Our strongest prejudice - partisan hostility

Jonathan Haidt points to the fascinating work by political scientists Shanto Iyengar and Sean Westwood, titled “Fear and Loathing Across Party Lines: New Evidence on Group Polarization.”, who found - in four studies designed to reveal prejudice based on race, gender, religion, or political party or ideology - that cross-partisan prejudice was the largest. For white participants who identified with a party, the cross-partisan effect was about 50 percent larger than the cross-race effect. Haidt points out that This is extremely bad news for America because:

...rising cross-partisan hostility means that Americans increasingly see the other side not just as wrong but as evil, as a threat to the very existence of the nation, according to Pew Research. Americans can expect rising polarization, nastiness, paralysis, and governmental dysfunction for a long time to come...This is extremely bad news for science and universities because universities are usually associated with the left...we can expect increasing hostility from Republican legislators toward universities and the things they desire, including research funding and freedom from federal and state control...This is a warning for the rest of the world because some of the trends that have driven America to this point are occurring in many other countries, including: rising education and individualism (which make people more ideological), rising immigration and ethnic diversity (which reduces social capital and trust), and stagnant economic growth (which puts people into a zero-sum mindset).

The situation is made worse by the "motive attribution asymmetry" that I have referenced in a previous post. Both sides of a political divide attribute their own aggressive behavior to love, but the opposite side's to hatred. Millions of Americans believe that their side is basically benevolent while the other side is evil and out to get them.

How learning shapes the empathic brain.

From Hein et al.:

Abstract

Deficits in empathy enhance conflicts and human suffering. Thus, it is crucial to understand how empathy can be learned and how learning experiences shape empathy-related processes in the human brain. As a model of empathy deficits, we used the well-established suppression of empathy-related brain responses for the suffering of out-groups and tested whether and how out-group empathy is boosted by a learning intervention. During this intervention, participants received costly help equally often from an out-group member (experimental group) or an in-group member (control group). We show that receiving help from an out-group member elicits a classical learning signal (prediction error) in the anterior insular cortex. This signal in turn predicts a subsequent increase of empathy for a different out-group member (generalization). The enhancement of empathy-related insula responses by the neural prediction error signal was mediated by an establishment of positive emotions toward the out-group member. Finally, we show that surprisingly few positive learning experiences are sufficient to increase empathy. Our results specify the neural and psychological mechanisms through which learning interacts with empathy, and thus provide a neurobiological account for the plasticity of empathic reactions.

Virtual reality going mainstream will enhance our understanding of consciousness.

These clips from Thomas Metzinger are fascinating:

2016 will be the year in which VR finally breaks through at the mass consumer level. What is more, users will soon be enabled to toggle between virtual, augmented, and substitutional reality, experiencing virtual elements intermixed with their “actual” physical environment or an omnidirectional video feed giving them the illusion of being in a different location in space and/or time, while insight may not always be preserved. Oculus Rift, Zeiss VR One, Sony PlayStation VR, HTC Vive, Samsung’s Galaxy Gear VR or Microsoft’s HoloLens are just the very beginning...

The real news, however, may be that the general public will gradually acquire a new and intuitive understanding of what their very own conscious experience really is and what it always has been. VR is the representation of possible worlds and possible selves, with the aim of making them appear as real as possible—ideally, by creating a subjective sense of “presence” in the user. Interestingly, some of our best theories of the human mind and conscious experience describe it in a very similar way: Leading theoretical neurobiologists like Karl Friston and eminent philosophers like Jakob Hohwy and Andy Clark describe it as the constant creation of internal models of the world, virtual neural representations of reality which express probability density functions and work by continuously generating hypotheses about the hidden causes of sensory input, minimizing their prediction error. In 1995, Finnish philosopher Antti Revonsuo already pointed out how conscious experience exactly is a virtual model of the world, a dynamic internal simulation, which in standard situations cannot be experienced as a virtual model because it is phenomenally transparent—we “look through it” as if we were in direct and immediate contact with reality. What is historically new, and what creates not only novel psychological risks but also entirely new ethical and legal dimensions, is that one virtual reality gets ever more deeply embedded into another virtual reality: The conscious mind of human beings, which has evolved under very specific conditions and over millions of years, now gets causally coupled and informationally woven into technical systems for representing possible realities. Increasingly, consciousness is not only culturally and socially embedded, but also shaped by a specific technological niche that, over time, quickly acquires rapid, autonomous dynamics and ever new properties. This creates a complex convolution, a nested form of information flow in which the biological mind and its technological niche influence each other in ways we are just beginning to understand.

How our brains change during the day.

I am reminded what a rigid daily schedule my body keeps and expects every time I vary my routine slightly (changing a meal time, exercise, happy hour, bedtime)...my body doesn't like it, feels off kilter. Travel of the sort I've been doing over the past month is a huge disrupter. I'm also clear that any demanding and analytical thinking I might want to do should happen before noontime, because by 4 p.m. (a low blood sugar time for the body), my mind has become very lazy.

McClung and collaborators have done the fascinating experiment of looking at gene expression during the day in brain areas important in learning, memory, and emotion, in 146 young and old brains, finding differences on aging. The brains were from subjects who had died suddenly, as in a car accident. They built on the work of Akil and collaborators who earlier had shown the activity of ~1000 genes varies in a daily pattern that allows the time of death to be predicted within an hour. That pattern was disrupted in people with major depressive disorders. From McClung's group:  

Significance

Circadian rhythms are important in nearly all processes in the brain. Changes in rhythms that come with aging are associated with sleep problems, problems with cognition, and nighttime agitation in elderly people. In this manuscript, we identified transcripts genome-wide that have a circadian rhythm in expression in human prefrontal cortex. Moreover, we describe how these rhythms are changed during normal human aging. Interestingly, we also identified a set of previously unidentified transcripts that become rhythmic only in older individuals. This may represent a compensatory clock that becomes active with the loss of canonical clock function. These studies can help us to develop therapies in the future for older people who suffer from cognitive problems associated with a loss of normal rhythmicity.

Abstract

With aging, significant changes in circadian rhythms occur, including a shift in phase toward a “morning” chronotype and a loss of rhythmicity in circulating hormones. However, the effects of aging on molecular rhythms in the human brain have remained elusive. Here, we used a previously described time-of-death analysis to identify transcripts throughout the genome that have a significant circadian rhythm in expression in the human prefrontal cortex [Brodmann’s area 11 (BA11) and BA47]. Expression levels were determined by microarray analysis in 146 individuals. Rhythmicity in expression was found in ∼10% of detected transcripts (P less than 0.05). Using a metaanalysis across the two brain areas, we identified a core set of 235 genes (q less than 0.05) with significant circadian rhythms of expression. These 235 genes showed 92% concordance in the phase of expression between the two areas. In addition to the canonical core circadian genes, a number of other genes were found to exhibit rhythmic expression in the brain. Notably, we identified more than 1,000 genes (1,186 in BA11; 1,591 in BA47) that exhibited age-dependent rhythmicity or alterations in rhythmicity patterns with aging. Interestingly, a set of transcripts gained rhythmicity in older individuals, which may represent a compensatory mechanism due to a loss of canonical clock function. Thus, we confirm that rhythmic gene expression can be reliably measured in human brain and identified for the first time (to our knowledge) significant changes in molecular rhythms with aging that may contribute to altered cognition, sleep, and mood in later life.

Nature's warning system.

A colleague in my Chaos and Complexity discussion group at the Univ. of Wisconsin passed on this Atlantic article in which my Zoology colleague Steve Carpenter is extensively quoted, which is well worth reading. Complex systems, like ecological food webs, the brain, and the climate, give off characteristic signals when a disastrous transformation is around the corner.

Higher inequality correlates with less generous rich people.

From Côté et. al.:

Research on social class and generosity suggests that higher-income individuals are less generous than poorer individuals. We propose that this pattern emerges only under conditions of high economic inequality, contexts that can foster a sense of entitlement among higher-income individuals that, in turn, reduces their generosity. Analyzing results of a unique nationally representative survey that included a real-stakes giving opportunity (n = 1,498), we found that in the most unequal US states, higher-income respondents were less generous than lower-income respondents. In the least unequal states, however, higher-income individuals were more generous. To better establish causality, we next conducted an experiment (n = 704) in which apparent levels of economic inequality in participants’ home states were portrayed as either relatively high or low. Participants were then presented with a giving opportunity. Higher-income participants were less generous than lower-income participants when inequality was portrayed as relatively high, but there was no association between income and generosity when inequality was portrayed as relatively low. This research finds that the tendency for higher-income individuals to be less generous pertains only when inequality is high, challenging the view that higher-income individuals are necessarily more selfish, and suggesting a previously undocumented way in which inequitable resource distributions undermine collective welfare... Our findings offer a more complete understanding of the association between income and generosity and have implications for contemporary debates about the social impact of unequal resource distributions.

A positive tonic: Human Progress Quantified

Edge.org has just posted responses to its 2016 question of the year "What do you consider the most interesting recent [scientific] news? What makes it important?" Over the next period of time I'm going to be posting edited clips from some of these responses, starting today with Steven Pinker's contribution on human progress:

Human intuition is a notoriously poor guide to reality...Fortunately, as the bugs in human cognition have become common knowledge, the workaround—objective data—has become more prevalent...Sports have been revolutionized by Moneyball, policy by Nudge, punditry by 538.com, forecasting by tournaments and prediction markets, philanthropy by effective altruism, the healing arts by evidence-based medicine.

The most interesting news is that the quantification of life has been extended to the biggest question of all: Have we made progress... in improving the human condition?...Most people agree that life is better than death, health better than disease, prosperity better than poverty, knowledge better than ignorance, peace better than war, safety better than violence, freedom better than coercion. That gives us a set of yardsticks by which we can measure whether progress has actually occurred. The interesting news is that the answer is mostly "yes."... the rate of homicides and war deaths had plummeted over time...People are living longer and healthier lives, not just in the developed world but globally. A dozen infectious and parasitic diseases are extinct or moribund. Vastly more children are going to school and learning to read. Extreme poverty has fallen worldwide from 85 to 10 percent. Despite local setbacks, the world is more democratic than ever. Women are better educated, marrying later, earning more, and in more positions of power and influence. Racial prejudice and hate crimes have decreased since data were first recorded. The world is even getting smarter: In every country, IQ has been increasing by three points a decade.

"Ecomodernists" such as Stewart Brand, Jesse Ausubel, and Ruth DeFries have shown that many indicators of environmental health have improved over the last half-century, and that there are long-term historical processes, such as the decarbonization of energy, the dematerialization of consumption, and the minimization of farmland that can be further encouraged...for all the ways in which the world today falls short of utopia, the norms and institutions of modernity have put us on a good track. We should work on improving them further, rather than burning them down in the conviction that nothing could be worse than our current decadence and in the vague hope that something better might rise from their ashes...quantified human progress emboldens us to seek more of it...The empowering feature of a graph is that it invites one to identify the forces that are pushing a curve up or down, and then to apply them to push it further in the same direction.

Boosting our brain plasticity.

Wow, this study by Forsyth et al. makes me want to run out and buy a bottle of D-cycloserine, which they show enhances experience-dependent learning, i.e. brain plasticity, in healthy adult humans. (Actually, it's expensive, and experimenting with it by yourself is not a good idea.)

 Significance

Experience-dependent plasticity is the capacity of the brain to undergo changes following environmental input and use, and is a primary means through which the adult brain enables new behavior. In the current study, we provide evidence that enhancing signaling at the glutamate N-methyl-D-aspartate receptor (NMDAR) can enhance the mechanism underlying many forms of experience-dependent plasticity (i.e., long-term potentiation of synaptic currents) and also enhance experience-dependent learning in healthy adult humans. This suggests exciting possibilities for manipulating plasticity in adults and has implications for treating neurological and neuropsychiatric disorders in which experience-dependent plasticity is impaired.

Abstract

Experience-dependent plasticity is a fundamental property of the brain. It is critical for everyday function, is impaired in a range of neurological and psychiatric disorders, and frequently depends on long-term potentiation (LTP). Preclinical studies suggest that augmenting N-methyl-D-aspartate receptor (NMDAR) signaling may promote experience-dependent plasticity; however, a lack of noninvasive methods has limited our ability to test this idea in humans until recently. We examined the effects of enhancing NMDAR signaling using D-cycloserine (DCS) on a recently developed LTP EEG paradigm that uses high-frequency visual stimulation (HFvS) to induce neural potentiation in visual cortex neurons, as well as on three cognitive tasks: a weather prediction task (WPT), an information integration task (IIT), and a n-back task. The WPT and IIT are learning tasks that require practice with feedback to reach optimal performance. The n-back assesses working memory. Healthy adults were randomized to receive DCS (100 mg; n = 32) or placebo (n = 33); groups were similar in IQ and demographic characteristics. Participants who received DCS showed enhanced potentiation of neural responses following repetitive HFvS, as well as enhanced performance on the WPT and IIT. Groups did not differ on the n-back. Augmenting NMDAR signaling using DCS therefore enhanced activity-dependent plasticity in human adults, as demonstrated by lasting enhancement of neural potentiation following repetitive HFvS and accelerated acquisition of two learning tasks. Results highlight the utility of considering cellular mechanisms underlying distinct cognitive functions when investigating potential cognitive enhancers.

Negative evaluation of counterstereotypical people by conservatives maintains their sense of certainty

Yet another study on differences in the psychology of conservative and liberal individuals:

People frequently use physical appearance stereotypes to categorize individuals when their group membership is not directly observable. Recent research indicates that political conservatives tend to use such stereotypes more than liberals do because they express a greater desire for certainty and order. In the present research, we found that conservatives were also more likely to negatively evaluate and distribute fewer economic resources to people who deviate from the stereotypes of their group. This occurred for people belonging to both preexisting and novel groups, regardless of whether the stereotypes were real or experimentally fabricated. Critically, conservatives only negatively evaluated counterstereotypical people when the stereotypes were functional—that is, when they expected that they would need to use the stereotypes at a later point to categorize individuals into groups. Moreover, increasing liberals’ desire for certainty led them to negatively evaluate counterstereotypical people just like conservatives did. Thus, conservatives are not only more likely to use stereotypes than are liberals, but are especially likely to negatively evaluate counterstereotypical people to organize the social world with greater certainty.

Dorsal and Ventral Right Brain Pathways for Prosody

Sammler et al. show that analysis of the emotional content, or vocal tone, of our speech is processed in dorsal and ventral streams of the right hemisphere much as phonology, syntax, and semantics are processed by dorsal and ventral streams of the left hemisphere:

Our vocal tone—the prosody—contributes a lot to the meaning of speech beyond the actual words. Indeed, the hesitant tone of a “yes” may be more telling than its affirmative lexical meaning. The human brain contains dorsal and ventral processing streams in the left hemisphere that underlie core linguistic abilities such as phonology, syntax, and semantics. Whether or not prosody — a reportedly right-hemispheric faculty — involves analogous processing streams is a matter of debate. Functional connectivity studies on prosody leave no doubt about the existence of such streams, but opinions diverge on whether information travels along dorsal or ventral pathways. Here we show, with a novel paradigm using audio morphing combined with multimodal neuroimaging and brain stimulation, that prosody perception takes dual routes along dorsal and ventral pathways in the right hemisphere. In experiment 1, categorization of speech stimuli that gradually varied in their prosodic pitch contour (between statement and question) involved (1) an auditory ventral pathway along the superior temporal lobe and (2) auditory-motor dorsal pathways connecting posterior temporal and inferior frontal/premotor areas. In experiment 2, inhibitory stimulation of right premotor cortex as a key node of the dorsal stream decreased participants’ performance in prosody categorization, arguing for a motor involvement in prosody perception. These data draw a dual-stream picture of prosodic processing that parallels the established left-hemispheric multi-stream architecture of language, but with relative rightward asymmetry.

Brain mitochondria function links anxiety with social subordination.

Hollis et al. make the fascinating observation that position in the social hierarchy of rats (dominant versus submissive) can be enhanced or diminished by stimulating or inhibiting energy metabolism of mitochondria in the nucleus accumbens, a brain region that regulates motivation and depression. It is interesting that several of the human dietary supplements that can be purchased from websites promoting brain rejuvenation contain stimulators of mitochondrial function. (I have noted one of these in a previous post.)

Dominance hierarchies are integral aspects of social groups, yet whether personality traits may predispose individuals to a particular rank remains unclear. Here we show that trait anxiety directly influences social dominance in male outbred rats and identify an important mediating role for mitochondrial function in the nucleus accumbens. High-anxious animals that are prone to become subordinate during a social encounter with a low-anxious rat exhibit reduced mitochondrial complex I and II proteins and respiratory capacity as well as decreased ATP and increased ROS production in the nucleus accumbens. A causal link for these findings is indicated by pharmacological approaches. In a dyadic contest between anxiety-matched animals, microinfusion of specific mitochondrial complex I or II inhibitors into the nucleus accumbens reduced social rank, mimicking the low probability to become dominant observed in high-anxious animals. Conversely, intraaccumbal infusion of nicotinamide, an amide form of vitamin B3 known to enhance brain energy metabolism, prevented the development of a subordinate status in high-anxious individuals. We conclude that mitochondrial function in the nucleus accumbens is crucial for social hierarchy establishment and is critically involved in the low social competitiveness associated with high anxiety. Our findings highlight a key role for brain energy metabolism in social behavior and point to mitochondrial function in the nucleus accumbens as a potential marker and avenue of treatment for anxiety-related social disorders.

Socioeconomic status, inflammatory reactivity, and social support.

Interesting work from John-Henderson et al., who suggest that social support is more effective in damping stress responses in people having childhoods with low socioeconomic status than in people with high childhood socioeconomic status.:

Low socioeconomic status (SES) during childhood confers risk for adverse health in adulthood. Accumulating evidence suggests that this may be due, in part, to the association between lower childhood SES and higher levels of pro-inflammatory cytokines. Drawing from literature showing that low childhood SES predicts exaggerated physiological reactivity to stressors and that lower SES is associated with a more communal, socially attuned orientation, we hypothesized that inflammatory reactivity would be more greatly affected by cues of social support among individuals whose childhood SES was low than among those whose childhood SES was high. In two studies, we found that individuals with lower subjective childhood SES exhibited greater reductions in pro-inflammatory cytokine reactivity to a stressor in the presence of a supportive figure (relative to conditions with an unsupportive or neutral figure). These effects were independent of current SES. This work helps illuminate SES-based differences in inflammatory reactivity to stressors, particularly among individuals whose childhood SES was low.

The need for affiliation - communities of kindness

I belong to the Gay Men's Chorus of South Florida, which completed a series of five Christmas season concerts over the past two weeks. Singing in these performances, and doing a piano duet accompaniment for one of the pieces, I was exhausted for several days. Being in the chorus reminds me of church and boy scout groups of my youth. It is a communal setting where there is a sense of family, laughter, love and community. I am struck by parallels with Mark Oppenheimer's description of another secular equivalent to church communities, the CrossFit gym movement.

A for-profit gym franchise founded in 2000 that now has 13,000 licensed operators serving at least two million exercisers, CrossFit — like television, sports fandom and health fads — has become the focus of study by researchers trying to pinpoint what constitutes religiosity in America.

Members speak about their "box," or gym..

...as others might speak about a church or synagogue community. The same is true of some 12-step program members, and devoted college-football fans. In an increasingly secular America, all sorts of activities and subcultures provide the meaning that in the past, at least as we imagine it, religious communities did.

The article outlines several parallels between CrossFit and religious communities. From one member:

What really struck us was the way in which people were bringing their kids to their box...or the way different workouts of the day were named after soldiers who had died in battle. So there’s all of these things you would expect to see in a church — remembering the dead through some sort of ritual, and intergenerational community.

In a similar vein, David Brooks writes about educational communities of character. He cites a number of examples of secondary school settings that emphasize kindness, respect, and responsibility in binding together a learning community.

Empathy is a choice, and can be trained.

I want to pass on some clips from a review by Cameron et al. that summarizes, and has links to, a number of studies that deal our ability to share the experiences of others.

While a single crying child or injured puppy tugs at our heartstrings, large numbers of suffering people, as in epidemics, earthquakes and genocides, do not inspire a comparable reaction...Not only does empathy seem to fail when it is needed most, but it also appears to play favorites. Recent studies have shown that our empathy is dampened or constrained when it comes to people of different races, nationalities or creeds. These results suggest that empathy is a limited resource, like a fossil fuel, which we cannot extend indefinitely or to everyone.

While we concede that the exercise of empathy is, in practice, often far too limited in scope, we dispute the idea that this shortcoming is inherent, a permanent flaw in the emotion itself. Inspired by a competing body of recent research, we believe that empathy is a choice that we make whether to extend ourselves to others...one of us, Daryl Cameron, along with the psychologist Keith Payne, conducted an experiment to see if ...motivational factors could explain why we seem more empathetic to single victims than to large numbers of them.

Participants in this study read about either one or eight child refugees from the Darfur region of Sudan. Half of the participants were led to expect that they would be asked to make a donation to the refugee or refugees, whereas the other half were not. When there was no financial cost involved in feeling empathy, people felt more empathy for the eight children than for the one child, reversing the usual bias. If insensitivity to mass suffering stemmed from an intrinsic limit to empathy, such financial factors shouldn’t have made a difference.

Likewise, in another recent study, the psychologists Karina Schumann, Jamil Zaki and Carol S. Dweck found that when people learned that empathy was a skill that could be improved — as opposed to a fixed personality trait — they engaged in more effort to experience empathy for racial groups other than their own. Empathy for people unlike us can be expanded, it seems, just by modifying our views about empathy.

Male and female brains do not constitute two distinct categories.

From Zoel et al.: Significance

Sex/gender differences in the brain are of high social interest because their presence is typically assumed to prove that humans belong to two distinct categories not only in terms of their genitalia, and thus justify differential treatment of males and females. Here we show that, although there are sex/gender differences in brain and behavior, humans and human brains are comprised of unique “mosaics” of features, some more common in females compared with males, some more common in males compared with females, and some common in both females and males. Our results demonstrate that regardless of the cause of observed sex/gender differences in brain and behavior (nature or nurture), human brains cannot be categorized into two distinct classes: male brain/female brain.

Abstract

Whereas a categorical difference in the genitals has always been acknowledged, the question of how far these categories extend into human biology is still not resolved. Documented sex/gender differences in the brain are often taken as support of a sexually dimorphic view of human brains (“female brain” or “male brain”). However, such a distinction would be possible only if sex/gender differences in brain features were highly dimorphic (i.e., little overlap between the forms of these features in males and females) and internally consistent (i.e., a brain has only “male” or only “female” features). Here, analysis of MRIs of more than 1,400 human brains from four datasets reveals extensive overlap between the distributions of females and males for all gray matter, white matter, and connections assessed. Moreover, analyses of internal consistency reveal that brains with features that are consistently at one end of the “maleness-femaleness” continuum are rare. Rather, most brains are comprised of unique “mosaics” of features, some more common in females compared with males, some more common in males compared with females, and some common in both females and males. Our findings are robust across sample, age, type of MRI, and method of analysis. These findings are corroborated by a similar analysis of personality traits, attitudes, interests, and behaviors of more than 5,500 individuals, which reveals that internal consistency is extremely rare. Our study demonstrates that, although there are sex/gender differences in the brain, human brains do not belong to one of two distinct categories: male brain/female brain.

Good news for the grumpy.

A dogma of the self-help and happiness industries is that unhappiness decreases health and longevity. Happy people are supposed to live longer. Not so, it turns out, according to a British study published in The Lancet that followed one million middle-aged women in Britan for 10 years. Previous work may have confused cause and effect, suggesting that unhappiness made people ill, when it was actually the other way around. Bottom line from the article:

In middle-aged women, poor health can cause unhappiness. After allowing for this association and adjusting for potential confounders, happiness and related measures of wellbeing do not appear to have any direct effect on mortality.

Loneliness hurts.

Reynolds points to an article by Cacioppo et. al., who contribute to a special issue of Cortex magazine on Neuro-cognitive mechanisms of social interactions. From her review:

For early humans, being alone was no way to live. Those on the tribe’s periphery faced increased risks of starvation, predation and early death. And so humans (like other communal creatures) evolved what seem to be specific biological reactions to social threats. A social animal that feels itself to be isolated from its kind begins to behave nervously and experiences unhealthy physiological responses. The body produces more stress-­related biochemicals, leading to inflammation and a reduced ability to fight viral infections. These adaptations might help explain why many chronically lonely people have an overabundance of stress-­related cells and weakened immune systems. But how they see the world — how loneliness affects their thinking — may be just as consequential to their health.

The abstract of the Cacioppo et. al. article, which finds that lonely people become inadvertently hypervigilant to social threats, which makes the loneliness worse:

Being on the social perimeter is not only sad, it is dangerous. Our evolutionary model of the effects of perceived social isolation (loneliness) on the brain as well as a growing body of behavioral research suggests that loneliness promotes short-term self-preservation, including an increased implicit vigilance for social, in contrast to nonsocial, threats. However, this hypothesis has not been tested previously in a neuroimaging study. We therefore used high density EEG and a social Stroop interference task to test the hypothesis that implicit attention to negative social, in contrast to nonsocial, Words in the Stroop task differs between individuals high versus low in loneliness and to investigate the brain dynamics of implicit processing for negative social (vs nonsocial) stimuli in lonely individuals, compared to nonlonely individuals (N = 70). The present study provides the first evidence that negative social stimuli are differentiated from negative nonsocial stimuli more quickly in the lonely than nonlonely brains. Given the timing of this differentiation in the brain and the fact that participants were performing a Stroop task, these results also suggest that these differences reflect implicit rather than explicit attentional differences between lonely and nonlonely individuals. Source estimates were performed for purposes of hypothesis generation regarding underlying neural mechanisms, and the results implicated the neural circuits reminiscent of orienting and executive control aspects of attention as contributing to these differences. Together, the results are in accord with the evolutionary model of loneliness.

A special issue of Science Magazine on aging.

You can see titles and abstracts of articles here. And, I want to pass on a section of one of the articles, “Healthy aging: The ultimate preventative medicine,” that lists interventions to delay aging that seem promising.

Abstract: Age is the greatest risk factor for nearly every major cause of mortality in developed nations. Despite this, most biomedical research focuses on individual disease processes without much consideration for the relationships between aging and disease. Recent discoveries in the field of geroscience, which aims to explain biological mechanisms of aging, have provided insights into molecular processes that underlie biological aging and, perhaps more importantly, potential interventions to delay aging and promote healthy longevity. Here we describe some of these advances, along with efforts to move geroscience from the bench to the clinic. We also propose that greater emphasis should be placed on research into basic aging processes, because interventions that slow aging will have a greater effect on quality of life compared with disease-specific approaches.  

Geroscience interventions with translational potential.

Dietary restriction: Dietary restriction (DR) is the most studied intervention for delaying aging. Although not universally effective, a majority of studies have documented significant increases in both life span and health span when DR is applied in laboratory models, including nonhuman primates. Limited studies also indicate important health benefits, including reversal of disease risk factors, in people who practice DR. Although DR is not a viable translational approach at the population level, research in this area has incited the search for alternative dietary modifications (e.g., low-protein diets) or small-molecule DR mimetics (e.g., mTOR inhibitors, see below) that can provide the health benefits of DR without requiring reduced food consumption.

Exercise: A large body of literature provides evidence that the health benefits of exercise are consistent with the enhancement of health span. However, poor compliance, especially in the elderly population, makes this intervention challenging to apply. Thus, there is high interest in developing pharmacologic interventions that would synergize with lower levels of exercise.

mTOR inhibitors: Rapamycin extends life span and promotes health span in mice, as well as in simpler organisms. Treatment beginning late in life is sufficient to extend life span, reverse cardiac decline, and improve immune function in mice. A recent study also reported that a rapamycin derivative significantly boosts immune function in elderly people .

Metformin and acarbose: Metformin and acarbose are widely used antidiabetes drugs. Metformin improves health span in mice and may slightly extend life span, whereas acarbose markedly extends life span in male mice and modestly extends life span in female mice. In a nonrandomized retrospective analysis, diabetic patients taking metformin have reduced mortality compared with diabetic patients not receiving metformin, and they may live longer than nondiabetics not receiving metformin.

NAD precursors and sirtuin activators: Nicotinamide adenine dinucleotide (NAD) precursors such as nicotinamide riboside and nicotinamide mononucleotide have been reported to improve health span in mouse models of muscle aging and cognitive decline. The mechanism of action is not clear, but it may involve activation of sirtuin NAD-dependent protein deacetylases, along with enhanced mitochondrial function. Other, possibly more specific, sirtuin activators also improve health span and slightly extend life span in mice.

Modifiers of senescence and telomere dysfunction:Senescent cells accumulate during aging and secrete factors that promote inflammation and cancer. Telomere dysfunction is a major cause of cell senescence, and strategies to enhance telomerase function offer promise for improving health span, although the possibility of increased cancer risk must be addressed. Likewise, genetic and pharmacological strategies to target and kill senescent cells enhance both life span and markers of health in short-lived mice with high levels of senescent cells.

Hormonal and circulating factors: Age-related changes in important hormones (including sex-steroids, growth hormone, and insulin-like growth factor 1) are well documented; however, the risks and benefits of hormone supplementation in aging remain largely controversial.  Heterochronic parabiosis experiments in which the circulatory system of an aged mouse is shared with that of a young mouse suggest that additional, more subtle humoral factors affect age-associated declines in several tissues, including the brain, muscle, liver, and heart. Some progress has been made toward defining these factors, and an effort is under way to determine whether transfusion of young plasma can delay Alzheimer’s disease.

Mitochondrial-targeted therapeutics: Mitochondrial dysfunction is a major contributor to aging and age-related diseases, although the mechanisms are more complex than initially suggested by the Harman’s free radical theory of aging. Attention is now being directed to interventions that augment mitochondrial function, energetics, and biogenesis, including mitochondrial-targeted antioxidants and NAD precursors.

Exercise helps your brain rewire.

Our brains are most capable of changing in response to experience when we are young, then this ability abruptly declines into adulthood. Lunghi and Sale do an interesting experiment showing how the plasticity that does remain can be enhanced by exercise. Covering one eye and watching a movie while relaxing in a chair boosts brain responses to the deprived eye. If study participants instead watched the movie while alternating 10 min. intervals of rest and cycling on a stationary bike, this enhancement of the deprived eye became much larger. A figure, followed by their abstract:

Brain plasticity, defined as the capability of cerebral neurons to change in response to experience, is fundamental for behavioral adaptability, learning, memory, functional development, and neural repair. The visual cortex is a widely used model for studying neuroplasticity and the underlying mechanisms. Plasticity is maximal in early development, within the so-called critical period, while its levels abruptly decline in adulthood. Recent studies, however, have revealed a significant residual plastic potential of the adult visual cortex by showing that, in adult humans, short-term monocular deprivation alters ocular dominance by homeostatically boosting responses to the deprived eye. In animal models, a reopening of critical period plasticity in the adult primary visual cortex has been obtained by a variety of environmental manipulations, such as dark exposure, or environmental enrichment, together with its critical component of enhanced physical exercise. Among these non-invasive procedures, physical exercise emerges as particularly interesting for its potential of application to clinics, though there has been a lack of experimental evidence available that physical exercise actually promotes visual plasticity in humans. Here we report that short-term homeostatic plasticity of the adult human visual cortex induced by transient monocular deprivation is potently boosted by moderate levels of voluntary physical activity. These findings could have a bearing in orienting future research in the field of physical activity application to clinical research.

Why doesn't economic growth lead to more happiness?

This is the Easterlin paradox, which I have mentioned in a previous post. Oishi and Kesebir now do an interesting analysis showing that economic growth is not associated with increases in happiness when it is accompanied by growing income inequality.:

One of the most puzzling social science findings in the past half century is the Easterlin paradox: Economic growth within a country does not always translate into an increase in happiness. We provide evidence that this paradox can be partly explained by income inequality. In two different data sets covering 34 countries, economic growth was not associated with increases in happiness when it was accompanied by growing income inequality. Earlier instances of the Easterlin paradox (i.e., economic growth not being associated with increasing happiness) can thus be explained by the frequent concurrence of economic growth and growing income inequality. These findings suggest that a more even distribution of growth in national wealth may be a precondition for raising nationwide happiness.