Unlocking adults’ implicit statistical learning by cognitive depletion

Smalle et al. make the fascinating observation that inhibition of our adult cognitive control system by non-invasive brain stimulation can unleash some of our infant implicit statistical learning abilities - the learning of novel words embedded in a string of spoken syllables. This suggests that adult language learning is antagonized by higher cognitive mechanisms.  

Significance

Statistical learning mechanisms enable extraction of patterns in the environment from infancy to adulthood. For example, they enable segmentation of continuous speech streams into novel words. Adults typically become aware of the hidden words even when passively listening to speech streams. It remains poorly understood how cognitive development and brain maturation affect implicit statistical learning (i.e., infant-like learning without awareness). Here, we show that the depletion of the cognitive control system by noninvasive brain stimulation or by demanding cognitive tasks boosts adults’ implicit but not explicit word-segmentation abilities. These findings suggest that the adult cognitive architecture constrains statistical learning mechanisms that are likely to contribute to early language acquisition and opens avenues to enhance language-learning abilities in adults.

Abstract

Human learning is supported by multiple neural mechanisms that maturate at different rates and interact in mostly cooperative but also sometimes competitive ways. We tested the hypothesis that mature cognitive mechanisms constrain implicit statistical learning mechanisms that contribute to early language acquisition. Specifically, we tested the prediction that depleting cognitive control mechanisms in adults enhances their implicit, auditory word-segmentation abilities. Young adults were exposed to continuous streams of syllables that repeated into hidden novel words while watching a silent film. Afterward, learning was measured in a forced-choice test that contrasted hidden words with nonwords. The participants also had to indicate whether they explicitly recalled the word or not in order to dissociate explicit versus implicit knowledge. We additionally measured electroencephalography during exposure to measure neural entrainment to the repeating words. Engagement of the cognitive mechanisms was manipulated by using two methods. In experiment 1 (n = 36), inhibitory theta-burst stimulation (TBS) was applied to the left dorsolateral prefrontal cortex or to a control region. In experiment 2 (n = 60), participants performed a dual working-memory task that induced high or low levels of cognitive fatigue. In both experiments, cognitive depletion enhanced word recognition, especially when participants reported low confidence in remembering the words (i.e., when their knowledge was implicit). TBS additionally modulated neural entrainment to the words and syllables. These findings suggest that cognitive depletion improves the acquisition of linguistic knowledge in adults by unlocking implicit statistical learning mechanisms and support the hypothesis that adult language learning is antagonized by higher cognitive mechanisms.

Children universally across societies enforce conventional norms but in culturally variable ways

From Kanngiesser et al. in PNAS:

Humans, as compared with other animals, create and follow conventional norms that determine how we greet each other, dress, or play certain games. Conventional norms are universal in all human societies, but it is an open question whether individuals in all societies also actively enforce conventional norms when others in their group break them. We investigated third-party enforcement of conventional norms in 5- to 8-y-old children (n = 376) from eight diverse small-scale and large-scale societies. Children learned the rules for playing a new sorting game and then, observed a peer who was apparently breaking them. Across societies, observer children intervened frequently to correct their misguided peer (i.e., more frequently than when the peer was following the rules). However, both the magnitude and the style of interventions varied across societies. Detailed analyses of children’s interactions revealed societal differences in children’s verbal protest styles as well as in their use of actions, gestures, and nonverbal expressions to intervene. Observers’ interventions predicted whether their peer adopted the observer’s sorting rule. Enforcement of conventional norms appears to be an early emerging human universal that comes to be expressed in culturally variable ways.

Transcranial stimulation of alpha oscillations up-regulates the default mode network

Interesting work from Clancy et al. on the brain's default mode network that carries out our self referential rumination: Significance

In the brain’s functional organization, the default mode network (DMN) represents a key architecture, whose dysregulation is involved in a host of major neuropsychiatric disorders. However, insights into the regulation of the DMN remain scarce. Through neural synchrony, the alpha-frequency oscillation represents another key underpinning of the brain’s organization and is thought to share an inherent interdependence with the DMN. Here, we demonstrated that transcranial alternating current stimulation of alpha oscillations (α-tACS) not only augmented alpha activity but also strengthened connectivity of the DMN, with the former serving as a mediator of the latter. These findings reveal that alpha oscillations can support DMN functioning. In addition, they identify an effective noninvasive approach to regulate the DMN via α-tACS.

Abstract

The default mode network (DMN) is the most-prominent intrinsic connectivity network, serving as a key architecture of the brain’s functional organization. Conversely, dysregulated DMN is characteristic of major neuropsychiatric disorders. However, the field still lacks mechanistic insights into the regulation of the DMN and effective interventions for DMN dysregulation. The current study approached this problem by manipulating neural synchrony, particularly alpha (8 to 12 Hz) oscillations, a dominant intrinsic oscillatory activity that has been increasingly associated with the DMN in both function and physiology. Using high-definition alpha-frequency transcranial alternating current stimulation (α-tACS) to stimulate the cortical source of alpha oscillations, in combination with simultaneous electroencephalography and functional MRI (EEG-fMRI), we demonstrated that α-tACS (versus Sham control) not only augmented EEG alpha oscillations but also strengthened fMRI and (source-level) alpha connectivity within the core of the DMN. Importantly, increase in alpha oscillations mediated the DMN connectivity enhancement. These findings thus identify a mechanistic link between alpha oscillations and DMN functioning. That transcranial alpha modulation can up-regulate the DMN further highlights an effective noninvasive intervention to normalize DMN functioning in various disorders.

Twitter amplifies the political right more than the political left

You should read this open source editorial in PNAS by Susan Fiske "Twitter Manipulates your feed: Ethical considerations," a commentary on the article by Huszár et al., "Algorithmic amplification of politics on Twitter," in the same issue. Here is the Huszár et al. abstract:  

Significance

The role of social media in political discourse has been the topic of intense scholarly and public debate. Politicians and commentators from all sides allege that Twitter’s algorithms amplify their opponents’ voices, or silence theirs. Policy makers and researchers have thus called for increased transparency on how algorithms influence exposure to political content on the platform. Based on a massive-scale experiment involving millions of Twitter users, a fine-grained analysis of political parties in seven countries, and 6.2 million news articles shared in the United States, this study carries out the most comprehensive audit of an algorithmic recommender system and its effects on political content. Results unveil that the political right enjoys higher amplification compared to the political left.

 Abstract

Content on Twitter’s home timeline is selected and ordered by personalization algorithms. By consistently ranking certain content higher, these algorithms may amplify some messages while reducing the visibility of others. There’s been intense public and scholarly debate about the possibility that some political groups benefit more from algorithmic amplification than others. We provide quantitative evidence from a long-running, massive-scale randomized experiment on the Twitter platform that committed a randomized control group including nearly 2 million daily active accounts to a reverse-chronological content feed free of algorithmic personalization. We present two sets of findings. First, we studied tweets by elected legislators from major political parties in seven countries. Our results reveal a remarkably consistent trend: In six out of seven countries studied, the mainstream political right enjoys higher algorithmic amplification than the mainstream political left. Consistent with this overall trend, our second set of findings studying the US media landscape revealed that algorithmic amplification favors right-leaning news sources. We further looked at whether algorithms amplify far-left and far-right political groups more than moderate ones; contrary to prevailing public belief, we did not find evidence to support this hypothesis. We hope our findings will contribute to an evidence-based debate on the role personalization algorithms play in shaping political content consumption.

Higher performance and fronto-parietal brain activity following active versus passive learning

From a brief open source PNAS report by Stillesjö et al. that has a nice graphic of the fMRI data supporting their observations:

We here demonstrate common neurocognitive long-term memory effects of active learning that generalize over course subjects (mathematics and vocabulary) by the use of fMRI. One week after active learning, relative to more passive learning, performance and fronto-parietal brain activity was significantly higher during retesting, possibly related to the formation and reactivation of semantic representations. These observations indicate that active learning conditions stimulate common processes that become part of the representations and can be reactivated during retrieval to support performance. Our findings are of broad interest and educational significance related to the emerging consensus of active learning as critical in promoting good long-term retention.

The Power of Us

A recent New York Times essay by Jon Mooallem, "Is life better when we're together?" is worth a read, and references work of Packer and Van Bavel described in their new book "The Power of Us." Their experiments, a continuation of work started by psychologist Henri Tafjel in the 1970s, illustrate how our social brains are programmed to organize us into "us" and "them" groups on the basis of sometimes completely arbitrary and trivial criteria, as in assigning a study group of subjects into groups A and B on the basis of a coin toss.  Tafjel's work is also referenced in another excellent article by Elizabeth Kolbert in The New Yorker, "How Politics Got So Polarized."  She reviews a number of recent books in this area, and also notes the phenomenon of "false polarization" - views of the extremes predominate as the moderate majority of people withdraw from the fray of commentary.

Here are some clips from the Mooallem article, the first noting Tafjel's experiments on high school students in Bristol, England.

...biases locked in right away. Overwhelmingly, people in Dr. Tajfel’s experiment gave more of the money he put at their disposal to members of their own group than the other. Moreover, they were bent on creating as large a disparity as possible, even when offered the option of maximizing the amount of money for everyone, at no cost. Their behavior seemed vindictive, “a clear case of gratuitous discrimination,” Dr. Tajfel wrote.

Since then, other researchers have run their own minimal group experiments, pushing those findings further. Dr. Packer and Dr. Van Bavel have split people into leopards and tigers, for example. Others have gone maximally minimal and divided people into group A and group B. Still, the pride — the readiness to connect — is always there. When you tell people they’re in group A, Dr. Packer says, those people are reliably psyched to be in group A. Stick leopard people in a brain imaging machine and show them a picture of a stranger, and their brain activity changes if they know that the stranger is a leopard person, too. Their positivity toward other leopard people increases and even supersedes racial biases that cut the other way.

Dr. Packer and Dr. Van Bavel call the minimal group studies “among the most important studies in the history of psychology.” They demonstrate that “the human sense of self — your gravitational center — does not stay in the same place. With a flip of a coin, people constructed entirely new identities in a matter of minutes.”...The rewards of this kind of connectedness wind up driving all kinds of wonderful human behavior, sometimes less obviously than we’d assume.

But it also leads to the behaviors shown by the insurrections of the Jan. 6, 2021 attack on the U.S. Capitol.

It’s hard to imagine more antisocial behavior than attempting to undo a democratic election with mayhem and violence. But the insurrectionists were doing it together, and pretty joyously, it seemed — snapping selfies, posting them to Facebook with stupid jokes in real time. It was, within their community, a prosocial activity, too.

When a system appears to be malfunctioning, indifferent, reckless or corrupt, that’s a kind of disaster, and people are likely to come together and respond, for better or worse...Some will be volunteers, and some will be vigilantes. But both may be reacting to a similar feeling of free fall, of tumbling. This doesn’t make them morally equivalent; in the end, morality is what keeps them from being equivalent. I know it’s important to keep drawing that distinction, to keep calling it out. I also know it’s not enough.

The rise and fall of rationality in language

Fascinating language analysis from Scheffer et al. that illustrates over the past decades a marked shift in public interest from the collective to the individual, and from rationality toward emotion:  

Significance

The post-truth era has taken many by surprise. Here, we use massive language analysis to demonstrate that the rise of fact-free argumentation may perhaps be understood as part of a deeper change. After the year 1850, the use of sentiment-laden words in Google Books declined systematically, while the use of words associated with fact-based argumentation rose steadily. This pattern reversed in the 1980s, and this change accelerated around 2007, when across languages, the frequency of fact-related words dropped while emotion-laden language surged, a trend paralleled by a shift from collectivistic to individualistic language.

Abstract

The surge of post-truth political argumentation suggests that we are living in a special historical period when it comes to the balance between emotion and reasoning. To explore if this is indeed the case, we analyze language in millions of books covering the period from 1850 to 2019 represented in Google nGram data. We show that the use of words associated with rationality, such as “determine” and “conclusion,” rose systematically after 1850, while words related to human experience such as “feel” and “believe” declined. This pattern reversed over the past decades, paralleled by a shift from a collectivistic to an individualistic focus as reflected, among other things, by the ratio of singular to plural pronouns such as “I”/”we” and “he”/”they.” Interpreting this synchronous sea change in book language remains challenging. However, as we show, the nature of this reversal occurs in fiction as well as nonfiction. Moreover, the pattern of change in the ratio between sentiment and rationality flag words since 1850 also occurs in New York Times articles, suggesting that it is not an artifact of the book corpora we analyzed. Finally, we show that word trends in books parallel trends in corresponding Google search terms, supporting the idea that changes in book language do in part reflect changes in interest. All in all, our results suggest that over the past decades, there has been a marked shift in public interest from the collective to the individual, and from rationality toward emotion.

Senolytic therapies for healthy longevity

An article on increasing longevity by getting rid of senescent cells (cells that have stopped dividing and generate products that accelerate aging) has been languishing in my queue of potential posts for over a year, and I want to finally give it a mention. (This continues the thread of MindBlog posts over the years that have dealt with anti-aging supplements. You can enter 'resveratrol' in the search box in the right column of this blog to get a sample. I've reported on several self experiments, none of which ended all that well. A 2008 post on my experimenting with a resveratrol supplement generated a comment thread that has continued for many years.)

Here is the abstract of the review article by Jan M. van Deursen in Science Magazine:

The estimated “natural” life span of humans is ∼30 years, but improvements in working conditions, housing, sanitation, and medicine have extended this to ∼80 years in most developed countries. However, much of the population now experiences aging-associated tissue deterioration. Healthy aging is limited by a lack of natural selection, which favors genetic programs that confer fitness early in life to maximize reproductive output. There is no selection for whether these alterations have detrimental effects later in life. One such program is cellular senescence, whereby cells become unable to divide. Cellular senescence enhances reproductive success by blocking cancer cell proliferation, but it decreases the health of the old by littering tissues with dysfunctional senescent cells (SNCs). In mice, the selective elimination of SNCs (senolysis) extends median life span and prevents or attenuates age-associated diseases (1, 2). This has inspired the development of targeted senolytic drugs to eliminate the SNCs that drive age-associated disease in humans.

A few clips from the article:

Much of our current knowledge about the properties of SNCs is based on experiments in cultured cells, largely because SNCs in tissues and organs are difficult to identify and collect. One key characteristic of SNCs is that they are in a state of permanent cell-cycle arrest....SNCs produce a bioactive “secretome,” referred to as the senescence-associated secretory phenotype (SASP). This can disrupt normal tissue architecture and function through diverse mechanisms, including recruitment of inflammatory immune cells, remodeling of the extracellular matrix, induction of fibrosis, and inhibition of stem cell function . Paradoxically, although cellular senescence has evolved as a tumor protective program, the SASP can include factors that stimulate neoplastic cell growth, tumor angiogenesis, and metastasis, thereby promoting the development of late-life cancers. Indeed, elimination of SNCs with aging attenuates tumor formation in mice, raising the possibility that senolysis might be an effective strategy to treat cancer.

The article proceeds to outline several different efforts to identify senolytic drug targets. It notes that:

...natural products with anticancer properties, such as quercetin and fisetin, and quercetin in combination with the pan-tyrosine kinase inhibitor dasatinib, have been reported to eliminate SNCs in vitro and in mice [M. Xu et al., Nat. Med. 24, 1246 (2018); M. J. Yousefzadeh et al., EBioMedicine 36, 18 (2018)]. Although quercetin, fisetin, and dasatinib are often referred to as senolytics, it should be noted that they each act on a myriad of pathways and mechanisms implicated in diverse biological processes. This makes it difficult to decipher how these drugs eliminate or otherwise impact SNCs and to attribute any therapeutic or detrimental effects they may have in clinical trials to senolysis.

A brief google search on these flavinoid antioxidant compounds (found in fruits and vegetables...strawberries, watercress, cilantro, etc.) finds a large number of "Life Extension" dietary supplements featuring them. There is no data on their effects on senolysis or life span in humans.

MindBlog gets an extreme comment on Covid

I've debated on whether it would be better to ignore (and not amplify by passing on) an extreme comment of a sort MindBlog almost never receives. It is sent as a response to, but does not actually comment on, last Wednesday's post on the David Brooks article "What Happened to American Conservatism."  Although I am in complete disagreement with the comment's content, I've decided to pass it on because  it is an instructive example of the quality, style, stance and arguments of a fraction of America's population large enough to guarantee the continued generation of Covid variants that will maintain Covid as a chronic disease for the foreseeable future.  Here's the comment:

Re the "the human condition"... The TRUE human condition or world we live in is about 2 pink elephants in the room and has never been on clearer display than with the deliberate global Covid Scam atrocity — check out “The 2 Married Pink Elephants In The Historical Room –The Holocaustal Covid-19 Coronavirus Madness: A Sociological Perspective & Historical Assessment Of The Covid “Phenomenon”” at w w w d o t CovidTruthBeKnown d o t c o m 

“[…] when you do things to people against their will and force them it destroys their spirit, it destroys the integrity of their body. […]. Being an adult is meaningless if you cannot even protect the integrity of your own body.” -- Jennifer Daniels, MD, MBA, Holistic Doctor 

If your employer (even educational or federal employers) wants you to take a Covid vaccine give him/her one of these form letters of exemption found at w w w d o t lc d o t o r g/exempt 

By the way, with the letters of "omicron" an alleged Covid variant you can spell "moronic"...

And further speaking of stupid herd people not getting the glaringly obvious truth/ie not getting the constant onslaught of BIG lies of the official authorities, the world we live in and what the human condition is really is encapsulated in the following reality... 

"2 weeks to flatten the curve has turned into...3 shots to feed your family!" --- Unknown

A musical offering.

For this day that was central in my Protestant Christian Texas childhood: a performance by the Netherlands Bach Society of the Gloria in Excelsis Deo from Bach's  Christmas Cantata BVW 191 first performed in Leipzig ~1742. There is joy in this music that transcends it’s religious origins. 

What Happened to American Conservatism?

I want to strongly recommed that you read David Brooks' article on conservatism in the January/February 2022 issue of The Atlantic. I read slowly though it three times, think it makes a compelling summary of our current political quandry, and wish that it offered more insight into possible ways out of our current predicament as we watch what seems to be an unstopable slippage back to pre-Enlightenment mentalities. Just a few clips of text towards the end of the piece:

...perhaps the biggest reason for conservatism’s decay into Trumpism was spiritual. The British and American strains of conservatism were built on a foundation of national confidence...By 2016, that confidence was in tatters. Communities were falling apart, families were breaking up, America was fragmenting. Whole regions had been left behind, and many elite institutions had shifted sharply left and driven conservatives from their ranks. Social media had instigated a brutal war of all against all, social trust was cratering, and the leadership class was growing more isolated, imperious, and condescending. “Morning in America” had given way to “American carnage” and a sense of perpetual threat.

...a pessimistic shadow conservatism has always lurked in the darkness, haunting the more optimistic, confident one. The message this shadow conservatism conveys is the one that Trump successfully embraced in 2016: Evil outsiders are coming to get us. But in at least one way, Trumpism is truly anti-conservative. Both Burkean conservatism and Lockean liberalism were trying to find ways to gentle the human condition, to help society settle differences without resort to authoritarianism and violence. Trumpism is pre-Enlightenment. Trumpian authoritarianism doesn’t renounce holy war; it embraces holy war, assumes it is permanent, in fact seeks to make it so. In the Trumpian world, disputes are settled by raw power and intimidation. The Trumpian epistemology is to be anti-epistemology, to call into question the whole idea of truth, to utter whatever lie will help you get attention and power. Trumpism looks at the tender sentiments of sympathy as weakness. Might makes right.

...the populist and nationalist forces are rising. All of life is seen as an incessant class struggle between oligarchic elites and the common volk. History is a culture-war death match. Today’s mass-market, pre-Enlightenment authoritarianism is not grateful for the inherited order but sees menace pervading it: You’ve been cheated. The system is rigged against you. Good people are dupes. Conspiracists are trying to screw you. Expertise is bogus. Doom is just around the corner. I alone can save us.

Trumpian Republicanism plunders, degrades, and erodes institutions for the sake of personal aggrandizement. The Trumpian cause is held together by hatred of the Other. Because Trumpians live in a state of perpetual war, they need to continually invent existential foes—critical race theory, nongendered bathrooms, out-of-control immigration. They need to treat half the country, metropolitan America, as a moral cancer, and view the cultural and demographic changes of the past 50 years as an alien invasion. Yet pluralism is one of America’s oldest traditions; to conserve America, you have to love pluralism. As long as the warrior ethos dominates the GOP, brutality will be admired over benevolence, propaganda over discourse, confrontation over conservatism, dehumanization over dignity. A movement that has more affection for Viktor Orbán’s Hungary than for New York’s Central Park is neither conservative nor American. This is barren ground for anyone trying to plant Burkean seedlings.

I’m content, as my hero Isaiah Berlin put it, to plant myself instead on the rightward edge of the leftward tendency—in the more promising soil of the moderate wing of the Democratic Party. If its progressive wing sometimes seems to have learned nothing from the failures of government and to promote cultural stances that divide Americans, at least the party as a whole knows what year it is. In 1980, the core problem of the age was statism, in the form of communism abroad and sclerotic, dynamism-sapping bureaucracies at home. In 2021, the core threat is social decay. The danger we should be most concerned with lies in family and community breakdown, which leaves teenagers adrift and depressed, adults addicted and isolated. It lies in poisonous levels of social distrust, in deepening economic and persisting racial disparities that undermine the very goodness of America—in political tribalism that makes government impossible.

To reduce the economic chasm that separates class from class, to ease the financial anxiety that renders life unstable for many people, to support parenting so that children can grow up with more stability—these are the goals of a party committed to ameliorating, not exploiting, a growing sense of hopelessness and alienation, of vanishing opportunity. Daniel Patrick Moynihan’s brilliant dictum—which builds on a Burkean wisdom forged in a world of animosity and corrosive flux—has never been more worth heeding than it is now: The central conservative truth is that culture matters most; the central liberal truth is that politics can change culture.

The Point is to Stop - a farewell to self help coaching

I want to pass on some points, paraphrase, and central clips from what is essentially a swan song offered by Mark Manson in his latest newsletter - a newsletter whose contents I have mentioned in a number of previous MindBlog posts. This Manson essay hits me between the eyes, because I'm very aware that one of my main motivations for doing this MindBlog since Feb. 2006, with it's 5,220 posts (and counting) is that it has turned out to be valuable self therapy for Deric (with this abstracting of Manson's current article being one example). 

He begins by referencing an older article noting that 

...the best way to judge the usefulness of self-help advice is by now many people eventually leave it behind.

He notes that people who seek out self help..

...do so with two different mindsets... the "Doctor People" ...look to a book, website or seminar to cure their emotional ails... the "Coach People"...want a mentor or coach..They want strategies, roadmaps, to know the right moves...the problem is that Doctor People see personal growth as information that is to be learned rather than a skill that must be practiced...Self-awareness, managing emotions, empathy, vulnerability are skills ..it can take years to become somewhat good at them... Coach People are in it for the long haul.

But what the Coach People don't get is that the whole point is to eventually stop. It's to leave. Because unlike chess or basketball, there's no world championship for anger management. Nobody is going to give you a trophy for mindfulness...the skill curves are different...In basketball or chess, the better you get, the more effort is required to further improve...in personal growth, the better you get, the less effort is required to further improve...personal growth skills have positive feedback loops bakes into them.. like skiing downhill..it takes a lot of effort to get some speed going, but once you're on your way, the most effective thing you can do to gain speed is nothing.

...what the Coach People miss is that the whole point of this stuff, the way to 'win,' is to one day be free of consciously having to think about it...At some point, you just have to live your damn life...Coach People who identify as the "personal growth" not only get trapped by it, but are likely to bore you at dinner parties with their stories about their ayahuasca retreats.

And, at this point in the article, Mason declares that he is going to leave behind his career as a Coach Person, move on from the self help world he started writing a blog about in 2008, the blog being his own therapy as "I tried to sort through my own shit." 

And now,

I'm no longer the guy at the top of the ski hill struggling to get going. I feel like the guy flying down, full speed ahead..to continue writing about these topics feels like unnecessarily planting my poles into the snow...the standard roadmap for self-help authors when they produce a hit book is to spend the next 20-30 years regurgitating the same ideas over and over again in various formats, on various stages, cashing the checks as they go. To me that sounds about as interesting as sticking my dick in a light socket...I've spent a lot of the past few years anxious and insecure that I would "lose my audience," by stepping away from self-help content. It's taken me way too long to listen to my own advice and just not give a fuck.

Manson then describes how he plans to leave behind a repository (The Subtle Art School) of what he has worked so hard to learn the past ten years, and leave his blog as an archive for posterity. 

The active grandparent hypothesis

Lieberman et al. suggest that selection in humans for lifelong physical activity, including during postreproductive years to provision offspring, promoted selection for energy allocation pathways which synergistically slow senescence and reduce vulnerability to many forms of chronic diseases. Here is their abstract (motivated readers can obtain a copy of the article from me):

The proximate mechanisms by which physical activity (PA) slows senescence and decreases morbidity and mortality have been extensively documented. However, we lack an ultimate, evolutionary explanation for why lifelong PA, particularly during middle and older age, promotes health. As the growing worldwide epidemic of physical inactivity accelerates the prevalence of noncommunicable diseases among aging populations, integrating evolutionary and biomedical perspectives can foster new insights into how and why lifelong PA helps preserve health and extend lifespans. Building on previous life-history research, we assess the evidence that humans were selected not just to live several decades after they cease reproducing but also to be moderately physically active during those postreproductive years. We next review the longstanding hypothesis that PA promotes health by allocating energy away from potentially harmful overinvestments in fat storage and reproductive tissues and propose the novel hypothesis that PA also stimulates energy allocation toward repair and maintenance processes. We hypothesize that selection in humans for lifelong PA, including during postreproductive years to provision offspring, promoted selection for both energy allocation pathways which synergistically slow senescence and reduce vulnerability to many forms of chronic diseases. As a result, extended human healthspans and lifespans are both a cause and an effect of habitual PA, helping explain why lack of lifelong PA in humans can increase disease risk and reduce longevity.

New articles on exercise and the brain

Gretchen Reynolds has done two recent brief reviews:

 The Quiet Brain of the Athlete describes work showing that the brains of fit, young athletes dial down extraneous noise and attend to important sounds better than those of other young people. 

And, 

 Staying physically active may protect the aging brain. Simple activities like walking boost immune cells in the brain that may help to keep memory sharp and even ward off Alzheimer’s disease.

Temporal Self-Compression

Brietzke and Meyer (open source) provide behavioral and neural evidence that our past and future selves are compressed as they move away from the present:  

Significance

For centuries, great thinkers have struggled to understand how people represent a personal identity that changes over time. Insight may come from a basic principle of perception: as objects become distant, they also become less discriminable or “compressed.” In Studies 1–3, we demonstrate that people’s ratings of their own personality become increasingly less differentiated as they consider more distant past and future selves. In Study 4, we found neural evidence that the brain compresses self-representations with time as well. When we peer out a window, objects close to us are in clear view, whereas distant objects are hard to tell apart. We provide evidence that self-perception may operate similarly, with the nuance of distant selves increasingly harder to perceive.

Abstract

A basic principle of perception is that as objects increase in distance from an observer, they also become logarithmically compressed in perception (i.e., not differentiated from one another), making them hard to distinguish. Could this basic principle apply to perhaps our most meaningful mental representation: our own sense of self? Here, we report four studies that suggest selves are increasingly non-discriminable with temporal distance from the present as well. In Studies 1 through 3, participants made trait ratings across various time points in the past and future. We found that participants compressed their past and future selves, relative to their present self. This effect was preferential to the self and could not be explained by the alternative possibility that individuals simply perceive arbitrary self-change with time irrespective of temporal distance. In Study 4, we tested for neural evidence of temporal self-compression by having participants complete trait ratings across time points while undergoing functional MRI. Representational similarity analysis was used to determine whether neural self-representations are compressed with temporal distance as well. We found evidence of temporal self-compression in areas of the default network, including medial prefrontal cortex and posterior cingulate cortex. Specifically, neural pattern similarity between self-representations was logarithmically compressed with temporal distance. Taken together, these findings reveal a “temporal self-compression” effect, with temporal selves becoming increasingly non-discriminable with distance from the present.

Severity and clinical course of depression correlates with altered connectivity in sensorimotor cortices.

Interesting work from Ray et al.,  

Significance

Research into neurobiology of depression primarily focuses on its complex psychological aspects. Here we propose an alternative approach and target sensorimotor alterations—a prominent but often neglected feature of depression. We demonstrated using resting-state functional MRI data and computational modeling that top-down and bottom-up information flow in sensory and motor cortices is altered with increasing depression severity in a way that is consistent with depression symptoms. Depression-associated changes were found to be consistent across sessions, amenable to treatment and of effect size sufficiently large to predict whether somebody has mild or severe depression. These results pave the way for an avenue of research into the neural underpinnings of mental health conditions.

Abstract

Functional neuroimaging research on depression has traditionally targeted neural networks associated with the psychological aspects of depression. In this study, instead, we focus on alterations of sensorimotor function in depression. We used resting-state functional MRI data and dynamic causal modeling (DCM) to assess the hypothesis that depression is associated with aberrant effective connectivity within and between key regions in the sensorimotor hierarchy. Using hierarchical modeling of between-subject effects in DCM with parametric empirical Bayes we first established the architecture of effective connectivity in sensorimotor cortices. We found that in (interoceptive and exteroceptive) sensory cortices across participants, the backward connections are predominantly inhibitory, whereas the forward connections are mainly excitatory in nature. In motor cortices these parities were reversed. With increasing depression severity, these patterns are depreciated in exteroceptive and motor cortices and augmented in the interoceptive cortex, an observation that speaks to depressive symptomatology. We established the robustness of these results in a leave-one-out cross-validation analysis and by reproducing the main results in a follow-up dataset. Interestingly, with (nonpharmacological) treatment, depression-associated changes in backward and forward effective connectivity partially reverted to group mean levels. Overall, altered effective connectivity in sensorimotor cortices emerges as a promising and quantifiable candidate marker of depression severity and treatment response.

The Science of Mind Reading

James Somers offers a fascinating article in the Nov. 29 issue of The New Yorker, which I recommend that you read. It describes the development of the technique of Latent Semantic Analysis (L.S.A) originating in the work of a psychologist named Charles Osgood nearly 70 years ago and now being applied to the analysis of fMRI recordings from people to infer what they are internally thinking or seeing.

In 2013, researchers at Google unleashed a descendant of it onto the text of the whole World Wide Web. Google’s algorithm turned each word into a “vector,” or point, in high-dimensional space. The vectors generated by the researchers’ program, word2vec, are eerily accurate: if you take the vector for “king” and subtract the vector for “man,” then add the vector for “woman,” the closest nearby vector is “queen.” Word vectors became the basis of a much improved Google Translate, and enabled the auto-completion of sentences in Gmail. Other companies, including Apple and Amazon, built similar systems. Eventually, researchers realized that the “vectorization” made popular by L.S.A. and word2vec could be used to map all sorts of things. Today’s facial-recognition systems have dimensions that represent the length of the nose and the curl of the lips, and faces are described using a string of coördinates in “face space.” Chess A.I.s use a similar trick to “vectorize” positions on the board. The technique has become so central to the field of artificial intelligence that, in 2017, a new, hundred-and-thirty-five-million-dollar A.I. research center in Toronto was named the Vector Institute. Matthew Botvinick, a professor at Princeton whose lab was across the hall from Norman’s, and who is now the head of neuroscience at DeepMind, Alphabet’s A.I. subsidiary, told me that distilling relevant similarities and differences into vectors was “the secret sauce underlying all of these A.I. advances.”

 

Subsequent sections of the article describe how machine learning has been brought to brain imaging with voxels of neural activity serving as dimensions in a kind of thought space.

...today’s thought-decoding researchers mostly look for specific thoughts that have been defined in advance. But a “general-purpose thought decoder,” Norman told me, is the next logical step for the research. Such a device could speak aloud a person’s thoughts, even if those thoughts have never been observed in an fMRI machine. In 2018, Botvinick, Norman’s hall mate, co-wrote a paper in the journal Nature Communications titled “Toward a Universal Decoder of Linguistic Meaning from Brain Activation.” Botvinick’s team had built a primitive form of what Norman described: a system that could decode novel sentences that subjects read silently to themselves. The system learned which brain patterns were evoked by certain words, and used that knowledge to guess which words were implied by the new patterns it encountered.

In praise of Sheeple - why we shouldn't always think for ourselves

A friend pointed out this interesting article by Ian Leslie, which I recommend that you read. I pass on a few clips at the end of his exposition:

...the human instinct to copy rather than think for ourselves is good for us, up to a point. Cultural anthropologists have done the most to establish that our instinct to copy parents and peers helps us to learn, to get along, to organise, to bond, and ultimately to build the shared behaviours that enable us to survive and progress. They’ve discovered that compared to other primates humans “over-imitate”: we copy even when there’s no reason to.

In a much-replicated experiment, a complicated-looking box is presented to chimps and the researchers demonstrate how to access a bit of food inside. They include some unnecessary steps: tapping the box three times, fiddling with a bolt, whatever. The chimps quickly work out all they need to do is pull a door and grab the food, and ignore the superfluous actions. Do this experiment with very small humans, however, and the kids copy all the actions. The chimps are more efficient and in a way more ‘rational’ but it’s the other primate which has built cities, ships and cathedrals.

Traditions we don’t understand ought not to be dismissed too quickly, since the collective intelligence of the past dwarves our own. In The Secret of Our Success, the anthropologist Joseph Henrich argues that individual humans are not nearly as smart as we think and that it is culture that makes us a successful species. The Naskapi, a foraging tribe from north-eastern Canada, hunt caribou. They have to decide where to hunt, which isn’t straightforward because if they visit one location too often the caribou know to stay away. The best hunting strategy therefore requires randomisation.

But individuals like to think they’re smart and left to their own devices, Naskapi hunters probably wouldn’t be satisfied with setting out in a random direction every day; they’d come up with brilliant plans which proved to be disastrous. Tradition saves them. To decide where to go, the hunters use a divination ritual which involves heating a caribou shoulder blade over hot coals until cracks and spots start to appear on it; the resulting pattern is then used as a map. In a sense it’s a mindless ritual, but it’s also a randomising device which helps the hunters overcome their decision-making biases.

Here’s what I like about the dupes. When everyone around them behaved in a certain way, their first thought wasn’t “I must be smarter than them”. It was, “They must know something I don’t”. There is an admirable humility to that, even if, in this case, it led them to say or do something absurd. The ability of individual humans to think for ourselves is crucial to progress; equally crucial is that we trust, sometimes unthinkingly, in judgements made by others, alive or dead. Societies where too few people are willing to question norms and traditions tend to stagnate and to perpetuate injustices. But there is a positive side to conformism, too. Just as in an imaginary nightclub on fire there’s a good chance that a passing group will lead you to an exit, there’s a good chance that whatever the people around you say is right, is right, even if you don’t fully understand why yet. Society functions best when we’re sheepish.

What is a DAO? Who needs humans?

A DAO is a Decentralised Autonomous Organisation. My son pointed out this intriguing and also somewhat terrifying video to me. Like Mark Zuckerberg's corporate "Meta" fantasies another step towards tearing our evolved biolgical bodies and social brains away from the organic tactile contacts with each other for which they were designed.

 

The Science of Hugs?

Schultz describes an entertaining bit of work pursuing the obvious done by Düren et.al. Guys hugging each other use their arms differently than women do, more frequently doing a crisscross hug (on the left) than a neck-waist hug (on the right), most likely because the neck-waist hug feels a bit more intimate.

Without prompting the students on how to hug, the researchers found the crisscross style was more common, accounting for 66 out of 100 hugs. The preference for crisscross was especially prevalent in pairs of men, with 82% of 28 observed pairs opting for the style. Neither emotional closeness nor height had significant effects on the style of hugging; however, the researchers note that most participants were relatively close in height, and they guess that neck-waist might be more common when heights differ more drastically.