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

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

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

The sapient paradox

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

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

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

Merlin's review succinctly summarizes the views of conference contributors on these issues.

Risk and reward processing in different prefrontal areas

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

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

Can evolution explain how minds work?

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

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

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

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

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

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

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

Cortical thinning in people with familial risk for major depression

From Peterson et al:

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

The Green Brain

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

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

...where nearly all dollars for climate investigation are directed toward physical or biological projects, the notion that vital environmental solutions will be attained through social-science research — instead of improved climate models or innovative technologies — is an aggressively insurgent view.

But in fact,

...climate change is anthropogenic...More or less, people have agreed on that. That means it’s caused by human behavior. That’s not to say that engineering solutions aren’t important. But if it’s caused by human behavior, then the solution probably also lies in changing human behavior.

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

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

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

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

Music and the brain - rhythm and pleasure

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

To shed light on how humans can learn to understand music, we need to discover what the perceptual capabilities with which infants are born. Beat induction, the detection of a regular pulse in an auditory signal, is considered a fundamental human trait that, arguably, played a decisive role in the origin of music. Theorists are divided on the issue whether this ability is innate or learned. We show that newborn infants develop expectation for the onset of rhythmic cycles (the downbeat), even when it is not marked by stress or other distinguishing spectral features. Omitting the downbeat elicits brain activity associated with violating sensory expectations. Thus, our results strongly support the view that beat perception is innate.

Also, Blood and Zatorre on brain imaging during experiencing pleasurable music:

We used positron emission tomography to study neural mechanisms underlying intensely pleasant emotional responses to music. Cerebral blood flow changes were measured in response to subject-selected music that elicited the highly pleasurable experience of “shivers-down-the-spine” or “chills.” Subjective reports of chills were accompanied by changes in heart rate, electromyogram, and respiration. As intensity of these chills increased, cerebral blood flow increases and decreases were observed in brain regions thought to be involved in reward/motivation, emotion, and arousal, including ventral striatum, midbrain, amygdala, orbitofrontal cortex, and ventral medial prefrontal cortex. These brain structures are known to be active in response to other euphoria-inducing stimuli, such as food, sex, and drugs of abuse. This finding links music with biologically relevant, survival-related stimuli via their common recruitment of brain circuitry involved in pleasure and reward.

A bird that follows human eye movements.

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

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

Chimps exchange meat for sex

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

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

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

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

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

The shoplifting "high"

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

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

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

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

The power of positive thinking.

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

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

Automatically extracting group membership from faces.

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

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

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

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

Science by machine....

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

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

...by automatically searching motion-tracking data captured from various physical systems, ranging from simple harmonic oscillators to chaotic double-pendula. Without any prior knowledge about physics, kinematics, or geometry, the algorithm discovered Hamiltonians, Lagrangians, and other laws of geometric and momentum conservation. The discovery rate accelerated as laws found for simpler systems were used to bootstrap explanations for more complex systems, gradually uncovering the "alphabet" used to describe those systems.

King et al. constructed a robot scientist named Adam that used artificial intelligence to come up with a hypothesis about genes in baker’s yeast and the enzymes produced by the genes. It then designed and ran experiments to test its hypothesis. Using the results, it revised its hypothesis and ran more experiments before arriving at its conclusions. From their abstract:

Adam has autonomously generated functional genomics hypotheses about the yeast Saccharomyces cerevisiae and experimentally tested these hypotheses by using laboratory automation. We have confirmed Adam's conclusions through manual experiments. To describe Adam's research, we have developed an ontology and logical language. The resulting formalization involves over 10,000 different research units in a nested treelike structure, 10 levels deep, that relates the 6.6 million biomass measurements to their logical description. This formalization describes how a machine contributed to scientific knowledge.

Pride

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

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

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

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

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

Sleeping to reset overstimulated brain connections

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

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

Donlea et al. find that disrupting any one of three genes, including period, an integral component of the circadian clock, prevents flies from sleeping longer after a socially stimulating day. Restoring the genes in just 16 so-called ventral lateral neurons--out of some 200,000 neurons in the fly brain--is enough to restore increased sleep after social enrichment...The circadian clock tells animals when to sleep, but the duration of sleep depends on how long they've been awake and what they've done during that time...the same social experiences that increase the need for sleep also increase the number of synapses between lateral ventral neurons and their partners in the brainstem. After sleep, synapse numbers had declined

However,

...it's unlikely that downscaling happens only during sleep or that synaptic strengthening is limited to waking hours. Human and rodent studies have suggested that sleep may be important for consolidating newly formed memories, a process that's widely assumed to depend on strengthening synapses.

Cognitive gains in bilingual infants

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

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

Illusory control

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

Three experiments demonstrated that the experience of power leads to an illusion of personal control. Regardless of whether power was experientially primed (Experiments 1 and 3) or manipulated through roles (manager vs. subordinate; Experiment 2), it led to perceived control over outcomes that were beyond the reach of the power holder. Furthermore, this illusory control mediated the influence of power on several self-enhancement and approach-related outcomes reported in the power literature, including optimism (Experiment 2), self-esteem (Experiment 3), and action orientation (Experiment 3). These results demonstrate the theoretical importance of perceived control as a generative cause of and driving force behind many of power's far-reaching effects. A fourth experiment ruled out an alternative explanation: that positive mood, rather than illusory control, is at the root of power's effects.

Here is a bit more detail from the article (slightly edited) on the procedures that produced the predicted results:

Experiment 1 manipulated power by asking participants to recall an experience with high power, an experience with low power, or an event unrelated to power. Illusory control was measured using a classic die-rolling paradigm in which participants are offered a reward for predicting the outcome of a roll and are given a choice of rolling the die themselves or having another person roll the die for them. Choosing to roll the die reflects an illusory sense of control; it indicates that the actor believes he or she can personally influence the outcome of the random roll and, thus, increase the odds of obtaining the reward. We predicted that participants in the high-power condition would be more likely than those in the other two conditions to choose to roll the die.

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

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

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

Social motives for syntax.

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

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

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

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

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

Social isolation enhances neuroinflammatory response to stroke.

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

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