Genetics of successful placebo response to stress.

Here is a fascinating piece of work from Furmark et al., showing that placebo treatment of stress in subjects with social anxiety disorder (reflected by reducted amygdala activity during public speaking) was successful only in individuals with particular forms of serotonin transporter and tryptophan hydroxylase genes. This demonstrates a link between genetically controlled serotonergic modulation of amygdala activity and placebo-induced anxiety relief. The experiments were done in the context of a study evaluating a potential anti-anxiety drug and matching placebo provided by GlaxoSmithKline.

Placebo may yield beneficial effects that are indistinguishable from those of active medication, but the factors underlying proneness to respond to placebo are widely unknown. Here, we used functional neuroimaging to examine neural correlates of anxiety reduction resulting from sustained placebo treatment under randomized double-blind conditions, in patients with social anxiety disorder. Brain activity was assessed during a stressful public speaking task by means of positron emission tomography before and after an 8 week treatment period. Patients were genotyped with respect to the serotonin transporter-linked polymorphic region (5-HTTLPR) and the G-703T polymorphism in the tryptophan hydroxylase-2 (TPH2) gene promoter. Results showed that placebo response was accompanied by reduced stress-related activity in the amygdala, a brain region crucial for emotional processing. However, attenuated amygdala activity was demonstrable only in subjects who were homozygous for the long allele of the 5-HTTLPR or the G variant of the TPH2 G-703T polymorphism, and not in carriers of short or T alleles. Moreover, the TPH2 polymorphism was a significant predictor of clinical placebo response, homozygosity for the G allele being associated with greater improvement in anxiety symptoms. Path analysis supported that the genetic effect on symptomatic improvement with placebo is mediated by its effect on amygdala activity. Hence, our study shows, for the first time, evidence of a link between genetically controlled serotonergic modulation of amygdala activity and placebo-induced anxiety relief.

Upper limb amputees can sense a rubber hand as their own

A further observation on the brain plasticity shown during the rubber hand illusion (mentioned in the Dec. 24 posting) is made by Ehrsson et al., who find that the illusion can induced in upper limb amputees:

We describe how upper limb amputees can be made to experience a rubber hand as part of their own body. This was accomplished by applying synchronous touches to the stump, which was out of view, and to the index finger of a rubber hand, placed in full view (26 cm medial to the stump). This elicited an illusion of sensing touch on the artificial hand, rather than on the stump and a feeling of ownership of the rubber hand developed. This effect was supported by quantitative subjective reports in the form of questionnaires, behavioural data in the form of misreaching in a pointing task when asked to localize the position of the touch, and physiological evidence obtained by skin conductance responses when threatening the hand prosthesis. Our findings outline a simple method for transferring tactile sensations from the stump to a prosthetic limb by tricking the brain, thereby making an important contribution to the field of neuroprosthetics where a major goal is to develop artificial limbs that feel like a real parts of the body.

Musing on the topic of well-being or happiness...

On seeing this Op-Ed piece by Lyubomirsky in the NYTimes I realized that this is the author, an academic researcher, who has put out a book that I am currently scanning titled "The How of Happiness: A Scientific Approach to Getting the Life You Want." The NYTimes Op-Ed piece notes that the reason that most of us are not more dejected than one might expect by the market meltdown and recession is that the fortunes of virtually everyone have been compromised, and we care more about social comparison, status and rank than about the absolute value of our bank accounts or reputations.

With regard to the book, Ms. Lyubomirsky can not be accused of being a skilled prose stylist, but her writing does offer a meat and potatoes list of behavioral tips on activities that have been shown in double blind studies on fairly large groups of real people to enhance well-being, namely:

Expressing gratitude
Cultivating Optimism
Avoiding over thinking and social comparison
Practicing acts of kindness
Nurturing relationships
Developing strategies for coping.
Learning to forgive
Doing more activities that truly engage you.
Savoring Life’s joys
Committing to your goals
Practicing religion and spirituality
Taking care of your body.

She suggests taking the four of these that seem most congenial to you, and working on those rather than tackling the whole list.

My take on this well-being stuff is that it does boil down to some fairly discrete mental operations, being a matter of executive (frontal lobe) function - to put some things in your mind and not others - images of coherence and well being versus random input from the environment and the old pandora’s box of your past. This is essentially cognitive therapy, letting one thing express rather than another (making a distinction such as: ‘this is a part of my brain that is not working to my advantage’). It does not have to be an energy draining self-coercion of one part of ourselves going to war with another, but rather is a self choosing of one option over another. You are what you spend your time doing.

Hemispheric shift of categorical color perception during brain development.

Franklin et al. show an interesting shift in categorical perception of colors from right to left hemisphere as infants learn the words that distinguish the relevant category boundaries, showing an influence of language on the functional organization of the brain.

Categorical perception (CP) of color is the faster and more accurate discrimination of two colors from different categories than two colors from the same category, even when same- and different-category chromatic separations are equated. In adults, color CP is lateralized to the left hemisphere (LH), whereas in infants, it is lateralized to the right hemisphere (RH). There is evidence that the LH bias in color CP in adults is due to the influence of color terms in the LH. Here we show that the RH to LH switch in color CP occurs when the words that distinguish the relevant category boundary are learned. A colored target was shown in either the left- or right-visual field on either the same- or different-category background, with equal hue separation for both conditions. The time to initiate an eye movement toward the target from central fixation at target onset was recorded. Color naming and comprehension was assessed. Toddlers were faster at detecting targets on different- than same-category backgrounds and the extent of CP did not vary with level of color term knowledge. However, for toddlers who knew the relevant color terms, the category effect was found only for targets in the RVF (LH), whereas for toddlers learning the color terms, the category effect was found only for targets in the LVF (RH). The findings suggest that lateralization of color CP changes with color term acquisition, and provide evidence for the influence of language on the functional organization of the brain.

Sharing today's New York Times

How social status shapes race.

Penner and Saperstein carry out an interesting analysis of data from the National Longitudinal Survey of Youth (NLSY), which contains multiple measures of interviewer-classified and self-identified race over a twenty-year period. Their abstract, followed by one figure from the paper:

We show that racial perceptions are fluid; how individuals perceive their own race and how they are perceived by others depends in part on their social position. Using longitudinal data from a representative sample of Americans, we find that individuals who are unemployed, incarcerated, or impoverished are more likely to be seen and identify as black and less likely to be seen and identify as white, regardless of how they were classified or identified previously. This is consistent with the view that race is not a fixed individual attribute, but rather a changeable marker of status.


Figure - Racial self-identification and cumulative social status, 2002. Source: National Longitudinal Survey of Youth. (A) The percentage of respondents who self-identified as white in 2002, restricted to respondents who identified as white in 1979. (B) The percentage of respondents who identified as black in 2002, restricted to respondents who identified as black in 1979. Ever-incarcerated refers to whether the respondent was ever interviewed while in prison; ever-unemployed refers to whether the respondent was ever unemployed for more than 4 months in a calendar year; and ever-impoverished refers to whether the respondent's household income was ever below the poverty line. Error bars, ± 1SE.

Altering our self-face recognition

In the wake of several recent posts on the rubber hand illusion, which alters our sense of where our hand is in space, I thought this observation by Tsakiris was interesting: multisensory input to our face (Synchronous tactile stimulation while watching another person's face being similarly touched) causes a bias in recognizing our own face. Here is the abstract:

How do I know the person I see in the mirror is really me? Is it because I know the person simply looks like me, or is it because the mirror reflection moves when I move, and I see it being touched when I feel touch myself? Studies of face-recognition suggest that visual recognition of stored visual features inform self-face recognition. In contrast, body-recognition studies conclude that multisensory integration is the main cue to selfhood. The present study investigates for the first time the specific contribution of current multisensory input for self-face recognition. Participants were stroked on their face while they were looking at a morphed face being touched in synchrony or asynchrony. Before and after the visuo-tactile stimulation participants performed a self-recognition task. The results show that multisensory signals have a significant effect on self-face recognition. Synchronous tactile stimulation while watching another person's face being similarly touched produced a bias in recognizing one's own face, in the direction of the other person included in the representation of one's own face. Multisensory integration can update cognitive representations of one's body, such as the sense of ownership. The present study extends this converging evidence by showing that the correlation of synchronous multisensory signals also updates the representation of one's face. The face is a key feature of our identity, but at the same time is a source of rich multisensory experiences used to maintain or update self-representations.

The net generation

Hurt offers a review of Tapscott's recent book "Growing up Digital", which defines the 81 million people born between 1977 to 1997 that make up 27% of the population as the "net generation" (following generations X and Y).

"As the first global generation ever, the Net Geners are smarter, quicker and more tolerant of diversity than their predecessors,” Tapscott writes. “They care strongly about justice and the problems faced by their society and are typically engaged in some kind of civic activity at school, at work or in their communities."

Mr. Tapscott devotes an entire chapter to examining how Net Geners are already using their collective power to transform society — as evidenced by their impact on Barack Obama’s presidential campaign...He documents how Mr. Obama capitalized on interactive social networking sites like Facebook and MySpace that inspired the participation of millions of small donors, while Hillary Rodham Clinton relied on relatively old broadcast-style media like television and e-mail to attract much lower numbers of mostly large donors.

Mr. Tapscott identifies eight norms of many members of the Net Generation: they prize freedom; they want to customize things; they enjoy collaboration; they scrutinize everything; they insist on integrity in institutions and corporations; they want to have fun even at school or work; they believe that speed in technology and all else is normal; and they regard constant innovation as a fact of life.

He cites recent brain-imaging and childhood-development studies to buttress his contention that Internet use by Net Geners has fundamentally changed — and improved — the way their brains are wired. Noting that raw I.Q. scores have been climbing by three points a decade since World War II across racial, income and regional boundaries, Mr. Tapscott asserts that Net Geners are also developing valuable skills that do not show up on standard I.Q. tests.

“Not only do video game players notice more, they have highly developed spatial skills that are useful for architects, engineers and surgeons,” he says.

Men are red, women are green.

Here is a curious bit which I pass on from the Random Samples section of the Dec. 19 Science Magazine, describing the work of researchers at Brown University:

Men are colored like Mars, but women are greenish--and the difference may help explain how people perceive la difference...Cognitive scientist Michael Tarr and grad student Adrian Nestor made the discovery by averaging mug shots of 200 white males and females into a single androgynous face. They then obscured it further with randomly placed red and green pixels.

Three volunteers looked at 20,000 different versions of the image--some redder, others greener--and told the researchers which sex they thought each face represented. The result: Faces with green pixels were tagged as female and those with more red pixels as male. The color of the cheekbones, nose, and sides of the mouth were particularly important to decisions, says Tarr, whose paper is in press in Psychological Science.

Marlene Behrmann, a psychologist at Carnegie Mellon University in Pittsburgh, Pennsylvania, says the fact that people subconsciously recognize the red-green distinction "means there is something evolutionarily and ecologically important about color that extends even into the human central nervous system."

Bach oratorio on period instruments.

Cognitive benefits of a walk in the woods

An article by Berman et al. in Psychological Science (PDF here) shows that immersion in a natural environment leads to more than simply a sense of feeling refreshed, it also recharges our cognitive batteries:

We compare the restorative effects on cognitive functioning of interactions with natural versus urban environments. Attention restoration theory (ART) provides an analysis of the kinds of environments that lead to improvements in directed-attention abilities. Nature, which is filled with intriguing stimuli, modestly grabs attention in a bottom-up fashion, allowing top-down directed-attention abilities a chance to replenish. Unlike natural environments, urban environments are filled with stimulation that captures attention dramatically and additionally requires directed attention (e.g., to avoid being hit by a car), making them less restorative. We present two experiments that show that walking in nature or viewing pictures of nature can improve directed-attention abilities as measured with a backwards digit-span task and the Attention Network Task, thus validating attention restoration theory.

Seasonal Nostalgia

I alternatively want to feel warm and cushy or gag myself with a spoon on watching this.

Knowing where and knowing how to get there - a dissociation in the rubber hand illusion.

Kammers et al. show that during the rubber hand illusion (in which watching a rubber hand being stroked while our own unseen hand is synchronously stroked induces a relocation of the sensed position of our own hand towards the rubber hand) our actual ballistic hand movements resist the illusion. Their abstract contains some useful references:

In the well-known rubber hand illusion (RHI), watching a rubber hand being stroked while one's own unseen hand is synchronously stroked, induces a relocation of the sensed position of one's own hand towards the rubber hand [Botvinick, M., & Cohen, J. (1998). Rubber hands ‘feel’ touch that eyes see. Nature, 391(6669), 756]. As one has lost the veridical location of one's hand, one should not be able to correctly guide one's hand movements. An accurate representation of the location of body parts is indeed a necessary pre-requisite for any correct motor command [Graziano, M. S. A., & Botvinick, M. M. (1999). How the brain represents the body: Insights from neurophysiology and psychology. In D. Gopher, & A. Koriat (Eds.), Attention and performance XVII—Cognitive regulation of performance interaction of theory and application (pp. 136–157)]. However, it has not yet been investigated whether action is indeed affected by the proprioceptive drift towards the rubber hand, nor has the resistance of visual capture in the RHI to new proprioceptive information been assessed. In the present two kinematic experiments, we show for the first time that action resists the RHI and that the RHI resists action. In other words, we show a dissociation between illusion-insensitive ballistic motor responses and illusion-sensitive perceptual bodily judgments. Moreover, the stimulated hand was judged closer to the rubber hand for the perceptual responses, even after active movements. This challenges the view that any proprioceptive update through active movement of the stimulated hand erases the illusion. These results expand the knowledge about representations of the body in the healthy brain, and are in line with the currently most used dissociation between two types of body representations so far mainly based on neuropsychological patients [Paillard, J. (1991). Knowing where and knowing how to get there. In J. Paillard (Ed.), Brain and space (pp. 461–481); Paillard, J. (1999). Body schema and body image: A double dissociation in deafferented patients. In G. N. Gantchev, S. Mori, & J.Massion (Eds.), Motor control, today and tomorrow (pp. 197–214)].

Effect of candidate appearance on election outcomes - neural correlates

An interesting open access article from Adolphs and collaborators:

Election outcomes correlate with judgments based on a candidate's visual appearance, suggesting that the attributions viewers make based on appearance, so-called thin-slice judgments, influence voting. Yet, it is not known whether the effect of appearance on voting is more strongly influenced by positive or negative attributions, nor which neural mechanisms subserve this effect. We conducted two independent brain imaging studies to address this question. In Study 1, images of losing candidates elicited greater activation in the insula and ventral anterior cingulate than images of winning candidates. Winning candidates elicited no differential activation at all. This suggests that negative attributions from appearance exert greater influence on voting than do positive. We further tested this hypothesis in Study 2 by asking a separate group of participants to judge which unfamiliar candidate in a pair looked more attractive, competent, deceitful and threatening. When negative attribution processing was enhanced (specifically, under judgment of threat), images of losing candidates again elicited greater activation in the insula and ventral anterior cingulate. Together, these findings support the view that negative attributions play a critical role in mediating the effects of appearance on voter decisions, an effect that may be of special importance when other information is absent.

Enhanced perception of threat during limited attention

This open access article from Dolan's and collaborators builds on previous studies on the role of the amygdala in pre-attentive processing of potential threats, noting parts of the brain that become active during threat identification during periods of compromised attention. Their abstract:

The ability to process stimuli that convey potential threat, under conditions of limited attentional resources, confers adaptive advantages. This study examined the neurobiology underpinnings of this capacity. Employing an attentional blink paradigm, in conjunction with functional magnetic resonance imaging, we manipulated the salience of the second of 2 face target stimuli (T2), by varying emotionality. Behaviorally, fearful T2 faces were identified significantly more than neutral faces. Activity in fusiform face area increased with correct identification of T2 faces. Enhanced activity in rostral anterior cingulate cortex (rACC) accounted for the benefit in detection of fearful stimuli reflected in a significant interaction between target valence and correct identification. Thus, under conditions of limited attention resources activation in rACC correlated with enhanced processing of emotional stimuli. We suggest that these data support a model in which a prefrontal "gate" mechanism controls conscious access of emotional information under conditions of limited attentional resources.

In the same issue of Cerebral Cortex, another Dolan collaboration uses a masked face priming paradigm to show that face responsive regions of the brain become active in the absence of awareness of faces that are presented.

Our motor cortex responds to musical rhythms.

From Chen et al. :

Perception and actions can be tightly coupled; but does a perceptual event dissociated from action processes still engage the motor system? We conducted 2 functional magnetic resonance imaging studies involving rhythm perception and production to address this question. In experiment 1, on each trial subjects 1st listened in anticipation of tapping, and then tapped along with musical rhythms. Recruitment of the supplementary motor area, mid-premotor cortex (PMC), and cerebellum was observed during listen with anticipation. To test whether this activation was related to motor planning or rehearsal, in experiment 2 subjects naively listened to rhythms without foreknowledge that they would later tap along with them. Yet, the same motor regions were engaged despite no action–perception connection. In contrast, the ventral PMC was only recruited during action and action-coupled perceptual processes, whereas the dorsal part was only sensitive to the selection of actions based on higher-order rules of temporal organization. These functional dissociations shed light on the nature of action–perception processes and suggest an inherent link between auditory and motor systems in the context of rhythm.

Video Introduction to Experimental Philosophy

A MindBlog reader points us to this site, which uses a a YouTube video to better explain the concept of intention and the role our moral judgments play in our perception of intent.

Avian Dancing

From the New York Times Magazine special issue on 'Year in Ideas 2008', slightly edited:

Here you see a large white bird balanced on the back of an office chair, bobbing his head, stomping his feet and ... dancing just like a human. Snowball’s videos are changing the way researchers understand the neurology of music and dancing.

Aniruddh Patel, senior fellow at the Neurosciences Institute in California, got the link from a friend. He saw not just a funny bird but also a potential solution to a scientific argument dating back to Darwin: some researchers say that human brains have been specially wired by natural selection for dancing, because dancing confers survival benefits through group bonding. If that were true, according to Patel, you would see dancing only in animals that, like humans, have a long history of music and dance, which no other species has. The fact that only humans dance has long been seen as evidence supporting the evolution argument.

So Patel sent an e-mail message to Snowball’s owner, Irena Schulz, and asked to study her bird. “The obvious question was whether he was just mimicking somebody,” Patel said. To answer that, he made CDs of Snowball’s favorite song (“Everybody (Backstreet’s Back)” by the Backstreet Boys) at various speeds. Schulz videotaped Snowball dancing to each version, and then Patel graphed Snowball’s movement against the music’s beat. “Like a child, he synched to the music for stretches of time, then danced a little faster or a little slower, but always in a rhythmic way,” Patel says. “Statistically those periods when he’s locked onto the beat are not by chance — they really do indicate sensitivity to the beat and an ability to synchronize with it.”

What’s most interesting to Patel is that this ability is present in birds but not in primates, our closest animal relatives. “This is no coincidence,” he says. Patel says dancing is associated with our vocal abilities, not musical hard wiring. Humans and parrots are two of the few species with brains wired for vocal learning — hearing sounds (like words), then coordinating complex movements (lips, tongues, vocal cords) to reproduce those sounds. Other animals who have this ability: dolphins, seals and whales. “In theory,” he says, “they may be able to dance, too. We just don’t know it yet.”

Crisis of Confidence for Masters of the Universe

An interesting article by Friedman in the NYTimes on psychological effects of the market meltdown.

Over the last few months, I have seen a group of patients, all men, who experienced a near collapse in their self-esteem, though none of them were clinically depressed...
Another patient summed it up: “I used to be a master-of-the-universe kind of guy, but this cut me down to size.”

I have plenty of female patients who work in finance at high levels, but none of them has had this kind of psychological reaction. I can’t pretend this is a scientific survey, but I wonder if men are more likely than women to respond this way. At the risk of trading in gender stereotypes, do men rely disproportionately more on their work for their self-esteem than women do? Or are they just more vulnerable to the inevitable narcissistic injury that comes with performing poorly or losing one’s job?

A different patient was puzzled not by his anxiety about the market, but by his total lack of self-confidence. He had always had an easy intuitive feel for finance. But in the wake of the market collapse, he seriously questioned his knowledge and skill.

On Wall Street, though, a rising tide lifts many boats and vice versa, which means that there are many people who succeed — or fail — through no merit or fault of their own.

This observation might ease a sense of personal responsibility for the economic crisis, but it was of little comfort to my patients. I think this is because for many of them, the previously expanding market gave them a sense of power along with something as strong as a drug: thrill.

The human brain is acutely attuned to rewards like money, sex and drugs. It turns out that the way a reward is delivered has an enormous impact on its strength. Unpredictable rewards produce much larger signals in the brain’s reward circuit than anticipated ones. Your reaction to situations that are either better or worse than expected is generally stronger to those you can predict.

My patients lost more than money in the market. Beyond the rush and excitement, they lost their sense of competence and success. At least temporarily: I have no doubt that, like the economy, they will recover. But it’s a reminder of just how fragile our self-confidence can be.

Why are we so nice? ...because generosity wins.

Here is a further entry in Nature's "Being Human" series, in which Martin Nowak points out that mathematical models predict, and experiments confirm, that generosity is an essential feature of winning strategies in games that explore human interactions. 'Prosocial behaviour' has evolved within a framework of direct or indirect reciprocity, and the latter may have provided selection pressure for social intelligence and language. A few excerpts:

Only if certain mechanisms are involved can natural selection favour individuals who reduce their own fitness to increase that of a competitor. One such mechanism is direct reciprocity: my strategy depends on what you have done to me. Another is indirect reciprocity: my strategy depends on what you have done to me and on what you have done to others.

In both, mathematical analysis shows that winning strategies tend to be generous, hopeful and forgiving. Generous here means not seeking to get more than one's opponent; hopeful means cooperating in the first move or in the absence of information; and forgiving means attempting to re-establish cooperation after an accidental defection. These three traits are related. If I am generous, it is easier for me to forgive, and also to be hopeful and take the risk of cooperating with newcomers.

Experiments have confirmed the success of generosity. A typical set-up involves students and computer screens. The computer pairs random individuals. One person, the donor, is asked if she wishes to transfer some money to the recipient. She is informed about the recipient's decisions in previous rounds with other players. The experiment shows that people base their decision on what the recipient has done before. Generous people are more likely to receive donations.

Similar reputation-based systems operate in e-commerce. When buying a camera online, you might consider both the price and the seller's reputation. Consumers are willing to pay higher prices if the seller is thought to be reliable. Successful websites are those with good reputations.

So why aren't humans always 'generous, hopeful and forgiving'? Part of the explanation may be that cooperation is never a stable state. Mathematical studies show that it is constantly challenged by defection. In a society of defectors where no-one helps, a cluster of cooperating individuals can emerge if, by chance, a few people start playing a direct reciprocity strategy called tit-for-tat: I do whatever you have done to me. Tit-for-tat can't persist for long because its appetite for revenge is self-destructive. It is soon replaced by 'generous tit-for-tat'. Here, I cooperate whenever you have cooperated, but sometimes even when you have defected. In other words, I am forgiving. For a while, cooperation thrives. But in a generous tit-for-tat population, the emergence of unconditional cooperators eventually invites the invasion of defectors. This leads to cycles of cooperation and defection — which could account, at least in part, for the mix of cooperators and defectors that persists in human societies.

Mathematical models allow a precise investigation of fundamental aspects of human behaviour. The games described here occur in every society. Ancestral humans spent most of their time in small groups where interactions were repeated. The same is true for most dealings in modern life: repeat encounters are always possible and reputation is typically at stake. The evolution of prosocial behaviour cannot be understood outside the framework of direct or indirect reciprocity. Indeed, I believe that games of indirect reciprocity have provided the crucial selection pressures for social intelligence and language.

In such games, social intelligence is needed to monitor and interpret the interactions of others. We follow with great interest what our fellow creatures do to us and to others. When deciding how to act, we take into account — often subconsciously — the possible consequences for our own reputation. Moreover, our own observations are often not enough; we want to learn from the experiences of others. Spreading the rumours of indirect reciprocity requires language. As my colleague David Haig once remarked "for direct reciprocity you need a face, for indirect reciprocity you need a name".