Structural Whitening

I pass on this summary by Rai of a study by Anicich et al. in J. Exp. Soc. Psychol:

As the US population becomes more racially diverse, it is unclear how ethnic white populations will respond to these demographic changes. Anicich et al. found experimentally that when white Americans were given the opportunity to populate fictional cities, they imposed greater racial segregation in areas that they frequented more often, such as work or school, because they feel greater anxiety around non-whites. In a follow-up study, the authors examined policies at tennis and golf clubs across the United States, and found that in areas with higher racial diversity, clubs engaged in more exclusionary behavior, such as enacting strict dress codes. These findings suggest that as racial diversity increases, white Americans may respond by trying to structure their environment in more segregated ways.

And here is the abstract of the article:

The current research explores how local racial diversity affects Whites' efforts to structure their local communities to avoid incidental intergroup contact. In two experimental studies (N = 509; Studies 1a-b), we consider Whites' choices to structure a fictional, diverse city and find that Whites choose greater racial segregation around more (vs. less) self-relevant landmarks (e.g., their workplace and children's school). Specifically, the more time they expect to spend at a landmark, the more they concentrate other Whites around that landmark, thereby reducing opportunities for incidental intergroup contact. Whites also structure environments to reduce incidental intergroup contact by instituting organizational policies that disproportionately exclude non-Whites: Two large-scale archival studies (Studies 2a-b) using data from every U.S. tennis (N = 15,023) and golf (N = 10,949) facility revealed that facilities in more racially diverse communities maintain more exclusionary barriers (e.g., guest policies, monetary fees, dress codes) that shield the patrons of these historically White institutions from incidental intergroup contact. In a final experiment (N = 307; Study 3), we find that Whites' anticipated intergroup anxiety is one driver of their choices to structure environments to reduce incidental intergroup contact in more (vs. less) racially diverse communities. Our results suggest that despite increasing racial diversity, White Americans structure local environments to fuel a self-perpetuating cycle of segregation.

Evidence that monkeys have conscious awareness of self - they know what they saw.

Ben-Haim et al. Disentangle perceptual awareness from nonconscious processing in rhesus monkeys  

Significance

Many animals perform complex intelligent behaviors, but the question of whether animals are aware while doing so remains a long debated but unanswered question. Here, we develop a new approach to assess whether nonhuman animals have awareness by utilizing a well-known double dissociation of visual awareness—cases in which people behave in completely opposite ways when stimuli are processed consciously versus nonconsciously. Using this method, we found that a nonhuman species—the rhesus monkey—exhibits the very same behavioral signature of both nonconscious and conscious processing. This opposite double dissociation of awareness firstly allows stripping away the long inherent ambiguity when interpreting the processes governing animal behavior. Collectively, it provides robust support for two distinct awareness modes in nonhuman animals.

Abstract

Scholars have long debated whether animals, which display impressive intelligent behaviors, are consciously aware or not. Yet, because many complex human behaviors and high-level functions can be performed without conscious awareness, it was long considered impossible to untangle whether animals are aware or just conditionally or nonconsciously behaving. Here, we developed an empirical approach to address this question. We harnessed a well-established cross-over double dissociation between nonconscious and conscious processing, in which people perform in completely opposite ways when they are aware of stimuli versus when they are not. To date, no one has explored if similar performance dissociations exist in a nonhuman species. In a series of seven experiments, we first established these signatures in humans using both known and newly developed nonverbal double-dissociation tasks and then identified similar signatures in rhesus monkeys (Macaca mulatta). These results provide robust evidence for two distinct modes of processing in nonhuman primates. This empirical approach makes it feasible to disentangle conscious visual awareness from nonconscious processing in nonhuman species; hence, it can be used to strip away ambiguity when exploring the processes governing intelligent behavior across the animal kingdom. Taken together, these results strongly support the existence of both nonconscious processing as well as functional human-like visual awareness in nonhuman animals.

(Note: Establishing double dissociation of awareness used a nonverbal spatial-cueing paradigm. Motivated readers can email me to obtain a PDF of the article which describes this paradigm.)

People have shaped most of terrestrial nature for at least 12,000 years

From Ellis et al.L 

Significance

The current biodiversity crisis is often depicted as a struggle to preserve untouched habitats. Here, we combine global maps of human populations and land use over the past 12,000 y with current biodiversity data to show that nearly three quarters of terrestrial nature has long been shaped by diverse histories of human habitation and use by Indigenous and traditional peoples. With rare exceptions, current biodiversity losses are caused not by human conversion or degradation of untouched ecosystems, but rather by the appropriation, colonization, and intensification of use in lands inhabited and used by prior societies. Global land use history confirms that empowering the environmental stewardship of Indigenous peoples and local communities will be critical to conserving biodiversity across the planet.

Abstract

Archaeological and paleoecological evidence shows that by 10,000 BCE, all human societies employed varying degrees of ecologically transformative land use practices, including burning, hunting, species propagation, domestication, cultivation, and others that have left long-term legacies across the terrestrial biosphere. Yet, a lingering paradigm among natural scientists, conservationists, and policymakers is that human transformation of terrestrial nature is mostly recent and inherently destructive. Here, we use the most up-to-date, spatially explicit global reconstruction of historical human populations and land use to show that this paradigm is likely wrong. Even 12,000 y ago, nearly three quarters of Earth’s land was inhabited and therefore shaped by human societies, including more than 95% of temperate and 90% of tropical woodlands. Lands now characterized as “natural,” “intact,” and “wild” generally exhibit long histories of use, as do protected areas and Indigenous lands, and current global patterns of vertebrate species richness and key biodiversity areas are more strongly associated with past patterns of land use than with present ones in regional landscapes now characterized as natural. The current biodiversity crisis can seldom be explained by the loss of uninhabited wildlands, resulting instead from the appropriation, colonization, and intensifying use of the biodiverse cultural landscapes long shaped and sustained by prior societies. Recognizing this deep cultural connection with biodiversity will therefore be essential to resolve the crisis.

Motivated readers can obtain a PDF of the article by emailing me.

Excess mortality rates since 2000 in the US compared with Europe.

Interesting, from Preston and Vierboom. Just the numbers, no commentary on the causes (mainly opioid crisis?).

We use three indexes to identify how age-specific mortality rates in the United States compare to those in a composite of five large European countries since 2000. First, we examine the ratio of age-specific death rates in the United States to those in Europe. These show a sharp deterioration in the US position since 2000. Applying European age-specific death rates in 2017 to the US population, we then show that adverse mortality conditions in the United States resulted in 400,700 excess deaths that year. Finally, we show that these excess deaths entailed a loss of 13.0 My of life. In 2017, excess deaths and years of life lost in the United States represent a larger annual loss of life than that associated with the COVID-19 epidemic in 2020.

Age-specific comparisons of US and European mortality: 2000, 2010,2017. Source: HMD (12). (A) Ratio of US age-specific death rate to Europeanstandard. (B) Change in US death count if US had European age-specificdeath rates. (C) Years of life lost based on US life expectancies and US/European comparisons of age-specific death rates

Embracing diversity can disadvantage minorities

From Starck et al.:  

Significance

There are numerous reasons why institutions of higher education may choose to embrace diversity. A common rationale sanctioned by the US Supreme Court is that diversity provides compelling educational benefits and is thus instrumentally useful. We show that such instrumental rationales are the predominant rationale for diversity efforts in American higher education, are preferred by White Americans and not by Black Americans, that they are expected to advantage White Americans, and that they correspond to greater racial disparities in academic achievement. Overall, these findings suggest that the rationales behind universities’ embrace of diversity have nonlegal consequences that should be considered in institutional decision making.

Abstract

It is currently commonplace for institutions of higher education to proclaim to embrace diversity and inclusion. Though there are numerous rationales available for doing so, US Supreme Court decisions have consistently favored rationales which assert that diversity provides compelling educational benefits and is thus instrumentally useful. Our research is a quantitative/experimental effort to examine how such instrumental rationales comport with the preferences of White and Black Americans, specifically contrasting them with previously dominant moral rationales that embrace diversity as a matter of intrinsic values (e.g., justice). Furthermore, we investigate the prevalence of instrumental diversity rationales in the American higher education landscape and the degree to which they correspond with educational outcomes. Across six experiments, we showed that instrumental rationales correspond to the preferences of White (but not Black) Americans, and both parents and admissions staff expect Black students to fare worse at universities that endorse them. We coded university websites and surveyed admissions staff to determine that, nevertheless, instrumental diversity rationales are more prevalent than moral ones are and that they are indeed associated with increasing White–Black graduation disparities, particularly among universities with low levels of moral rationale use. These findings indicate that the most common rationale for supporting diversity in American higher education accords with the preferences of, and better relative outcomes for, White Americans over low-status racial minorities. The rationales behind universities’ embrace of diversity have nonlegal consequences that should be considered in institutional decision making.

Sensitivity to geometric shape: A putative signature of human singularity

From Sablé-Meyer et al.:

Among primates, humans are special in their ability to create and manipulate highly elaborate structures of language, mathematics, and music. Here we show that this sensitivity to abstract structure is already present in a much simpler domain: the visual perception of regular geometric shapes such as squares, rectangles, and parallelograms. We asked human subjects to detect an intruder shape among six quadrilaterals. Although the intruder was always defined by an identical amount of displacement of a single vertex, the results revealed a geometric regularity effect: detection was considerably easier when either the base shape or the intruder was a regular figure comprising right angles, parallelism, or symmetry rather than a more irregular shape. This effect was replicated in several tasks and in all human populations tested, including uneducated Himba adults and French kindergartners. Baboons, however, showed no such geometric regularity effect, even after extensive training. Baboon behavior was captured by convolutional neural networks (CNNs), but neither CNNs nor a variational autoencoder captured the human geometric regularity effect. However, a symbolic model, based on exact properties of Euclidean geometry, closely fitted human behavior. Our results indicate that the human propensity for symbolic abstraction permeates even elementary shape perception. They suggest a putative signature of human singularity and provide a challenge for nonsymbolic models of human shape perception.

What coffee does to body and mind

I am completely dependent on coffee, starting every morning with this stimulant and continuing small sips until a lunchtime cappuccino terminates my consumption for the day. Thus I found this article by Michael Gross on the history of caffeine consumption by humans and animals completely fascinating. I'll pass on just the first few paragraphs to whet your appetite, and let you download the complete article if you would like to continue reading on to Gross's discussion of coffee's effects on brain and mind. 

 

Johann Sebastian Bach never wrote an opera, simply because his employers had no use for one and kept him busy with other things. An intriguing glimpse at what the world missed is afforded by the secular cantata Schweigt stille, plaudert nicht (BWV 211), a half-hour mini-opera about a young woman addicted to coffee and her father trying to persuade her to quit. Bach is thought to have composed the work known as the ‘coffee cantata’ on the words of Picander in the 1730s, when he was the St Thomas Cantor at Leipzig and conducted an orchestra at the Café Zimmermann as a sideline.

It dates from a time when coffee was a new-fangled fashion craze gradually spreading across Europe. From myth-shrouded origins in the kingdom of Sheba, today’s Yemen or Ethiopia, the culture of making and drinking coffee expanded across the Arabian Peninsula and into the Ottoman Empire, reaching its capital, Istanbul, in 1554. After the Ottoman advance into Europe was stopped just outside Vienna in 1683, the victorious Austrians confiscated the coffee supplies of the fleeing Turks and used them to launch their legendary coffee-house culture, which spread across Europe. An independent early entry route was provided by Venetian traders.

From the beginnings of this spread there had been attempts by religious leaders, in both Islamic and Christian societies, to ban coffee, as they found its powerful stimulating effect suspicious. Thus, the lively conflict in Bach’s coffee cantata reflected a very real debate that must have taken place many times between lovers of the dark brew and authorities suspicious of its effects.

Ancient Greece's Army of Lovers

This post is under MindBlog's "random and curious stuff" category. A piece by Daniel Mendelsohn in The New Yorker:

Comprising a hundred and fifty male couples, Thebes’s Sacred Band was undefeated until it was wiped out in 338 B.C. In the nineteenth century, the mass grave of the men was found.

Image courtesy Hellenic Ministry of Culture and Sports, Directorate of the Management of the National Archive of Monuments, Department of the Historical Archive of Antiquities and Restorations

In June, 1818, during a visit to central Greece, a young English architect named George Ledwell Taylor went out riding with some friends in order to explore the ruins of an ancient town called Chaeronea. As Taylor’s party neared its destination, his horse took a “fearful stumble,” as he later recalled, on a stone in the roadway; on further inspection, he saw that the stone was, in fact, part of a sculpture. Energetic digging eventually revealed an animal head nearly six feet high—or, as Taylor put it, a “colossal head of the Lion.”

That definite article and the capital “L” are crucial. Taylor realized that he had uncovered a famous monument, mentioned in some historical sources but since lost, known as the Lion of Chaeronea. The Englishman had been studying a work called “The Description of Greece,” by Pausanias, a geographer of the second century A.D., which states that the gigantic figure of the sitting animal had been erected to commemorate a remarkable military unit that had perished there. The lion, Pausa­nias surmised, represented “the spirit of the men.”

The unit to which those men belonged was known as the Sacred Band. Comprising three hundred warriors from the city of Thebes, it was among the most fearsome fighting forces in Greece, undefeated until it was wiped out at the Battle of Chaeronea, in 338 B.C.—an engagement during which Philip of Macedon and his son, the ­future Alexander the Great, crushed a coalition of Greek city-states led by Athens and Thebes. Scholars see Chaeronea as the death knell of the Classi­cal Era of Greek history.

Others might find the story interesting for different reasons. Not the least of these is that the Band was composed entirely of lovers: precisely a hundred and fifty couples, whose valor, so the Greeks thought, was due to the fact that no man would ever exhibit cowardice or act dishonorably in front of his beloved. In Plato’s Symposium, a dialogue about love, a character remarks that an army made up of such lovers would “conquer all mankind.”

Sixty years after George Taylor’s horse stumbled, further excavations revealed a large rectangular burial site near the Lion. Drawings that were made at the site show seven rows of skeletons, two hundred and fifty-four in all. For “The Sacred Band” (Scribner), a forthcoming book by the classicist James Romm, the illustrator Markley Boyer collated those nineteenth-century drawings to produce a reconstruction of the entire mass grave. Black marks indicate wounds. A number of warriors were buried with arms linked; if you look closely, you can see that some were holding hands. ♦

Gamma-frequency oscillations link different brain regions during learning.

Fernández-Ruiz et al. demonstrate that specific, projected gamma-frequency oscillation patterns dynamically engage functionally related cell assemblies across brain regions in a task-specific manner. I pass along their entire structured abstract:  

INTRODUCTION

Learning induces a dynamic reorganization of brain circuits but the neuronal mechanisms underlying this process are not well understood. Interregional gamma-frequency oscillations (~30 to 150 Hz) have been postulated as a mechanism to precisely coordinate upstream and downstream neuronal ensembles, for example, in the hippocampal system. The lateral (LEC) and medial (MEC) entorhinal cortex receive inputs from two distinct streams of cortical hierarchy (the “what” and the “where” pathways) and convey these neuronal messages to the hippocampus. However, the mechanisms by which such messages are packaged and integrated or segregated by hippocampal circuits had yet to be explored.

RATIONALE

Neuronal assemblies firing within gamma time frames in an upstream region can most effectively discharge their downstream partners. This gamma-time-scale organization appears essential for physiological functions because manipulations that impair precision timing of spikes in the hippocampus often affect behavior. However, direct support for distinct gamma-frequency communication in appropriate behavioral situations is missing. To bring physiological operations closer to behavior, we designed “spatial” and “object” learning tasks and examined the selective engagement of gamma-frequency communication between the MEC and LEC inputs and their target neuronal assemblies in the hippocampal dentate gyrus. We combined these correlational observations with optogenetic perturbation of gamma oscillations in LEC and MEC, respectively, to test their roles in pathway-specific neuronal communication and learning.

RESULTS

During spatial learning, fast gamma (100 to 150 Hz) oscillations synchronized MEC and dentate gyrus and entrained predominantly granule cells. During object learning, slow gamma (30 to 50 Hz) oscillations synchronized LEC and dentate gyrus and preferentially recruited mossy cells and CA3 pyramidal neurons, suggesting task-specific routing of MEC and LEC messages in the form of gamma-cycle-spike packets of selected cell types. The low- and high-frequency gamma sub-bands were dominant in the outer and middle third of the dentate molecular layer, respectively, and their amplitude maxima were locked to different phases of theta oscillations.

Gamma frequency optogenenetic perturbation of MEC and LEC led to learning impairments in a spatial and object learning task, respectively. In the same animals, the dentate layer–specific low- and high-frequency gamma sub-bands and spike-gamma LFP coupling were selectively reduced, coupled with deterioration of spatial and object-related firing of dentate neurons.

CONCLUSION

These findings demonstrate that distinct gamma-frequency-specific communication between MEC and LEC and hippocampal cell assemblies are critical for routing task-relevant information, and our selective gamma-band perturbation experiments suggest that they support specific aspects of learning. We hypothesize that sending neuronal messages by segregated gamma-frequency carriers allows a target “reader” area to disambiguate convergent inputs. In general, these results demonstrate that specific projected gamma patterns dynamically engage functionally related cell assemblies across brain regions in a task-specific manner.

Vision: What’s so special about words?

Readers are sensitive to the statistics of written language. New work by Vidal et al. suggests that this sensitivity may be driven by the same domain-general mechanisms that enable the visual system to detect statistical regularities in the visual environment. 

Highlights

• Readers presented with orthographic-like stimuli are sensitive to bigram frequencies 

• An analogous effect emerges with images of made-up objects and visual gratings 

• These data suggest that the reading system might rely on general-purpose mechanisms 

• This calls for considering reading in the broader context of visual neuroscience

Summary

As writing systems are a relatively novel invention (slightly over 5 kya), they could not have influenced the evolution of our species. Instead, reading might recycle evolutionary older mechanisms that originally supported other tasks and preceded the emergence of written language. Accordingly, it has been shown that baboons and pigeons can be trained to distinguish words from nonwords based on orthographic regularities in letter co-occurrence. This suggests that part of what is usually considered reading-specific processing could be performed by domain-general visual mechanisms. Here, we tested this hypothesis in humans: if the reading system relies on domain-general visual mechanisms, some of the effects that are often found with orthographic material should also be observable with non-orthographic visual stimuli. We performed three experiments using the same exact design but with visual stimuli that progressively departed from orthographic material. Subjects were passively familiarized with a set of composite visual items and tested in an oddball paradigm for their ability to detect novel stimuli. Participants showed robust sensitivity to the co-occurrence of features (“bigram” coding) with strings of letter-like symbols but also with made-up 3D objects and sinusoidal gratings. This suggests that the processing mechanisms involved in the visual recognition of novel words also support the recognition of other novel visual objects. These mechanisms would allow the visual system to capture statistical regularities in the visual environment. We hope that this work will inspire models of reading that, although addressing its unique aspects, place it within the broader context of vision.

Useful Delusions

I want to pass on to MindBlog readers some background information on the recent book "Useful Delusions: The Power and Paradox of the Self-Deceiving Brain" by Shankar Vedantam, host of NPR’s “The Hidden Brain,” and science writer Bill Mesler. It was compiled by a member of the four person program committee of the Austin Rainbow Forum discussion group to which I belong.

This Hidden Brain podcast interview with Shankar Vedantum is a great resource for those up to the challenge of sitting in a comfortable chair for an hour listening to a great conversation while enjoying a pleasant beverage.

And here are a few alternatives for the listening challenged:

A book excerpt at the Hidden Brain website.

And, book reviews from The New York Journal of Books, and The Wall Street Journal.

Why does passion matter more in individualistic cultures?

Tsai does an interesting commentary  (open source) on work noted in MindBlog's recent post on an article by Li et al.  Some clips:

Our research finds that, because achieving independence requires increased arousal and action, cultures that foster these goals value high-arousal positive states like passion, excitement, and enthusiasm. In contrast, because achieving interdependence requires decreased arousal and action, cultures that foster these goals value low-arousal positive states like calm, peacefulness, and balance.

These ideals matter because people use them to judge their own feelings, and, perhaps even more importantly, to judge the feelings of others. For instance, because European Americans value excitement more than Hong Kong Chinese, they rate “excited” faces (with broad toothy smiles) as much friendlier and warmer than “calm” faces (with closed smiles), compared to Hong Kong Chinese. And, because European Americans perceive excited (vs. calm) faces as friendlier and warmer, they share more money with excited vs. calm partners in economic games (e.g., the Dictator Game), compared to East Asians.

Experiencing and expressing cultural ideals can have life-altering consequences in the real world. When deciding whom to lend to on a web-based microlending platform (Kiva.com), people from countries with an excitement ideal loaned more to borrowers who had “excited” smiles in their profile photos and less to borrowers who had “calm” smiles. In a business setting, when selecting an intern, European Americans viewed the “ideal applicant” as being more excited (vs. calm), and chose more excited (vs. calm) applicants than Hong Kong Chinese did. Even in health settings, European Americans chose excitement-focused physicians who promoted dynamic lifestyles (vs. calm-focused physicians who promoted relaxing lifestyles) more than Hong Kong Chinese did. Interestingly, European Americans also recalled and adhered to the recommendations of the excitement- versus calm-focused physician more than East Asian Americans did. These findings suggest that people may also be more receptive to the advice and feedback of people who express their cultural ideal.

...in the context of a European American focus on passion, calm East Asian Americans are often inaccurately judged to be “cold” and “stoic” . This may explain why, compared to European Americans, East Asian Americans are less likely to be promoted to top leadership positions, a problem often described as “the Bamboo Ceiling”. But this might be avoided if teachers, employers, and other decision makers in individualistic cultures understood that in many cultures — as illustrated by the findings of Li et al. — passion matters less. Instead of passion, people are finding, following, and fueling calm, balance, and the other affective states that their cultures value more.

The Psychology of Fake News

Pennycook and Rand do a fascinating open source article in Trends in Cognitive Science on the psychology of fake news.  Their highlights and summary: 

Recent evidence contradicts the common narrative that partisanship and politically motivated reasoning explain why people fall for 'fake news'. 

Poor truth discernment is linked to a lack of careful reasoning and relevant knowledge, as well as to the use of familiarity and source heuristics. 

There is also a large disconnect between what people believe and what they will share on social media, and this is largely driven by inattention rather than by purposeful sharing of misinformation. 

Effective interventions can nudge social media users to think about accuracy, and can leverage crowdsourced veracity ratings to improve social media ranking algorithms.

We synthesize a burgeoning literature investigating why people believe and share false or highly misleading news online. Contrary to a common narrative whereby politics drives susceptibility to fake news, people are ‘better’ at discerning truth from falsehood (despite greater overall belief) when evaluating politically concordant news. Instead, poor truth discernment is associated with lack of careful reasoning and relevant knowledge, and the use of heuristics such as familiarity. Furthermore, there is a substantial disconnect between what people believe and what they share on social media. This dissociation is largely driven by inattention, more so than by purposeful sharing of misinformation. Thus, interventions can successfully nudge social media users to focus more on accuracy. Crowdsourced veracity ratings can also be leveraged to improve social media ranking algorithms.

How dopamine leads to hallucinations

Hallucinations (perceptual experiences without external stimuli) seen in conditions such as schizophrenia are thought to result from giving too much weight to priors, creating an imbalance at the expense of actual sensory evidence. Sustained high-dopamine tone in the striatum has been proposed to contribute to this imbalance; however, it has remained unclear how the dopaminergic perturbation leads to the generation of hallucinations. Schmack et al. have developed a cross-species computational psychiatry approach to directly relate human and rodent behavior and used this approach to study the neural basis of hallucination-like perception in mice. Here is the summary of their results and their conclusion:   

RESULTS

We set up analogous auditory detection tasks for humans and mice. Both humans and mice were presented with an auditory stimulus in which a tone signal was embedded in a noisy background on half of the trials. Humans pressed one of two buttons to report whether or not they heard a signal, whereas mice poked into one of two choice ports. Humans indicated how confident they were in their report by positioning a cursor on a slider; mice expressed their confidence by investing variable time durations to earn a reward. In humans, hallucination-like percepts—high-confidence false alarms—were correlated with the tendency to experience spontaneous hallucinations, as quantified by a self-report questionnaire. In mice, hallucination-like percepts increased with two manipulations known to induce hallucinations in humans: administration of ketamine and the heightened expectation of hearing a signal. We then used genetically encoded dopamine sensors with fiber photometry to monitor dopamine dynamics in the striatum. We found that elevations in dopamine levels before stimulus onset predicted hallucination-like perception in both the ventral striatum and the tail of the striatum. We devised a computational model that explains the emergence of hallucination-like percepts as a consequence of faulty perceptual inference when prior expectations outweigh sensory evidence. Our model clarified how hallucination-like percepts can arise from fluctuations in two distinct types of expectations: reward expectations and perceptual expectations. In mice, dopamine fluctuations in the ventral striatum reflected reward expectations, whereas in the tail of the striatum they resembled perceptual expectations. We optogenetically boosted dopamine in the tail of the striatum and observed that increasing dopamine induced hallucination-like perception. This effect was rescued by the administration of haloperidol, an antipsychotic drug that blocks D2 dopamine receptors.

CONCLUSION

We established hallucination-like perception as a quantitative behavior in mice for modeling the subjective experience of a cardinal symptom of psychosis. We found that hallucination-like perception is mediated by dopamine elevations in the striatum and that this can be explained by encoding different kinds of expectations in distinct striatal subregions. These findings support the idea that hallucinations arise as faulty perceptual inferences due to elevated dopamine producing a bias in favor of prior expectations against current sensory evidence. Our results also yield circuit-level insights into the long-standing dopamine hypothesis of psychosis and provide a rigorous framework for dissecting the neural circuit mechanisms involved in hallucinations. We propose that this approach can guide the development of novel treatments for schizophrenia and other psychotic disorders.

A Dendrite-Focused Framework for Understanding the Actions of Ketamine and Psychedelics

I pass on the highlioght points from an interesting review (open source, with a useful graphic) of how the similar therapeutic effects of ketamine and psychedelics might be explained:

Ketamine can relieve symptoms of depression and anxiety, therefore filling a critically unmet psychiatric need. A few small-scale clinical studies suggest serotonergic psychedelics may have similar therapeutic effects.

Ketamine may both enhance and suppress dendritic excitability, through microcircuit interactions involving disinhibition.

Serotonergic psychedelics may both enhance and suppress excitability, through targeting coexpressed receptors.

Spatial mismatch in the opposing drug actions on dendritic excitability is predicted to steer plasticity actions towards certain synapses and cell types.

We present a dendrite-focused framework as a novel lens to view the actions of ketamine and serotonergic psychedelics on cortical circuits.

False memories can be reversed without damage to true memories.

 Oeberst et al.  demonstrate the effectiveness of source sensitization, which involves alerting participants that their memories could come from external sources, and false memory sensitization, which involves informing individuals that repeatedly being asked to recollect events can produce false memories. The two strategies could be widely implemented in real-world settings and do not require interviewers to know any ground truths.:  

Significance

Human memory is fallible and malleable. In forensic settings in particular, this poses a challenge because people may falsely remember events with legal implications that never actually happened. Despite an urgent need for remedies, however, research on whether and how rich false autobiographical memories can be reversed under realistic conditions (i.e., using reversal strategies that can be applied in real-world settings) is virtually nonexistent. The present study therefore not only replicates and extends previous demonstrations of false memories but, crucially, documents their reversibility after the fact: Employing two ecologically valid strategies, we show that rich but false autobiographical memories can mostly be undone. Importantly, reversal was specific to false memories (i.e., did not occur for true memories).

Abstract

False memories of autobiographical events can create enormous problems in forensic settings (e.g., false accusations). While multiple studies succeeded in inducing false memories in interview settings, we present research trying to reverse this effect (and thereby reduce the potential damage) by means of two ecologically valid strategies. We first successfully implanted false memories for two plausible autobiographical events (suggested by the students’ parents, alongside two true events). Over three repeated interviews, participants developed false memories (measured by state-of-the-art coding) of the suggested events under minimally suggestive conditions (27%) and even more so using massive suggestion (56%). We then used two techniques to reduce false memory endorsement, source sensitization (alerting interviewees to possible external sources of the memories, e.g., family narratives) and false memory sensitization (raising the possibility of false memories being inadvertently created in memory interviews, delivered by a new interviewer). This reversed the false memory build-up over the first three interviews, returning false memory rates in both suggestion conditions to the baseline levels of the first interview (i.e., to ∼15% and ∼25%, respectively). By comparison, true event memories were endorsed at a higher level overall and less affected by either the repeated interviews or the sensitization techniques. In a 1-y follow-up (after the original interviews and debriefing), false memory rates further dropped to 5%, and participants overwhelmingly rejected the false events. One strong practical implication is that false memories can be substantially reduced by easy-to-implement techniques without causing collateral damage to true memories.

The case against reality

Over the past year I've dipped into and out of Donald Hoffman's ideas several times, looking back at Geffer's article in Granta Magazine, Hoffman's TED talk, and sections of his 2019 book "The Case Against Reality: Why Evolution Hid the Truth from Our Eyes." Mainly for my future reference (I forget things, and use my MindBlog posts to go back and look them up), I'm attempting to put down the bare bones of his arguments with a selection of clips from these various sources.

As we go about our daily lives, we tend to assume that our perceptions — sights, sounds, textures, tastes — are an accurate portrayal of the real world...If they were not, wouldn’t evolution have weeded us out by now?...This hunch is wrong. On the contrary, our perceptions of snakes and apples, and even of space and time, do not reveal objective reality...It is a theorem of evolution by natural selection that wallops our hunches.

Does natural selection really favor seeing reality as it is? Fortunately, we don't have to wave our hands and guess; evolution is a mathematically precise theory. We can use the equations of evolution to check this out. We can have various organisms in artificial worlds compete and see which survive and which thrive, which sensory systems are more fit. A key notion in those equations is fitness...Fitness is not the same thing as reality as it is, and it's fitness, and not reality as it is, that figures centrally in the equations of evolution... we have run hundreds of thousands of evolutionary game simulations with lots of different randomly chosen worlds and organisms that compete for resources in those worlds. Some of the organisms see all of the reality, others see just part of the reality, and some see none of the reality, only fitness. Who wins? ...perception of reality goes extinct. In almost every simulation, organisms that see none of reality but are just tuned to fitness drive to extinction all the organisms that perceive reality as it is. So the bottom line is, evolution does not favor veridical, or accurate perceptions. Those perceptions of reality go extinct. Fitness beats truth (This is the "FBT theorem").

A metaphor can help our intuitions. Suppose you’re writing an email, and the icon for its file is blue, rectangular, and in the center of your desktop. Does this mean that the file itself is blue, rectangular, and in the center of your computer? Of course not...The purpose of a desktop interface is not to show you the “truth” of the computer—where “truth," in this metaphor, refers to circuits, voltages, and layers of software. Rather, the purpose of an interface is to hide the “truth” and to show simple graphics that help you perform useful tasks such as crafting emails and editing photos. If you had to toggle voltages to craft an email, your friends would never hear from you. That is what evolution has done. It has endowed us with senses that hide the truth and display the simple icons we need to survive long enough to raise offspring... Perception is not a window on objective reality. It is an interface that hides objective reality behind a veil of helpful icons...Evolution has shaped our senses to keep us alive. We have to take them seriously: if you see a speeding Maserati, don’t leap in front of it; if you see a moldy apple, don’t eat it. But it is a mistake of logic to assume that if we must take our senses seriously then we are required—or even entitled—to take them literally.

We used to think that the Earth is flat because it looks that way. Then we thought that the Earth is the unmoving center of reality because it looks that way. We were wrong. We had misinterpreted our perceptions. Now we believe that spacetime and objects are the nature of reality as it is. The theory of evolution is telling us that once again, we're wrong. We're misinterpreting the content of our perceptual experiences. There's something that exists when you don't look, but it's not spacetime and physical objects. It's...hard for us to let go of spacetime and objects...we're blind to our own blindnesses...By peering through the lens of a telescope we discovered that the Earth is not the unmoving center of reality, and by peering through the lens of the theory of evolution we discovered that spacetime and objects are not the nature of reality. When I have a perceptual experience that I describe as a red tomato, I am interacting with reality, but that reality is not a red tomato and is nothing like a red tomato...And here's the kicker: When I have a perceptual experience that I describe as a brain, or neurons, I am interacting with reality, but that reality is not a brain or neurons and is nothing like a brain or neurons. And that reality, whatever it is, is the real source of cause and effect in the world -- not brains, not neurons. Brains and neurons have no causal powers. They cause none of our perceptual experiences, and none of our behavior. Brains and neurons are a species-specific set of symbols, a hack.

Plasticity during our development of mapping time on to space.

A previous mindblog post has pointed to work showing how culture shapes our spatial conceptions of time. Starr and Srinivasan now address the development of spatial representations of time in three dimension in children from different cultures.:

Across cultures, people frequently communicate about time in terms of space. English speakers in the United States, for example, might “look forward” to the future or gesture toward the left when talking about the past. As shown by these examples, different dimensions of space are used to represent different temporal concepts. Here, we explored how cultural factors and individual differences shape the development of two types of spatiotemporal representations in 6- to 15-year-old children: the horizontal/vertical mental timeline (in which past and future events are placed on a horizontal or vertical line that is external to the body) and the sagittal mental timeline (in which events are placed on a line that runs through the front-back axis of the body). We tested children in India because the prevalence of both horizontal and vertical calendars there provided a unique opportunity to investigate how calendar orientation and writing direction might each influence the development of the horizontal/vertical mental timeline. Our results suggest that the horizontal/vertical mental timeline and the sagittal mental timeline are constructed in parallel throughout childhood and become increasingly aligned with culturally-conventional orientations. Additionally, we show that experience with calendars may influence the orientation of children's horizontal/vertical mental timelines, and that individual differences in children's attitudes toward the past and future may influence the orientation of their sagittal mental timelines. Taken together, our results demonstrate that children are sensitive to both cultural and personal factors when building mental models of time.

Measuring happiness in small steps.

I find this Brook's self help essay - that I came across while browsing the news during this morning's coffee - to be a nice brief tonic. His basic message is that small steps are more likely to make you happier than hard-to-achieve lifelong goals. I pass on his three summary nostrums here and recommend that you scan his list of brief essays on "How to build a life" in the Atlantic Magazine.  

1. Live in “day-tight compartments.”

The scientific literature is clear that goals can bring a lot of happiness when they are short term, achievable, and leading us toward ultimate success—in other words, when achieving them indicates that we are making progress...set an end goal, then break it into manageable steps: one year, one month, one week, one day.

2. Focus on the journey.

...see major goals not as the only way to achieve happiness but as points of navigation that set a direction for your lifelong journey. That way, when storms arise and new opportunities present themselves, you can set a new goal and gracefully let go of your old one, thereby avoiding disappointment and missed opportunities.

3. Set intrinsic goals.

Extrinsic goals — money, power, and prestige — can be the hardest to achieve because they are inherently zero-sum: In the pursuit of scarce resources, we crowd one another out. By contrast, intrinsic goals—based on love and personal growth—are positive-sum, and thus more likely to lead to success: My efforts to love and grow as a person are not crowded by your efforts; on the contrary, they can be complementary...they are the goals most associated with happiness...intrinsic goals are akin to what the writer David Brooks calls “eulogy virtues”: the things you would want people to remember you for at the end of your life.

Brain mechanism by which testosterone reduces generosity

 Interesting work from Jianxin Ou et al.:

Significance

Testosterone is associated with aggressive behavior in both animals and humans. Here, we establish a link between increased testosterone and selfishness in economic decision making and identify the neural mechanisms through which testosterone reduces generosity in a double-blind, placebo-controlled, between-participant study. We find that testosterone induces more selfish choices, particularly when distant others are concerned. Moreover, it disrupts the representation of other-regarding value in local activity and functional connectivity involving the temporoparietal junction and subcortical regions involved in reward processing. Our study provides causal evidence for a testosterone-mediated neurohormonal link between generosity and the valuation system.

Abstract

Recent evidence has linked testosterone, a major sex hormone, to selfishness in economic decision-making. Here, we aimed to investigate the neural mechanisms through which testosterone reduces generosity by combining functional MRI with pharmacological manipulation among healthy young males in a double-blind, placebo-controlled, between-subject design. After testosterone or placebo gel administration, participants performed a social discounting task in which they chose between selfish options (benefiting only the participant) and generous options (providing also some benefit to another person at a particular social distance). At the behavioral level, testosterone reduced generosity compared to the placebo. At the neural level (n = 60), the temporoparietal junction (TPJ) encoded the other-regarding value of the generous option during generous choices, and this effect was attenuated by testosterone, suggesting that testosterone reduced the consideration of other’s welfare as underpinned by TPJ activity. Moreover, TPJ activity more strongly reflected individual differences in generosity in the placebo than the testosterone group. Furthermore, testosterone weakened the relation between the other-regarding value of generous decisions and connectivity between the TPJ and a region extending from the insula into the striatum. Together, these findings suggest that a network encompassing both cortical and subcortical components underpins the effects of testosterone on social preferences.