain disorders. The theory has no use for psychiatry’s many separate categories for disorders, and it would give genetic findings an entirely new dimension.

The theory leans heavily on the work of David Haig of Harvard. It was Dr. Haig who argued in the 1990s that pregnancy was in part a biological struggle for resources between the mother and unborn child. On one side, natural selection should favor mothers who limit the nutritional costs of pregnancy and have more offspring; on the other, it should also favor fathers whose offspring maximize the nutrients they receive during gestation, setting up a direct conflict.
I strongly recommend that you read the article, which goes on to give a lucid explanation of how gene imprinting regulates this competition.

Language evolution embedded in cooperative social context

Another installment in the Nature series "Being Human" is offered by Szathmáry and Számadó , who put the case that language evolved in a highly social, cooperative context as one of a suite of uniquely human traits, meriting special status because of the opportunities that it opened up.

The subliminal power of logos

An interesting article by Rob Walker in the New York Times Magazine: "The Brand-ness of Strangers."

In one study, each subject was shown 20 photographs of people in various situations and instructed to focus on facial expressions. Afterward, each subject was offered a bottle of water from a selection of four brands. The experiment had nothing to do with facial expressions and everything to do with which kind of water they chose: the subjects had been divided into groups, based on how many of the photos they viewed incidentally included a bottle of Dasani water. Among those who looked at Dasani-free pictures, about 17 percent chose that brand. But about 40 percent of those who viewed a group of pictures that included 12 with a Dasani presence made the brand their pick. Since subjects who actually noticed the brand in the pictures were eliminated from the results, that spike in popularity evidently came from exposure that the subjects weren’t even aware of.
He discusses the very successful Ralph Lauren logo
Needless to say, a successful logo like Polo’s isn’t easy to create. But having attained and maintained such a level of familiarity, that logo may now be as effective as any of Ralph Lauren’s seductive ads — and for exactly the opposite reason: Not because it catches our attention, but because it doesn’t.

Sunday, November 16, 2008

Is the financial meltdown a guy thing?

Dobrzynski asks whether traders have become prisoners of their endocrine systems — ruled by testosterone, the elixir of male aggressiveness, during a bull market; and by cortisol, a steroid that helps the body deal with stress, when the bears take over.

Friday, November 14, 2008

From Genes to Social Behavior

The Nov. 7 issue of Science Magazine is a gold mine of articles on genetics and behavior. I'm giving you here a clip from from the introduction to this special issue by Jasny et al. that contains links to the individual articles.

When it comes to behavior, we have moved beyond genetic determinism. Our genes do not lock us into certain ways of acting; rather, genetic influences are complicated and mutable and are only one of many factors affecting behavior. In their editorial, Landis and Insel (p. 821) elaborate on this idea, explaining that proteins encoded by genes direct the formation of multicomponent neural circuits, which are the true substrates of behavior, as these circuits respond to internal and outside stimuli.

Why do we study the genetic underpinnings of behavior? One reason is to understand how certain behaviors evolve. Conserved neural pathways can be tied to the evolution of social behaviors (Robinson et al., p. 896), and the conserved peptides oxytocin and vasopressin regulate social cognition and reproductive behaviors in many species (Donaldson and Young, p. 900). In a News story, Pennisi focuses on a region of chromosome 17 that has a complicated pattern of evolution in humans and other primates and is linked in unexpected ways to various disorders, including mental retardation, learning disabilities, and dementias.

Genetics can help us understand why identical circumstances can elicit different behavioral responses among individuals. Genetic differences are reflected in variations in behavior; activation of distinct versions of a hormone receptor gene, an example Donaldson and Young present, results in monogamous behavior in one species of vole but not in another. Conversely, as Robinson et al. describe, insights from recent work show that perceiving social information--such as bird songs or dominance behavior from cichlid fish--from another individual of the same species can itself alter gene expression in the brain, with downstream effects on physiology and behavior.

The potent genetic tools available for Drosophila have uncovered many genes that, when deleted, disrupt behaviors. This, in turn, has allowed dissection of the neural circuits that control essential behaviors. One of the best understood is a social activity necessary for reproduction--stereotypical mating behavior--as outlined by Dickson (p. 904). Genetic methods have also led to the understanding of another class of behaviors: those driven by the circadian clock. The genetic basis of the clock was elegantly worked out in Drosophila, followed by a similar achievement in mice. The reasons for these successes are outlined by Takahashi in his Perspective (p. 909), in which he also explains what tools will be needed to attain similar advances for other behaviors in mice.

Humans are not as genetically tractable as mice or flies, and human behavior is not as stereotypical. Holden's News story on the strengths and shortcomings of genetic studies of personality illustrates this point (p. 892). So do Cotton and some members of the Human Variome Project community in a Policy Forum (p. 861) that describes how the genes and loci associated with disorders of the nervous system are a particular challenge to geneticists and clinical neurologists in need of reliable diagnostic tests. And in a Perspective on a critical human social activity--politics--Fowler and Schreiber (p. 912) argue that genetics and neurobiology have much to teach us about how our leaders are chosen.

Some believe that psychology is the last frontier of genetic analysis. This special section provides a sampling of our early explorations.

Suffering Souls

A fascinating article in The New Yorker by John Seabrook on the search for the roots of psychopathy, the condition of moral emptiness that affects between fifteen to twenty-five per cent of the North American prison population, and is believed by some psychologists to exist in one per cent of the general adult male population. (Female psychopaths are thought to be much rarer.) Psychopaths don’t exhibit the manias, hysterias, and neuroses that are present in other types of mental illness. Their main defect, what psychologists call “severe emotional detachment”—a total lack of empathy and remorse—is concealed, and harder to describe than the symptoms of schizophrenia or bipolar disorder. It focuses on the work of Kent Kiehl, who has installed an fMRI scanner in a New Mexico prison. His theory, published in Psychiatry Research, in 2006, is that psychopathy is caused by a defect in what he calls “the paralimbic system,” a network of brain regions, stretching from the orbital frontal cortex to the posterior cingulate cortex, that are involved in processing emotion, inhibition, and attentional control.

Thursday, November 13, 2008

Most popular MindBlog posts...

I sometimes glance at several of the free services that offer to monitor activity on one's blog (Feedburner, Google Analytics, Quantcast, etc). I thought this compilation of the most widely read posts on this blog was interesting. You can find any of them by entering a few words of the title in the search box in the left column.


And, in this vein, here is the history of subscribers to the RSS feed of this blog:

Sleep loss produces false memories.

From Diekelmann et al. :

People sometimes claim with high confidence to remember events that in fact never happened, typically due to strong semantic associations with actually encoded events. Sleep is known to provide optimal neurobiological conditions for consolidation of memories for long-term storage, whereas sleep deprivation acutely impairs retrieval of stored memories. Here, focusing on the role of sleep-related memory processes, we tested whether false memories can be created (a) as enduring memory representations due to a consolidation-associated reorganization of new memory representations during post-learning sleep and/or (b) as an acute retrieval-related phenomenon induced by sleep deprivation at memory testing. According to the Deese, Roediger, McDermott (DRM) false memory paradigm, subjects learned lists of semantically associated words (e.g., “night”, “dark”, “coal”,…), lacking the strongest common associate or theme word (here: “black”). Subjects either slept or stayed awake immediately after learning, and they were either sleep deprived or not at recognition testing 9, 33, or 44 hours after learning. Sleep deprivation at retrieval, but not sleep following learning, critically enhanced false memories of theme words. This effect was abolished by caffeine administration prior to retrieval, indicating that adenosinergic mechanisms can contribute to the generation of false memories associated with sleep loss.

Wednesday, November 12, 2008

Undoing cocaine's consequences.

In animal experiments stressful and aversive conditions can enhance drug-seeking and drug intake, while stress-reducing manipulations and nondrug rewards can reduce such behaviors. The acquisition of addiction-related behaviors such as sensitization and drug self-administration is attenuated in animals housed in enriched environments containing novel toys, food, and conspecifics with which to interact, compared with those housed in standard laboratory conditions. But, how is this relevant to treating drug-addicted humans, who present for treatment only after drug use is acquired? Recent work by Solinas et al. now suggests that environmental enrichment can still exert its beneficial effects on addiction-related behaviors even after they are established. Their abstract:

Environmental conditions can dramatically influence the behavioral and neurochemical effects of drugs of abuse. For example, stress increases the reinforcing effects of drugs and plays an important role in determining the vulnerability to develop drug addiction. On the other hand, positive conditions, such as environmental enrichment, can reduce the reinforcing effects of psychostimulants and may provide protection against the development of drug addiction. However, whether environmental enrichment can be used to “treat” drug addiction has not been investigated. In this study, we first exposed mice to drugs and induced addiction-related behaviors and only afterward exposed them to enriched environments. We found that 30 days of environmental enrichment completely eliminates behavioral sensitization and conditioned place preference to cocaine. In addition, housing mice in enriched environments after the development of conditioned place preference prevents cocaine-induced reinstatement of conditioned place preference and reduces activation of the brain circuitry involved in cocaine-induced reinstatement. Altogether, these results demonstrate that environmental enrichment can eliminate already established addiction-related behaviors in mice and suggest that environmental stimulation may be a fundamental factor in facilitating abstinence and preventing relapse to cocaine addiction.

During learning - competition between two memory systems.

An interesting bit of work from Lee et al.:

The multiple memory systems framework proposes that distinct circuits process and store different sorts of information; for example, spatial information is processed by a circuit that includes the hippocampus, whereas certain forms of instrumental conditioning depend on the striatum. Disruption of hippocampal function can enhance striatum-dependent learning in some paradigms, which has been interpreted as evidence that these systems can compete with one another in an intact animal. However, it remains unclear whether such competition can occur in the opposite direction, as suggested by the multiple memory systems framework, or is unidirectional. We addressed this question using lesions and genetic manipulations in mice. Impairment of dorsal striatal function with either excitotoxic lesions or transgenic inhibition of the transcription factor cAMP response element-binding protein, which disrupts striatal synaptic plasticity, impaired striatum-dependent cued learning but enhanced hippocampus-dependent spatial learning. Conversely, excitotoxic lesions of the dorsal hippocampus disrupted spatial learning and enhanced cued learning. This double dissociation demonstrates bidirectional competition that constitutes strong evidence for the parallel operation of distinct memory systems.

Tuesday, November 11, 2008

Enhanced logical consistency in autism.

Dolan's group has an interesting open access article in J. Neuroscience showing:

behavioral evidence that autism spectrum disorder (ASD) subjects show a reduced susceptibility to the framing effect and psycho-physiological evidence that they fail to incorporate emotional context into the decision-making process.
From their introduction:
Logical consistency across decisions, regardless of how choices are presented, is a central tenet of rational choice theory and the cornerstone of modern economic and political science. Empirical data challenge this perspective by showing that humans are highly susceptible to the manner or context in which options are cast, resulting in a decision bias termed the "framing effect". We have previously shown that the amygdala mediates this framing bias, a finding that highlights the importance of incorporating emotional processes within models of human decision making. An ability to integrate emotional contextual information into the decision process provides a useful heuristic in decision making under uncertainty. This is a factor that is likely to assume considerable importance during social interactions in which information about others is often incomplete, ambiguous, and not easily amenable to standard inferential reasoning processes.

In this study, we investigated the effect of contextual frame on choice behavior of individuals with autistic spectrum disorder (ASD). Autism is a neurodevelopmental disorder characterized by deficits in social interaction, qualitative impairments in communication, and repetitive and stereotyped patterns of behavior, interests, and activities. From Kanner's earliest description, it has been recognized that individuals with ASD have a strong tendency to focus on parts rather than global aspects of objects of interest and are unable to integrate disparate information into a meaningful whole (weak central coherence theory).

We previously proposed that susceptibility to a framing bias reflects the operation of an affect heuristic. Here, we show that individuals with ASD, a condition characterized by marked behavioral inflexibility, demonstrate a decreased susceptibility to framing resulting in an unusual enhancement in logical consistency that is paradoxically more in line with the normative prescriptions of rationality at the core of the current economics theory. Furthermore, insensitivity in these subjects to a contextual framing bias was associated with a failure to express a differential autonomic response to contextual cues as indexed in skin conductance responses (SCRs), a standard measure of emotional processing. Our findings suggest that a more consistent pattern of choice in the ASD group reflects a failure to incorporate emotional cues into the decision process, an enhanced economic "rationality" that may come at a cost of reduced behavioral flexibility.

Using both sides of your brain.

Schmidt writes a review article on specializations of the two hemispheres, which are seen in all vertebrates. He gives several examples of interhemispheric switching, and then focuses on the example of song production in passerine birds.

Monday, November 10, 2008

Chill-out...

From the "Random Samples" section of the Oct. 31 Science Magazine:

Psychologists at the University of Hertfordshire, U.K., last week unveiled what they are billing as "the world's most relaxing room." The 160-square-meter space, bathed in green lights with an artificially lit blue sky, is furnished with soft mats and lavender-scented pillows "to create a relaxing environment with no sense of threat," explains the project's mastermind Richard Wiseman.

The design is based on research on the effects of light, scent, and music in relaxation. "Cold colors such as blue and green tend to be perceived as calming, whereas warm colors can be perceived as arousing," explains Birgitta Gatersleben, an environmental psychologist from the University of Surrey in Guildford, U.K. Lavender is said to reduce anxiety and induce sleep by lowering the levels of the stress hormone cortisol. The room also features specially composed music with a slow, steady beat and low-frequency tones.

So far, the room's 200 visitors have given it mixed reviews. "Some people absolutely love it and can't have enough of it," Wiseman says. "But people who thrive on and need stress to work absolutely hate it."

The project was designed to be easy to replicate in offices and other real-life environments. "I would like to see relaxation rooms in public spaces," Wiseman adds. "If we pay 20p to use a toilet in King's Cross train station, why not pay for 20 minutes of peace?"

Symbolic markers, cultural groups, and ingroup favoritism

A 'This week in Science' section of Science Magazine points to the work of Efferson et al. :

In human social interactions, it is not uncommon to draw inferences about hidden characteristics (attitudes, beliefs, or behavioral norms) on the basis of observable markers that may bear no fundamental connection to the underlying quantity but have become associated with specific groups over time. For instance, individuals sporting insignia of the Boston Red Sox or Manchester United may be classified as friends (or foes, if one should happen to be a New York Yankees or Chelsea fan). Although much research has been devoted to how a member of one cultural or ethnic group views other in-group and out-group members, less is known about the process by which symbolic markers come to be used as signals to define group membership. Efferson et al. have designed a laboratory-based economic game in which subjects were free to associate arbitrary markers with varying payoffs. Cultural groups (those in which members had adopted the same marker) and consequent ingroup favoritism developed only when the marker was both predictive of behavior in the game as well as changeable over time.
The abstract from Efferson et al.:
Cultural boundaries have often been the basis for discrimination, nationalism, religious wars, and genocide. Little is known, however, about how cultural groups form or the evolutionary forces behind group affiliation and ingroup favoritism. Hence, we examine these forces experimentally and show that arbitrary symbolic markers, though initially meaningless, evolve to play a key role in cultural group formation and ingroup favoritism because they enable a population of heterogeneous individuals to solve important coordination problems. This process requires that individuals differ in some critical but unobservable way and that their markers be freely and flexibly chosen. If these conditions are met, markers become accurate predictors of behavior. The resulting social environment includes strong incentives to bias interactions toward others with the same marker, and subjects accordingly show strong ingroup favoritism. When markers do not acquire meaning as accurate predictors of behavior, players show a markedly reduced taste for ingroup favoritism. Our results support the prominent evolutionary hypothesis that cultural processes can reshape the selective pressures facing individuals and so favor the evolution of behavioral traits not previously advantaged.

Friday, November 07, 2008

Values of early music training.

Forgeard et al. show that children who receive at least three years of instrumental music training outperform their control counterparts on auditory discrimination abilities and fine motor skills, as well as vocabulary and nonverbal reasoning skills. They did not confirm a suggestion from previous research that music training enhances heightened spatial skills, phonemic awareness, or mathematical abilities.

The creationists go to war over the brain.

A Zoology colleague of mine pointed out an article by Amander Gefter (PDF here) in The New Scientist on a group of "non-materialist neuroscientists" that is trying to resurrect Cartesian Dualism. It is particularly sad that one of these is Jeffrey Schwartz, who has done classic work showing how cognitive therapy can amelioate obsessive compulsive disorder.

Schwartz used scanning technology to look at the neural patterns thought to be responsible for OCD. Then he had patients use "mindful attention" to actively change their thought processes, and this showed up in the brain scans: patients could alter their patterns of neural firing at will. From such experiments, Schwartz and others argue that since the mind can change the brain, the mind must be something other than the brain, something non-material. In fact, these experiments are entirely consistent with mainstream neurology - the material brain is changing the material brain.

Clearly, while there is a genuine attempt to appropriate neuroscience, it will not influence US laws or education in the way that anti-evolution campaigns can because neuroscience is not taught as part of the core curriculum in state-funded schools. But as Andy Clark, professor of logic and metaphysics at the University of Edinburgh, UK, emphasises: "This is real and dangerous and coming our way." He and others worry because scientists have yet to crack the great mystery of how consciousness could emerge from firing neurons. "Progress in science is slow on many fronts," says John Searle, a philosopher at the University of California, Berkeley. "We don't yet have a cure for cancer, but that doesn't mean cancer has spiritual causes." And for Patricia Churchland, a philosopher of neuroscience at the University of California, San Diego, "it is an argument from ignorance. The fact something isn't currently explained doesn't mean it will never be explained or that we need to completely change not only our neuroscience but our physics." The attack on materialism proposes to do just that, but it all turns on definitions. "At one time it looked like all physical causation was push/pull Newtonianism," says Owen Flanagan, professor of philosophy and neurobiology at Duke University, North Carolina. "Now we have a new understanding of physics. What counts as material has changed. Some respectable philosophers think that we might have to posit sentience as a fundamental force of nature or use quantum gravity to understand consciousness. These stretch beyond the bounds of what we today call 'material', and we haven't discovered everything about nature yet. But what we do discover will be natural, not supernatural."

And as Clark observes: "This is an especially nasty mind-virus because it piggybacks on some otherwise reasonable thoughts and worries. Proponents make such potentially reasonable points as 'Oh look, we can change our brains just by changing our minds,' but then leap to the claim that mind must be distinct and not materially based. That doesn't follow at all. There's nothing odd about minds changing brains if mental states are brain states: that's just brains changing brains."

Thursday, November 06, 2008

A conference on "Happiness and its Causes."

There is a "Happiness and its Causes" conference in San Francisco Nov. 24-25, with very flashy marketing and quite a cast of stars: Paul Ekman, Robert Sapolsky, Anne Harrington and others.

Our brain's large scale functional architecture.

He et al. have published an important study that shows correlations between spontaneous fluctuations in slow cortical potentials recorded by electrocorticography and fMRI BOLD signals are maintained across wakefulness, slow-wave sleep, and rapid-eye-movement sleep. Balduzzi et al. note in their review of the work that the study

... makes it clear that both BOLD and ECoG fluctuations display a pattern of regional correlations, or functional connectivity, which closely reflects those regions' anatomical connectivity. Inverting a well known adagio, what wires together, fires together. Indeed, it seems that it could not be otherwise. If neurons are connected in a certain way, and if they are spontaneously active, functional connectivity is bound to reflect anatomical connectivity, just like traffic patterns must reflect the underlying roadmap.
The reviewers also give a nice description of alternative ideas about what the brain's spontaneous or background activity might be for:
The steady depolarization and firing of neurons, even when the brain is supposedly “at rest,” also called the “default mode” of activity, consumes approximately two-thirds of the brain's already disproportionate energy budget, so it better do something useful. For instance, spontaneous activity may be important for the brain's trillions of synapses, perhaps by keeping them exercised or consolidating and renormalizing their strength. Another notion is that spontaneous activity may be necessary to maintain a fluid state of readiness that allows the cortex to rapidly enter any of a number of available states or firing patterns—a kind of metastability. Theoretical work suggests that the repertoire of available states is maximal under moderate spontaneous activity, and shrinks dramatically with either complete inactivity or hyperactivity. But what kind of neural states? One possibility is that the cortex is like a sea undulating gently, and that evoked or task-related responses would be like small ripples on its surface. This possibility is consistent with fMRI studies, because spontaneous slow fluctuations in BOLD are as large or larger than those evoked by stimuli. Also, it would fit nicely with the trial-to-trial variability of behavioral responses. Another possibility is that there are distinct modes of neuronal activity, such as a READY mode and a GO mode (and possibly an inhibited, STOP mode). Spontaneous activity would then be the READY mode of neuronal firing signaling the absence of preferred stimuli (an ongoing, low-level buzz). By contrast, in the GO mode, neurons, or local populations of neurons, would signal the presence of a preferred stimulus by firing at much higher rates for short periods of time (a brief and loud shout). Unit recording studies have provided plenty of evidence that neurons respond strongly and distinctly to specific stimuli. In this view, the cortex would be more like a sea pierced by sharp islands. On the other hand, the slow hemodynamic response function underlying the BOLD signal may make fMRI partly blind to the distinction between slow, low-amplitude fluctuations in firing and fast, high-amplitude bursts of activity. If there are two modes of neural activity, it bears keeping in mind that neurons in the READY mode would be as necessary as neurons in the GO mode in specifying different cognitive states, just as the background is as necessary as the foreground.

The belt of enlightenment...

A map, via Andrew Sullivan's blog, of the counties, mainly in Arkansas through Appalachia, in which more people voted republican in 2008 than in 2004. Overlaps with maps of ignorance, racism and poverty. Not many MindBlog readers in this region!

Could you figure this out?

Get the peanut out of the tube:

Wednesday, November 05, 2008

Language conflict in the bilingual brain

An open access article by Van Heuven et al. in Cerebral Cortex:

The large majority of humankind is more or less fluent in 2 or even more languages. This raises the fundamental question how the language network in the brain is organized such that the correct target language is selected at a particular occasion. Here we present behavioral and functional magnetic resonance imaging data showing that bilingual processing leads to language conflict in the bilingual brain even when the bilinguals’ task only required target language knowledge. This finding demonstrates that the bilingual brain cannot avoid language conflict, because words from the target and nontarget languages become automatically activated during reading. Importantly, stimulus-based language conflict was found in brain regions in the LIPC associated with phonological and semantic processing, whereas response-based language conflict was only found in the pre-supplementary motor area/anterior cingulate cortex when language conflict leads to response conflicts.

Disputed definitions: paradigm shift

NatureNews has an interesting article on words whose definitions get scientists most worked up. Take 'paradigm shift,' for example:

Paradigm shift has a definite origin and originator: Thomas Kuhn, writing in his 1962 book The Structure of Scientific Revolutions, argued against the then prevalent view of science as an incremental endeavour marching ever truthwards. Instead, said Kuhn, most science is "normal science", which fills in the details of a generally accepted, shared conceptual framework. Troublesome anomalies build up, however, and eventually some new science comes along and overturns the previous consensus. Voilà, a paradigm shift. The classic example, Kuhn said, is the Copernican revolution, in which Ptolemaic theory was swept away by putting the Sun at the centre of the Solar System. Post-shift, all previous observations had to be reinterpreted.

Kuhn's theory about how science works was arguably a paradigm shift of its own, by changing the way that academics think about science. And scientists have been using the phrase ever since.

In a postscript to the second edition of his book, Kuhn explained that he used the word 'paradigm' in at least two ways (noting that one "sympathetic reader" had found 22 uses of the term). In its broad form, it encompasses the "entire constellation of beliefs, values, techniques and so on shared by the members of a given community". More specifically it refers to "the concrete puzzle-solutions" that are used as models for normal science post-shift.

Scientists who use the term today don't usually mean that their field has undergone a Copernican-scale revolution, to the undying annoyance of many who hew to Kuhn's narrower definition. But their usage might qualify under his broader one. And so usage becomes a matter of opinion and, perhaps, vanity.

The use of the term in titles and abstracts of leading journals jumped from 30 papers in 1991 to 124 in 1998, yet very few of these papers garnered more than 10 citations apiece1. Several scientists contacted for this article who had used paradigm shift said that, in retrospect, they were having second thoughts. In 2002, Stuart Calderwood, an oncologist at Harvard Medical School in Boston, Massachusetts, used it to describe the discovery that 'heat shock proteins', crucial to cell survival, could work outside the cell as well as in2. "If you work in a field for a long time and everything changes, it does seem like a revolution," he says. But now he says he may have misused the phrase because the discovery was adding to, rather than overturning, previous knowledge in the field.

Arvid Carlsson, of the University of Gothenburg in Sweden stands by his use of the phrase. "Until a certain time, the paradigm was that cells communicate almost entirely by electrical signals," says Carlsson. "In the 1960s and '70s, this changed. They do so predominantly by chemical signals. In my opinion, this is dramatic enough to deserve the term paradigm shift." Few would disagree: base assumptions were overturned in this case, and Carlsson's own work on the chemical neurotransmitter dopamine (which was instrumental in this particular shift) earned him the 2000 Nobel Prize in Physiology or Medicine

Unless a Nobel prize is in the offing, it might be wise for scientists to adopt the caution of contemporary historians of science and think twice before using a phrase with a complex meaning and a whiff of self promotion. "Scientists all want to be the scientists that generate a new revolution," says Kuhn's biographer, Alexander Bird, a philosopher at the University of Bristol, UK. "But if Kuhn is right, most science is normal science and most people can't perform that role."

Tuesday, November 04, 2008

A break from watching the election returns....

The psychology of voting - US readers: VOTE TODAY!

An interesting article in today's New York Times Science section by Benedict Carey, on the value of voting beyond politics.

Neuroeconomics - the neural circuitry of overbidding

Delgado et al. offer an interesting article in Science Magazine suggesting that fear of loss may mediate overbidding in auctions. Here is their abstract, followed by comments in a review by Maskin.

We take advantage of our knowledge of the neural circuitry of reward to investigate a puzzling economic phenomenon: Why do people overbid in auctions? Using functional magnetic resonance imaging (fMRI), we observed that the social competition inherent in an auction results in a more pronounced blood oxygen level–dependent (BOLD) response to loss in the striatum, with greater overbidding correlated with the magnitude of this response. Leveraging these neuroimaging results, we design a behavioral experiment that demonstrates that framing an experimental auction to emphasize loss increases overbidding. These results highlight a role for the contemplation of loss in understanding the tendency to bid "too high." Current economic theories suggest overbidding may result from either "joy of winning" or risk aversion. By combining neuroeconomic and behavioral economic techniques, we find that another factor, namely loss contemplation in a social context, may mediate overbidding in auctions.
Maskin's comments are based on followup experiments not mentioned in the abstract:
The fMRI data show that subjects experience a lower blood oxygen level in the striatum in response to losing an auction, but no significant change in reaction to winning one. The authors interpret this result as suggesting that subjects experience "fear of losing" and that this fear accounts for their overbidding. But actually modeling fear explicitly--making it precise--does not seem straightforward.

A natural modeling device would be simply to subtract something from the subject's payoff when she loses. However, such a modification would not accord with the authors' findings in their subsequent experiment. In the follow-up, there were two treatments: one in which a subject is initially given a bonus sum of money S but told that she has to return it if she loses the auction; the other in which the subject is promised that if she wins she will get S. The two treatments are, ex post, identical: In both cases, the subject ends up with the bonus if and only if she wins. However, in practice, subjects bid more in the former treatment than the latter. Such behavior sharply contradicts the "payment subtraction" hypothesis, under which behavior in the two treatments would be the same. Moreover, it seems difficult to find a natural alternative formulation of the "fear of losing" idea that explains the results simultaneously from both Delgado et al. experiments. Even so, there is a well-known principle that could account for the behavioral discrepancy between the two treatments in the follow-up experiment: the "endowment" effect. When a subject is given a bonus S at the outset, she may become possessive and so move more aggressively to retain it than she would act to obtain a contingent bonus at the end of the experiment.

As for why subjects overbid, perhaps the answer is that high-bid auctions are just too complex for a typical buyer to analyze completely systematically. The buyer will easily see that she has to shade her bid (bid strictly below v) to get a positive payoff. Still, she won't want to shade too much because shading reduces her probability of winning. A simple rule of thumb would be to shade just a little. But this leads immediately to overbidding, because risk-neutral equilibrium bidding entails a great deal of shading: A buyer will bid only one-half her valuation.

The behavioral revolution in economics

In light of the work by Delgado et al. mentioned in today's other posting, I thought it appropriate to pass on this NY Times Op-Ed piece by David Brooks, on the decline of economic models that presume that people are mostly engaged in rationally calculating and maximizing their self-interest. Rather, people put great energy in perceiving things that aren't true. Brooks emphasizes the work of Taleb:

Taleb believes that our brains evolved to suit a world much simpler than the one we now face. His writing is idiosyncratic, but he does touch on many of the perceptual biases that distort our thinking: our tendency to see data that confirm our prejudices more vividly than data that contradict them; our tendency to overvalue recent events when anticipating future possibilities; our tendency to spin concurring facts into a single causal narrative; our tendency to applaud our own supposed skill in circumstances when we’ve actually benefited from dumb luck.

And looking at the financial crisis, it is easy to see dozens of errors of perception. Traders misperceived the possibility of rare events. They got caught in social contagions and reinforced each other’s risk assessments. They failed to perceive how tightly linked global networks can transform small events into big disasters.

Monday, November 03, 2008

Explanatory Neurophilia - seduction without cause

Trout discusses the work of Weinberg (mentioned in a previous post) who has shown in a series of experiment how non-expert consumers of behavioral explanations assign greater standing to explanations that contain neuroscientific details, even if these details provide no additional explanatory value. He discusses the part that this ‘placebic’ information might play in producing a potentially misleading sense of intellectual fluency and, consequently, an unreliable sense of understanding. I'm passing the article on to you here.

Happiness, Eudaimonia, etc.

As I was doing some homework in preparation for a gig as a talking heading ‘expert’ on a web radio show called “Make Me Happy” I ran across this 2002 article, “Pleasure, Meaning & Eudaimonia” by Martin Seligman.

So the core thesis in Authentic Happiness is that there are three very different routes to happiness. First the Pleasant Life, consisting in having as many pleasures as possible and having the skills to amplify the pleasures. This is, of course, the only true kind of happiness on the Hollywood view. Second, the Good Life, which consists in knowing what your signature strengths are, and then recrafting your work, love, friendship, leisure and parenting to use those strengths to have more flow in life. Third, the Meaningful Life, which consists of using your signature strengths in the service of something that you believe is larger than you are.

Sunday, November 02, 2008

MindBlog as election worker...

I got a call from the Obama campaign asking if I would work as a poll watcher at an election polling site on Tuesday. I said yes, went to the training session yesterday (shown at left), and came away in awe of the micro-analytical detail and power of the Obama ground effort. Our main job is to be sure people make it through the long waiting lines, give out registration information and assistance, be alert for any signs of voter intimidation. Another class of poll worker, designated a "Houdini", records the identity of every voter, and at 30 min- 1hr intervals calls in the information to command central, which takes those names off the canvass and phone lists to reallocate resources in real time towards getting out the people who haven't voted.

What is the difference between a 40 and a 70 year old brain...

A piece by Dr. Robert Epstein relevant to the current presidential election.