Theories of consciousness

A valuable summary article from Anil Seth and Time Bayne. The article has excelent graphics demonstrating the four main models of consciousness that are the focus of most current attention and research. Motivated readers can request a copy of the whole article from me.  

Abstract

Recent years have seen a blossoming of theories about the biological and physical basis of consciousness. Good theories guide empirical research, allowing us to interpret data, develop new experimental techniques and expand our capacity to manipulate the phenomenon of interest. Indeed, it is only when couched in terms of a theory that empirical discoveries can ultimately deliver a satisfying understanding of a phenomenon. However, in the case of consciousness, it is unclear how current theories relate to each other, or whether they can be empirically distinguished. To clarify this complicated landscape, we review four prominent theoretical approaches to consciousness: higher-order theories, global workspace theories, re-entry and predictive processing theories and integrated information theory. We describe the key characteristics of each approach by identifying which aspects of consciousness they propose to explain, what their neurobiological commitments are and what empirical data are adduced in their support. We consider how some prominent empirical debates might distinguish among these theories, and we outline three ways in which theories need to be developed to deliver a mature regimen of theory-testing in the neuroscience of consciousness. There are good reasons to think that the iterative development, testing and comparison of theories of consciousness will lead to a deeper understanding of this most profound of mysteries.

The allure of conspiracy theories.

Edsall does a nice essay on the allure of conspiracy theories which are playing a significant role in the current decline of a humane America being helplessly guided by the public's reactivity to the politics of entertainment. It's worth a read, here are few edited clips:

The stolen election conspiracy theory has, in effect, become the adhesive holding the dominant Trump wing of the party in lock-step. This particular conspiracy theory joins the network of sub-theories that unite Trump loyalists, who allege that an alliance of Democratic elites and urban political machines have secretly joined forces to deny the will of the people, corralling the votes of illegal immigrants and the dead, while votes cast by Trump supporters are tossed into the trash....In a 2017 essay, Uscinski et al. recognized the central role of conspiracy theories in Trump’s rise to the presidency:

Trump, as a disruptive candidate, could not compete on the party establishment’s playing field...Trump’s solution is what we call ‘conspiracy theory politics.’... boiled down to a single unifying claim: Political elites have abandoned the interests of regular Americans in favor of foreign interests. For Trump, the political system was corrupt and the establishment could not be trusted. It followed, then, that only a disrupter could stop the corruption.

Jonathan Haidt, a social psychologist at N.Y.U.’s Stern School of Business, noted that spreading a lie can serve as a shibboleth — something like a password used by one set of people to identify other people as members of a particular group:

Many who study religion have noted that it’s the very impossibility of a claim that makes it a good signal of one’s commitment to the faith. You don’t need faith to believe obvious things. Proclaiming that the election was stolen surely does play an identity-advertising role in today’s America.

Magnetic stimulation of the brain can improve cognitive impairment

An open source article from Liu et al. in the journal Cerebral Cortex reports that repetitive transcranial magnetic stimulation (rTMS) over the bilateral angular gyrus in patients with probable Alzheimer’s disease resulted in up to 8 weeks of significantly improved cognitive function.:

Dementia causes a substantial global economic burden, but effective treatment is lacking. Recently, studies have revealed that gamma-band waves of electrical brain activity, particularly 40 Hz oscillations, are closely associated with high-order cognitive functions and can activate microglia to clear amyloid-β deposition. Here, we found that compared with sham stimulation, applying 40-Hz high-frequency repetitive transcranial magnetic stimulation (rTMS) over the bilateral angular gyrus in patients with probable Alzheimer’s disease (AD; n = 37) resulted in up to 8 weeks of significantly improved cognitive function. Power spectral density analysis of the resting-state electroencephalography (EEG) demonstrated that 40-Hz rTMS modulated gamma-band oscillations in the left posterior temporoparietal region. Further testing with magnetic resonance imaging and TMS-EEG revealed the following: 40-Hz rTMS 1) prevented gray matter volume loss, 2) enhanced local functional integration within bilateral angular gyrus, as well as global functional integration in bilateral angular gyrus and the left middle frontal gyrus, 3) strengthened information flow from the left posterior temporoparietal region to the frontal areas and strengthened the dynamic connectivity between anterior and posterior brain regions. These findings demonstrate that modulating gamma-band oscillations effectively improves cognitive function in patients with probable AD by promoting local, long-range, and dynamic connectivity within the brain.

Effortless training of attention and self-control

I pass on the highlights statement from a fascinating opinion piece by Tang et al. (motivated readers can obtain a copy of the text from me). 

Highlights

A long-held belief in cognitive science is that training attention and self-control must recruit effort. Therefore, various effortful training programs such as attention or working memory training have been developed to improve attention and self-control (or executive function). However, effortful training has limited far-transfer effects.

A growing literature suggests a new way of effortless training for attention and self-control. Effortless training – such as nature exposure, flow experience, and effortless practices – has shown promising effects on improving attention and self-control.

Effortful training requires cognitive control supported by the frontoparietal network to sustain mental effort over the course of training. Effortless training engages autonomic control with less effort, and is supported by the anterior and posterior cingulate cortex, striatum, and parasympathetic nervous system (PNS).

For the past 50 years, cognitive scientists have assumed that training attention and self-control must be effortful. However, growing evidence suggests promising effects of effortless training approaches such as nature exposure, flow experience, and effortless practice on attention and self-control. This opinion article focuses on effortless training of attention and self-control. We begin by introducing our definitions of effortful and effortless training and reviewing the growing literature on these two different forms of training. We then discuss the similarities and differences in their respective behavioral outcomes and neural correlates. Finally, we propose a putative neural mechanism of effortless training. We conclude by highlighting promising directions for research, development, and application of effortless training.

Figure Legend: Core brain regions and their functions during effortless training.

Three colored areas represent the anterior cingulate cortex–posterior cingulate cortex (ACC–PCC)–striatum (APS) and their corresponding functions during training. The broken line arrows indicate that these regions actively communicate with each other during effortless training.

MindBlog in Crypto-Land

Unless you have been hiding in a cave (not a bad place to be these days) you have doubtless been following the current crash of the stock market and the even more dramatic implosion of the cryptocurrency bubble.  From dizzying highs (see The New Get-Rich-Faster Job in Silicon Valley: Crypto Start-Ups) the values of BitCoin, Etherium and other cryptocurrencies have cratered, while critiques of the blockchains and cryptocurrencies have become more numerous (see How ‘Trustless’ Is Bitcoin, Really?,  Crypto, Houses, Sneakers, Rolexes: How FOMO Drove the Economy,  From the Big Short to the Big Scam (Krugman),  Why bitcoin is worse than a Madoff-style Ponzi scheme.

In this post I’ve decided to pass on a chronicle of my own experience with crypto-world to date - so I know where I can look it up later,  and also as a basis for passing on any further entanglements or results.  [MindBlog has taken a similar tack in reporting its (generally unsuccessful) experiments with dietary supplements meant to enhance our vitality or longevity.]

In early 2021 my techie son (an eCommerce website developer) decided to gamble $1,000 by purchasing two Helium Miners (hotspots) whose antennas connected them to a Helium ‘People’s Network’ - a decentralized wireless infrastructure powered by the Helium Blockchain for use by the IoT  (“Internet of Things” - thermostats, water and gas meters, scooter rentals, etc.).  These miners started generating ‘HNT’ tokens, the Helium cryptocurrency. Tokens valued at over $600,000 soon accumulated, and he cashed out $100,000 of this… for a thousand-fold return on investment! 

I read the hype, drank the kool aid, decided to follow in his footsteps, and put in a bit of ‘mad money’ I was willing to loose...  Here is the Rake’s Progress:

At the end on Nov. 2021 I set up a Coinbase account linked to my real world bank account, bought $1000 of USCD ‘stable coins’ and used them on Dec. 9 to pay for two Bobcat 300 Helium Miners (the step up and down on the left in the Coinbase App screenshot below.)  Then I decided to speculate a bit, and on Dec. 31 bought $1000 of Ethereum (ETH coins), now worth $280.99 (shown by the jagged downward line on the screenshot taken June 18).  Perfect timing!

The Bobcat 300 miners were ordered on Dec. 9….. then came a series of emails describing factory closings in China,  Covid shutdowns, supply chain blockages,  etc….  They finally arrived on June 9 (which seems light years later in cyber-world time) and are being set up now.

 

AND, by now they are being overshined by the appearance of the latest shiny new toy,  the Bobcat 500 (5G) miner, which with a CBRS (Citizens Broadcast Radio Service) operating "Cell" on the 5G cellular network can earn cryptocurrency by providing 5G cellular coverage.  So, naturally I’ve just bought one of these (with “delivery in 4-8 weeks”....we've been there before, see above).  Here are its claims to be a  big deal…

The current Bobcat 300 miners, just about to be setup, will still be grinding away, hopefully earning some HNT,  but their IoT niche is now depicted as occupying 1.2% of this glorious new world.

To be continued.....

 

 

Testerone production in adult men is regulated by an adolescent period sensitive to family experiences.

 From Gettler et al.:

Significance

Testosterone influences how animals devote energy and time toward reproduction, including opposing demands of mating and competition versus parenting. Reflecting this, testosterone often declines in new fathers and lower testosterone is linked to greater caregiving. Given these roles, there is strong interest in factors that affect testosterone, including early-life experiences. In this multidecade study, Filipino sons whose fathers were present and involved with raising them when they were adolescents had lower testosterone when they later became fathers, compared to sons whose fathers were present but uninvolved or were not coresident. Sons’ own parenting behaviors did not explain these patterns. These results connect key social experiences during adolescence to adult testosterone, and point to possible intergenerational effects of parenting style.

Abstract

Across vertebrates, testosterone is an important mediator of reproductive trade-offs, shaping how energy and time are devoted to parenting versus mating/competition. Based on early environments, organisms often calibrate adult hormone production to adjust reproductive strategies. For example, favorable early nutrition predicts higher adult male testosterone in humans, and animal models show that developmental social environments can affect adult testosterone. In humans, fathers’ testosterone often declines with caregiving, yet these patterns vary within and across populations. This may partially trace to early social environments, including caregiving styles and family relationships, which could have formative effects on testosterone production and parenting behaviors. Using data from a multidecade study in the Philippines (n = 966), we tested whether sons’ developmental experiences with their fathers predicted their adult testosterone profiles, including after they became fathers themselves. Sons had lower testosterone as parents if their own fathers lived with them and were involved in childcare during adolescence. We also found a contributing role for adolescent father–son relationships: sons had lower waking testosterone, before and after becoming fathers, if they credited their own fathers with their upbringing and resided with them as adolescents. These findings were not accounted for by the sons’ own parenting and partnering behaviors, which could influence their testosterone. These effects were limited to adolescence: sons’ infancy or childhood experiences did not predict their testosterone as fathers. Our findings link adolescent family experiences to adult testosterone, pointing to a potential pathway related to the intergenerational transmission of biological and behavioral components of reproductive strategies.

The brain signature of choosing to accept pain in exchange for future reward

From Coll et al.: 

Significance

We often willingly experience pain to reach a goal. However, potential pain can also prevent reckless action. How do we consider future pain when deciding on the best course of action? To date, the precise neural mechanisms underlying the valuation of future pain remain unknown. Using functional MRI, we derive a whole-brain signature of the value of future pain capable of predicting participants’ choices to accept pain in exchange for a reward. We show that this signature is characterized by a distributed pattern of activity with clear contributions from structures encoding reward and salience, notably the ventral and dorsal striatum. These findings highlight how the brain assigns value to future pain when choosing the best course of action.

Abstract

Pain is a primary driver of action. We often must voluntarily accept pain to gain rewards. Conversely, we may sometimes forego potential rewards to avoid associated pain. In this study, we investigated how the brain represents the decision value of future pain. Participants (n = 57) performed an economic decision task, choosing to accept or reject offers combining various amounts of pain and money presented visually. Functional MRI (fMRI) was used to measure brain activity throughout the decision-making process. Using multivariate pattern analyses, we identified a distributed neural representation predicting the intensity of the potential future pain in each decision and participants’ decisions to accept or avoid pain. This neural representation of the decision value of future pain included negative weights located in areas related to the valuation of rewards and positive weights in regions associated with saliency, negative affect, executive control, and goal-directed action. We further compared this representation to future monetary rewards, physical pain, and aversive pictures and found that the representation of future pain overlaps with that of aversive pictures but is distinct from experienced pain. Altogether, the findings of this study provide insights on the valuation processes of future pain and have broad potential implications for our understanding of disorders characterized by difficulties in balancing potential threats and rewards.

Neural signatures of major depressive, anxiety, and stress-related disorders

Some fascintating observation from Zhukovsky et al.,  (open source, nice graphics of brain imaging results) who find that major depressive and anxiety disorders share functional and structural neural signatures, but stress-related disorders are distinct from these. Also, better cognitive function is associated with lower connectivity of specific nodes of the default mode and frontoparietal networks.

Significance

Major depressive, anxiety, and stress-related disorders are highly comorbid and may affect similar neurocircuitry and cognitive processes. However, the neurocircuitry underlying shared dimensions of cognitive impairment is unclear and holds the promise of reimagining psychiatric nosology. Here we leverage population imaging data (n = 27,132) to show that while major depressive and anxiety disorders share functional and structural neural signatures, stress-related disorders are distinct from these two conditions. We report that better cognitive function is associated with lower connectivity of specific nodes of the default mode and frontoparietal networks. These findings provide population benchmarks for brain–cognition associations in healthy participants and those with lifetime major depressive and anxiety disorders, advancing our understanding of intrinsic brain networks underlying cognitive dysfunction.

Abstract

The extent of shared and distinct neural mechanisms underlying major depressive disorder (MDD), anxiety, and stress-related disorders is still unclear. We compared the neural signatures of these disorders in 5,405 UK Biobank patients and 21,727 healthy controls. We found the greatest case–control differences in resting-state functional connectivity and cortical thickness in MDD, followed by anxiety and stress-related disorders. Neural signatures for MDD and anxiety disorders were highly concordant, whereas stress-related disorders showed a distinct pattern. Controlling for cross-disorder genetic risk somewhat decreased the similarity between functional neural signatures of stress-related disorders and both MDD and anxiety disorders. Among cases and healthy controls, reduced within-network and increased between-network frontoparietal and default mode connectivity were associated with poorer cognitive performance (processing speed, attention, associative learning, and fluid intelligence). These results provide evidence for distinct neural circuit function impairments in MDD and anxiety disorders compared to stress disorders, yet cognitive impairment appears unrelated to diagnosis and varies with circuit function.

The Conscious Turing Machine - a blueprint for conscious machines.

I want to point to a paper in the current PNAS by Blum and Blum, "A theory of consciousness from a theoretical computer science perspective: Insights from the Conscious Turing Machine," as well as a copmmentary on it by Oliveira. I do this before diving in to read it and hopefully understand it myself, to alert consciousness mavens of its appearance. A first glance through it makes me think that getting a grip on understanding the model will take considerable effort on my part. Perhaps I will emerge with some commentary, perhaps not.... I pass on the Blum and Blum opening statements:  

Significance

This paper provides evidence that a theoretical computer science (TCS) perspective can add to our understanding of consciousness by providing a simple framework for employing tools from computational complexity theory and machine learning. Just as the Turing machine is a simple model to define and explore computation, the Conscious Turing Machine (CTM) is a simple model to define and explore consciousness (and related concepts). The CTM is not a model of the brain or cognition, nor is it intended to be, but a simple substrate-independent computational model of (the admittedly complex concept of) consciousness. This paper is intended to introduce this approach, show its possibilities, and stimulate research in consciousness from a TCS perspective.

Abstract

This paper examines consciousness from the perspective of theoretical computer science (TCS), a branch of mathematics concerned with understanding the underlying principles of computation and complexity, including the implications and surprising consequences of resource limitations. We propose a formal TCS model, the Conscious Turing Machine (CTM). The CTM is influenced by Alan Turing's simple yet powerful model of computation, the Turing machine (TM), and by the global workspace theory (GWT) of consciousness originated by cognitive neuroscientist Bernard Baars and further developed by him, Stanislas Dehaene, Jean-Pierre Changeux, George Mashour, and others. Phenomena generally associated with consciousness, such as blindsight, inattentional blindness, change blindness, dream creation, and free will, are considered. Explanations derived from the model draw confirmation from consistencies at a high level, well above the level of neurons, with the cognitive neuroscience literature.

Stories move the heart - literally

Continuing my thread of heart activity realted posts (here, and here), I'll mention that I've enjoyed reading this open access PNAS Science and Culture article by Carolyn Beans on the meaning and usefulness of heart rate fluctuations. Here are the starting paragraphs:

In June 2019, at the University of Birmingham in England, psychologist Damian Cruse invited 27 young adults to come to the lab, on separate occasions, and listen to the same clips from an audiobook of Jules Verne’s 20,000 Leagues Under the Sea. Sitting alone, each donned headphones and electrocardiogram (EKG) equipment while a voice with a British accent recounted tales of a mysterious monster taking down ships. When researchers later compared volunteers’ heart rates, a curious phenomenon emerged: The heart rates of nearly two-thirds of the participants rose and fell together as the story progressed (1).

“It’s not that the beats align synchronously, but rather the heart rate fluctuations go up and down in unison,” explains Lucas Parra, a biomedical engineer at City College of New York, and co-senior author on the study.

Research has already shown that brain activity can synchronize when listeners pay attention to the same video or story (2). Now, Parra and others are finding that the heart, too, offers insight into who is really paying attention to a story. Potential applications are myriad. With heart rate recordings from smart watches, a webinar host may one day learn whether the audience is engaged, or a doctor could offer a family insight into whether a loved one will recover consciousness.

But the technology is new and researchers are still grappling with how to harness heart rate data responsibly, even as they continue to explore why stories move hearts in synchrony in the first place.

I am not my problem

An explanation of the strange title of this post: Sometimes a new idea spontaneously appears from nowhere as I am waking in the morning. The title of this post - the (apparently nonsensical) sentence "I am not my problem” - is the latest example. The sentence can to be parsed to indicate in this instance that the "I" is referring to the illusory narrative self that our social brains have been designed by evolution to generate, and the "my" refers to our intuition or sensing of the vastly complex underlying interacting body systems (respiratory, circulatory, neuronal, muscular, endocrine, sensory, etc.) from which this veneer of a self rises. The brain is mainly not for thinking. It appears that several styles of meditation practice can expand our awareness of this fundamental generative layer. The "am not my problem" tries to make the point that distinguishing these systems can prove useful in trying to determine the origins of particular feelings or behaviors. 

As I’m writing these words I begin to realize that my “novel” waking insight isn’t so novel, but more an elaboration or restatement of my post of Friday, March 13, 2020, on “the relief of not being yourself,” which described another spontaneous rising of ideas associated with the transition between sleep and wakefulness. I repeat that text here:

What a relief to know that this is not me, it is just the contents of my consciousness, which shift around all the time and are never the same twice. What has changed, after 45 years of doing an introspective personal journal, is that this sentence has become clear and true for me. It is a prying loose from the illusion of the sensing and executive “I”, self, the homunculus inside.

There is a particular feeling of renewal, starting over, in the first moments of the transition to seeing - rather than immersed in being - one of the contents of consciousness. Meditation practice can be seen as training the ability to inhabit this state for longer periods of time, to experience the self or I as co-equal with other contents of consciousness like seeing, hearing, feeling. It is having thoughts without a thinker, having a self without a self.

What is inside is the animal mirror of expanded consciousness, no longer locked into one or another of its contractions. This feels to me like a potentially irreversible quantum bump, a phase or state change in my ongoing awareness (perhaps a long term increase in my brain’s attentional mode activity alongside a decrease its default mode’s mind wandering?...also frontal suppression of amygdalar reactivity?)

Beginnings

The title of this post is the title of one of the mini-essays in a piece on my website, written 20 years ago, called "MINDSTUFF: BONBONS FOR THE CURIOUS USER." I re-discovered it while working on a lecture I'm giving this fall, and find the writing much more engaging than what I am currently generating!

 

BEGINNINGS

We are forever barred from recalling the buzzing cacophony that greeted our entry into this world. Our remembering brains had not formed, they had not begun to construct a world for themselves outside the womb. And yet, they had a very ancient kind of knowledge formed over millions of years. They knew to look for a face, they knew to direct muscles of the mouth to draw milk from a mother's breast. From a very rudimentary beginning repertoire they began fashioning a network of sensing and acting to finally generate the extraordinary machines that can read a page like this one.

In both the womb and with the growing baby, the story is a record of sensuality, of kinesthetic, visual, auditory, tasting and smelling histories that form themselves into a predictable order. A sense of past and of anticipation of the predictable future form a base non verbal imaged story line on which the layers of human language begin to build themselves. A smooth continuity informs the transformation of communication from gestures and simple sounds to strings of words with subjects, objects and verbs that form into stories about why, what, how, where. This transformation does not occur in feral children raised by surrogate animal parents, they appear to remain locked in the more present centered mental space of animals - a space that gives no flicker of reflectivity. The requirement is for not only our distinctively human genes but also a cultural context of human communication through gesture and language kept alive, altered, and transmitted by successive generations. We are tools of our our tools.

The programming of our brain regions central to social interactions is just as biological as the workings of a liver or kidney. It involves involuntary linkages of our primitive mammalian or limbic brain and its neuroendocrinology to status, sex, affiliation, power - mechanisms whose fundamental aspects we share with prairie voles and cichlid fish. Unique to humans is the self conscious confabulator or self-constructor that provides a new level of nudging, specification, control over these processes. It is this confabulator that generates what we take to be the world, what we take to be social sources of validation. All are in fact internal self creations that are assayed by their utility.

Heart rate variability as a marker of stress and health - measurements with the 'magic ring'

This post is a follow-up to the previous post on brain-heart interplay in emotional arousal, and points to Thayer et al.'s meta-analysis of heart rate variability (HRV) and neuroimaging studies to evaluate HRV as a marker of stress and health. I'm curious about the practical usefulness of the heart rate (HR) and heart rate variability (HRV) measurements that have been reported by the Oura Ring bio-monitor I purchased over six months ago, and has been measuring my sleep, heart rate, activity, and body temperature (I call it the 'magic ring'). I'm finding an allmost complete correlation between the ring's HRV overnight measurements and my subjective sense of robustness and health on waking in the mornings. HRV is lower after a previous day of physical, social, (or gastronomic!) stress, and higher after a day of rest and relaxation. Here I pass on just one clip from the text:

Resting HRV, in our view, is a marker for flexible dynamic regulation of autonomic activity; thus, higher HRV signals the availability of context- and goal-based control of emotions. We have investigated the role of HRV in emotional regulation at two different levels of analysis. One level is at the trait or tonic level where individual differences in resting HRV have been associated with differences in emotional regulation. We have shown that individuals with higher levels of resting HRV, compared to those with lower resting levels, produce context appropriate emotional responses as indexed by emotion-modulated startle responses, fear-potentiated startle responses, and phasic heart rate responses in addition to behav- ioral and self-reported emotional responses (Melzig et al., 2009; Ruiz-Padial et al., 2003; Thayer and Brosschot, 2005). In addition, we have recently shown that individuals with low resting HRV show delayed recovery from psychological stressors of cardiovascular, endocrine, and immune responses compared to those with higher levels of resting HRV (Weber et al., 2010). Thus, individuals with higher resting levels of HRV appear more able to produce context appropriate responses including appropriate recovery after the stressor has ended.

And here is the article's abstract:

The intimate connection between the brain and the heart was enunciated by Claude Bernard over 150 years ago. In our neurovisceral integration model we have tried to build on this pioneering work. In the present paper we further elaborate our model and update it with recent results. Specifically, we per- formed a meta-analysis of recent neuroimaging studies on the relationship between heart rate variability and regional cerebral blood flow. We identified a number of regions, including the amygdala and ventro- medial prefrontal cortex, in which significant associations across studies were found. We further propose that the default response to uncertainty is the threat response and may be related to the well known neg- ativity bias. Heart rate variability may provide an index of how strongly ‘top–down’ appraisals, mediated by cortical-subcortical pathways, shape brainstem activity and autonomic responses in the body. If the default response to uncertainty is the threat response, as we propose here, contextual information repre- sented in ‘appraisal’ systems may be necessary to overcome this bias during daily life. Thus, HRV may serve as a proxy for ‘vertical integration’ of the brain mechanisms that guide flexible control over behavior with peripheral physiology, and as such provides an important window into understanding stress and health.

Brain-Heart interplay in emotional arousal - resolving a hundred year old debate

Candia-Rivera et al. do a fascinating piece of work that answers some long-standing issues in the century old debate on the role of the autonomic nervous system in feelings. I will be slowly re-reading this paper a number of times. The introduction provides an excellent review of contrasting theories of what emotions are.

...The debate about the role of the ANS in emotions can be condensed into two views: specificity or causation. The specificity view is related to the James–Lange theory, which states that bodily responses precede emotions’ central processing, meaning that bodily states would be a response to the environment, followed by an interpretation carried out by the CNS that would result in the feeling felt. However, causation theories represent an updated view of the James–Lange theory, suggesting that peripheral changes influence the conscious emotional experience....While more “classical” theories point to emotions as “the functional states of the brain that provide causal explanations of certain complex behaviors—like evading a predator or attacking prey”, other theories suggest how they are constructions of the world, not reactions to it (see MindBlog posts on Lisa Feldman Barretts work). Namely, emotions are internal states constructed on the basis of previous experiences as predictive schemes to react to external stimuli.

Here is a clip from the discussion of their open source paper, followed by the significance and abstract sections at the begninning of the article:

....To the best of our knowledge, major novelties of the current study with respect to prior state of the art are related to 1) the uncovering of the directed functional interplay between central and peripheral neural dynamics during an emotional elicitation, using ad-hoc mathematical models for synchronized EEG and ECG time series; 2) the uncovering of temporal dynamics of cortical and cardiovascular neural control during emotional processing in both ascending, from the heart to the brain, and descending, from the brain to the heart, functional directions; and 3) the experimental support for causation theories of physiological feelings.

In the frame of investigating the visceral origin of emotions, main findings of this study suggest that ascending BHI (brain-heart interplay) coupling initiates emotional processing and is mainly modulated by the subjective experience of emotional arousal. Such a relationship between arousal and ascending BHI may not be related to the attention levels, as controlled with two different neural correlates of attention. The main interactions begin through afferent vagal pathways (HF power) sustaining EEG oscillations, in which the theta band was repeatedly found related to major vagal modulations. In turn, with a later onset, this ascending modulation actually triggers a cascade of cortical neural activations that, in turn, modulate directed neural control onto the heart, namely from-brain-to-heart interplay. Concurrent bidirectional communication between the brain and body occurs throughout the emotional processing at specific timings, reaching a maximum coupling around 15 to 20 s from the elicitation onset, involving both cardiac sympathetic and vagal activity.

From the beginning of the article;  

Significance

We investigate the temporal dynamics of brain and cardiac activities in healthy subjects who underwent an emotional elicitation through videos. We demonstrate that, within the first few seconds, emotional stimuli modulate heartbeat activity, which in turn stimulates an emotion intensity (arousal)–specific cortical response. The emotional processing is then sustained by a bidirectional brain–heart interplay, where the perceived arousal level modulates the amplitude of ascending heart-to-brain neural information flow. These findings may constitute fundamental knowledge linking neurophysiology and psychiatric disorders, including the link between depressive symptoms and cardiovascular disorders.

Abstract

A century-long debate on bodily states and emotions persists. While the involvement of bodily activity in emotion physiology is widely recognized, the specificity and causal role of such activity related to brain dynamics has not yet been demonstrated. We hypothesize that the peripheral neural control on cardiovascular activity prompts and sustains brain dynamics during an emotional experience, so these afferent inputs are processed by the brain by triggering a concurrent efferent information transfer to the body. To this end, we investigated the functional brain–heart interplay under emotion elicitation in publicly available data from 62 healthy subjects using a computational model based on synthetic data generation of electroencephalography and electrocardiography signals. Our findings show that sympathovagal activity plays a leading and causal role in initiating the emotional response, in which ascending modulations from vagal activity precede neural dynamics and correlate to the reported level of arousal. The subsequent dynamic interplay observed between the central and autonomic nervous systems sustains the processing of emotional arousal. These findings should be particularly revealing for the psychophysiology and neuroscience of emotions.

Experiential appreciation as a pathway to meaning in life

I have resumed cruising journals' tables of contents after a lapse due to shifting my attention elsewhere, and just came across this interesting open source paper in Nature Human Biology. This work resonates with me because I sometimes feel that my experience of listening to and performing music (piano) provides me with more than sufficient "MIL"...here is the abstract from Kim et al.:  

Abstract

A key research program within the meaning in life (MIL) literature aims to identify the key contributors to MIL. The experience of existential mattering, purpose in life and a sense of coherence are currently posited as three primary contributors to MIL. However, it is unclear whether they encompass all information people consider when judging MIL. Based on the ideas of classic and contemporary MIL scholars, the current research examines whether valuing one’s life experiences, or experiential appreciation, constitutes another unique contributor to MIL. Across seven studies, we find support for the idea that experiential appreciation uniquely predicts subjective judgements of MIL, even after accounting for the contribution of mattering, purpose and coherence to these types of evaluations. Overall, these findings support the hypothesis that valuing one’s experiences is uniquely tied to perceptions of meaning. Implications for the incorporation of experiential appreciation as a fundamental antecedent of MIL are discussed.

Why is a moving hand less sensitive to touch than a stationary hand?

Fuehrer et al. do a nice piece showing how our brains' predictive processing can alter our sensory experience:  

Significance

Tactile sensations on a moving hand are perceived weaker than when presented on the same but stationary hand. There is an ongoing debate about whether this weaker perception is based on sensorimotor predictions or is due to a blanket reduction in sensitivity. Here, we show greater suppression of sensations matching predicted sensory feedback. This reinforces the idea of precise estimations of future body sensory states suppressing the predicted sensory feedback. Our results shine light on the mechanisms of human sensorimotor control and are relevant for understanding clinical phenomena related to predictive processes.

Abstract

The ability to sample sensory information with our hands is crucial for smooth and efficient interactions with the world. Despite this important role of touch, tactile sensations on a moving hand are perceived weaker than when presented on the same but stationary hand. This phenomenon of tactile suppression has been explained by predictive mechanisms, such as internal forward models, that estimate future sensory states of the body on the basis of the motor command and suppress the associated predicted sensory feedback. The origins of tactile suppression have sparked a lot of debate, with contemporary accounts claiming that suppression is independent of sensorimotor predictions and is instead due to an unspecific mechanism. Here, we target this debate and provide evidence for specific tactile suppression due to precise sensorimotor predictions. Participants stroked with their finger over textured objects that caused predictable vibrotactile feedback signals on that finger. Shortly before touching the texture, we probed tactile suppression by applying external vibrotactile probes on the moving finger that either matched or mismatched the frequency generated by the stroking movement along the texture. We found stronger suppression of the probes that matched the predicted sensory feedback. These results show that tactile suppression is specifically tuned to the predicted sensory states of a movement.

Mozart and Brahms Piano Trios at an 80th birthday house concert

This post falls in the 'random curious stuff' category mentioned under MindBlog's title. On May 15, one day before my 80th birthday, my piano trio invited friends and family to a Sunday afternoon house concert at the home of our cellist on Cat Mountain in the Northwest Hills of Austin Texas. I have posted the individual movements of the Mozart Piano Trio No. 2 in B flat major, K. 502 and the Brahms Piano Trio No. 1 in B major, Op. 8 on my YouTube channel, as well as in playlists that play through all the movements of each piece. 

To give you a sample, this post passes on the last movements of the two trios. 

The allegretto of the Mozart Trio.

 

The allegro of the Brahms trio. 

Harmonics of the social brain

Interesting work from Mague et al. on the brain-wide network in mice that encodes rewarding social experience: 

Highlights

• Machine learning model discovers and integrates circuits into affective brain network 

• Brain-wide network encodes rewarding social experience of individual mice 

• Causal activation of network sub-circuits selectively induces social behavior 

• Social brain network fails to encode individual behavior in a mouse model of autism

Summary

The architecture whereby activity across many brain regions integrates to encode individual appetitive social behavior remains unknown. Here we measure electrical activity from eight brain regions as mice engage in a social preference assay. We then use machine learning to discover a network that encodes the extent to which individual mice engage another mouse. This network is organized by theta oscillations leading from prelimbic cortex and amygdala that converge on the ventral tegmental area. Network activity is synchronized with cellular firing, and frequency-specific activation of a circuit within this network increases social behavior. Finally, the network generalizes, on a mouse-by-mouse basis, to encode individual differences in social behavior in healthy animals but fails to encode individual behavior in a ‘high confidence’ genetic model of autism. Thus, our findings reveal the architecture whereby the brain integrates distributed activity across timescales to encode an appetitive brain state underlying individual differences in social behavior.

How stress might help reduce dementia and alzheimer’s.

The post today (my 80th birthday) points to experimental results relevant to my interest in not losing my marbles anytime soon. Fauzia points to work by Avezov and collaborators (open source) showing that the accumulation of aggregates of misfolded proteins in the endoplasmic reticulum of brain cells that is associated with dementia and Alzheimer's can be reversed by stressing cells with chemicals or heat, activating molecular chaperones that in turn untangle or remove protein aggregates. How much stress is just enough, but not to much, isn't clear. The abstract of the work:

Protein synthesis is supported by cellular machineries that ensure polypeptides fold to their native conformation, whilst eliminating misfolded, aggregation prone species. Protein aggregation underlies pathologies including neurodegeneration. Aggregates’ formation is antagonised by molecular chaperones, with cytoplasmic machinery resolving insoluble protein aggregates. However, it is unknown whether an analogous disaggregation system exists in the Endoplasmic Reticulum (ER) where ~30% of the proteome is synthesised. Here we show that the ER of a variety of mammalian cell types, including neurons, is endowed with the capability to resolve protein aggregates under stress. Utilising a purpose-developed protein aggregation probing system with a sub-organellar resolution, we observe steady-state aggregate accumulation in the ER. Pharmacological induction of ER stress does not augment aggregates, but rather stimulate their clearance within hours. We show that this dissagregation activity is catalysed by the stress-responsive ER molecular chaperone – BiP. This work reveals a hitherto unknow, non-redundant strand of the proteostasis-restorative ER stress response.

The tabula sapiens consortium - mapping cell types in the human body

It is hard to keep up with the mind boggling advances that pop up in almost every issue of Science Magazine. In a perspective article Liu and Zhang describe the findings of the “Tabula Sapiens Consortium” that has now provided a molecular reference atlas for more than 400 cell types of the human body by measuring the messenger RNA molecules in each of nearly 500,000 cells from 24 tissues and organs. Multiple laboratories used single-cell transcriptomics to measure the messenger RNA molecules in each of nearly 500,000 cells from 24 tissues and organs Here is a single clip summary clip from Liu and Zhang:

...the Tabula Sapiens Consortium discovered that endothelial cells from lung, heart, uterus, liver, pancreas, fat, and muscle exhibit the most distinct transcriptional signatures, suggesting highly specialized functions, whereas endothelial cells from the thymus, vasculature, prostate, and eye resemble one another. The pan-tissue approach led to the discovery of SLC14A1 (solute carrier family 14 member 1) as a marker for heart endothelial cells, likely reflecting specialized metabolism in cardiac blood vessels. Eraslan et al. also found rare cell types, such as neuroendocrine cells in the prostate and enteric neurons in the esophagus. Additionally, the corroborative use of both high-throughput 10X and full-length SMART-seq2 single-cell transcriptome data allowed the quantification of splicing isoform usage at the single-cell level, thereby revealing differential exon usage patterns for genes, including MYL6 (myosin light chain 6) and CD47, in different cell-type compartments.