Beyond anger.

A feature of our current political polarization is the pent up anger felt by both far-left and far-right political partisans against each other, sometimes including dehumanization and demonization of the opposite side. Aeon offers a brief essay by Martha Nussbaum that is worth reading. A few clips and a comment:

A good place to begin is Aristotle’s definition: not perfect, but useful, and a starting point for a long Western tradition of reflection. Aristotle says that anger is a response to a significant damage to something or someone one cares about, and a damage that the angry person believes to have been wrongfully inflicted. He adds that although anger is painful, it also contains within itself a hope for payback.

Nussbaum takes payback, or revenge, as a flawed way of making sense of the world. Except..

There is one, and I think only one, situation in which the payback idea does make sense. That is when I see the wrong as entirely and only what Aristotle calls a ‘down-ranking’: a personal humiliation, seen as entirely about relative status. If the problem is not the injustice itself, but the way it has affected my ranking in the social hierarchy, then I really can achieve something by humiliating the wrongdoer: by putting him relatively lower, I put myself relatively higher, and if status is all I care about, I don’t need to worry that the real wellbeing problems created by the wrongful act have not been solved.

I don't think Nussbaum gives sufficient emphasis to payback, or punishment, as a means to upholding and enforcing social norms. The main part of her essay describes Nelson Mandela's extraordinary actions in overcoming anger to bring together two parts of a deeply divided nation.

Whether the anger in question is personal, or work-related, or political, it requires exacting effort against one’s own habits and prevalent cultural forces. Many great leaders have understood this struggle, but none more deeply than Nelson Mandela...he knew that there could be no successful nation when two groups were held apart by suspicion, resentment, and the desire to make the other side pay for the wrongs they had done. Even though those wrongs were terrible, cooperation was necessary for nationhood.

Nussbaum gives examples of Mandela bringing people together:

When the ANC (African National Congress) voted to replace the old Afrikaner national anthem with the anthem of the freedom movement, he persuaded them to adopt, instead, the anthem that is now official, which includes the freedom anthem (using three African languages), a verse of the Afrikaner hymn, and a concluding section in English. When the ANC wanted to decertify the rugby team as a national team, correctly understanding the sport’s long connection to racism, Mandela, famously, went in the other direction, backing the rugby team to a World Cup victory and, through friendship, getting the white players to teach the sport to young black children.

We need our own Nelson Mandela to begin to heal the current alt-right/alt-left standoff!

Hold your nose to prevent obesity?

Smell clearly affects the anticipation and appreciation of food. Riera et al. show (in mice) that activity in olfactory sensory neurons also influences energy regulation. Mice who lose their sense of smell become leaner, not because they eat less, but because increased sympathetic nerve activity causes increased fat-burning activity.

Highlights

•Loss of adult olfactory neurons protects against diet-induced obesity 

•Loss of smell after obesity also reduces fat mass and insulin resistance 

•Loss of IGF1 receptors in olfactory sensory neurons (OSNs) improves olfaction 

•Loss of IGF1R in OSNs increases adiposity and insulin resistance

Summary

Olfactory inputs help coordinate food appreciation and selection, but their role in systemic physiology and energy balance is poorly understood. Here we demonstrate that mice upon conditional ablation of mature olfactory sensory neurons (OSNs) are resistant to diet-induced obesity accompanied by increased thermogenesis in brown and inguinal fat depots. Acute loss of smell perception after obesity onset not only abrogated further weight gain but also improved fat mass and insulin resistance. Reduced olfactory input stimulates sympathetic nerve activity, resulting in activation of β-adrenergic receptors on white and brown adipocytes to promote lipolysis. Conversely, conditional ablation of the IGF1 receptor in OSNs enhances olfactory performance in mice and leads to increased adiposity and insulin resistance. These findings unravel a new bidirectional function for the olfactory system in controlling energy homeostasis in response to sensory and hormonal signals.

Our broken economy, in one simple chart

You probably have seen this chart from a NYTimes article by now, but I want to pass it on just in case. Also getting it into the list of MindBlog posts makes it easier for me to search for and recall it. The graph shows income growth over the past 34 years versus income percentile for those living in 1980 and in 2014.

Neural correlates of the positive effects of gratitude.

Fox offers a review noting studies showing that gratitude activates area of the medial prefrontal cortex of the brain associated with understanding other people’s perspectives, empathy, and feelings of relief - an area of the brain that also is massively connected to the systems in the body and brain that regulate emotion and support the process of stress relief. He points in particular to the work of Kini et al.. Their abstract:

Gratitude is a common aspect of social interaction, yet relatively little is known about the neural bases of gratitude expression, nor how gratitude expression may lead to longer-term effects on brain activity. To address these twin issues, we recruited subjects who coincidentally were entering psychotherapy for depression and/or anxiety. One group participated in a gratitude writing intervention, which required them to write letters expressing gratitude. The therapy-as-usual control group did not perform a writing intervention. After three months, subjects performed a “Pay It Forward” task in the fMRI scanner. In the task, subjects were repeatedly endowed with a monetary gift and then asked to pass it on to a charitable cause to the extent they felt grateful for the gift. Operationalizing gratitude as monetary gifts allowed us to engage the subjects and quantify the gratitude expression for subsequent analyses. We measured brain activity and found regions where activity correlated with self-reported gratitude experience during the task, even including related constructs such as guilt motivation and desire to help as statistical controls. These were mostly distinct from brain regions activated by empathy or theory of mind. Also, our between groups cross-sectional study found that a simple gratitude writing intervention was associated with significantly greater and lasting neural sensitivity to gratitude – subjects who participated in gratitude letter writing showed both behavioral increases in gratitude and significantly greater neural modulation by gratitude in the medial prefrontal cortex three months later.

Fox also points to an article suggesting a role for mu-Opioids in mediating the positive effects of gratitude.

Exposure to and recall of violence reduce short-term memory and cognitive control

From Bogliacino et al.:

Significance

Research on violence has mainly focused on its consequences on individuals’ health and behavior. This study establishes the effects of exposure to violence on individuals’ short-term memory and cognitive control. These are key factors affecting individual well-being and societal development. We sampled Colombian civilians who were exposed either to urban violence or to warfare. We found that higher exposure to violence significantly reduces short-term memory and cognitive control only in the group actively recalling emotional states linked with such experiences. This finding demonstrates and characterizes the long-lasting effects of violence. Existing studies have found effects of poverty on cognitive control similar to those that we found for violence. This set of findings supports the validity of the cognitive theory underpinning these studies.

Abstract

Previous research has investigated the effects of violence and warfare on individuals' well-being, mental health, and individual prosociality and risk aversion. This study establishes the short- and long-term effects of exposure to violence on short-term memory and aspects of cognitive control. Short-term memory is the ability to store information. Cognitive control is the capacity to exert inhibition, working memory, and cognitive flexibility. Both have been shown to affect positively individual well-being and societal development. We sampled Colombian civilians who were exposed either to urban violence or to warfare more than a decade earlier. We assessed exposure to violence through either the urban district-level homicide rate or self-reported measures. Before undertaking cognitive tests, a randomly selected subset of our sample was asked to recall emotions of anxiety and fear connected to experiences of violence, whereas the rest recalled joyful or emotionally neutral experiences. We found that higher exposure to violence was associated with lower short-term memory abilities and lower cognitive control in the group recalling experiences of violence, whereas it had no effect in the other group. This finding demonstrates that exposure to violence, even if a decade earlier, can hamper cognitive functions, but only among individuals actively recalling emotional states linked with such experiences. A laboratory experiment conducted in Germany aimed to separate the effect of recalling violent events from the effect of emotions of fear and anxiety. Both factors had significant negative effects on cognitive functions and appeared to be independent from each other.

Leisure just as enjoyable before as after work is done.

From O'Brien and Roney:

Four studies reveal that (a) people hold a robust intuition about the order of work and leisure and that (b) this intuition is sometimes mistaken. People prefer saving leisure for last, believing they would otherwise be distracted by looming work (Study 1). In controlled experiments, however, although subjects thought their enjoyment would be spoiled when they played a game before rather than after a laborious problem-solving task, got a massage before rather than after midterms, and consumed snacks and watched videos before rather than after a stressful performance, in reality these experiences were similarly enjoyable regardless of order (Studies 2 through 4). This misprediction was indeed mediated by anticipated distraction and was therefore attenuated after people were reminded of the absorbing nature of enjoyable activities (Studies 3 and 4). These studies highlight the power of hedonic experience within the moment of consumption, which has implications for managing (or mismanaging) everyday work and leisure. People might postpone leisure and overwork for future rewards that could be just as pleasurable in the present.

Perception of being overweight predicts future health and well-being

An interesting bit from Daly et al.:

Identifying oneself as being overweight may be associated with adverse health outcomes, yet prospective tests of this possibility are lacking. Over 7 years, we examined associations between perceptions of being overweight and subsequent health in a sample of 3,582 U.S. adults. Perceiving oneself as being overweight predicted longitudinal declines in subjective health (d = −0.22, p less than .001), increases in depressive symptoms (d = 0.09, p less than .05), and raised levels of physiological dysregulation (d = 0.24, p less than .001), as gauged by clinical indicators of cardiovascular, inflammatory, and metabolic functioning. These associations remained after controlling for a range of potential confounders and were observed irrespective of whether perceptions of being overweight were accurate or inaccurate. This research highlights the possibility that identifying oneself as overweight may act independently of body mass index to contribute to unhealthy profiles of physiological functioning and impaired health over time. These findings underscore the importance of evaluating whether weight-feedback interventions may have unforeseen adverse consequences.

In group favoritism shown by 17 month old infants.

Jin and Baillargeon make observations that suggest an early origin of the 'us and them' perspective being taken to extremes in our current political climate.

One pervasive facet of human interactions is the tendency to favor ingroups over outgroups. Remarkably, this tendency has been observed even when individuals are assigned to minimal groups based on arbitrary markers. Why is mere categorization into a minimal group sufficient to elicit some degree of ingroup favoritism? We consider several accounts that have been proposed in answer to this question and then test one particular account, which holds that ingroup favoritism reflects in part an abstract and early-emerging sociomoral expectation of ingroup support. In violation-of-expectation experiments with 17-mo-old infants, unfamiliar women were first identified (using novel labels) as belonging to the same group, to different groups, or to unspecified groups. Next, one woman needed instrumental assistance to achieve her goal, and another woman either provided the necessary assistance (help event) or chose not to do so (ignore event). When the two women belonged to the same group, infants looked significantly longer if shown the ignore as opposed to the help event; when the two women belonged to different groups or to unspecified groups, however, infants looked equally at the two events. Together, these results indicate that infants view helping as expected among individuals from the same group, but as optional otherwise. As such, the results demonstrate that from an early age, an abstract expectation of ingroup support contributes to ingroup favoritism in human interactions.

Redistribution is supported by compassion, envy, and self interest, but not sense of fairness.

A huge collaboration looks at support for redistribution of wealth from an evolutionary psychology perspective:

Significance

Markets have lifted millions out of poverty, but considerable inequality remains and there is a large worldwide demand for redistribution. Although economists, philosophers, and public policy analysts debate the merits and demerits of various redistributive programs, a parallel debate has focused on voters’ motives for supporting redistribution. Understanding these motives is crucial, for the performance of a policy cannot be meaningfully evaluated except in the light of intended ends. Unfortunately, existing approaches pose ill-specified motives. Chief among them is fairness, a notion that feels intuitive but often rests on multiple inconsistent principles. We show that evolved motives for navigating interpersonal interactions clearly predict attitudes about redistribution, but a taste for procedural fairness or distributional fairness does not.

Abstract

Why do people support economic redistribution? Hypotheses include inequity aversion, a moral sense that inequality is intrinsically unfair, and cultural explanations such as exposure to and assimilation of culturally transmitted ideologies. However, humans have been interacting with worse-off and better-off individuals over evolutionary time, and our motivational systems may have been naturally selected to navigate the opportunities and challenges posed by such recurrent interactions. We hypothesize that modern redistribution is perceived as an ancestral scene involving three notional players: the needy other, the better-off other, and the actor herself. We explore how three motivational systems—compassion, self-interest, and envy—guide responses to the needy other and the better-off other, and how they pattern responses to redistribution. Data from the United States, the United Kingdom, India, and Israel support this model. Endorsement of redistribution is independently predicted by dispositional compassion, dispositional envy, and the expectation of personal gain from redistribution. By contrast, a taste for fairness, in the sense of (i) universality in the application of laws and standards, or (ii) low variance in group-level payoffs, fails to predict attitudes about redistribution.

Smiles for love, sympathy, and war.

From Rychlowska et al.:

A smile is the most frequent facial expression, but not all smiles are equal. A social-functional account holds that smiles of reward, affiliation, and dominance serve basic social functions, including rewarding behavior, bonding socially, and negotiating hierarchy. Here, we characterize the facial-expression patterns associated with these three types of smiles. Specifically, we modeled the facial expressions using a data-driven approach and showed that reward smiles are symmetrical and accompanied by eyebrow raising, affiliative smiles involve lip pressing, and dominance smiles are asymmetrical and contain nose wrinkling and upper-lip raising. A Bayesian-classifier analysis and a detection task revealed that the three smile types are highly distinct. Finally, social judgments made by a separate participant group showed that the different smile types convey different social messages. Our results provide the first detailed description of the physical form and social messages conveyed by these three types of functional smiles and document the versatility of these facial expressions.  (click on figure to enlarge). 

Why it's a bad idea to tell students that words are violence

A piece by Haidt and Lukianoff contesting several points made by Lisa Friedman in a much discussed NYTimes Grey Matter essay is worth a read. After noting that Friedman makes the valid and well known point that chronic stress can cause physical damage to the body, they contest her logic that follows:

Feldman Barrett used these empirical findings to advance a syllogism: “If words can cause stress, and if prolonged stress can cause physical harm, then it seems that speech—at least certain types of speech—can be a form of violence.” It is logically true that if A can cause B and B can cause C, then A can cause C. But following this logic, the resulting inference should be merely that words can cause physical harm, not that words are violence. If you’re not convinced, just re-run the syllogism starting with “gossiping about a rival,” for example, or “giving one’s students a lot of homework.” Both practices can cause prolonged stress to others, but that doesn’t turn them into forms of violence.

Friedman also notes that brief adversity, like being exposed to a distasteful perspective, can be a 'good kind of stress,' not harmful to the body, but rather building more resilience and strength. She notes further that a political or social climate exposing people to hateful words or casual brutality, can be toxic to the body, and then follows with a second invalid point:

That’s why it’s reasonable, scientifically speaking, not to allow a provocateur and hatemonger like Milo Yiannopoulos to speak at your school. He is part of something noxious, a campaign of abuse. There is nothing to be gained from debating him, for debate is not what he is offering.

Haidt and Lukianoff:

But wait, wasn’t Feldman Barrett’s key point the contrast between short- and long-term stressors? What would have happened had Yiannopoulos been allowed to speak at Berkeley? He would have faced a gigantic crowd of peaceful protesters, inside and outside the venue. The event would have been over in two hours. Any students who thought his words would cause them trauma could have avoided the talk and left the protesting to others. Anyone who joined the protests would have left with a strong sense of campus solidarity. And most importantly, all Berkeley students would have learned an essential lesson for life in 2017: How to encounter a troll without losing one’s cool. (The goal of a troll, after all, is to make people lose their cool.)

A positive mood from listening to music broadens our auditory attention.

An addition to the literature from Putkinen et al. expanding on previous findings that positive mood broadens visual attention:

Previous studies indicate that positive mood broadens the scope of visual attention, which can manifest as heightened distractibility. We used event-related potentials (ERP) to investigate whether music-induced positive mood has comparable effects on selective attention in the auditory domain. Subjects listened to experimenter-selected happy, neutral or sad instrumental music and afterwards participated in a dichotic listening task. Distractor sounds in the unattended channel elicited responses related to early sound encoding (N1/MMN) and bottom-up attention capture (P3a) while target sounds in the attended channel elicited a response related to top-down-controlled processing of task-relevant stimuli (P3b). For the subjects in a happy mood, the N1/MMN responses to the distractor sounds were enlarged while the P3b elicited by the target sounds was diminished. Behaviorally, these subjects tended to show heightened error rates on target trials following the distractor sounds. Thus, the ERP and behavioral results indicate that the subjects in a happy mood allocated their attentional resources more diffusely across the attended and the to-be-ignored channels. Therefore, the current study extends previous research on the effects of mood on visual attention and indicates that even unfamiliar instrumental music can broaden the scope of auditory attention via its effects on mood.

Default mode network and the wandering mind.

The respective roles of attentional and default mode networks in our brains has been the subject of numerous MindBlog posts (enter 'default mode' in the search box in the left column). Here is a further installment from Poerio et al.:

Experiences such as mind-wandering illustrate that cognition is not always tethered to events in the here-and-now. Although converging evidence emphasises the default mode network (DMN) in mind-wandering, its precise contribution remains unclear. The DMN comprises cortical regions that are maximally distant from primary sensory and motor cortex, a topological location that may support the stimulus-independence of mind-wandering. The DMN is functionally heterogeneous, comprising regions engaged by memory, social cognition and planning; processes relevant to mind-wandering content. Our study examined the relationships between: (i) individual differences in resting-state DMN connectivity, (ii) performance on memory, social and planning tasks and (iii) variability in spontaneous thought, to investigate whether the DMN is critical to mind-wandering because it supports stimulus-independent cognition, memory retrieval, or both. Individual variation in task performance modulated the functional organization of the DMN: poor external engagement was linked to stronger coupling between medial and dorsal subsystems, while decoupling of the core from the cerebellum predicted reports of detailed memory retrieval. Both patterns predicted off-task future thoughts. Consistent with predictions from component process accounts of mind-wandering, our study suggests a 2-fold involvement of the DMN: (i) it supports experiences that are unrelated to the environment through strong coupling between its sub-systems; (ii) it allows memory representations to form the basis of conscious experience.

The real threat of artificial intelligence

I want to pass on some clips from a very cogent article by Kai-Fu Lee (chairman and chief executive of Sinovation Ventures, a venture capital firm, and the president of its Artificial Intelligence Institute). Then you might like to note the article by Gary Marcus suggesting that A.I. has a long way to go before bringing us to the crisis Lee suggests. (Note added 2/28/2018...an email from a reader points to Bookmark's guide to A.I., which describes benefits and threats of various kinds of A.I. and gives each a 'terminator score.')

What is artificial intelligence today? Roughly speaking, it’s technology that takes in huge amounts of information from a specific domain (say, loan repayment histories) and uses it to make a decision in a specific case (whether to give an individual a loan)...This kind of A.I. is spreading to thousands of domains (not just loans), and as it does, it will eliminate many jobs. Bank tellers, customer service representatives, telemarketers, stock and bond traders, even paralegals and radiologists will gradually be replaced by such software. Over time this technology will come to control semiautonomous and autonomous hardware like self-driving cars and robots, displacing factory workers, construction workers, drivers, delivery workers and many others.

Unlike the Industrial Revolution and the computer revolution, the A.I. revolution is not taking certain jobs (artisans, personal assistants who use paper and typewriters) and replacing them with other jobs (assembly-line workers, personal assistants conversant with computers). Instead, it is poised to bring about a wide-scale decimation of jobs — mostly lower-paying jobs, but some higher-paying ones, too...This transformation will result in enormous profits for the companies that develop A.I., as well as for the companies that adopt it.

We are thus facing two developments that do not sit easily together: enormous wealth concentrated in relatively few hands and enormous numbers of people out of work. What is to be done?

The solution to the problem of mass unemployment, I suspect, will involve “service jobs of love.” These are jobs that A.I. cannot do, that society needs and that give people a sense of purpose. Examples include accompanying an older person to visit a doctor, mentoring at an orphanage and serving as a sponsor at Alcoholics Anonymous — or, potentially soon, Virtual Reality Anonymous (for those addicted to their parallel lives in computer-generated simulations). The volunteer service jobs of today, in other words, may turn into the real jobs of the future.

Who will pay for these jobs? Here is where the enormous wealth concentrated in relatively few hands comes in. It strikes me as unavoidable that large chunks of the money created by A.I. will have to be transferred to those whose jobs have been displaced. This seems feasible only through Keynesian policies of increased government spending, presumably raised through taxation on wealthy companies.

The Keynesian approach I have sketched out may be feasible in the United States and China, which will have enough successful A.I. businesses to fund welfare initiatives via taxes. But what about other countries? ...They face two insurmountable problems. First, most of the money being made from artificial intelligence will go to the United States and China. A.I. is an industry in which strength begets strength...The other challenge for many countries that are not China or the United States is that their populations are increasing, especially in the developing world. While a large, growing population can be an economic asset (as in China and India in recent decades), in the age of A.I. it will be an economic liability because it will comprise mostly displaced workers, not productive ones.

So if most countries will not be able to tax ultra-profitable A.I. companies to subsidize their workers, what options will they have? I foresee only one: Unless they wish to plunge their people into poverty, they will be forced to negotiate with whichever country supplies most of their A.I. software — China or the United States — to essentially become that country’s economic dependent, taking in welfare subsidies in exchange for letting the “parent” nation’s A.I. companies continue to profit from the dependent country’s users. Such economic arrangements would reshape today’s geopolitical alliances.

One way or another, we are going to have to start thinking about how to minimize the looming A.I.-fueled gap between the haves and the have-nots, both within and between nations. Or to put the matter more optimistically: A.I. is presenting us with an opportunity to rethink economic inequality on a global scale. These challenges are too far-ranging in their effects for any nation to isolate itself from the rest of the world.

Buying time promotes happiness.

A nice piece from Whillans et al.:

Significance

Despite rising incomes, people around the world are feeling increasingly pressed for time, undermining well-being. We show that the time famine of modern life can be reduced by using money to buy time. Surveys of large, diverse samples from four countries reveal that spending money on time-saving services is linked to greater life satisfaction. To establish causality, we show that working adults report greater happiness after spending money on a time-saving purchase than on a material purchase. This research reveals a previously unexamined route from wealth to well-being: spending money to buy free time.

Abstract

Around the world, increases in wealth have produced an unintended consequence: a rising sense of time scarcity. We provide evidence that using money to buy time can provide a buffer against this time famine, thereby promoting happiness. Using large, diverse samples from the United States, Canada, Denmark, and The Netherlands (n = 6,271), we show that individuals who spend money on time-saving services report greater life satisfaction. A field experiment provides causal evidence that working adults report greater happiness after spending money on a time-saving purchase than on a material purchase. Together, these results suggest that using money to buy time can protect people from the detrimental effects of time pressure on life satisfaction.

Cognitive reappraisal in frontal cortex underlies placebo analgesia.

Interesting work from van der Meulen et al.:

Placebo analgesia (PA) depends crucially on the prefrontal cortex (PFC), which is assumed to be responsible for initiating the analgesic response. Surprisingly little research has focused on the psychological mechanisms mediated by the PFC and underlying PA. One increasingly accepted theory is that cognitive reappraisal—the reinterpretation of the meaning of adverse events—plays an important role, but no study has yet addressed the possible functional relationship with PA. We studied the influence of individual differences in reappraisal ability on PA and its prefrontal mediation. Participants completed a cognitive reappraisal ability task, which compared negative affect evoked by pictures in a reappraise versus a control condition. In a subsequent fMRI session, PA was induced using thermal noxious stimuli and an inert skin cream. We found a region in the left dorsolateral PFC, which showed a positive correlation between placebo-induced activation and (i) the reduction in participants’ pain intensity ratings; and (ii) cognitive reappraisal ability scores. Moreover, this region showed increased placebo-induced functional connectivity with the periaqueductal grey, indicating its involvement in descending nociceptive control. These initial findings thus suggest that cognitive reappraisal mechanisms mediated by the dorsolateral PFC may play a role in initiating pain inhibition in PA.

Different languages use different systems of nerve cells.

From Xu et al.:

A large body of previous neuroimaging studies suggests that multiple languages are processed and organized in a single neuroanatomical system in the bilingual brain, although differential activation may be seen in some studies because of different proficiency levels and/or age of acquisition of the two languages. However, one important possibility is that the two languages may involve interleaved but functionally independent neural populations within a given cortical region, and thus, distinct patterns of neural computations may be pivotal for the processing of the two languages. Using functional magnetic resonance imaging (fMRI) and multivariate pattern analyses, we tested this possibility in Chinese-English bilinguals when they performed an implicit reading task. We found a broad network of regions wherein the two languages evoked different patterns of activity, with only partially overlapping patterns of voxels in a given region. These regions, including the middle occipital cortices, fusiform gyri, and lateral temporal, temporoparietal, and prefrontal cortices, are associated with multiple aspects of language processing. The results suggest the functional independence of neural computations underlying the representations of different languages in bilinguals.

The world’s laziest countries.

From Althoff et al.:

To be able to curb the global pandemic of physical inactivity and the associated 5.3 million deaths per year, we need to understand the basic principles that govern physical activity. However, there is a lack of large-scale measurements of physical activity patterns across free-living populations worldwide. Here we leverage the wide usage of smartphones with built-in accelerometry to measure physical activity at the global scale. We study a dataset consisting of 68 million days of physical activity for 717,527 people, giving us a window into activity in 111 countries across the globe. We find inequality in how activity is distributed within countries and that this inequality is a better predictor of obesity prevalence in the population than average activity volume. Reduced activity in females contributes to a large portion of the observed activity inequality. Aspects of the built environment, such as the walkability of a city, are associated with a smaller gender gap in activity and lower activity inequality. In more walkable cities, activity is greater throughout the day and throughout the week, across age, gender, and body mass index (BMI) groups, with the greatest increases in activity found for females. Our findings have implications for global public health policy and urban planning and highlight the role of activity inequality and the built environment in improving physical activity and health.

From Erickson's summary of the work:

Interestingly, the average number of steps stepped was not correlated to obesity levels in a particular country...In places where some people got lots of steps and others got just a tiny amount, obesity levels were higher...Sweden had one of the smallest gaps between activity rich and activity poor...it also had one of the lowest rates of obesity...That pattern becomes even more clear when you compare the United States to Mexico. The countries have a similar step average, but Mexico's activity inequality and obesity levels are both much lower...When activity inequality is greatest, women's activity is reduced much more dramatically than men's activity, and thus the negative connections to obesity can affect women more greatly.

The brain circuits of a winner.

Social dominance in mice depends on winning social contests. Zhou et al. manipulate synapses connecting the thalamus and dorsomedial prefrontal cortex to show that they store memory of previous winning or losing:

Mental strength and history of winning play an important role in the determination of social dominance. However, the neural circuits mediating these intrinsic and extrinsic factors have remained unclear. Working in mice, we identified a dorsomedial prefrontal cortex (dmPFC) neural population showing “effort”-related firing during moment-to-moment competition in the dominance tube test. Activation or inhibition of the dmPFC induces instant winning or losing, respectively. In vivo optogenetic-based long-term potentiation and depression experiments establish that the mediodorsal thalamic input to the dmPFC mediates long-lasting changes in the social dominance status that are affected by history of winning. The same neural circuit also underlies transfer of dominance between different social contests. These results provide a framework for understanding the circuit basis of adaptive and pathological social behaviors.

When is stress good for you?

I want to point to an interesting essay by Bruce McEwen, a well known Rockefeller Univ. researcher who has studied mechanisms of stress for many years. A few clips from the first part of his article:

…not all stress is the same. ‘Good stress’ involves taking a chance on something one wants, like interviewing for a job or school, or giving a talk before strangers, and feeling rewarded when successful. ‘Tolerable stress’ means that something bad happens, like losing a job or a loved one, but we have the personal resources and support systems to weather the storm. ‘Toxic stress’ is ….something so bad that we don’t have the personal resources or support systems to navigate it, something that could plunge us into mental or physical ill health and throw us for a loop.

Biochemical mediators such as cortisol and adrenalin help us to adapt – as long as they are turned on in a balanced way when we need them, and then turned off again when the challenge is over. When that does not happen, these ‘hormones of stress’ can cause unhealthy changes in brain and body – for example, high or low blood pressure, or an accumulation of belly fat. When wear and tear on the body results from imbalance of the ‘mediators’, we use the term ‘allostatic load’. When wear and tear is strongest, we call it allostatic overload, and this is what occurs in toxic stress. An example is when bad health behaviours such as smoking, drinking and loneliness result in hypertension and belly fat, causing coronary artery blockade. In short, the mediators that help us to adapt and maintain our homeostasis to survive can also contribute to the well-known diseases of modern life.

…what really affects our health and wellbeing are the more subtle, gradual and long-term influences from our social and physical environment – our family and neighbourhood, the demands of a job, shift work and jet lag, sleeping badly, living in an ugly, noisy and polluted environment, being lonely, not getting enough physical activity, eating too much of the wrong foods, smoking, drinking too much alcohol. All these contribute to allostatic load and overload through the same biological mediators that help us to adapt and stay alive.

McEwen continues with an informative description of the mechanisms through which our brains both regulate and are compromised by stress.