Genes that turned wildcats into kitty cats.

Reaction of my Abyssinian cat, Melvin, to finding that his genome had been sequenced.

David Grimm summarizes work by Montague et al., who sequenced the genome of a female Abyssinian cat, a domestic breed, and compared it with genome assemblies of six other domestic breeds, two wild cat species, and four other mammals to find genomic differences that might underlie cat biology and domestication. The authors found that, compared with wild cat genomes, domestic cat genomes displayed evidence of natural selection in genes linked to memory, fear-conditioning behavior, and stimulus-reward learning, suggesting that the genetic changes may underlie the evolution of tameness.

Cooperating with the future - how to sustain resources.

From Hauser et al., an experiment showing that if resource extraction decision are made by vote rather than individually, the resource can be sustained. Voting is effective for two reasons. First, it allows a majority of cooperators to restrain defectors. Second, it reassures conditional cooperators that their efforts are not futile. Voting, however, only promotes sustainability if it is binding for all involved. A summary of this work by Kerri Smith has a nice explanatory video. Here is the abstract:

Overexploitation of renewable resources today has a high cost on the welfare of future generations. Unlike in other public goods games, however, future generations cannot reciprocate actions made today. What mechanisms can maintain cooperation with the future? To answer this question, we devise a new experimental paradigm, the ‘Intergenerational Goods Game’. A line-up of successive groups (generations) can each either extract a resource to exhaustion or leave something for the next group. Exhausting the resource maximizes the payoff for the present generation, but leaves all future generations empty-handed. Here we show that the resource is almost always destroyed if extraction decisions are made individually. This failure to cooperate with the future is driven primarily by a minority of individuals who extract far more than what is sustainable. In contrast, when extractions are democratically decided by vote, the resource is consistently sustained. Voting is effective for two reasons. First, it allows a majority of cooperators to restrain defectors. Second, it reassures conditional cooperators16 that their efforts are not futile. Voting, however, only promotes sustainability if it is binding for all involved. Our results have implications for policy interventions designed to sustain intergenerational public goods.

Humor and Health

I want to point to this item by Jennifer Gibson that reminds me how useful it might be for me to "lighten up" just a little bit, try to get a daily laugh. Her article, with 11 article citations at its end, points to studies that suggest laughter, humor, or mirth improve short term memory and learning ability, lower stress hormone levels, improve immune function, lower blood pressure, etc.

Chemicals that delay or reverse effects of aging.

I scan for articles on aging in my wanderings through journals and pass on the following two, on chemical compounds that delay or reverse the effects of aging:

Mowia et al. suggest the prospect of an anti-aging pill that might extend life span and delay onset of age-related diseases. They fed mice a synthetic activator of SIRT1 (NAD-dependent deactylase sirtuin 1) from 6 months of age for the rest of their (∼3-year) life span. The treated mice had 5% and 10% increases in maximum and mean life span, respectively. They also resisted many problems associated with human aging. Here's the abstract:

Increased expression of SIRT1 extends the lifespan of lower organisms and delays the onset of age-related diseases in mammals. Here, we show that SRT2104, a synthetic small molecule activator of SIRT1, extends both mean and maximal lifespan of mice fed a standard diet. This is accompanied by improvements in health, including enhanced motor coordination, performance, bone mineral density, and insulin sensitivity associated with higher mitochondrial content and decreased inflammation. Short-term SRT2104 treatment preserves bone and muscle mass in an experimental model of atrophy. These results demonstrate it is possible to design a small molecule that can slow aging and delay multiple age-related diseases in mammals, supporting the therapeutic potential of SIRT1 activators in humans.

Gervain et al. find an instance of restoring brain plasticity characteristic of early life to an adult brain with valporate, a very simple organic structure (enter 'valporate' in google images to see the structure):

Absolute pitch, the ability to identify or produce the pitch of a sound without a reference point, has a critical period, i.e., it can only be acquired early in life. However, research has shown that histone-deacetylase inhibitors (HDAC inhibitors) enable adult mice to establish perceptual preferences that are otherwise impossible to acquire after youth. In humans, we found that adult men who took valproate (VPA) (a HDAC inhibitor) learned to identify pitch significantly better than those taking placebo—evidence that VPA facilitated critical-period learning in the adult human brain. Importantly, this result was not due to a general change in cognitive function, but rather a specific effect on a sensory task associated with a critical-period.

Big data in Neuroscience

I want to pass on an interesting graphic from a piece by Sejnowski, Churchland, and Movshon that introduces a "Focus on big data" series of articles in the November issue of Nature Neuroscience, on the challenges presented by the overwhelming flood of data on the brain being generated by new recording and visualization techniques, from the ultra-micro to the macro scale. (I'm afraid on looking at the whole ensemble of articles I quickly start seeing only gibble-gabble as my-eyes-glaze-over...) The graphic illustrates the spatial and temporal domain, and the increase in the number, of techniques that have appeared since 1988.

Each colored region represents the useful domain of spatial and temporal resolution for one method available for the study of the brain. Open regions represent measurement techniques; filled regions, perturbation techniques. Inset, a cartoon rendition of the methods available in 1988, notable for the large gaps where no useful method existed. The regions allocated to each domain are somewhat arbitrary and represent our own estimates. EEG, electroencephalography; MEG, magnetoencephalography; PET, positron emission tomography; VSD, voltage-sensitive dye; TMS, transcranial magnetic stimulation; 2-DG, 2-deoxyglucose.

The internet and the mind

This is a brief post to point to Jacob Silverman's quick reviews of four books that consider how enhanced connectivity might be altering us.

MDMA (ecstasy) enhances emotional empathy and prosocial behavior

Maybe a hit of NDMA, the party drug ecstasy (not to be confused with the methamphetamine of crystal meth, which is another derivative of the core amphetamine structure), would be good for the wingnuts in both political parties! From Hysek et al.:

3,4-Methylenedioxymethamphetamine (MDMA, ‘ecstasy’) releases serotonin and norepinephrine. MDMA is reported to produce empathogenic and prosocial feelings. It is unknown whether MDMA in fact alters empathic concern and prosocial behavior. We investigated the acute effects of MDMA using the Multifaceted Empathy Test (MET), dynamic Face Emotion Recognition Task (FERT) and Social Value Orientation (SVO) test. We also assessed effects of MDMA on plasma levels of hormones involved in social behavior using a placebo-controlled, double-blind, random-order, cross-over design in 32 healthy volunteers (16 women). MDMA enhanced explicit and implicit emotional empathy in the MET and increased prosocial behavior in the SVO test in men. MDMA did not alter cognitive empathy in the MET but impaired the identification of negative emotions, including fearful, angry and sad faces, in the FERT, particularly in women. MDMA increased plasma levels of cortisol and prolactin, which are markers of serotonergic and noradrenergic activity, and of oxytocin, which has been associated with prosocial behavior. In summary, MDMA sex-specifically altered the recognition of emotions, emotional empathy and prosociality. These effects likely enhance sociability when MDMA is used recreationally and may be useful when MDMA is administered in conjunction with psychotherapy in patients with social dysfunction or post-traumatic stress disorder.

Trajectories of aging.

This post points to another of the articles in the Science special issue on aging. Lindenberger summarizes key features of human cognitive aging from the combined perspectives of life-span psychology and the cognitive neuroscience of aging, and notes a number of longitudinal studies that suggest that leading an intellectually challenging, physically active, and socially engaged life may mitigate losses and consolidate gains during cognitive aging. Here is a summary figure from the article:

Figure. An individual’s range of possible cognitive developmental trajectories from early to late adulthood.

The blue curve shows the most likely developmental path under normal circumstances. The fading of the background color indicates that more extreme paths are less likely. The functional threshold represents a level of functioning below which goal-directed action in the individual’s ecology will be severely compromised. The red curve represents the hope that changes in organism-environment interactions during adulthood move the individual onto a more positive trajectory. Beneficial changes may consist in the mitigation of risk factors, such as vascular conditions, metabolic syndrome, or chronic stress; the strengthening of enhancing factors, such as neuroplasticity; or both.

Are we really conscious?

I've done a post on Graziano's 'attention schema' theory of conscious, and thought I would pass on some clips from his recent exposition of the model in a NYTimes piece. In the title, and in the text below, a few qualifying phrases might have avoided the strong responses to Graziano in the letters to the editor that I also note below. I've added some qualifiers in brackets [ ]. For the inflammatory title "Are we really conscious?" what about adding [in the way we commonly suppose?].

...the argument here is that there is no subjective impression [in the way we commonly suppose]; there is only information in a data-processing device. When we look at a red apple, the brain computes information about color. It also computes information about the self and about a (physically incoherent) property of subjective experience. The brain’s cognitive machinery accesses that interlinked information and derives several conclusions: There is a self, a me; there is a red thing nearby; there is such a thing as subjective experience; and I have an experience of that red thing. Cognition is captive to those internal models. Such a brain would inescapably conclude it has subjective experience.

I concede that this approach is counterintuitive. One reason is that it seems to leave a gap in the logic: Why would the brain waste energy computing information about subjective awareness and attributing that property to itself, if the brain doesn’t in fact have this property?

This is where my own work comes in. In my lab at Princeton, my colleagues and I have been developing the “attention schema” theory of consciousness, which may explain why that computation is useful and would evolve in any complex brain. Here’s the gist of it:

Take again the case of color and wavelength. Wavelength is a real, physical phenomenon; color is the brain’s approximate, slightly incorrect model of it. In the attention schema theory, attention is the physical phenomenon and awareness is the brain’s approximate, slightly incorrect model of it. In neuroscience, attention is a process of enhancing some signals at the expense of others. It’s a way of focusing resources. Attention: a real, mechanistic phenomenon that can be programmed into a computer chip. Awareness: a cartoonish reconstruction of attention that is as physically inaccurate as the brain’s internal model of color.

In this theory, awareness is not an illusion. It’s a caricature. Something — attention — really does exist, and awareness is a distorted accounting of it.

One reason that the brain needs an approximate model of attention is that to be able to control something efficiently, a system needs at least a rough model of the thing to be controlled. Another reason is that to predict the behavior of other creatures, the brain needs to model their brain states, including their attention. This theory pulls together evidence from social neuroscience, attention research, control theory and elsewhere.

Almost all other theories of consciousness are rooted in our intuitions about awareness. Like the intuition that white light is pure [when it is in fact a spectrum of all colors], our intuitions about awareness come from information computed deep in the brain. But the brain computes models that are caricatures of real things. And as with color, so with consciousness: It’s best to be skeptical of intuition.

The letters in response to the above take Graziano to task for "explaining consciousness away" when what he is trying to do is not discount our experience of awareness or selfhood, but make a description of the physical process that actually constitutes them, a description that is counter-intuitive, but I think more likely to be correct than anything I've see thus far.

Antidepressant and nerve growth stimulating effects of exercise - a mechanism.

Yau et al. find that a hormone secreted by fat cells during exercise alleviates depression-like behaviors in mice and boosts new nerve cell synthesis in the hippocampus. The hormone, or compounds that enhance its effectiveness, are potential antidepressant drugs. I copy below their significance section and the abstract with some of the chemical details.

Significance

This study unmasks a previously unidentified functional role of adiponectin (a hormone secreted by adipocytes) in modulating hippocampal neurogenesis and alleviating depression-like behaviors. To our knowledge, this is the first report showing that adiponectin may be an essential factor that mediates the antidepressant effects of physical exercise on the brain by adiponectin receptor 1-mediated activation of AMP-activated protein kinase. Our results reveal a possible mechanism by which exercise increases hippocampal neurogenesis and also suggest a promising therapeutic treatment for depression.

Abstract

Adiponectin (ADN) is an adipocyte-secreted protein with insulin-sensitizing, antidiabetic, anti-inflammatory, and antiatherogenic properties. Evidence is also accumulating that ADN has neuroprotective activities, yet the underlying mechanism remains elusive. Here we show that ADN could pass through the blood–brain barrier, and elevating its levels in the brain increased cell proliferation and decreased depression-like behaviors. ADN deficiency did not reduce the basal hippocampal neurogenesis or neuronal differentiation but diminished the effectiveness of exercise in increasing hippocampal neurogenesis. Furthermore, exercise-induced reduction in depression-like behaviors was abrogated in ADN-deficient mice, and this impairment in ADN-deficient mice was accompanied by defective running-induced phosphorylation of AMP-activated protein kinase (AMPK) in the hippocampal tissue. In vitro analyses indicated that ADN itself could increase cell proliferation of both hippocampal progenitor cells and Neuro2a neuroblastoma cells. The neurogenic effects of ADN were mediated by the ADN receptor 1 (ADNR1), because siRNA targeting ADNR1, but not ADNR2, inhibited the capacity of ADN to enhance cell proliferation. These data suggest that adiponectin may play a significant role in mediating the effects of exercise on hippocampal neurogenesis and depression, possibly by activation of the ADNR1/AMPK signaling pathways, and also raise the possibility that adiponectin and its agonists may represent a promising therapeutic treatment for depression.

Aging: sit less and shape up your attitude

I'm continuing to clean out my queue of aging articles that have been languishing as potential posts...

Reynolds points to two studies. In one, Swedish researchers showed that a group of 68 year old couch potatoes who spent less time sitting and more time in an exercise program had longer telomere caps at the end of their DNA (the caps shorten with aging). The interesting finding was that this was related not to the exercise, but to simply not sitting down as much. A second article reviewed a large database of Canadian adults to find that longer amounts to time spent standing correlated with lower mortality rates.

Span does a review (linking to original articles) of work showing, for example that people who hold more positive views towards aging live 7.5 years longer on average than those who think negatively about aging, and recover more quickly from disabilities. Age stereotypes have a powerful effect, people become what they think. Thinking of older age as a time when one can feel capable, active, full of life, a time of wisdom, self-realization and satisfaction, is rather different from imagining it to be a time of becoming useless, helpless or devalued. A growing body of research shows that people with the latter attitudes are less likely to seek preventive medical care and die earlier, and more likely to suffer memory loss and poor physical functioning.

One interesting bit of work shows that subliminal intervention (flashing positive about aging on a screen so briefly that the brain registers them but they are not perceived) significantly strengthened positive age stereotypes and self-perceptions of age. The abstract:

Negative age stereotypes that older individuals assimilate from their culture predict detrimental outcomes, including worse physical function. We examined, for the first time, whether positive age stereotypes, presented subliminally across multiple sessions in the community, would lead to improved outcomes. Each of 100 older individuals (age = 61–99 years, M = 81) was randomly assigned to an implicit-positive-age-stereotype-intervention group, an explicit-positive-age-stereotype-intervention group, a combined implicit- and explicit-positive-age-stereotype-intervention group, or a control group. Interventions occurred at four 1-week intervals. The implicit intervention strengthened positive age stereotypes, which strengthened positive self-perceptions of aging, which, in turn, improved physical function. The improvement in these outcomes continued for 3 weeks after the last intervention session. Further, negative age stereotypes and negative self-perceptions of aging were weakened. For all outcomes, the implicit intervention’s impact was greater than the explicit intervention’s impact. The physical-function effect of the implicit intervention surpassed a previous study’s 6-month-exercise-intervention’s effect with participants of similar ages. The current study’s findings demonstrate the potential of directing implicit processes toward physical-function enhancement over time.

Mind wandering that makes effort more efficient.

MindBlog has done numerous posts on our brains' default mode and executive control networks, with the idea usually being that activating the default network or mind wandering during an attention demanding task can impair performance. Spreng et al. now do a study showing that it also can improve performance if the mind wandering is congruent with the task itself. In this case the default and executive control networks appear to relate external goals and internal meaning:

Substantial neuroimaging evidence suggests that spontaneous engagement of the default network impairs performance on tasks requiring executive control. We investigated whether this impairment depends on the congruence between executive control demands and internal mentation. We hypothesized that activation of the default network might enhance performance on an executive control task if control processes engage long-term memory representations that are supported by the default network. Using fMRI, we scanned 36 healthy young adult humans on a novel two-back task requiring working memory for famous and anonymous faces. In this task, participants (1) matched anonymous faces interleaved with anonymous face, (2) matched anonymous faces interleaved with a famous face, or (3) matched a famous faces interleaved with an anonymous face. As predicted, we observed a facilitation effect when matching famous faces, compared with anonymous faces. We also observed greater activation of the default network during these famous face-matching trials. The results suggest that activation of the default network can contribute to task performance during an externally directed executive control task. Our findings provide evidence that successful activation of the default network in a contextually relevant manner facilitates goal-directed cognition.

What is literature good for?

I pass on this fetching clutch of points on the usefulness of reading literature (rather than brief tweets, and blog posts like this) from Alain de Botton's School of Life, via Maria Popova's "Brain Pickings" (both are sites well worth checking out). Literature:

SAVES YOU TIME

It looks like it's wasting time, but literature is actually the ultimate time-saver – because it gives us access to a range of emotions and events that it would take you years, decades, millennia to try to experience directly. Literature is the greatest reality simulator – a machine that puts you through infinitely more situations than you can ever directly witness.

MAKES YOU NICER

Literature performs the basic magic of what things look like though someone else's point of view; it allows us to consider the consequences of our actions on others in a way we otherwise wouldn't; and it shows us examples of kindly, generous, sympathetic people.

Literature deeply stands opposed to the dominant value system – the one that rewards money and power. Writers are on the other side – they make us sympathetic to ideas and feelings that are of deep importance but can't afford airtime in a commercialized, status-conscious, and cynical world.

IS A CURE FOR LONELINESS

We're weirder than we like to admit. We often can't say what's really on our minds. But in books we find descriptions of who we genuinely are and what events, described with an honesty quite different from what ordinary conversation allows for. In the best books, it's as if the writer knows us better than we know ourselves – they find the words to describe the fragile, weird, special experiences of our inner lives... Writers open our hearts and minds, and give us maps to our own selves, so that we can travel in them more reliably and with less of a feeling of paranoia or persecution...

PREPARES YOU FOR FAILURE

All of our lives, one of our greatest fears is of failure, of messing up, of becoming, as the tabloids put it, "a loser." Every day, the media takes us into stories of failure. Interestingly, a lot of literature is also about failure – in one way or another, a great many novels, plays, poems are about people who messed up... Great books don't judge as harshly or as one-dimensionally as the media...

Why do we like sad music?

I have earlier noted work on how, in both Eastern and Western music and vocalization, major modes are associated with positive emotions, and minor modes with darker emotions, and I've also mentioned Kawakami's work on how music can be perceived as sad, but yet be accompanied by the experience of positive emotions. Now Taruffi and Koelsch have done an online survey with both Western and Eastern participants (N = 772) that probes the rewarding aspects of music-evoked sadness. Their results suggest four different rewards of music-evoked sadness: reward of imagination, emotion regulation, empathy, and no “real-life” implications:

This study explores listeners’ experience of music-evoked sadness. Sadness is typically assumed to be undesirable and is therefore usually avoided in everyday life. Yet the question remains: Why do people seek and appreciate sadness in music? We present findings from an online survey with both Western and Eastern participants (N = 772). The survey investigates the rewarding aspects of music-evoked sadness, as well as the relative contribution of listener characteristics and situational factors to the appreciation of sad music. The survey also examines the different principles through which sadness is evoked by music, and their interaction with personality traits. Results show 4 different rewards of music-evoked sadness: reward of imagination, emotion regulation, empathy, and no “real-life” implications. Moreover, appreciation of sad music follows a mood-congruent fashion and is greater among individuals with high empathy and low emotional stability. Surprisingly, nostalgia rather than sadness is the most frequent emotion evoked by sad music. Correspondingly, memory was rated as the most important principle through which sadness is evoked. Finally, the trait empathy contributes to the evocation of sadness via contagion, appraisal, and by engaging social functions. The present findings indicate that emotional responses to sad music are multifaceted, are modulated by empathy, and are linked with a multidimensional experience of pleasure. These results were corroborated by a follow-up survey on happy music, which indicated differences between the emotional experiences resulting from listening to sad versus happy music. This is the first comprehensive survey of music-evoked sadness, revealing that listening to sad music can lead to beneficial emotional effects such as regulation of negative emotion and mood as well as consolation. Such beneficial emotional effects constitute the prime motivations for engaging with sad music in everyday life.

Positive thinking can sabotage desired outcomes.

The point is a simple one - imagining success in attaining a goal can make one strive less diligently towards it. Gabriele Oettingen has summarized her research over the past 15-20 years on how this plays out in different areas of endeavour, in a new book “Rethinking Positive Thinking: Inside the New Science of Motivation.” (I know this because she has done what now seems imperative for for getting one's ideas to briefly rise about the noise level facing readers in the general public: she has done a marketing piece in The New York Times - another example of this is Graziano's piece on his theory of consciousness also in the "Gray Matter" NYTimes series - to which I devoted an extended MindBlog post ).

Oettingen's NYTimes piece gives links to her studies showing that women in a weight reduction program who imaged successful completion of the program lost fewer pounds than those who imagined themselves less positively, and that students instructed to imagine a great week ahead report feeling less energized and accomplish less than students instructed to write down any thoughts about the coming week. She then notes experiments on what she suggests as the most effective strategy, combining positive thinking with realism by mentally contrasting them.

A mechanism underlying intractable political conflicts.

Waytz et al. do an interesting piece of work directly relevant to the polarized mid-term election that just occurred, finding a cognitive bias that drives conflict between American Democrats and Republicans and ethnoreligious conflict between Israelis and Palestinians. (Note, "ingroup love" refers to compassion and empathy toward one's own group, and "outgroup hate" refers to dislike and animosity toward the opposing group.) I pass on both the significance statement and the abstract:

Significance

Political conflict between American Democrats and Republicans and ethnoreligious conflict between Israelis and Palestinians seem intractable, despite the availability of reasonable compromise solutions in both cases. This research demonstrates a fundamental cognitive bias driving such conflict intractability: Adversaries attribute their ingroup’s actions to ingroup love more than outgroup hate and attribute their outgroup’s actions to outgroup hate more than ingroup love. This biased attributional pattern increases beliefs and intentions associated with conflict intractability, including unwillingness to negotiate and unwillingness to vote for compromise solutions. In addition, offering financial incentives for accuracy in evaluating one’s outgroup mitigates this biased attributional pattern and its consequences. Understanding this bias and how to alleviate it can contribute to conflict resolution on a global scale.

Abstract

Five studies across cultures involving 661 American Democrats and Republicans, 995 Israelis, and 1,266 Palestinians provide previously unidentified evidence of a fundamental bias, what we term the “motive attribution asymmetry,” driving seemingly intractable human conflict. These studies show that in political and ethnoreligious intergroup conflict, adversaries tend to attribute their own group’s aggression to ingroup love more than outgroup hate and to attribute their outgroup’s aggression to outgroup hate more than ingroup love. Study 1 demonstrates that American Democrats and Republicans attribute their own party’s involvement in conflict to ingroup love more than outgroup hate but attribute the opposing party’s involvement to outgroup hate more than ingroup love. Studies 2 and 3 demonstrate this biased attributional pattern for Israelis and Palestinians evaluating their own group and the opposing group’s involvement in the current regional conflict. Study 4 demonstrates in an Israeli population that this bias increases beliefs and intentions associated with conflict intractability toward Palestinians. Finally, study 5 demonstrates, in the context of American political conflict, that offering Democrats and Republicans financial incentives for accuracy in evaluating the opposing party can mitigate this bias and its consequences. Although people find it difficult to explain their adversaries’ actions in terms of love and affiliation, we suggest that recognizing this attributional bias and how to reduce it can contribute to reducing human conflict on a global scale.

Aging - predictors of cognitive abilities.

The Oct. 31 issue of Science Magazine has a special section of articles on the aging brain. I point in particular to Underwood's article, "Starting young", which describes the followup on a Scottish national intelligence test performed on every 11 year old in the country in 1932 and 1947. The finding was that an individual's level of intelligence at age 11 is the most powerful predictor of late-life cognitive ability — not diet, social engagement, or any other virtuous activity. Scores at age 11 predicted about 50% of the variance in the IQs at age 77 in a cohort of individuals living in the Lothian region near Edinburgh (1641 of the original 5000 people tested were assessed.) Note the bottom line indicated in the final clip below:

By having an intelligence measure from even earlier in life, the Lothian studies are helping distinguish glitter from gold in the vast literature on factors correlated with cognition. A good recent example is Deary's analysis of the potential benefits of drinking, Thompson says. A smattering of correlational studies suggest that drinking small amounts of wine has positive effects on cognition late in life—indeed, Deary initially found a similar result when he first looked for a relationship between alcohol consumption and cognitive performance in the Lothian cohort. When he accounted for the participants' IQ scores on the Scottish Mental Survey, however, the perceived benefit dissolved. Rather than gaining cognitive benefit from drinking wine when they were older, “people who drank more were already likely to be smart,” Deary says.

The Lothian cohort has similarly challenged other reported influences on cognition, such as diet, body mass index, and caffeine consumption. None of those factors seems to have any effect on cognitive skills in the Lothian cohort when childhood intelligence is accounted for, Deary says. Even the effects of social and intellectual activity disappeared when he took into account how bright children were at age 11, possibly because those children are more likely to end up being socially and intellectually engaged.

And a final clip:

...the growing body of data from the Lothian Birth Cohort studies and other aging research supports a theory that some describe irreverently, and a little brutally, as the “water tank hypothesis”: The better put-together your brain is early on, thanks to good genes and, to some extent, a favorable early life environment, the more cognitive reserves you have to lose to neurodegeneration. In other words, Martin says, “the more you start out with in the tank, the longer it takes to draw down.”

Liberals and conservatives have different smell preferences.

A post faintly appropriate to this election day that is deciding the outcomes of very polarized contests of liberals and conservatives...Arthur Brooks points to an interesting article by McDermott et al. suggesting that our human mate preference - known to influenced more by political attitudes more than any other social, behavioral, or physical trait except religion - may be reflected in our smell preferences! Some clips from McDermott et al.:

Here we integrate extant studies of attraction, ideology, and olfaction and explore the possibility that assortation on political attitudes may result, in part, from greater attraction to the scent of those with shared ideology. We conduct a study in which individuals evaluated the body odor of unknown others, observing that individuals are more attracted to their ideological concomitants.

We conducted a study where participants rated the attractiveness of the body odor of unknown strong liberals and strong conservatives, hereafter referred to as “target” subjects; all “evaluator” subjects remained blind to the ideology of the target samples. One hundred forty-six participants between 18–40 years old were drawn from a large city in the northeast United States... Twenty-one target participants were selected for their high scores on opposite ends of the political spectrum (10 liberals and 11 conservatives) and provided body odor samples...Eleven of these target participants were female and 10 were male. Ideology was measured using the standard 7-point (strongly liberal to strongly conservative) American National Election Studies (ANES) self-report measure.

... individuals find the smell of those who are more ideologically similar to themselves more attractive than those endorsing opposing ideologies; recall that participants never saw the individuals whose smells they were evaluating, and the order of target subjects was randomized for each evaluator. Thus, the recognition of political alignment occurred through the medium of attraction, not recognition.

Some insight on the potency of odor might be gained from the participants’ comments and physical reactions during the study... a participant asked the experimenter if she could take one of the vials home with her because she thought it was “the best perfume I ever smelled”; the vial was from a male who shared an ideology similar to the evaluator. She was preceded by another respondent with an ideology opposite to the person who provided the exact same sample; this participant reported that that vial had “gone rancid” and suggested it needed to be replaced. In this way, different participants experienced the exact same stimulus in radically different ways only moments apart.

Memory reactivation during rest supports upcoming learning of related content.

I have found that a brief period of rest, around 20 minutes or so, after I have worked on learning the notes and fingering of a new piano piece, has a huge effect on the ease of my subsequent learning and consolidation of the difficult passage when I return to practice. Now Schlicting and Preston have looked at the neural basis of this enhancement of subsequent learning of related material. I pass on both their statement of significance and their abstract:

Significance

How our brains capture and store new information is heavily influenced by what we already know. While prior work demonstrates that existing memories are spontaneously reactivated and strengthened in the brain during passive rest periods, the prospective benefits of spontaneous offline reactivation for future learning remain unknown. Here, we use functional MRI to interrogate how reactivation and interregional coupling support the ability to learn related content in later situations. We find that offline processing of prior memories is associated with better subsequent learning. Our results provide a mechanistic account of the circumstances under which prior knowledge can come to facilitate—as opposed to interfere with—new learning, serving as a strong foundation upon which new content is encoded.

Abstract

Although a number of studies have highlighted the importance of offline processes for memory, how these mechanisms influence future learning remains unknown. Participants with established memories for a set of initial face–object associations were scanned during passive rest and during encoding of new related and unrelated pairs of objects. Spontaneous reactivation of established memories and enhanced hippocampal–neocortical functional connectivity during rest was related to better subsequent learning, specifically of related content. Moreover, the degree of functional coupling during rest was predictive of neural engagement during the new learning experience itself. These results suggest that through rest-phase reactivation and hippocampal–neocortical interactions, existing memories may come to facilitate encoding during subsequent related episodes.

A mechanism underlying our current political paralysis

Thomas Edsall points to the fascinating work of Berkeley graduate students Broockman and Ahler, who puncture the common assumption that a large segment of the electorate is made up of moderates who hunger for centrist compromise. From their September paper, a pessimistic conclusion (slightly edited):

Because each citizen prefers a different mix of policies, there is no one mix a politician could adopt that would broadly satisfy citizens. (For example, a citizen might support liberal tax policies but be opposed to same-sex marriage, but would be defined as moderate if those responses are averaged.) Thus it is natural that many citizens appear frustrated with the choices they have in American elections; yet, given the relatively idiosyncratic nature of citizens’ own preference bundles, it is also unclear that there is dramatic room for improvement.

Because each citizen’s pattern of views across issues appears unique, each citizen is likely to be “disconnected” from the positions their representatives take in his or her own way, a situation which the election of more moderates – or more of any other one particular kind of politician – could not broadly resolve.

The only resolution of this impasse would seem to be for citizens to 'chill out' a bit on the moralistic energy of their 'right way' on a particular issue, and feel more tolerance for other positions. I remember in the 'good old days' of Lyndon Johnson's 1960's presidency, how opponents seemed willing to bend just a bit more and value getting a result, even if it compromised their values. (Even, by the way, though opponents of Medicare were perhaps more virulent than current opponents of The Affordable Care Act.)