Tuesday, September 30, 2008

Can you see me?

Check out this interesting piece from John Tierney on modern camouflage that is based on knowledge of how a deer's eye perceives the world.

Male promiscuity versus monogamy in humans nudged by same genes as in Prarie Voles

A series of elegant experiments done on meadow voles versus prairie voles (promiscuous versus monogamous males) show that the different behaviors correlate with genetic variation in the gene for a vasopressin receptor (V1aR). Nonmonogamous meadow voles become more monogamous when V1aR density is increased in relevant brain areas by using viral vector gene transfer. As you might suspect, a similar genetic variation has now been shown by Walum et al.(open access) to correlate with pair-bonding behavior in human males. (I would be most curious to know whether I have the repeat polymorphism that would correlate with my wandering ways!) Here is their abstract:
Pair-bonding has been suggested to be a critical factor in the evolutionary development of the social brain. The brain neuropeptide arginine vasopressin (AVP) exerts an important influence on pair-bonding behavior in voles. There is a strong association between a polymorphic repeat sequence in the 5′ flanking region of the gene (avpr1a) encoding one of the AVP receptor subtypes (V1aR), and proneness for monogamous behavior in males of this species. It is not yet known whether similar mechanisms are important also for human pair-bonding. Here, we report an association between one of the human AVPR1A repeat polymorphisms (RS3) and traits reflecting pair-bonding behavior in men, including partner bonding, perceived marital problems, and marital status, and show that the RS3 genotype of the males also affects marital quality as perceived by their spouses. These results suggest an association between a single gene and pair-bonding behavior in humans, and indicate that the well characterized influence of AVP on pair-bonding in voles may be of relevance also for humans.

Monday, September 29, 2008

The sucker to saint effect.

Here is an interesting tidbit in Psychological Science from Jordan and Monin. They suggest we protect our own self image by feeling morally superior when we otherwise might feel foolish.
When people's rationality and agency are implicitly called into question by the more expedient behavior of others, they sometimes respond by feeling morally superior; this is referred to as the sucker-to-saint effect. In Experiment 1, participants who completed a tedious task and then saw a confederate quit the same task elevated their own morality over that of the confederate, whereas participants who simply completed the task or simply saw the confederate quit did not. In Experiment 2, this effect was eliminated by having participants contemplate a valued personal quality before encountering the rebellious confederate, a result suggesting a role for self-threat in producing moralization. These studies demonstrate that moral judgments can be more deeply embedded in judges' immediate social contexts—and driven more by motivations to maintain self-image—than is typically appreciated in contemporary moral-psychology research. Rather than uphold abstract principles of justice, moral judgment may sometimes just help people feel a little less foolish.

Brain processing of action language influenced by sports experience.

There is abundant evidence that if we train and enhance our skill at a particular kind of action (piano playing, serving a tennis ball, etc.) areas of the premotor and motor cortex involved in the skill increase their relative area. Beilock et al. now provide evidence, in an open access article, that specialized (sports) motor experience enhances action-related language understanding by recruitment of left dorsal lateral premotor cortex, a region normally devoted to higher-level action selection and implementation—even when there is no intention to perform a real action. Thus, the language system is sufficiently plastic and dynamic to encompass expertise-related neural recruitment outside core language networks.

Friday, September 26, 2008

A memory activates the same brain cells as the original experience.

A fascinating observation from Gelbard-Sagiv et al., who studied patients with pharmacologically intractable epilepsy with implanted depth electrodes to localize the focus of seizure onset. Benedict Carey discusses the work. Here is the original abstract:
The emergence of memory, a trace of things past, into human consciousness is one of the greatest mysteries of the human mind. Whereas the neuronal basis of recognition memory can be probed experimentally in human and nonhuman primates, the study of free recall requires that the mind declare the occurrence of a recalled memory (an event intrinsic to the organism and invisible to an observer). Here, we report the activity of single neurons in the human hippocampus and surrounding areas when subjects first view television episodes consisting of audiovisual sequences and again later when they freely recall these episodes. A subset of these neurons exhibited selective firing, which often persisted throughout and following specific episodes for as long as 12 seconds. Verbal reports of memories of these specific episodes at the time of free recall were preceded by selective reactivation of the same hippocampal and entorhinal cortex neurons. We suggest that this reactivation is an internally generated neuronal correlate of the subjective experience of spontaneous emergence of human recollection.

The teenage brain.

Harvard Magazine has an interesting brief article describing work on the teenage brain being done at Harvard Medical School.

Thursday, September 25, 2008

Online brain and cognitive science courses

Every week or so I get an email from a reader asking "how do I find out more about......" or "what is a good book on...." Apart from specific information that I can pass on, I should mention here what I suggest to them (in addition to a google search using proper search terms): The MIT open course ware, for example in Brain and Cognitive science, is amazing. There are a total of 1800 offerings in all college areas.

A taste test for depression?

From a report by Cahoon on the July Physiological Society Meetings in Cambridge, UK.
Melichar and Donaldson gave healthy volunteers a tiny dab of faint flavor on the tongue and asked if they could taste it. The sample was so diluted that they couldn't. The researchers then gave the volunteers pills that boosted brain levels of one of two neurotransmitters, serotonin or noradrenaline. To boost serotonin, for example, patients took a Prozac-like drug known as a selective serotonin-reuptake inhibitor. When volunteers got a serotonin jump, they were suddenly able to taste the feeble flavor if it was bitter or sweet. With noradrenaline boosted, the volunteers were able to taste the dab if it was bitter or sour. Donaldson and Melichar suspected that depressed people had blunted taste buds--the illness is often tied to a lack of either neurotransmitter--and that the right antidepressant would allow depressed people to experience the true vibrancy of flavors.
Experiments are being planned to determine the validity of a taste test for depression:
If those results validate the flavor test, it could become the equivalent of the cholesterol test that persuades someone to take action against heart disease. "The patient has no objective marker" that tells them they're depressed, says Melichar. As a result, he notes, a lot of people end up not taking their medication.

Moreover, given that the researchers have found that serotonin is linked to sweet and noradrenaline is linked to sour, the taste test could be a useful way to determine which drug to use, a big plus because antidepressants can take several weeks or more to have an effect. And with this disease, time is of the essence--if treated within 3 months of becoming depressed, a person has a very good chance of getting better.

Wednesday, September 24, 2008

Training young brains to behave

Benedict Carey offers an informative article on brain development in children, and the growth of self control as the prefrontal cortex matures. The article has an excellent interactive graphic that permits you to move a slider and see brain changes during development.

Social exclusion causes unconscious mimicry

Lakin et al. make some interesting observations on our reactions to being socially excluded by others, we are likely to unconsciously start mimicking their behaviors:
Research across various disciplines has demonstrated that social exclusion has devastating psychological, emotional, and behavioral consequences. Excluded individuals are therefore motivated to affiliate with others, even though they may not have the resources, cognitive or otherwise, to do so. The current research explored whether nonconscious mimicry of other individuals—a low-cost, low-risk, automatic behavior—might help excluded individuals address threatened belongingness needs. Our first experiment demonstrated that excluded people mimic a subsequent interaction partner more than included people do. A second experiment showed that individuals excluded by an in-group selectively (and nonconsciously) mimic a confederate who is an in-group member more than a confederate who is an out-group member. The relationship between exclusion and mimicry suggests that there are automatic behaviors people can use to recover from the experience of being excluded. In addition, this research demonstrates that nonconscious mimicry is selective and sensitive to context.

Tuesday, September 23, 2008

Chill out aids

A few links for calming your mental chatter during these tumultuous financial times:
Worriers Annonymous
Sacred Geometry

Gender gaps widen

A New York Times article by John Tierney describes the work of Schmitt and others:
When men and women take personality tests, some of the old Mars-Venus stereotypes keep reappearing. On average, women are more cooperative, nurturing, cautious and emotionally responsive. Men tend to be more competitive, assertive, reckless and emotionally flat. Clear differences appear in early childhood and never disappear.

What’s not clear is the origin of these differences. Evolutionary psychologists contend that these are innate traits inherited from ancient hunters and gatherers. Another school of psychologists asserts that both sexes’ personalities have been shaped by traditional social roles, and that personality differences will shrink as women spend less time nurturing children and more time in jobs outside the home.

To test these hypotheses, a series of research teams have repeatedly analyzed personality tests taken by men and women in more than 60 countries around the world. For evolutionary psychologists, the bad news is that the size of the gender gap in personality varies among cultures. For social-role psychologists, the bad news is that the variation is going in the wrong direction. It looks as if personality differences between men and women are smaller in traditional cultures like India’s or Zimbabwe’s than in the Netherlands or the United States. A husband and a stay-at-home wife in a patriarchal Botswanan clan seem to be more alike than a working couple in Denmark or France. The more Venus and Mars have equal rights and similar jobs, the more their personalities seem to diverge.

...new data from 40,000 men and women on six continents...suggests that as wealthy modern societies level external barriers between women and men, some ancient internal differences are being revived...biggest changes recorded by the researchers involve the personalities of men, not women. Men in traditional agricultural societies and poorer countries seem more cautious and anxious, less assertive and less competitive than men in the most progressive and rich countries of Europe and North America.

“Humanity’s jaunt into monotheism, agriculturally based economies and the monopolization of power and resources by a few men was ‘unnatural’ in many ways,” Dr. Schmitt says, alluding to evidence that hunter-gatherers were relatively egalitarian. “In some ways modern progressive cultures are returning us psychologically to our hunter-gatherer roots,” he argues. “That means high sociopolitical gender equality over all, but with men and women expressing predisposed interests in different domains. Removing the stresses of traditional agricultural societies could allow men’s, and to a lesser extent women’s, more ‘natural’ personality traits to emerge.”

Monday, September 22, 2008

Cherokee story for a Monday morning...

While I was doing some idle web cruising using StumbleUpon this item came up, which I thought was a good way to frame one basic cognitive therapy technique:
One evening an old Cherokee told his grandson about a battle that goes on inside people.

He said, "My son, the battle is between two wolves inside us all.

One is Evil. It is anger, envy, jealousy, sorrow, regret, greed, arrogance, self-pity, guilt, resentment, inferiority, lies, false pride, superiority, and ego.

The other is Good. It is joy, peace, love, hope, serenity, humility, kindness, benevolence, empathy, generosity, truth, compassion and faith."

The grandson thought about it for a minute and then asked his grandfather: "Which wolf wins?"

The old Cherokee simply replied, "The one you feed."

Neural correlates of Zen meditation

The complete title of the article by Pagoni et al. is “Thinking about Not-Thinking”: Neural Correlates of Conceptual Processing during Zen Meditation. Here is their abstract:
Recent neuroimaging studies have identified a set of brain regions that are metabolically active during wakeful rest and consistently deactivate in a variety the performance of demanding tasks. This “default network” has been functionally linked to the stream of thoughts occurring automatically in the absence of goal-directed activity and which constitutes an aspect of mental behavior specifically addressed by many meditative practices. Zen meditation, in particular, is traditionally associated with a mental state of full awareness but reduced conceptual content, to be attained via a disciplined regulation of attention and bodily posture. Using fMRI and a simplified meditative condition interspersed with a lexical decision task, we investigated the neural correlates of conceptual processing during meditation in regular Zen practitioners and matched control subjects. While behavioral performance did not differ between groups, Zen practitioners displayed a reduced duration of the neural response linked to conceptual processing in regions of the default network, suggesting that meditative training may foster the ability to control the automatic cascade of semantic associations triggered by a stimulus and, by extension, to voluntarily regulate the flow of spontaneous mentation.

Friday, September 19, 2008

Bad mothering, good fathering..

Two interesting pieces of work on the chemistry underlying parental care of children:

Lerch-Haner et al. find in mice that serotonergic function is required for the nurturing and survival of offspring. Mothers with a specific disruption in serotonin neuron development built poor-quality nests and did not keep their offspring huddled together, leaving the litter exposed to the cold. Their litters died within a few days of birth despite adequate nursing. When these mothers' young were fostered by normal mothers immediately after birth, their odds of living rose to normal.

Prudom et al. find in Marmosets (a bi-parental primate) that fathers exposed to isolated scents of their infant displayed a significant drop in serum testosterone levels within 20 min after exposure, enhancing their positive infant care.

YouTube for test tubes...

Something I have been unaware of: A YouTube for scientists called The Journal of Visualized Experiments (JoVE). It is now now being indexed in the popular US National Library of Medicine repositories MEDLINE and PubMed. Many of my experimental successes (more than 15 years ago) were based on extremely subtle manual manipulations of visual receptor cells and their parts. They would have been SO much easier to communicate in this new format.

Thursday, September 18, 2008

Our brains try multiple meanings before a word is finished.

Here are fascinating observations from Revill et al.. Their imaging data provides evidence of activation of relevant perceptual brain regions in response to the semantics (meaning) of a word while lexical competition is in process and before the word is fully recognized:
As a spoken word unfolds over time, it is temporarily consistent with the acoustic forms of multiple words. Previous behavioral research has shown that, in the face of temporary ambiguity about how a word will end, multiple candidate words are briefly activated. Here, we provide neural imaging evidence that lexical candidates only temporarily consistent with the input activate perceptually based semantic representations. An artificial lexicon and novel visual environment were used to target human MT/V5 and an area anterior to it which have been shown to be recruited during the reading of motion words. Participants learned words that referred to novel objects and to motion or color/texture changes that the objects underwent. The lexical items corresponding to the change events were organized into phonologically similar pairs differing only in the final syllable. Upon hearing spoken scene descriptions in a posttraining verification task, participants showed greater activation in the left hemisphere anterior extent of MT/V5 when motion words were heard than when nonmotion words were heard. Importantly, when a nonmotion word was heard, the level of activation in the anterior extent of MT/V5 was modulated by whether there was a phonologically related competitor that was a motion word rather than another nonmotion word. These results provide evidence of activation of a perceptual brain region in response to the semantics of a word while lexical competition is in process and before the word is fully recognized.

Development of sharing in human children.

Unlike chimpanzees, young children develop a particular form of other-regarding behaviour, called inequality aversion, between the ages of three and eight. On average, three- and four- year-olds behave selfishly whereas seven- and eight-year-olds prefer situations that remove inequality - within their group, that is. Here is the abstract from Fehr et al, who carried out studies with 229 Swiss boys and girls between 3 and 8 years of age to note changes in other-regarding behavior with age:
Human social interaction is strongly shaped by other-regarding preferences, that is, a concern for the welfare of others. These preferences are important for a unique aspect of human sociality—large scale cooperation with genetic strangers—but little is known about their developmental roots. Here we show that young children's other-regarding preferences assume a particular form, inequality aversion that develops strongly between the ages of 3 and 8. At age 3–4, the overwhelming majority of children behave selfishly, whereas most children at age 7–8 prefer resource allocations that remove advantageous or disadvantageous inequality. Moreover, inequality aversion is strongly shaped by parochialism, a preference for favoring the members of one's own social group. These results indicate that human egalitarianism and parochialism have deep developmental roots, and the simultaneous emergence of altruistic sharing and parochialism during childhood is intriguing in view of recent evolutionary theories which predict that the same evolutionary process jointly drives both human altruism and parochialism.

Wednesday, September 17, 2008

Symmetrical bodies are the sexiest...an underlying reason

Why do we find someone attractive? The observations of Brown et al. support the idea that we find symmetrical human bodies most attractive, and that this signals underlying genotypic or phenotypic quality. (Across many species and taxa, higher body assymetry is associated with increased morbidity and mortality, decreased fecundity, and other variables linked to natural and sexual selection.) Here is their abstract:
Body size and shape seem to have been sexually selected in a variety of species, including humans, but little is known about what attractive bodies signal about underlying genotypic or phenotypic quality. A widely used indicator of phenotypic quality in evolutionary analyses is degree of symmetry (i.e., fluctuating asymmetry, FA) because it is a marker of developmental stability, which is defined as an organism's ability to develop toward an adaptive end-point despite perturbations during its ontogeny. Here we sought to establish whether attractive bodies signal low FA to observers, and, if so, which aspects of attractive bodies are most predictive of lower FA. We used a 3D optical body scanner to measure FA and to isolate size and shape characteristics in a sample of 77 individuals (40 males and 37 females). From the 3D body scan data, 360° videos were created that separated body shape from other aspects of visual appearance (e.g., skin color and facial features). These videos then were presented to 87 evaluators for attractiveness ratings. We found strong negative correlations between FA and bodily attractiveness in both sexes. Further, sex-typical body size and shape characteristics were rated as attractive and correlated negatively with FA. Finally, geometric morphometric analysis of joint configurations revealed that sex-typical joint configurations were associated with both perceived attractiveness and lower FA for male but not for female bodies. In sum, body size and shape seem to show evidence of sexual selection and indicate important information about the phenotypic quality of individuals.

Stress during pregnancy hard on males

Mueller and Bale offer more information on what stress in female mice during pregnancy can do, particularly to male offspring:
Prenatal stress is associated with an increased vulnerability to neurodevelopmental disorders, including autism and schizophrenia. To determine the critical time window when fetal antecedents may induce a disease predisposition, we examined behavioral responses in offspring exposed to stress during early, mid, and late gestation. We found that male offspring exposed to stress early in gestation displayed maladaptive behavioral stress responsivity, anhedonia, and an increased sensitivity to selective serotonin reuptake inhibitor treatment. Long-term alterations in central corticotropin-releasing factor (CRF) and glucocorticoid receptor (GR) expression, as well as increased hypothalamic–pituitary–adrenal (HPA) axis responsivity, were present in these mice and likely contributed to an elevated stress sensitivity. Changes in CRF and GR gene methylation correlated with altered gene expression, providing important evidence of epigenetic programming during early prenatal stress. In addition, we found the core mechanism underlying male vulnerability may involve sex-specific placenta responsivity... in male placentas but not females. Examination of placental epigenetic machinery revealed basal sex differences, providing further evidence that sex-specific programming begins very early in pregnancy, and may contribute to the timing and vulnerability of the developing fetus to maternal perturbations. Overall, these results indicate that stress experience early in pregnancy may contribute to male neurodevelopmental disorders through impacts on placental function and fetal development.

Tuesday, September 16, 2008

More on digitial intimacy - MindBlog followers and demographics

No sooner have I done yesterday's posting on the 'ambient intimacy' generated by services like Facebook and Twitter than I find on logging in to my Blogger.com dashboard (menu) page a new icon indicating a feature I have been unaware of, 'followers' of the blog. I added the 'gadget' to the left column of this blog (I'll try anything once), and on reading a bit further discover that it appears to deal only with followers who have blogger accounts. They can choose to have the fact that they are following the blog be either private or have their name listed in the box.

I try not to pay attention to the myriad ways one can monitor a blog's traffic, but when the Scientific American people asked me to join their 'Partner's Network' (see the icon in the left column) they asked me to sign on to the quantcast.com analysis site. If you go to quantcast.com and simply enter mindblog.dericbownds.net in the box, you immediately get a detailed demongraphic analysis of this blog's readers: sex, age, income, and how many addicts, regulars, and passers-by there are.

Our aging brains - impaired suppression of distracting information

This work from Gazzaley et al. strikes WAY to close to home for me, as a description of my own aging (66 year old) brain, and why I get frustrated with the n-back memory exercise. Their abstract:
In this study, electroencephalography (EEG) was used to examine the relationship between two leading hypotheses of cognitive aging, the inhibitory deficit and the processing speed hypothesis. We show that older adults exhibit a selective deficit in suppressing task-irrelevant information during visual working memory encoding, but only in the early stages of visual processing. Thus, the employment of suppressive mechanisms are not abolished with aging but rather delayed in time, revealing a decline in processing speed that is selective for the inhibition of irrelevant information. EEG spectral analysis of signals from frontal regions suggests that this results from excessive attention to distracting information early in the time course of viewing irrelevant stimuli. Subdividing the older population based on working memory performance revealed that impaired suppression of distracting information early in the visual processing stream is associated with poorer memory of task-relevant information. Thus, these data reconcile two cognitive aging hypotheses by revealing that an interaction of deficits in inhibition and processing speed contributes to age-related cognitive impairment.

Monday, September 15, 2008

Digital Intimacy

Several years ago I set up a facebook account, looked up the pages of the students who were taking my seminar course, and at the end of the term told them about my experiment. They were mortified to find the professor had seen their self revelations about their sexual and boozing habits - as anyone on the web could have done. Now my daughter and her friends are broadcasting their latest moods and movements via the FaceBook feed, twitter, etc. This sort of freaks me out, the last thing I want is to surrender the last vestiges of my privacy to the greater web community. But, as Clive Thompson points out in his New York Times Magazine article, this new kind of ambient intimacy makes possible a kind of awareness of others not possible before .
Social scientists have a name for this sort of incessant online contact. They call it “ambient awareness.” It is, they say, very much like being physically near someone and picking up on his mood through the little things he does — body language, sighs, stray comments — out of the corner of your eye. Facebook is no longer alone in offering this sort of interaction online. In the last year, there has been a boom in tools for “microblogging”: posting frequent tiny updates on what you’re doing. ... One of the most popular new tools is Twitter, a Web site and messaging service that allows its two-million-plus users to broadcast to their friends haiku-length updates — limited to 140 characters, as brief as a mobile-phone text message — on what they’re doing. There are other services for reporting where you’re traveling (Dopplr) or for quickly tossing online a stream of the pictures, videos or Web sites you’re looking at (Tumblr). And there are even tools that give your location. When the new iPhone, with built-in tracking, was introduced in July, one million people began using Loopt, a piece of software that automatically tells all your friends exactly where you are.

This is the paradox of ambient awareness. Each little update — each individual bit of social information — is insignificant on its own, even supremely mundane. But taken together, over time, the little snippets coalesce into a surprisingly sophisticated portrait of your friends’ and family members’ lives, like thousands of dots making a pointillist painting. This was never before possible, because in the real world, no friend would bother to call you up and detail the sandwiches she was eating. The ambient information becomes like “a type of E.S.P.,” as Haley described it to me, an invisible dimension floating over everyday life.

You could also regard the growing popularity of online awareness as a reaction to social isolation, the modern American disconnectedness that Robert Putnam explored in his book “Bowling Alone.” The mobile workforce requires people to travel more frequently for work, leaving friends and family behind, and members of the growing army of the self-employed often spend their days in solitude. Ambient intimacy becomes a way to “feel less alone,” as more than one Facebook and Twitter user told me.

What will happen in the next ten years?

Nature magazine asked this question of ten prominent researchers and business people. A common theme emerges: the integration of the worlds of matter and information, whether it be by the blurring of boundaries between online and real environments, touchy-feely feedback from a phone or chromosomes tucked away on databases.

Friday, September 12, 2008

Brooks on how the Republicans just don't get it....

I thought I would pass on this link to David Brook's op-ed piece in today's New York Times, on how Republican party dogma is completely clueless on basic facts about our social brains that have been clearly proven by psychologists, social scientists, cognitive neuroscientists, etc.

Watching practice change the brain cortex.

Our brain cortex is changed by different kinds of learning. These include factual knowledge that is recalled by a purposeful effort and requires the involvement of the explicit memory system (This system is involved in tasks such as spatial navigation and intensive studying). Changes also result from training implicit memory, which refers to intrinsic knowledge about how to perform an action and includes language learning, juggling, mirror reading, and musical training. Duerden and Laverdure-Dupont do a meta-analysis of six morphometric studies that have demonstrated both short- and long-term use-dependent changes caused by these different types of learning. Although structural changes are commonly found in brain regions known to be functionally involved in the particular skill under study, a meta-analytic review of these studies revealed that additional changes often occurred in associative regions including parietal and temporal cortices. studies examining explicit learning showed an overlap of increased gray matter density in the hippocampal gyrus.

Figure - Meta-analysis of voxel-based morphometric studies reporting increased gray matter density after learning in the cortex and cerebellum.

Inducing persistent false beliefs is easy.

Just look at the political scene... But, seriously, the work in question is this interest tidbit from Geraerts et al in Psychological Sciences (the latest issue of this journal is a gold mine of interesting articles. I am porting a few of those abstract to this blog...)
False beliefs and memories can affect people's attitudes, at least in the short term. But can they produce real changes in behavior? This study explored whether falsely suggesting to subjects that they had experienced a food-related event in their childhood would lead to a change in their behavior shortly after the suggestion and up to 4 months later. We falsely suggested to 180 subjects that, as children, they had gotten ill after eating egg salad. Results showed that, after this manipulation, a significant minority of subjects came to believe they had experienced this childhood event even though they had initially denied having experienced it. This newfound autobiographical belief was accompanied by the intent to avoid egg salad, and also by significantly reduced consumption of egg-salad sandwiches, both immediately and 4 months after the false suggestion. The false suggestion of a childhood event can lead to persistent false beliefs that have lasting behavioral consequences.

Thursday, September 11, 2008

Listening to Resveratrol

David Kent writes a well balanced article in American Scientist on issues of human longevity. A graphic and some text on the consequences of lifespan-prolonging therapies on population growth and demographic structure:
In the past century, disease-specific medicine reduced mortality at all ages, including the economically productive years between one's 20s and 60s. Historical trends show an increasing "rectangularization" of mortality rates over the past century, meaning that most people survive to an advanced age, at which point there is a precipitous increase in the number of deaths (green curves). Such data have led some researchers to theorize that the human lifespan is reaching an "ideal" length, beyond which substantial extension is not possible. However, discoveries about the basic mechanisms of aging may permit life expectancy to extend beyond this theoretical limit (red curves).

The rectangularization of the mortality curve implies that life-prolonging therapies will add years only at the end of life. Unless there is a shift in the retirement age, 21st-century medical innovation will have an even more dramatic effect on the dependency ratio (a measure of the portion of a population composed of those either too old or too young to work). Maintaining retirement as a widespread option at around 65, already an economic stretch, undoubtedly will become untenable. The price of longer life will almost certainly be a longer work life.

Chinese kids are ahead even before elementary school...

More sobering data from Siegler and Mu on occidental versus oriental child development. The superior mathematical knowledge of East Asian preschoolers is not limited to skills that are taught directly by parents or in school but is more general.
Kindergartners in China showed greater numerical knowledge than their age peers in the United States, not only when tested with arithmetic problems, which Chinese parents present to their children more often than U.S. parents do, but also when tested with number-line estimation problems, which were novel to the children in both countries. The Chinese kindergartners' number-line estimates were comparable to those of U.S. children 1 to 2 years more advanced in school. Individual differences in arithmetic and number-line-estimation performance were positively correlated within each country. These results indicate that performance differences between Chinese and U.S. children on both practiced and unpracticed mathematical tasks are substantial even before the children begin elementary school.

Wednesday, September 10, 2008

Watching the testosterone crash in anxious men who lose a contest.

This work from Maner et al. makes a rather blunt point:
Although theory suggests a link between social anxiety and social dominance, direct empirical evidence for this link is limited. The present experiment tested the hypothesis that socially anxious individuals, particularly men, would respond to a social-dominance threat by exhibiting decrements in their testosterone levels, an endocrinological change that typically reflects pronounced social submission in humans and other animals. Participants were randomly assigned to either win or lose a rigged face-to-face competition with a confederate. Although no zero-order relationship between social anxiety and level of testosterone was observed, testosterone levels showed a pronounced drop among socially anxious men who lost the competition. No significant changes were observed in nonanxious men or in women. This research provides novel insight into the nature and consequences of social anxiety, and also illustrates the utility of integrating social psychological theory with endocrinological approaches to psychological science.

Figure: Change in testosterone level as a function of experimental condition (losers vs. winners) and social anxiety (1 SD above the mean vs. 1 SD below the mean). Results are presented separately for men and women. Change scores were standardized within each gender.

La gazza ladra passes the mirror test - a crow with a self!

The Eurasian magpie belongs to the same bird family that includes the crows, ravens, and jays. de Waal writes a fascinating review of recent work by Prior et al. that demonstrates that magpies recognize themselves in a mirror - a test that persists as the gold standard of self-identity or 'personhood.' The experiments actually had better controls than many of those done with apes and human children...
...which generally fail to include “sham” marks. A sham mark is applied in the same way as a visible mark, and supposed to feel and smell the same, but cannot be visibly detected. In the magpie study, this was done by placing a black mark onto the magpies' black throat feathers.

Placed on the same black throat feathers, the visible mark—a tiny colored sticker—stood out, but only in a mirror. Put in front of a mirror, the magpies kept scratching with their foot until the mark was gone, whereas they left the sham mark alone. They also didn't do the same amount of frantic scratching if there was no mirror to see themselves in. Evidently, their self-preening was guided by visual feedback from the mirror.

de Waal also discusses work with other species and the “co-emergence hypothesis,” according to which the capacities for mirror self recognition and perspective-taking appear in tandem during both evolution and development.

Speaking of crows, Nijhuis writes a brief piece on work showing that crows recognize individual human faces.

Tuesday, September 09, 2008

Neural correlates of consciousness

I just came across this succinct and informative site in Scholarpedia curated by Christof Koch and Florian Mormann at Cal. Tech. It has some useful instructional graphics.

Midline structures in the brainstem and thalamus necessary to regulate the level of brain arousal. Small, bilateral lesions in many of these nuclei cause a global loss of consciousness. (From Koch, 2004, The Quest for Consciousness: A Neurobiological Approach. Roberts, Denver, CO.)

When a referee sees red...

It has been shown that wearing red sports attire has a positive impact on one's outcome in combat sports such as tae kwon do or wrestling. One speculation has been that this is due to an evolutionary or cultural association of the color red with dominance and aggression, with this association triggering a psychological effects (dominance/submission) in the competitors. Hagemann et al. offer evidence that perceptual bias in the referee is the more likely explanation, by showing that when tae kwon do referees watch videos of matches in which the competitors wear either read or blue protective gear:
The competitor wearing red protective gear was awarded an average of 13% (0.94 points) more points than the competitor wearing blue protective gear. The number of points awarded increased for a blue competitor who was digitally transformed into a red competitor, and decreased for a red competitor who was digitally transformed into a blue competitor.

Monday, September 08, 2008

Culture shapes how we look at faces.

Studies of eye movements have persistently revealed a systematic triangular sequence of fixations over the eye and the mouth, with dominance to the eyes, suggesting that the presence of a face triggers a universal, biologically-determined information extraction pattern. However, the literature is based on observations with adults from Western cultures only. Blais et al. have monitored the eye movements of Western Caucasian and East Asian observers while they learned, recognized, and categorized by race Western Caucasian and East Asian faces. Western Caucasian observers reproduced a scattered triangular pattern of fixations for faces of both races and across tasks. Contrary to intuition, East Asian observers focused more on the central region of the face. The work suggests that face processing does not rise from a universal sequence of perceptual events, but rather that the strategy employed to extract visual information from faces differs across cultures.

Sleep preferentially enhances our emotional memories

Interesting observations from Payne et al. Sleep can preserve our memory of negative objects seen and then forgotten during the day, but not the background in which they originally appeared :
Central aspects of emotional experiences are often well remembered at the expense of background details. Previous studies of such memory trade-offs have focused on memory after brief delays, but little is known about how these components of emotional memories change over time. We investigated the evolution of memory for negative scenes across 30 min, 12 daytime hours spent awake, and 12 nighttime hours including sleep. After 30 min, negative objects were well remembered at the expense of information about their backgrounds. Time spent awake led to forgetting of the entire negative scene, with memories of objects and their backgrounds decaying at similar rates. Sleep, in contrast, led to a preservation of memories of negative objects, but not their backgrounds, a result suggesting that the two components undergo differential processing during sleep. Memory for a negative scene develops differentially across time delays containing sleep and wake, with sleep selectively consolidating those aspects of memory that are of greatest value to the organism.

Friday, September 05, 2008

Our body language of pride and shame is innate

Tracy and Matsumoto have performed an interesting cross cultural study of nonverbal displays of pride and shame in sighted, blind, and congenitally blind individuals:
The research examined whether the recognizable nonverbal expressions associated with pride and shame may be biologically innate behavioral responses to success and failure. Specifically, we tested whether sighted, blind, and congenitally blind individuals across cultures spontaneously display pride and shame behaviors in response to the same success and failure situations—victory and defeat at the Olympic or Paralympic Games. Results showed that sighted, blind, and congenitally blind individuals from >30 nations displayed the behaviors associated with the prototypical pride expression in response to success. Sighted, blind, and congenitally blind individuals from most cultures also displayed behaviors associated with shame in response to failure. However, culture moderated the shame response among sighted athletes: it was less pronounced among individuals from highly individualistic, self-expression-valuing cultures, primarily in North America and West Eurasia. Given that congenitally blind individuals across cultures showed the shame response to failure, findings overall are consistent with the suggestion that the behavioral expressions associated with both shame and pride are likely to be innate, but the shame display may be intentionally inhibited by some sighted individuals in accordance with cultural norms.

Mean levels of pride and shame nonverbal behaviors spontaneously displayed in response to match wins and losses by congenitally blind athletes.

MindBlog strikes it rich...

Here is the result of the little box of Google adds that I let run in the left column of this blog starting a little over a year ago. They send you a check after your cut of the revenue from clicks on the advertisements reaches $100. I guess I had better not quit my day job (being a retired professor).

Thursday, September 04, 2008

Subjective/Objective - applying real-time fMRI

R. Christopher deCharms offers an interesting review article on exploring the mind-body interface with neuroimaging. Here is the abstract, followed by one figure. The PDF is here.
For centuries people have aspired to understand and control the functions of the mind and brain. It has now become possible to image the functioning of the human brain in real time using functional MRI (fMRI), and thereby to access both sides of the mind–brain interface — subjective experience (that is, one's mind) and objective observations (that is, external, quantitative measurements of one's brain activity) — simultaneously. Developments in neuroimaging are now being translated into many new potential practical applications, including the reading of brain states, brain–computer interfaces, communicating with locked-in patients, lie detection, and learning control over brain activation to modulate cognition or even treat disease.

a) Descartes used introspection as a way to perceive the mechanisms of the mind. This approach to observing the mind–brain interface is what people were limited to in the absence of technology. b) Today, using real-time functional MRI, it is possible to measure the level of activation from approx216 brain locations per second. Here, measured activation levels are represented as colours that have been overlaid onto a three-dimensional rendered set of anatomical brain images. c) Information from individual spatial points can be segregated into multiple anatomically defined three-dimensional regions of interest. Here the activation levels (represented as colours) of three brain regions are rendered on a translucent 'glass brain' view. d) Activation in these regions can either be plotted second-by-second in real time or can be presented to subjects in more abstract forms, such as this virtual-reality video display of a beach bonfire, in which each of the three elements of the flickering fire corresponds to activation in a particular brain region. Brain activation can control arbitrarily complex elements of computer-generated scenarios.

Predictability determines whether our attention fades away.

A universal feature of our sensory systems (vision, audition, touch, etc.) is that they adapt, or habituate, to a repeated stimulus - their reporting grows weaker. The common view is that this decrement in response is due largely to automatic processes in sensory neurons. Doing fMRI measurements of cortical responses to photographs of sequentially displayed faces, Summerfield et al. find evidence of a further 'top-down' mechanism for repetition suppression:
By manipulating the likelihood of stimulus repetition, we found that repetition suppression in the human brain was reduced when stimulus repetitions were improbable (and thus, unexpected). Our data suggest that repetition suppression reflects a relative reduction in top-down perceptual 'prediction error' when processing an expected, compared with an unexpected, stimulus.

Wednesday, September 03, 2008

Vasopressin receptor genes of philandering men

Wow, this little item went from online publications by Proc. Nat. Acad. Sci. yesterday straight to the NBC evening news I watched last night. We were bound eventually to find out that what's true for randy male prairie voles is also true for human males. Walum et al:
Pair-bonding has been suggested to be a critical factor in the evolutionary development of the social brain. The brain neuropeptide arginine vasopressin (AVP) exerts an important influence on pair-bonding behavior in voles. There is a strong association between a polymorphic repeat sequence in the 5′ flanking region of the gene (avpr1a) encoding one of the AVP receptor subtypes (V1aR), and proneness for monogamous behavior in males of this species. It is not yet known whether similar mechanisms are important also for human pair-bonding. Here, we report an association between one of the human AVPR1A repeat polymorphisms (RS3) and traits reflecting pair-bonding behavior in men, including partner bonding, perceived marital problems, and marital status, and show that the RS3 genotype of the males also affects marital quality as perceived by their spouses. These results suggest an association between a single gene and pair-bonding behavior in humans, and indicate that the well characterized influence of AVP on pair-bonding in voles may be of relevance also for humans.

We can use our visual cortex for touch

Merabet et al. perform the fascinating experiment of simply blindfolding normal subject for five days, during which intensive tactile training is carried out that improves the subjects' ability to read Braille characters. fMRI measurements reveal an increase in visual cortex responses to tactile stimulation during this period, suggesting that a non-visual input to the visual cortex is being unmasked.
...This increase in signal was no longer present 24 hours after blindfold removal. Finally, reversible disruption of occipital cortex function on the fifth day (by repetitive transcranial magnetic stimulation; rTMS) impaired Braille character recognition ability in the blindfold group but not in non-blindfolded controls. This disruptive effect was no longer evident once the blindfold had been removed for 24 hours.

Overall, our findings suggest that sudden and complete visual deprivation in normally sighted individuals can lead to profound, but rapidly reversible, neuroplastic changes by which the occipital cortex becomes engaged in processing of non-visual information. The speed and dynamic nature of the observed changes suggests that normally inhibited or masked functions in the sighted are revealed by visual loss. The unmasking of pre-existing connections and shifts in connectivity represent rapid, early plastic changes, which presumably can lead, if sustained and reinforced, to slower developing, but more permanent structural changes, such as the establishment of new neural connections in the blind.

Updating our memory requires its original context.

Here is some fascinating work by Hupbach et. al. A clip from a Science Magazine summary:
Recent research has shown that reactivating apparently stable memories can render them fragile and open to modification and to another round of stabilization in a process called reconsolidation. Hupbach et al. explored the conditions leading to the updating of episodic memory. They found that memory plasticity at reactivation provides a mechanism for updating memories, and that the latter are determined by the spatial context; that is, the "where" of episodic memory. Only when the memory was reactivated in the same context as when it was learned could new learning be incorporated into the existing store of knowledge; if reactivated in a new context, no updating occurred.
The abstract of the work:
Understanding the dynamics of memory change is one of the current challenges facing cognitive neuroscience. Recent animal work on memory reconsolidation shows that memories can be altered long after acquisition. When reactivated, memories can be modified and require a restabilization (reconsolidation) process. We recently extended this finding to human episodic memory by showing that memory reactivation mediates the incorporation of new information into existing memory. Here we show that the spatial context plays a unique role for this type of memory updating: Being in the same spatial context during original and new learning is both necessary and sufficient for the incorporation of new information into existing episodic memories. Memories are automatically reactivated when subjects return to an original learning context, where updating by incorporating new contents can occur. However, when in a novel context, updating of existing memories does not occur, and a new episodic memory is created instead.

Tuesday, September 02, 2008

The neural correlates of desire...

Kawabata and Zeki show that categorizing any stimulus according to its desirability activates three different brain areas: the superior orbito-frontal, the mid-cingulate, and the anterior cingulate cortices. The article has the usual pretty fMRI pictures. (Now - if we could just get a fix on the areas active in desire's satiation and avoid all the fuss of real life by just stimulating them directly!)

Predicting the choices of undecided voters - the unseen mind

Not to much of a surprise, but voters who declare themselves to be undecided may be fooling themselves, and are actually unconsciously biased towards one of the choices presented. As Wilson and Bar-Anan point out in their review of the work of Galdi et al.
Social psychologists have discovered an adaptive unconscious that allows people to size up the world extremely quickly, make decisions, and set goals--all while their conscious minds are otherwise occupied. The human mind operates largely out of view of its owners, possibly because that's the way it evolved to work initially, and because that's the way it works best, under many circumstances. Without such an efficient, powerful, and fast means of understanding and acting on the world, it would be difficult to survive. We would be stuck pondering every little decision, such as whether to put our left or right foot forward first, as the world sped by (2-7). But as a result, we are often strangers to ourselves, unable to observe directly the workings of our own minds.

Confabulation. As in this drawing by Saul Steinberg, people construct images of themselves. In real life, people do not realize that their self-knowledge is a construction, and fail to recognize that they possess a vast adaptive unconscious that operates out of their conscious awareness.

Here is the abstract of Galdi et al. that supports this picture using computer-based measures that assess implicit attitudes and traits:
Common wisdom holds that choice decisions are based on conscious deliberations of the available information about choice options. On the basis of recent insights about unconscious influences on information processing, we tested whether automatic mental associations of undecided individuals bias future choices in a manner such that these choices reflect the evaluations implied by earlier automatic associations. With the use of a computer-based, speeded categorization task to assess automatic mental associations (i.e., associations that are activated unintentionally, difficult to control, and not necessarily endorsed at a conscious level) and self-report measures to assess consciously endorsed beliefs and choice preferences, automatic associations of undecided participants predicted changes in consciously reported beliefs and future choices over a period of 1 week. Conversely, for decided participants, consciously reported beliefs predicted changes in automatic associations and future choices over the same period. These results indicate that decision-makers sometimes have already made up their mind at an unconscious level, even when they consciously indicate that they are still undecided.
A 'training of the conscious by the unconscious' is suggested by the observation that the conscious beliefs of the decided voters, which, at the first question period, showed no correlation with their automatic or implicit preferences, did, in fact, predict their implicit preferences during the second session. This suggests that the interaction between unconscious and conscious cognition is a two-way street.

Monday, September 01, 2008

Update on my "Biology of Mind" book - an ebook version

I had an email exchange yesterday with Michiel, in the Netherlands, who has now formatted the web version of my Biology of Mind book as a Sony-formatted file and also as raw HTML for conversion to whatever format you prefer. These are now posted at the mobileread site. (Here is the HTML version which you can simply download, un-zip, and drag into your web browser's window.) In the process, Michiel cleaned up some background noise in the illustrations, and I have placed his improved figures in my website's version of the book. I am most grateful to him for what was a rather major effort.

Ability to use symbols appeared 35 million years ago?

Humans are sometimes said to be distinguished as "The Symbolic Species." A Research Highlights note in Nature point to the work of Addessi et al., who show that capuchin monkeys, who diverged from the human lineage ~35 million years ago, can be trained to use and assign value to tokens (symbols) for different items of food.
...Elsa Addessi of the CNR, Italy's national research council, and her colleagues trained five monkeys to associate a particular token — such as a green chip, black plastic tube or a brass hook — with one of three specific types of food. They then gave the monkeys a series of choices, each time between different amounts of two food items or between two types of token...The value the monkeys assigned to a token was very similar to the value they gave to the food it represented, which suggests that the animals weighed up both real and symbolic options in an equivalent manner.

Cultural evolution in the laboratory

Kirby et al. offer experimental validation for the idea that cultural transmission can lead to the appearance of design without a designer. The abstract is below, and the experimental design best appreciated by examining the paper here:
We introduce an experimental paradigm for studying the cumulative cultural evolution of language. In doing so we provide the first experimental validation for the idea that cultural transmission can lead to the appearance of design without a designer. Our experiments involve the iterated learning of artificial languages by human participants. We show that languages transmitted culturally evolve in such a way as to maximize their own transmissibility: over time, the languages in our experiments become easier to learn and increasingly structured. Furthermore, this structure emerges purely as a consequence of the transmission of language over generations, without any intentional design on the part of individual language learners. Previous computational and mathematical models suggest that iterated learning provides an explanation for the structure of human language and link particular aspects of linguistic structure with particular constraints acting on language during its transmission. The experimental work presented here shows that the predictions of these models, and models of cultural evolution more generally, can be tested in the laboratory.