Eye movements are related to the contents of consciousness in REM (rapid eye movment) sleep

Senzai and Scanziani have recorded head direction cells in the anterior dorsal nucleus of the thalamus in mice during wake and sleep. The direction and amplitude of eye movements encoded the direction and amplitude of the heading of mice in their virtual environment during REM sleep. It was possible to predict the actual heading in the real and virtual world of the mice during wake and REM sleep, respectively, using saccadic eye movements. Their abstract:

Since the discovery of rapid eye movement (REM) sleep, the nature of the eye movements that characterize this sleep phase has remained elusive. Do they reveal gaze shifts in the virtual environment of dreams or simply reflect random brainstem activity? We harnessed the head direction (HD) system of the mouse thalamus, a neuronal population whose activity reports, in awake mice, their actual HD as they explore their environment and, in sleeping mice, their virtual HD. We discovered that the direction and amplitude of rapid eye movements during REM sleep reveal the direction and amplitude of the ongoing changes in virtual HD. Thus, rapid eye movements disclose gaze shifts in the virtual world of REM sleep, thereby providing a window into the cognitive processes of the sleeping brain.

Is History History?

I recommend that you read Bret Stephens fascinating NYTimes piece. Some clips:

The End of History was supposed to have happened back in 1989, the year the Berlin Wall fell and Francis Fukuyama announced the conclusive triumph of liberal democracy. We know how that thesis worked out. But what happens when the other kind of History — academic, not Hegelian — starts to collapse?...That’s a question that James H. Sweet, a professor of history at the University of Wisconsin, Madison, and the president of the American Historical Association, tried to raise earlier this month in a column titled “Is History History?” for the organization’s newsmagazine. It didn’t go well...Sweet’s core concern in the piece was the “trend toward presentism” — the habit of weighing the past against the social concerns and moral categories of the present.

Sweet was immediately attacked by the cancel culture of left-wing academics and felt obliged to issue an apology. Stevens notes that

...the larger shame is that Sweet had important things to say in his thoughtful column — things that the reaction to the column (and the reaction to the reaction) now risk burying...Between 2003 and 2013, a dwindling number of history Ph.D.s, he noted, were going to students doing work on topics preceding 1800. At the same time, historians were producing works that “collapse into the familiar terms of contemporary debates,” particularly those connected to identity politics.....“This new history,” he wrote, “often ignores the values and mores of people in their own times, as well as change over time, neutralizing the expertise that separates historians from those in other disciplines.”

...Sweet was warning that historians risked doing an injustice both to their own profession as well as to the past itself by falling victim to “the allure of political relevance.” His main example came from a recent visit to the Elmina Castle in Ghana..which has become a kind of shrine for African Americans seeking a place to memorialize enslaved ancestors...Sweet says as a historian of Africa, “less than 1 percent of the Africans passing through Elmina arrived in North America” — most...ended up in Brazil or the Caribbean. And those who were enslaved were often first brought to Elmina by other African brokers who promoted the slave trade just as cruelly and greedily as the Europeans with whom they did business.

That does nothing to diminish the evil of the trade, much less its relevance to America’s past and present...But it helps put it into a global context in which the roles of victim and victimizer seldom fall neatly along a color line. If that challenges current orthodoxy, it’s only because that orthodoxy is based on a simplistic understanding of history. The proper role of the historian is to complexify, not simplify; to show us historical figures in the context of their time, not reduce them to figurines that can be weaponized in our contemporary debates.

Above all, historians should make us understand the ways in which the past was distinct. This shouldn’t prevent us from making moral judgments about it. But we can make better judgments, informed by the knowledge that our forebears rarely acted with the benefit (or burden) of our assumptions, expectations, experiences and values. There’s a lesson in humility in that, as well as a reminder that we are only actors in time whose most cherished ideas may eventually seem strange, and sometimes abhorrent, to our descendants.

Sweet's column...

— which bent over backward to showcase his liberal bona fides — ignited the usual progressive furies. Anyone looking for further confirmation that modern academia has become a fundamentally ideological and coercive exercise masquerading as a scholarly and collegial one need have looked no further. It will be interesting to see if Sweet manages to hold on to his post as the American Historical Association’s president...If people are wondering how history ends, maybe this is how: when a scholarly discipline tries to turn itself into something it isn’t, making itself increasingly irrelevant in its desperate bid for relevancy.

Animals (including us) conjure model-based structures from random events

Superstitious learning is usually thought to be accounted for by conditioned association, but Jin et al. now show that monkeys can develop more complex cognitive structures independent of reinforcement:  

Significance

Past studies on learning and decision-making usually rely on the assumption that the task is learnable. However, humans and other animals often infer spurious relationships from coincidental associations, and it is unknown if this could be achieved without reward conditioning. Here, we exposed monkeys to sets of images that had a hidden hierarchical order and to unordered sets that lacked an underlying structure. Monkeys treated the unordered sets as if they had a hierarchical order even under reward schedules that incentivized random choices. The results cannot be explained by simple associative mechanisms that account for other types of spurious learning, suggesting that when presented with random events animals conjure elaborate model-based structures.

Abstract

Humans and other animals often infer spurious associations among unrelated events. However, such superstitious learning is usually accounted for by conditioned associations, raising the question of whether an animal could develop more complex cognitive structures independent of reinforcement. Here, we tasked monkeys with discovering the serial order of two pictorial sets: a “learnable” set in which the stimuli were implicitly ordered and monkeys were rewarded for choosing the higher-rank stimulus and an “unlearnable” set in which stimuli were unordered and feedback was random regardless of the choice. We replicated prior results that monkeys reliably learned the implicit order of the learnable set. Surprisingly, the monkeys behaved as though some ordering also existed in the unlearnable set, showing consistent choice preference that transferred to novel untrained pairs in this set, even under a preference-discouraging reward schedule that gave rewards more frequently to the stimulus that was selected less often. In simulations, a model-free reinforcement learning algorithm (Q-learning) displayed a degree of consistent ordering among the unlearnable set but, unlike the monkeys, failed to do so under the preference-discouraging reward schedule. Our results suggest that monkeys infer abstract structures from objectively random events using heuristics that extend beyond stimulus–outcome conditional learning to more cognitive model-based learning mechanisms.

Increasingly good artificial intelligence (A.I.) is offering us promise and peril.

I want to pass on a few items from my list of putative MindBlog posts on A.I. 

The first derives from an series of emails on A.I. sent to the listserve of the "Chaos and Complex Systems Discussion Group" at Univ. of Wisconsin, Madison, that I attended until my move to Austin Tx. They point to the kerfuffle started by suspended Google engineer Blake Lemoine over whether one of the company's experimental AIs called LaMDA had achieved sentience, and How belief in AI sentience is becoming a problem.

(By the way, If you want to set up your own chatbot for self therapy, that won't collect and sell personal info you may divulge to it, visit https://replika.com/.... I actually tried it out, was underwhelmed by its responses, so deleted my account.)

An article by Kevin Roose on the potentials and risks of A.I. is worth reading.  One amazing feat of A.I. has been solving the "protein-folding problem," which I (as a trained biochemist) have been following for over 50 years.

This summer, DeepMind announced that AlphaFold (an A.I. system descended from the Go-playing one) had made predictions of the three-dimensional structures of proteins from their one-dimensional amino acid sequences for nearly all of the 200 million proteins known to exist — producing a treasure trove of data that will help medical researchers develop new drugs and vaccines for years to come. Last year, the journal Science recognized AlphaFold’s importance, naming it the biggest scientific breakthrough of the year.

Here are a few further clips:

Even if the skeptics are right, and A.I. doesn’t achieve human-level sentience for many years, it’s easy to see how systems like GPT-3, LaMDA (language models) and DALL-E 2 (generating images from language descriptions) could become a powerful force in society. In a few years, the vast majority of the photos, videos and text we encounter on the internet could be A.I.-generated. Our online interactions could become stranger and more fraught, as we struggle to figure out which of our conversational partners are human and which are convincing bots. And tech-savvy propagandists could use the technology to churn out targeted misinformation on a vast scale, distorting the political process in ways we won’t see coming.

Ajeya Cotra, a senior analyst with Open Philanthropy who studies A.I. risk, estimated two years ago that there was a 15 percent chance of “transformational A.I.” — which she and others have defined as A.I. that is good enough to usher in large-scale economic and societal changes, such as eliminating most white-collar knowledge jobs — emerging by 2036...But in a recent post, Ms. Cotra raised that to a 35 percent chance, citing the rapid improvement of systems like GPT-3.

Because of how new many of these A.I. systems are, few public officials have any firsthand experience with tools like GPT-3 or DALL-E 2, nor do they grasp how quickly progress is happening at the A.I. frontier...we could end up with a repeat of what happened with social media companies after the 2016 election — a collision of Silicon Valley power and Washington ignorance, which resulted in nothing but gridlock and testy hearings...big tech companies investing billions in A.I. development — the Googles, Metas and OpenAIs of the world — need to do a better job of explaining what they’re working on, without sugarcoating or soft-pedaling the risks.

Does crypto-world really give us trustworthyness without gate keepers...? The answer is NO - It hides a new elite.

I try in the title of this post to summarize the basic conclusions of a fascinating NYTimes article by Siobhan Roberts. The article emphasizes the work of Alyussa Blackburn and others that has shown that Bitcoin activity, apart from using exorbitant amounts of electricity in generating its bitcoin token currency, has not in fact produced anonymous transactions, and its user community in fact contains a small elite group that actually wears the crown of being the arbiters of the network. (A more recent article by Yaffe-Bellany points out that Ethereum, the other major crypto platform, has a similar elite.... posing the same issues as the banks and internet companies that are self-interested gate keepers in the current financial world.)

“...Blackburn developed hacks for the period of time that was of particular interest: from the cryptocurrency’s start to when Bitcoin achieved parity with the U.S. dollar in February 2011, which coincided with the establishment of the Silk Road, a Bitcoin-based black market...Drip-by-drip, information leakage erodes the once-impenetrable blocks, carving out a new landscape of socioeconomic data,” Ms. Blackburn and her collaborators report in their new paper...Aggregating multiple leakages, Ms. Blackburn consolidated many Bitcoin addresses, which might have seemed to represent many miners, into few. She pieced together a catalog of agents and concluded that, in those first two years, 64 key players — some of whom were the community’s “founders,” as the researchers called them — mined most of the Bitcoin that existed at the time.

Although the analysis showed that the big players numbered 64 over two years, at any given moment, according to the researchers’ modeling, the effective size of that population was only five or six. And on many occasions, just one or two people held most of the mining power...As Ms. Blackburn described it, there were very few people “wearing the crown,” functioning as arbiters of the network — “which is not the ethos of decentralized trustless crypto,”...

Once Ms. Blackburn had assembled the catalog of agents, she analyzed the income they had reaped from mining. She found that within a few months of the cryptocurrency’s introduction — and contrary to Bitcoin’s egalitarian promise — a classic distribution of income inequality emerged: A small fraction of the miners held most of the wealth and power. (Mining income demonstrated what is called a Pareto distribution, after Vilfredo Pareto, a 19th-century economist.)

On several occasions, individual miners wielded more than 50 percent of the computational power and, as a result, could have taken over like a tyrant using what’s called a “51 percent attack.” For instance, they could have cheated the system and repeatedly spent the same Bitcoins on different transactions...to add a twist, Ms. Blackburn found that while some miners had the power to execute 51 percent attacks, they repeatedly chose not to. Rather, they acted altruistically — preserving the cryptocurrency’s integrity, even though the decentralization-based fraud-prevention mechanism had been compromised...Although Bitcoin was designed to rely on a decentralized, trustless network of anonymous agents, its early success rested instead on cooperation among a small group of altruistic founders.

For Glen Weyl, an economist at Microsoft Research who was consulted on the research, this finding demonstrates how decentralization played a rhetorical rather than substantive role. “And that rhetorical role was very powerful — it bound together this community, much as other myths have bound together other communities, like nations,” Dr. Weyl said; he and Mr. Lanier wrote about this research for CoinDesk. But the myth and the promise, he said, were in tension with the reality that emerged. “It’s just fascinatingly ironic, and also predictable, repeating the historical patterns it aspires to erase.”

Mr. Lanier called it “decentralization theater.” Cryptocurrencies create an illusion: “‘Now we’re in utopia. Everything’s decentralized. Everybody’s equal.’ There’s this notion of democracy without annoyance.”...But, he said, these systems end up hiding a new elite, which is probably just an old elite in a new arena. And the technology cuts both ways. “Whatever you think you can achieve using new algorithms, or big data, or whatever, can also be used against you,” Mr. Lanier said. “The same algorithms can be used by scientists to interrogate and investigate these castles that are put up by the new elite.”

One moral of the story, Ms. Blackburn said, is simply: “You have to be careful.” There is a limited timeline for encryption, “a horizon beyond which it will no longer be useful. When you are encrypting private data and making it public, you cannot assume that it’ll be private forever.”

The medium really is the message

I recommend that you read a recent Op-Ed piece by Ezra Klein that notes 20th-century media theorists who saw what was coming and tried to warn us. He quotes from Nicholas Carr’s 2010 book “The Shallows: What the Internet Is Doing to Our Brains.”:

Carr’s argument began with an observation, one that felt familiar:

The very way my brain worked seemed to be changing. It was then that I began worrying about my inability to pay attention to one thing for more than a couple of minutes. At first I’d figured that the problem was a symptom of middle-age mind rot. But my brain, I realized, wasn’t just drifting. It was hungry. It was demanding to be fed the way the Net fed it — and the more it was fed, the hungrier it became. Even when I was away from my computer, I yearned to check email, click links, do some Googling. I wanted to be connected.

McLuhan’s view is that mediums matter more than content; it’s the common rules that govern all creation and consumption across a medium that change people and society. Oral culture teaches us to think one way, written culture another. Television turned everything into entertainment, and social media taught us to think with the crowd...All this happens beneath the level of content. CNN and Fox News and MSNBC are ideologically different. But cable news in all its forms carries a sameness: the look of the anchors, the gloss of the graphics, the aesthetics of urgency and threat, the speed, the immediacy, the conflict, the conflict, the conflict.

Klein's (edited) comments on Postman's prophetic 1985 book "Amusing Ourselves to Death":

...the dystopia we must fear is not the totalitarianism of George Orwell’s “1984” but the narcotized somnolence of Aldous Huxley’s “Brave New World.” Television teaches us to expect that anything and everything should be entertaining. But not everything should be entertainment, and the expectation that it will be is a vast social and even ideological change...The border between entertainment and everything else has, and entertainers become the only ones able to fulfill our expectations for politicians....People who were viable politicians in a textual era are locked out of politics because they can not command the screen...Television, he writes, “serves us most ill when it co-opts serious modes of discourse — news, politics, science, education, commerce, religion — and turns them into entertainment packages...the line of Postman’s that holds me is his challenge to the critics who spend their time urging television to be better rather than asking what television is: “The trouble with such people is that they do not take television seriously enough.”

Klein continues:

I have come to think the same of today’s technologists: Their problem is that they do not take technology seriously enough. They refuse to see how it is changing us or even how it is changing them...Over the past decade, the narrative has turned against Silicon Valley. Puff pieces have become hit jobs, and the visionaries inventing our future have been recast as the Machiavellians undermining our present. My frustration with these narratives, both then and now, is that they focus on people and companies, not technologies. I suspect that is because American culture remains deeply uncomfortable with technological critique.

Americans are capitalists, and we believe nothing if not that if a choice is freely made, that grants it a presumption against critique. That is one reason it’s so hard to talk about how we are changed by the mediums we use. That conversation, on some level, demands value judgments. This was on my mind recently, when I heard Jonathan Haidt, a social psychologist who’s been collecting data on how social media harms teenagers, say, bluntly, “People talk about how to tweak it — oh, let’s hide the like counters. Well, Instagram tried — but let me say this very clearly: There is no way, no tweak, no architectural change that will make it OK for teenage girls to post photos of themselves, while they’re going through puberty, for strangers or others to rate publicly.”

What struck me about Haidt’s comment is how rarely I hear anything structured that way. He’s arguing three things. First, that the way Instagram works is changing how teenagers think. It is supercharging their need for approval of how they look and what they say and what they’re doing, making it both always available and never enough. Second, that it is the fault of the platform — that it is intrinsic to how Instagram is designed, not just to how it is used. And third, that it’s bad. That even if many people use it and enjoy it and make it through the gantlet just fine, it’s still bad. It is a mold we should not want our children to pass through.

Or take Twitter. As a medium, Twitter nudges its users toward ideas that can survive without context, that can travel legibly in under 280 characters. It encourages a constant awareness of what everyone else is discussing. It makes the measure of conversational success not just how others react and respond but how much response there is. It, too, is a mold, and it has acted with particular force on some of our most powerful industries — media and politics and technology. These are industries I know well, and I do not think it has changed them or the people in them (including me) for the better.

But what would? I’ve found myself going back to a wise, indescribable book that Jenny Odell, a visual artist, published in 2019, “How to Do Nothing: Resisting the Attention Economy.” In it she suggests that any theory of media must start with a theory of attention. “One thing I have learned about attention is that certain forms of it are contagious,” she writes. She continues:

When you spend enough time with someone who pays close attention to something (if you were hanging out with me, it would be birds), you inevitably start to pay attention to some of the same things. I’ve also learned that patterns of attention — what we choose to notice and what we do not — are how we render reality for ourselves, and thus have a direct bearing on what we feel is possible at any given time. These aspects, taken together, suggest to me the revolutionary potential of taking back our attention.

I think Odell frames both the question and the stakes correctly. Attention is contagious. What forms of it, as individuals and as a society, do we want to cultivate? What kinds of mediums would that cultivation require?

This is anything but an argument against technology, were such a thing even coherent. It’s an argument for taking technology as seriously as it deserves to be taken, for recognizing, as McLuhan’s friend and colleague John M. Culkin put it, “we shape our tools, and thereafter, they shape us.”

There is an optimism in that, a reminder of our own agency. And there are questions posed, ones we should spend much more time and energy trying to answer: How do we want to be shaped? Who do we want to become?

Our anterior insula signals salience and deviations from expectations via bursts of beta oscillations

Haufler et al. show that the insula signals salience and prediction errors via amplitude modulations of beta bursts (~15-40 Hertz, or cycles per second), which coincide with the near simultaneous recruitment of vast cortical territories. 

NEW & NOTEWORTHY

Functional imaging studies indicate that the anterior insula encodes salience and deviations from expectations. Beyond changing BOLD signals, however, the physiological underpinnings of these signals are unknown. By recording local field potentials in patients with epilepsy, we found that the anterior insula generates large bursts of beta oscillations whose amplitude is modulated by the salience of outcomes and deviations from expectations. Moreover, insular beta bursts coincide with the activation of many high-order cortical areas.

ABSTRACT:

Functional imaging studies indicate that the insula encodes the salience of stimuli and deviations from expectations, signals that can mobilize cognitive resources and facilitate learning. However, there is no information about the physiological underpinnings of these phenomena beyond changing BOLD signals. To shed light on this question, we analyzed intracerebral local field potentials (LFPs) in five patients with epilepsy of both genders performing a virtual reality task that featured varying odds of monetary rewards and losses. Upon outcome disclosure, the anterior (but not the posterior) insula generated bursts of beta oscillations whose amplitudes were lower for neutral than positive and negative outcomes, consistent with a salience signal. Moreover, beta burst power was higher when outcomes deviated from expectations, whether the outcome was better or worse than expected, indicating that the insula provides an unsigned prediction error signal. Last, in relation to insular beta bursts, many higher-order cortical areas exhibited robust changes in LFP activity that ranged from spectrally nonspecific or differentiated increases in gamma power to bursts of beta activity that closely resembled the insular beta bursts themselves. Critically, the activity of these other cortical regions was more closely tied in time to insular bursts than task events, suggesting that they are associated with particularly significant cognitive phenomena. Overall, our findings suggest that the insula signals salience and prediction errors via amplitude modulations of beta bursts, which coincide with the near simultaneous recruitment of vast cortical territories.

The brain chemistry underlying mental exhaustion.

Emily Underwood does a review of work by Wiehler et al. (open source) on the brain chemistry underlying mental fatigue, also describing several reservations expressed by other researchers. From her description:

The researchers divided 39 paid study participants into two groups, assigning one to a series of difficult cognitive tasks that were designed to induce mental exhaustion. In one, participants had to decide whether letters and numbers flashing on a computer screen in quick succession were green or red, uppercase or lowercase, and other variations. In another, volunteers had to remember whether a number matched one they’d seen three characters earlier...As the day dragged on, the researchers repeatedly measured cognitive fatigue by asking participants to make choices that required self-control—deciding to forgo cash that was immediately available so they could earn a larger amount later, for example. The group that had been assigned to more difficult tasks made about 10% more impulsive choices than the group with easier tasks, the researchers observed. At the same time, their glutamate levels rose by about 8% in the lateral prefrontal cortex—a pattern that did not show up in the other group...

Here is the Wiehler et al. abstract:  

Highlights

• Cognitive fatigue is explored with magnetic resonance spectroscopy during a workday 

• Hard cognitive work leads to glutamate accumulation in the lateral prefrontal cortex 

• The need for glutamate regulation reduces the control exerted over decision-making 

• Reduced control favors the choice of low-effort actions with short-term rewards

Summary

Behavioral activities that require control over automatic routines typically feel effortful and result in cognitive fatigue. Beyond subjective report, cognitive fatigue has been conceived as an inflated cost of cognitive control, objectified by more impulsive decisions. However, the origins of such control cost inflation with cognitive work are heavily debated. Here, we suggest a neuro-metabolic account: the cost would relate to the necessity of recycling potentially toxic substances accumulated during cognitive control exertion. We validated this account using magnetic resonance spectroscopy (MRS) to monitor brain metabolites throughout an approximate workday, during which two groups of participants performed either high-demand or low-demand cognitive control tasks, interleaved with economic decisions. Choice-related fatigue markers were only present in the high-demand group, with a reduction of pupil dilation during decision-making and a preference shift toward short-delay and little-effort options (a low-cost bias captured using computational modeling). At the end of the day, high-demand cognitive work resulted in higher glutamate concentration and glutamate/glutamine diffusion in a cognitive control brain region (lateral prefrontal cortex [lPFC]), relative to low-demand cognitive work and to a reference brain region (primary visual cortex [V1]). Taken together with previous fMRI data, these results support a neuro-metabolic model in which glutamate accumulation triggers a regulation mechanism that makes lPFC activation more costly, explaining why cognitive control is harder to mobilize after a strenuous workday.

Even novices intuit complex music theory,

Bridget Alex does a nice summary of work by Weis and Peretz showing that people without musical training naturally improvise melodies that have hallmarks of tunes composed by professionals. Most individuals follow the arcane rules of music composition, even those who are unaware those rules exist. Here is the research article abstract:

Humans spontaneously invent songs from an early age. Here, we exploit this natural inclination to probe implicit musical knowledge in 33 untrained and poor singers (amusia). Each sang 28 long improvisations as a response to a verbal prompt or a continuation of a melodic stem. To assess the extent to which each improvisation reflects tonality, which has been proposed to be a core organizational principle of musicality and which is present within most music traditions, we developed a new algorithm that compares a sung excerpt to a probability density function representing the tonal hierarchy of Western music. The results show signatures of tonality in both nonmusicians and individuals with congenital amusia, who have notorious difficulty performing musical tasks that require explicit responses and memory. The findings are a proof of concept that improvisation can serve as a novel, even enjoyable method for systematically measuring hidden aspects of musicality across the spectrum of musical ability.

Reproducability crisis in machine learning systems that inform immediate or future actions

I have by now accumulated a list of articles on a growing debate over naive scientists, especially social scientists, botching their research by using machine learning techniques they don't understand. They can't 'show their work' or provide enough information for others to reproduce their results. This article by Harrison is a short and succinct summary that includes links to other publications, and you should check out the article by Gibney in Nature Magazine.

Alcohol, neuronal plasticity, and mitochondrial trafficking

Hernandez and Kaun provide a nice description of work by Knabbe et al. with summary graphics. Here is the start of their text:

Consumption of alcohol creates a sense of euphoria, reduces inhibition, and increases sociability and impulsivity. The age at which alcohol is first experienced is a key factor contributing to the likelihood to misuse alcohol. However, the impacts of the first experience of alcohol on the molecules in the brain at these key developmental stages are not well understood. Knabbe et al. endeavored to address the neuromolecular alterations resulting from acute alcohol by combining hippocampal proteomics with somatosensory and motor cortex protein, dendrite, axon, and mitochondrial analysis in adolescent mice. Evidence from this array of preparations led to the hypothesis that alcohol disrupted mitochondrial trafficking, and using Drosophila they demonstrated a functional role for mitochondrial trafficking in cue-induced alcohol preference.

The cross-assay and cross-species approach outlined in Knabbe et al. proved to be an effective way of discovering how alcohol hijacks brain mechanisms. Animals from flies to humans maintain functionally consistent neurotransmitter systems, neural circuit mechanisms, and molecular pathways underlying reward.

And here is the abstract from Knabbe et al.:

Alcohol intoxication at early ages is a risk factor for the development of addictive behavior. To uncover neuronal molecular correlates of acute ethanol intoxication, we used stable-isotope-labeled mice combined with quantitative mass spectrometry to screen more than 2,000 hippocampal proteins, of which 72 changed synaptic abundance up to twofold after ethanol exposure. Among those were mitochondrial proteins and proteins important for neuronal morphology, including MAP6 and ankyrin-G. Based on these candidate proteins, we found acute and lasting molecular, cellular, and behavioral changes following a single intoxication in alcohol-naïve mice. Immunofluorescence analysis revealed a shortening of axon initial segments. Longitudinal two-photon in vivo imaging showed increased synaptic dynamics and mitochondrial trafficking in axons. Knockdown of mitochondrial trafficking in dopaminergic neurons abolished conditioned alcohol preference in Drosophila flies. This study introduces mitochondrial trafficking as a process implicated in reward learning and highlights the potential of high-resolution proteomics to identify cellular mechanisms relevant for addictive behavior.

A systematic review of microdosing - research on low dose psychedelics

I pass on the link to this review by Polito and Liknaitzky. Their abstract:

The use of low doses of psychedelic substances (microdosing) is attracting increasing interest. This systematic review summarises all empirical microdosing research to date, including a set of infrequently cited studies that took place prior to prohibition. Specifically, we reviewed 44 studies published between 1955 and 2021, and summarised reported effects across six categories: mood and mental health; wellbeing and attitude; cognition and creativity; personality; changes in conscious state; and neurobiology and physiology. Studies showed a wide range in risk of bias, depending on design, age, and other study characteristics. Laboratory studies found changes in pain perception, time perception, conscious state, and neurophysiology. Self-report studies found changes in cognitive processing and mental health. We review data related to expectation and placebo effects, but argue that claims that microdosing effects are largely due to expectancy are premature and possibly wrong. In addition, we attempt to clarify definitional inconsistencies in the microdosing literature by providing suggested dose ranges across different substances. Finally, we provide specific design suggestions to facilitate more rigorous future research.

Music training enhances auditory and linguistic processing.

From Neves et al.:  

Highlights

• Systematic review and meta-analysis of neurobehavioral effects of music training. 

• We ask whether music training shapes auditory-perceptual and linguistic skills. 

• Multivariate meta-analytic models are combined with narrative synthesis. 

• Music training has a positive effect on auditory and linguistic processing. 

• Our work informs research on plasticity, transfer, and music-based interventions.

Abstract

It is often claimed that music training improves auditory and linguistic skills. Results of individual studies are mixed, however, and most evidence is correlational, precluding inferences of causation. Here, we evaluated data from 62 longitudinal studies that examined whether music training programs affect behavioral and brain measures of auditory and linguistic processing (N = 3928). For the behavioral data, a multivariate meta-analysis revealed a small positive effect of music training on both auditory and linguistic measures, regardless of the type of assignment (random vs. non-random), training (instrumental vs. non-instrumental), and control group (active vs. passive). The trim-and-fill method provided suggestive evidence of publication bias, but meta-regression methods (PET-PEESE) did not. For the brain data, a narrative synthesis also documented benefits of music training, namely for measures of auditory processing and for measures of speech and prosody processing. Thus, the available literature provides evidence that music training produces small neurobehavioral enhancements in auditory and linguistic processing, although future studies are needed to confirm that such enhancements are not due to publication bias.

Old hearts learn new tricks

Nusinovich's summary in Science Magazine of work by Lerchenmüller et al.:

Aging-related diseases such as heart failure and other cardiovascular disorders are the leading causes of death in many countries, and they are becoming increasingly common worldwide as the number of older people increases. The ability of the heart to produce new cardiomyocytes decreases with age, which makes it more difficult to repair damage and increases the risk of heart failure. However, a study by Lerchenmüller et al. suggests that exercise may offer some help in this regard even if started late in life. The authors had previously reported that voluntary exercise can stimulate the generation of cardiomyocytes in young adult mouse hearts, and now they have also observed this phenomenon in aged animals.

Here is the results statement of the article:

Cardiomyogenesis was observed at a significantly higher frequency in exercised compared with sedentary aged hearts on the basis of the detection of mononucleated/diploid 15N-thymidine–labeled cardiomyocytes. No mononucleated/diploid 15N-thymidine–labeled cardiomyocyte was detected in sedentary aged mice. The annual rate of mononucleated/diploid 15N-thymidine–labeled cardiomyocytes in aged exercised mice was 2.3% per year. This compares with our previously reported annual rate of 7.5% in young exercised mice and 1.63% in young sedentary mice. Transcriptional profiling of young and aged exercised murine hearts and their sedentary controls revealed that exercise induces pathways related to circadian rhythm, irrespective of age. One known oscillating transcript, however, that was exclusively upregulated in aged exercised hearts, was isoform 1.4 of regulator of calcineurin, whose regulation and functional role were explored further.

Dissecting and improving motor skill acquisition in older adults

 From the introduction of Elvira et al. (open source):

We designed a study intended to identify (i) the main factors leading to differences in motor skill acquisition with aging and (ii) the effect of applying noninvasive brain stimulation during motor training. Comparing different components of motor skill acquisition in young and older adults, constituting the extremes of performance in this study, we found that the improvement of the sequence-tapping task is maximized by the early consolidation of the spatial properties of the sequence in memory (i.e., sequence order), leading to a reduced error of execution, and by the optimization of its temporal features (i.e., chunking). We found the consolidation of spatiotemporal features to occur early in training in young adults, suggesting the emergence of motor chunks to be a direct consequence of committing the sequence elements to memory. This process, seemingly less efficient in older adults, could be partially restored using atDCS by enabling the early consolidation of spatial features, allowing them to prioritize the increase of their speed of execution, ultimately leading to an earlier consolidation of motor chunks. This separate consolidation of spatial and temporal features seen in older adults suggests that the emergence of temporal patterns, commonly identified as motor chunks at a behavioral level, stem from the optimization of the execution of the motor sequence resulting from practice, which can occur only after the sequence order has been stored in memory.

Here is their abstract:

Practicing a previously unknown motor sequence often leads to the consolidation of motor chunks, which enable its accurate execution at increasing speeds. Recent imaging studies suggest the function of these structures to be more related to the encoding, storage, and retrieval of sequences rather than their sole execution. We found that optimal motor skill acquisition prioritizes the storage of the spatial features of the sequence in memory over its rapid execution early in training, as proposed by Hikosaka in 1999. This process, seemingly diminished in older adults, was partially restored by anodal transcranial direct current stimulation over the motor cortex, as shown by a sharp improvement in accuracy and an earlier yet gradual emergence of motor chunks. These results suggest that the emergence of motor chunks is preceded by the storage of the sequence in memory but is not its direct consequence; rather, these structures depend on, and result from, motor practice.

Motor learning without movement

Fascinating work from Kim et al. on the influence of the prediction errors that are essential in calibrating actions of our predictive minds:

Significance

Our brains control aspects of our movements without conscious awareness, allowing many of us to effortlessly pick up a glass of water or wave hello. Here, we demonstrate that this implicit motor system can learn to refine movements that we plan but ultimately decide not to perform. Participants planned to reach to a target but sometimes withheld these reaches while an animation simulated missing the target. Afterward, participants unknowingly reached opposite the direction of the apparent mistake, indicating that the implicit motor system had learned from the animated error. These findings indicate that movement is not strictly necessary for motor adaptation, and we can learn to update our actions without physically performing them.

Abstract

Prediction errors guide many forms of learning, providing teaching signals that help us improve our performance. Implicit motor adaptation, for instance, is thought to be driven by sensory prediction errors (SPEs), which occur when the expected and observed consequences of a movement differ. Traditionally, SPE computation is thought to require movement execution. However, recent work suggesting that the brain can generate sensory predictions based on motor imagery or planning alone calls this assumption into question. Here, by measuring implicit motor adaptation during a visuomotor task, we tested whether motor planning and well-timed sensory feedback are sufficient for adaptation. Human participants were cued to reach to a target and were, on a subset of trials, rapidly cued to withhold these movements. Errors displayed both on trials with and without movements induced single-trial adaptation. Learning following trials without movements persisted even when movement trials had never been paired with errors and when the direction of movement and sensory feedback trajectories were decoupled. These observations indicate that the brain can compute errors that drive implicit adaptation without generating overt movements, leading to the adaptation of motor commands that are not overtly produced.

Brain changes, or the absence thereof, associated with mindfulness training.

Richard Davidson and his collaborators (open source, with useful graphics) inject a note of sanity into evaluating widely reported claims of brain changes induced by mindfulness meditation techniques. They note in their introduction:

Findings from a few small studies have permeated popular media with the notion that a few weeks of training in mindfulness-based stress reduction (MBSR) can lead to measurable changes in brain structure and have been cited over 3200 times, combined. However, there is a lack of replication (conceptual or direct) or confirmatory analysis of these findings in a fully randomized trial. Moreover, a recent meta-analysis found that the proportion of high-quality publications in this domain have not improved over time, although there are a growing number of high-quality studies being conducted.

Their abstract:

Studies purporting to show changes in brain structure following the popular, 8-week mindfulness-based stress reduction (MBSR) course are widely referenced despite major methodological limitations. Here, we present findings from a large, combined dataset of two, three-arm randomized controlled trials with active and waitlist (WL) control groups. Meditation-naïve participants (n = 218) completed structural magnetic resonance imaging scans during two visits: baseline and postintervention period. After baseline, participants were randomly assigned to WL (n = 70), an 8-week MBSR program (n = 75), or a validated, matched active control (n = 73). We assessed changes in gray matter volume, gray matter density, and cortical thickness. In the largest and most rigorously controlled study to date, we failed to replicate prior findings and found no evidence that MBSR produced neuroplastic changes compared to either control group, either at the whole-brain level or in regions of interest drawn from prior MBSR studies.

Wolf attacks predict far-right voting

Under MindBlog's category of "random curious stuff" I couldn't resist passing on the following bit of quirky political analysis from von Hohenberg and Hager:

Does the return of large carnivores affect voting behavior? We study this question through the lens of wolf attacks on livestock. Sustained environmental conservation has allowed the wolf (Canis lupus) to make an impressive and unforeseen comeback across Central Europe in recent years. While lauded by conservationists, local residents often see the wolf as a threat to economic livelihoods, particularly those of farmers. As populists appear to exploit such sentiments, the wolf’s reemergence is a plausible source for far-right voting behavior. To test this hypothesis, we collect fine-grained spatial data on wolf attacks and construct a municipality-level panel in Germany. Using difference-in-differences models, we find that wolf attacks are accompanied by a significant rise in far-right voting behavior, while the Green party, if anything, suffers electoral losses. We buttress this finding using local-level survey data, which confirms a link between wolf attacks and negative sentiment toward environmental protection. To explore potential mechanisms, we analyze Twitter posts, election manifestos, and Facebook ads to show that far-right politicians frame the wolf as a threat to economic livelihoods.

Emotional contagion and prosocial behavior

Keysers et al. do an open source review of studies on emotional contagion and prosocial behavior in rodents, whose brain regions necessary for emotional contagion closely resemble those associated with human empathy:

Rats and mice show robust emotional contagion by aligning their fear and pain to that of others.

Brain regions necessary for emotional contagion in rodents closely resemble those associated with human empathy; understanding the biology of emotional contagion in rodents can thus shed light on the evolutionary origin and mechanisms of human empathy.

Cingulate area 24 in rats and mice contains emotional mirror neurons that map the emotions of others onto the witnesses’ own emotions.

Emotional contagion prepares animals to deal with threats by using others as sentinels; the fact that rodents approach individuals in distress facilitates such contagion.

In some conditions, rats and mice learn to prefer actions that benefit others, with notable individual differences. This effect depends on structures that overlap with those of emotional contagion.

Efficiently irrational: deciphering the riddle of human choice

Highlights of an open source article from Paul Glimcher:

A central question for decision-making scholars is: why are humans and animals so predictably inconsistent in their choices? In the language of economics, why are they irrational?

Data suggest that this reflects an optimal trade-off between the precision with which the brain represents the values of choices and the biological costs of that precision. Increasing representational precision may improve choice consistency, but the metabolic cost of increased precision is significant.

Given the cost of precision, the brain might use efficient value-encoding mechanisms that maximize informational content. Mathematical analyses suggest that a mechanism called divisive normalization approximates maximal efficiency per action potential in decision systems.

Behavioral studies appear to validate this claim. Inconsistencies produced by decision-makers can be well modeled as the byproduct of efficient divisive normalization mechanisms that maximize information while minimizing metabolic costs.