How exercise supports the brain

From Leiter et al. "Selenium mediates exercise-induced adult neurogenesis and reverses learning deficits induced by hippocampal injury and aging":

Highlights 

• Selenium mediates the exercise-induced increase in adult hippocampal neurogenesis 

• Selenium increases hippocampal precursor proliferation and adult neurogenesis 

• Selenium reverses cognitive decline in aging and in hippocampal injury 

Summary 

Although the neurogenesis-enhancing effects of exercise have been extensively studied, the molecular mechanisms underlying this response remain unclear. Here, we propose that this is mediated by the exercise-induced systemic release of the antioxidant selenium transport protein, selenoprotein P (SEPP1). Using knockout mouse models, we confirmed that SEPP1 and its receptor low-density lipoprotein receptor-related protein 8 (LRP8) are required for the exercise-induced increase in adult hippocampal neurogenesis. In vivo selenium infusion increased hippocampal neural precursor cell (NPC) proliferation and adult neurogenesis. Mimicking the effect of exercise through dietary selenium supplementation restored neurogenesis and reversed the cognitive decline associated with aging and hippocampal injury, suggesting potential therapeutic relevance. These results provide a molecular mechanism linking exercise-induced changes in the systemic environment to the activation of quiescent hippocampal NPCs and their subsequent recruitment into the neurogenic trajectory.

Addicted to dreaming.

Dopamine (DA) is usually associated with pleasure and addiction. Now Hasegawa et al. show that release of DA in the basolateral amygdala (BLA), a brain structure associated with emotional processing, can trigger rapid eye movement (REM) dreaming sleep in mice.

The sleep cycle is characterized by alternating non–rapid eye movement (NREM) and rapid eye movement (REM) sleeps. The mechanisms by which this cycle is generated are incompletely understood. We found that a transient increase of dopamine (DA) in the basolateral amygdala (BLA) during NREM sleep terminates NREM sleep and initiates REM sleep. DA acts on dopamine receptor D2 (Drd2)–expressing neurons in the BLA to induce the NREM-to-REM transition. This mechanism also plays a role in cataplectic attacks—a pathological intrusion of REM sleep into wakefulness—in narcoleptics. These results show a critical role of DA signaling in the BLA in initiating REM sleep and provide a neuronal basis for sleep cycle generation.

The manly art of self-promotion

Exley and Kessler suggest that gender wage gaps may have roots in men being more self-promoting than women:

We run a series of experiments involving over 4,000 online participants and over 10,000 school-aged youth. When individuals are asked to subjectively describe their performance on a male-typed task relating to math and science, we find a large gender gap in self-evaluations. This gap arises when self-evaluations are provided to potential employers, and thus measure self-promotion, and when self-evaluations are not driven by incentives to promote. The gender gap in self-evaluations proves to be persistent and arises as early as the sixth grade. No gender gap arises if individuals are asked about their performance on a more female-typed task.

Genes for loving nature.

From Chang et al.:

Nature experiences have been linked to mental and physical health. Despite the importance of understanding what determines individual variation in nature experience, the role of genes has been overlooked. Here, using a twin design (TwinsUK, number of individuals = 2,306), we investigate the genetic and environmental contributions to a person’s nature orientation, opportunity (living in less urbanized areas), and different dimensions of nature experience (frequency and duration of public nature space visits and frequency and duration of garden visits). We estimate moderate heritability of nature orientation (46%) and nature experiences (48% for frequency of public nature space visits, 34% for frequency of garden visits, and 38% for duration of garden visits) and show their genetic components partially overlap. We also find that the environmental influences on nature experiences are moderated by the level of urbanization of the home district. Our study demonstrates genetic contributions to individuals’ nature experiences, opening a new dimension for the study of human–nature interactions.

The Life Cycle of Outrage

 I have to pass on this great piece by Mark Manson on the life cycle of a 'significant event'.  

A feeling of loss in the abstraction of all those beautiful things into streams and algorithms...

I pass on a single paragraph from A.O.Scott's recent essay "Shelf Life: Our Collections and the Passage of Time" and suggest you read the whole piece, an engaging illustrated commentary on generational and cultural change:

And that is the substance, so to speak, of Klosterman’s (author of "The Nineties") relentless cataloging and Aksel’s (a character in "The Worst Person in the World" comedy series) lamentation for lost record stores. The digitization of culture — the abstraction of all those beautiful things into streams and algorithms — feels to many of us like a permanent loss. What kind of a loss can be hard to specify, since there is also clearly a benefit. In the old days, Aksel might not have been able to watch “Dog Day Afternoon” over and over again. He might have had to wait until it showed up at a revival house, or until the previous customer returned the only VHS copy to the video store. Now he can stream “Back to Dungaree High” on a playlist with his other favorites. Klosterman can watch any episode of “Seinfeld” or “The Simpsons” any time he wants.

Listening to our bodies can make us more resilient to stress

Jane Brody points to work from Haas et al. suggesting that resilience is more about body awareness than rational thinking. In their experiments subjects who had more subjective awareness of their internal feelings were less emotionally reactive to stress (showing less heart rate increase, shallow breathing, blood adrenaline increase), and recovered more quickly from it. Increased awareness of interoceptive stress signals from the body appears to enable stronger top-down suppression of the stress response. Here is the abstract from the Haas et al. article:

This study examined neural processes of resilience during aversive interoceptive processing. Forty-six individuals were divided into three groups of resilience Low (LowRes), high (HighRes), and normal (NormRes), based on the Connor-Davidson Resilience Scale (2003). Participants then completed a task involving anticipation and experience of loaded breathing during functional magnetic resonance imaging (fMRI) recording. Compared to HighRes and NormRes groups, LowRes self-reported lower levels of interoceptive awareness and demonstrated higher insular and thalamic activation across anticipation and breathing load conditions. Thus, individuals with lower resilience show reduced attention to bodily signals but greater neural processing to aversive bodily perturbations. In low resilient individuals, this mismatch between attention to and processing of interoceptive afferents may result in poor adaptation in stressful situations.

AI-synthesized faces are indistinguishable from real faces and more trustworthy

A sobering open source aricle from Nightingale and Farid than suggests the impossibility of sorting our the real from the fake. Synthesized faces tend to look more like average faces which themselves are deemed more trustworthy.

Artificial intelligence (AI)–synthesized text, audio, image, and video are being weaponized for the purposes of nonconsensual intimate imagery, financial fraud, and disinformation campaigns. Our evaluation of the photorealism of AI-synthesized faces indicates that synthesis engines have passed through the uncanny valley and are capable of creating faces that are indistinguishable—and more trustworthy—than real faces.

Seven Habits That Lead to Happiness in Old Age

I want to point to this self-help article by Arthur Brooks in The Atlantic, part of his 'How to Build a Life' series. It's bottom line, derived from data in the famous Harvard Study of Adult Development begun in 1938, is that Happy-well seniors accumulate resources and habits in their Happiness 401(k)s during their younger lives by practicing the following injunctions. 

1. Don't smoke 

2. Watch your drinking 

3. Maintain a healthy body weight 

4. Prioritize physical movement in your life 

5. Practice coping mechanisms 

6 Keep learning 

 7 Cultivate stable long term relationships.

Reconsidering evidence of moral contagion in online social networks

Burton et al. raise some cautions about recent studies seeming to show that inclusion of emotional terms in social media text messages increases message diffusion. Here is a clip from their text, followed by the article abstract:

...we created an absurd factor for illustrative purposes, what we call XYZ contagion, and tested whether the number of X’s, Y’s and Z’s included in messages’ text predicted diffusion...Our analysis found XYZ contagion to be present in four of our six corpora such that the presence of the letters X, Y and Z predicted an increase in message diffusion: COVID-19 tweets...#MeToo tweets...#MuellerReport tweets...2016 US Election tweets...While there was no positive relationship between the presence of X, Y and Z and message diffusion in the #WomensMarch and Post-Brexit tweets, the finding that XYZ contagion passes a key test of robustness, viz. out-of-sample prediction, demonstrates the potential of large-scale social media datasets to contain spurious correlations

Abstract

The ubiquity of social media use and the digital data traces it produces has triggered a potential methodological shift in the psychological sciences away from traditional, laboratory-based experimentation. The hope is that, by using computational social science methods to analyse large-scale observational data from social media, human behaviour can be studied with greater statistical power and ecological validity. However, current standards of null hypothesis significance testing and correlational statistics seem ill-suited to markedly noisy, high-dimensional social media datasets. We explore this point by probing the moral contagion phenomenon, whereby the use of moral-emotional language increases the probability of message spread. Through out-of-sample prediction, model comparisons and specification curve analyses, we find that the moral contagion model performs no better than an implausible XYZ contagion model. This highlights the risks of using purely correlational evidence from large observational datasets and sounds a cautionary note for psychology’s merge with big data.

Predictions help neurons, and the brain, learn

From the PNAS Journal Club, a review of a publication by Luczak et. al. that suggest that neurons might be able to predict their own future activity, and learn to improve the accuracy of those predictions. The review expands on the Luczak et al abstract, which I pass on here:

Understanding how the brain learns may lead to machines with human-like intellectual capacities. It was previously proposed that the brain may operate on the principle of predictive coding. However, it is still not well understood how a predictive system could be implemented in the brain. Here we demonstrate that the ability of a single neuron to predict its future activity may provide an effective learning mechanism. Interestingly, this predictive learning rule can be derived from a metabolic principle, whereby neurons need to minimize their own synaptic activity (cost) while maximizing their impact on local blood supply by recruiting other neurons. We show how this mathematically derived learning rule can provide a theoretical connection between diverse types of brain-inspired algorithm, thus offering a step towards the development of a general theory of neuronal learning. We tested this predictive learning rule in neural network simulations and in data recorded from awake animals. Our results also suggest that spontaneous brain activity provides ‘training data’ for neurons to learn to predict cortical dynamics. Thus, the ability of a single neuron to minimize surprise—that is, the difference between actual and expected activity—could be an important missing element to understand computation in the brain.

Consciousness is supported by near-critical slow cortical electrodynamics

An open source offering from Toker et al. that has a nice summary graphic.:  

Significance

What changes in the brain when we lose consciousness? One possibility is that the loss of consciousness corresponds to a transition of the brain’s electric activity away from edge-of-chaos criticality, or the knife’s edge in between stability and chaos. Recent mathematical developments have produced tools for testing this hypothesis, which we apply to cortical recordings from diverse brain states. We show that the electric activity of the cortex is indeed poised near the boundary between stability and chaos during conscious states and transitions away from this boundary during unconsciousness and that this transition disrupts cortical information processing.

Abstract

Mounting evidence suggests that during conscious states, the electrodynamics of the cortex are poised near a critical point or phase transition and that this near-critical behavior supports the vast flow of information through cortical networks during conscious states. Here, we empirically identify a mathematically specific critical point near which waking cortical oscillatory dynamics operate, which is known as the edge-of-chaos critical point, or the boundary between stability and chaos. We do so by applying the recently developed modified 0-1 chaos test to electrocorticography (ECoG) and magnetoencephalography (MEG) recordings from the cortices of humans and macaques across normal waking, generalized seizure, anesthesia, and psychedelic states. Our evidence suggests that cortical information processing is disrupted during unconscious states because of a transition of low-frequency cortical electric oscillations away from this critical point; conversely, we show that psychedelics may increase the information richness of cortical activity by tuning low-frequency cortical oscillations closer to this critical point. Finally, we analyze clinical electroencephalography (EEG) recordings from patients with disorders of consciousness (DOC) and show that assessing the proximity of slow cortical oscillatory electrodynamics to the edge-of-chaos critical point may be useful as an index of consciousness in the clinical setting.

Illusory faces are more likely to be perceived as male than female

Interesting observations from Wardle et al.:

Despite our fluency in reading human faces, sometimes we mistakenly perceive illusory faces in objects, a phenomenon known as face pareidolia. Although illusory faces share some neural mechanisms with real faces, it is unknown to what degree pareidolia engages higher-level social perception beyond the detection of a face. In a series of large-scale behavioral experiments (ntotal = 3,815 adults), we found that illusory faces in inanimate objects are readily perceived to have a specific emotional expression, age, and gender. Most strikingly, we observed a strong bias to perceive illusory faces as male rather than female. This male bias could not be explained by preexisting semantic or visual gender associations with the objects, or by visual features in the images. Rather, this robust bias in the perception of gender for illusory faces reveals a cognitive bias arising from a broadly tuned face evaluation system in which minimally viable face percepts are more likely to be perceived as male.

Our brains store concepts as sensory-motor and affective information

Fascinating work from Fernandino et al., who show that concept representations are not independent of sensory-motor experience: 

Significance

The ability to identify individual objects or events as members of a kind (e.g., “knife,” “dog,” or “party”) is a fundamental aspect of human cognition. It allows us to quickly access a wealth of information pertaining to a newly encountered object or event and use it to guide our behavior. How is this information represented in the brain? We used functional MRI to analyze patterns of brain activity corresponding to hundreds of familiar concepts and quantitatively characterized the informational structure of these patterns. Our results indicate that conceptual knowledge is stored as patterns of neural activity that encode sensory-motor and affective information about each concept, contrary to the long-held idea that concept representations are independent of sensory-motor experience.

Abstract

The nature of the representational code underlying conceptual knowledge remains a major unsolved problem in cognitive neuroscience. We assessed the extent to which different representational systems contribute to the instantiation of lexical concepts in high-level, heteromodal cortical areas previously associated with semantic cognition. We found that lexical semantic information can be reliably decoded from a wide range of heteromodal cortical areas in the frontal, parietal, and temporal cortex. In most of these areas, we found a striking advantage for experience-based representational structures (i.e., encoding information about sensory-motor, affective, and other features of phenomenal experience), with little evidence for independent taxonomic or distributional organization. These results were found independently for object and event concepts. Our findings indicate that concept representations in the heteromodal cortex are based, at least in part, on experiential information. They also reveal that, in most heteromodal areas, event concepts have more heterogeneous representations (i.e., they are more easily decodable) than object concepts and that other areas beyond the traditional “semantic hubs” contribute to semantic cognition, particularly the posterior cingulate gyrus and the precuneus.

How to want less

I've just enjoyed reading through an article by Arthur Brooks, "How to want less" in The Atlantic, which is adapted from his new book "From Strength to Strength: Finding Success, Happiness, and Deep Purpose in the Second Half of Life." I recommend that you read through it. After repeating the point that evolution didn't design us to be happy, but rather to pass on our genes, he notes:

In fact, our natural state is dissatisfaction punctuated by brief moments of satisfaction. You might not like the hedonic treadmill, but Mother Nature thinks it’s pretty great. She likes watching you strive to achieve an elusive goal, because strivers get the goods—even if they don’t enjoy them for long. More mates, better mates, better chances of survival for our children—these ancient mandates are responsible for much of the code that runs incessantly in the deep recesses of our brains. It doesn’t matter whether you’ve found your soul mate and would never stray; the algorithms designed to get us more mates (or allow us to make an upgrade) continue whirring, which is why you still want to be attractive to strangers. Neurobiological instinct—which we experience as dissatisfaction—is what drives us forward....There are many other, related examples of evolved tendencies that militate against enduring happiness—for example, the tendency toward jealous misery in our romantic relationships.

He notes the history of similar recurring solutions to these problems, for example in the sayings of the Buddha, St. Thomas Aquinas - and even Mick Jagger (in his classic "I can't get no satisfaction"). His self help suggestion is to:

...absorb the teachings of Thomas Aquinas and the Buddha—or for that matter, modern social science—and commit to stop trying to add more and more, but instead start taking things away.

In truth, our formula, Satisfaction = getting what you want, leaves out one key component. To be more accurate, it should be:

Satisfaction = what you have ÷ what you want

All of our evolutionary and biological imperatives focus us on increasing the numerator—our haves. But the more significant action is in the denominator—our wants. The modern world is made up of clever ways to make our wants explode without us realizing it.

Brooks offers three habits he has found useful in beating the dissatisfaction curse: 

I. Go from Prince to Sage (the models of Thomas Aquinas and the Buddha...repudiating the world's reward in favor of inner wisdom and helping others) 

II Make a Reverse Bucket List (repudiate getting more 'stuff' and instead list intrinsic sources of happiness or satisfaction that come from with and revolve around love, relationships, and deep purpose...having little to do with the admiration of strangers.) 

III. Get Smaller (live in the present, not the past or future.)

A special issue of Social Cognitive and Affective Neuroscience on tDCS

I want to point to this special open source issue of Social Cognitive and Affective Neuroscience. Paulo Boggio provides an interesting historical introduction, staring in Roman times with the use of the electrical discharge of the torpedo fish to treat headaches (imagine being treated with fish applications over your head!). The articles in the issue consider the effects of low-intensity direct current stimulation of the surface of the scalp on prosocial behavior, aggression, impulsivity, etc. A review article by Galli et al. considers the use of tDCS to relieve the symptomatology of individuals with affective or social cognition disorders. (DIY kits for home experimentrs - which I would not recommend - abound on the internet, regular flashlight batteries being a sufficient source of the low currents used.)

Expression unleashed: The evolutionary & cognitive foundations of human communication

I'm passing on the abstract of a dense but interesting article by Christophe Heintz and Thom Scott-Phillips that will be published in Behavioral and Brain Science and is now being circulated for comment by reviewers. Motivated readers can request a PDF of the article from me.

Human expression is open-ended, versatile and diverse, ranging from ordinary language use to painting, from exaggerated displays of affection to micro-movements that aid coordination. Here we present and defend the claim that this expressive diversity is united by an interrelated suite of cognitive capacities, the evolved functions of which are the expression and recognition of informative intentions. We describe how evolutionary dynamics normally leash communication to narrow domains of statistical mutual benefit, and how they are unleashed in humans. The relevant cognitive capacities are cognitive adaptations to living in a partner choice social ecology; and they are, correspondingly, part of the ordinarily developing human cognitive phenotype, emerging early and reliably in ontogeny. In other words, we identify distinctive features of our species’ social ecology to explain how and why humans, and only humans, evolved the cognitive capacities that, in turn, lead to massive diversity and open-endedness in means and modes of expression. Language use is but one of these modes of expression, albeit one of manifestly high importance. We make cross-species comparisons, describe how the relevant cognitive capacities can evolve in a gradual manner, and survey how unleashed expression facilitates not only language use but novel behaviour in many other domains too, focusing on the examples of joint action, teaching, punishment and art, all of which are ubiquitous in human societies but relatively rare in other species. Much of this diversity derives from graded aspects of human expression, which can be used to satisfy informative intentions in creative and new ways. We aim to help reorient cognitive pragmatics, as a phenomenon that is not a supplement to linguistic communication and on the periphery of language science, but rather the foundation of the many of the most distinctive features of human behaviour, society and culture.

MindBlog is 16 years old... It's first post: "Dangerous Ideas"

I repeat MindBlog's first post... of ideas that are now considered more commonplace than dangerous. Edge.org soldiers on, but its 'annual question' addressed to prominent thinkers disappeared several years ago. Here is the post: 

Edge.org is a website sponsored by the "Reality Club" (i.e. John Brockman, literary agent/impressario/socialite). Brockman has assembled a stable of scientists and other thinkers that he defines as a "third culture" that takes the place of traditional intellectuals in redefining who and what we are.... Each year a question is formulated for all to write on... In 2004 it was "What do you believe is true even though you cannot prove it?" The question for 2005 was "What is your dangerous idea?"

The responses organize themselves into several areas. Here are selected thumbnail summaries most directly relevant to human minds. I've not included cosmology and physics. Go to edge.org to read the essays

I. Nature of the human self or mind (by the way see my "I-Illusion" essay on my website):

Paulos - The self is a conceptual chimera
Shirky - Free will is going away
Nisbett - We are ignorant of our thinking processes
Horgan - We have no souls
Bloom - There are no souls, mind has a material basis.
Provine - This is all there is.
Anderson - Brains cannot become minds without bodies
Metzinger - Is being intellectually honest about the issue of free will compatible with preserving one's mental health?
Clark - Much of our behavior is determined by non-conscious, automatic uptake of cues and information
Turkle - Simulation will replace authenticity as computer simulation becomes fully naturalized.
Dawkins - A faulty person is no different from a faulty car. There is a mechanism determining behavior that needs to be fixed. The idea of responsibility is nonsense.
Smith - What we know may not change us. We will continue to conceive ourselves as centres of experience, self-knowing and free willing agents.

II. Natural explanations of culture

Sperber - Culture is natural.
Taylor - The human brain is a cultural artifact.
Hauser- There is a universal grammar of mental life.
Pinker - People differ genetically in their average talents and temperaments.
Goodwin - Similar coordinating patterns underlie biological and cultural evolution.
Venter - Revealing the genetic basis of personality and behavior will create societal conflicts.


III. Fundamental changes in political, economic, social order

O'donnell - The state will disappear.
Ridley - Government is the problem not the solution.
Shermer - Where goods cross frontiers armies won't.
Harari -Democracy is on its way out.
Csikszentmihalyi- The free market myth is destroying culture.
Goleman - The internet undermines the quality of human interaction.
Harris - Science must destroy religion.
Porco - Confrontation between science and religion might end when role played by science in lives of people is the same played by religion today.
Bering - Science will never silence God
Fisher - Drugs such as antidepressants jeopardize feelings of attachment and love
Iacoboni - Media Violence Induces Imitative Violence - the Problem with Mirrors
Morton - Our planet is not in peril, just humans are. 

Attention and executive functions - improvements and declines with ageing.

From Verissimo et al.:

Many but not all cognitive abilities decline during ageing. Some even improve due to lifelong experience. The critical capacities of attention and executive functions have been widely posited to decline. However, these capacities are composed of multiple components, so multifaceted ageing outcomes might be expected. Indeed, prior findings suggest that whereas certain attention/executive functions clearly decline, others do not, with hints that some might even improve. We tested ageing effects on the alerting, orienting and executive (inhibitory) networks posited by Posner and Petersen’s influential theory of attention, in a cross-sectional study of a large sample (N = 702) of participants aged 58–98. Linear and nonlinear analyses revealed that whereas the efficiency of the alerting network decreased with age, orienting and executive inhibitory efficiency increased, at least until the mid-to-late 70s. Sensitivity analyses indicated that the patterns were robust. The results suggest variability in age-related changes across attention/executive functions, with some declining while others improve.

How fast people respond to each other is a metric of social connection.

From Templeton et al.:  

Significance

Social connection is critical for our mental and physical health yet assessing and measuring connection has been challenging. Here, we demonstrate that a feature intrinsic to conversation itself—the speed with which people respond to each other—is a simple, robust, and sufficient metric of social connection. Strangers and friends feel more connected when their conversation partners respond quickly. Because extremely short response times (less than 250 ms) preclude conscious control, they provide an honest signal that even eavesdroppers use to judge how well two people “click.”

Abstract

Clicking is one of the most robust metaphors for social connection. But how do we know when two people "click"? We asked pairs of friends and strangers to talk with each other and rate their felt connection. For both friends and strangers, speed in response was a robust predictor of feeling connected. Conversations with faster response times felt more connected than conversations with slower response times, and within conversations, connected moments had faster response times than less-connected moments. This effect was determined primarily by partner responsivity: People felt more connected to the degree that their partner responded quickly to them rather than by how quickly they responded to their partner. The temporal scale of these effects (less than 250 ms) precludes conscious control, thus providing an honest signal of connection. Using a round-robin design in each of six closed networks, we show that faster responders evoked greater feelings of connection across partners. Finally, we demonstrate that this signal is used by third-party listeners as a heuristic of how well people are connected: Conversations with faster response times were perceived as more connected than the same conversations with slower response times. Together, these findings suggest that response times comprise a robust and sufficient signal of whether two minds “click.”