Wednesday, February 19, 2020

Winner of Dance your PhD 2019 contest - Social experiences in larval zebrafish and their brains

The videos of several of the contestants can be see at this link, where you will also find a description of the work and people behind the winner, a very creative visual treat, shown here:

Monday, February 17, 2020

MindBlog is starting its 15th year...

I’ve just realized that MindBlog, whose first post was on February 8, 2006, has just entered its 15th year. That first post, “Dangerous Ideas” looks like it could have been posted today. It summarized responses to an 'annual question' presented by Edge.org , whose last question, "What is the last question?," was asked in 2018. Here is the 2006 post:

Dangerous Ideas.......

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

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

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

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

II. Natural explanations of culture

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


III. Fundamental changes in political, economic, social order

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

Friday, February 14, 2020

Mindfulness as an antidote to the intrusions of artificial intelligence?

I want to point to a very interesting New Yorker Magazine article by Ian Parker describing the life and ideas of Yuval Harari, whose work has been the subject of numerous MindBlog posts. A series of five sequential MindBlog posts, starting on 12/31/18, presented an abstracted version of his book "21 Lessons for the 21st Century". Here are some clips from the article that especially caught my attention:
His proposition, often repeated, is that humanity faces three primary threats: nuclear war, ecological collapse, and technological disruption. Other issues that politicians commonly talk about—terrorism, migration, inequality, poverty—are lesser worries, if not distractions... Harari highlights the technological one...“Think about a situation where somebody in Beijing or San Francisco knows what every citizen in Israel is doing at every moment—all the most intimate details about every mayor, member of the Knesset, and officer in the Army, from the age of zero.” He added, “Those who will control the world in the twenty-first century are those who will control data.”
The aspect of a technological dystopia that most preoccupies him—losing mental autonomy to A.I.—can be at least partly countered, in his view, by citizens cultivating greater mindfulness. He collects examples of A.I. threats. He refers, for instance, to recent research suggesting that it’s possible to measure people’s blood pressure by processing video of their faces.
...his writing underscores the importance of equanimity. In a section of “Sapiens” titled “Know Thyself,” Harari describes how the serenity achieved through meditation can be “so profound that those who spend their lives in the frenzied pursuit of pleasant feelings can hardly imagine it.” “21 Lessons” includes extended commentary on the life of the Buddha, who “taught that the three basic realities of the universe are that everything is constantly changing, nothing has any enduring essence, and nothing is completely satisfying.” Harari continues, “You can explore the furthest reaches of the galaxy, of your body, or of your mind, but you will never encounter something that does not change, that has an eternal essence, and that completely satisfies you... ‘What should I do?’ ask people, and the Buddha advises, ‘Do nothing. Absolutely nothing.’ ”
According to Harari's book “Sapiens,” progress is basically an illusion; the Agricultural Revolution was “history’s biggest fraud,” and liberal humanism is a religion no more founded on reality than any other...In the schema of “Sapiens,” money is a “fiction,” as are corporations and nations. Harari uses “fiction” where another might say “social construct.” (He explained to me, “I would almost always go for the day-to-day word, even if the nuance of the professional word is a bit more accurate.”) Harari further proposes that fictions require believers, and exert power only as long as a “communal belief” in them persists. Every social construct, then, is a kind of religion: a declaration of universal human rights is not a manifesto, or a program, but the expression of a benign delusion; an activity like using money, or obeying a stoplight, is a collective fantasy, not a ritual.

Monday, February 10, 2020

Amazing technology - a total body PET scanner with 100ms resolution.

From Zhang et al. at UC Davis (check out the video, showing injection of 18F-fluorodeoxyglucose into a vein in the right leg):
A 194-cm-long total-body positron emission tomography/computed tomography (PET/CT) scanner (uEXPLORER), has been constructed to offer a transformative platform for human radiotracer imaging in clinical research and healthcare. Its total-body coverage and exceptional sensitivity provide opportunities for innovative studies of physiology, biochemistry, and pharmacology. The objective of this study is to develop a method to perform ultrahigh (100 ms) temporal resolution dynamic PET imaging by combining advanced dynamic image reconstruction paradigms with the uEXPLORER scanner. We aim to capture the fast dynamics of initial radiotracer distribution, as well as cardiac motion, in the human body. The results show that we can visualize radiotracer transport in the body on timescales of 100 ms and obtain motion-frozen images with superior image quality compared to conventional methods. The proposed method has applications in studying fast tracer dynamics, such as blood flow and the dynamic response to neural modulation, as well as performing real-time motion tracking (e.g., cardiac and respiratory motion, and gross body motion) without any external monitoring device (e.g., electrinjocardiogram, breathing belt, or optical trackers).



A few clips from their text:
This high temporal resolution tracer imaging technique opens up the opportunity for new applications, such as studying fast pharmacodynamics, using shorter-lived radionuclides (e.g., 82Rb, 13N, and 15O), and performing motion-frozen scans of the heart, lung, and gastrointestinal tract.
PET with high temporal resolution also has potential applications in the characterization of normal and abnormal brain function. Although functional MRI can detect changes associated with cerebral blood flow (CBF), our approach has the potential to directly measure the absolute value of CBF and cerebral metabolic rate of oxygen. The advantage of CBF as determined with diffusible tracers in PET is that it measures blood flow at the nutrient capillary level (not only in large vessels). During the stimulation, parameters derived within a window of a second may show better correlation with postsynaptic activity and less hemodynamic lag. Moreover, these methods could be used for localizing neural activity by correlating it with specific neurotransmitter activity. Furthermore, without the artifacts induced by cardiac and respiratory motion, ultrafast PET may allow analysis of metabolic processes within atherosclerotic plaques and evaluate their distribution and characteristics throughout the cardiovascular system. Finally, high temporal resolution PET together with the TB coverage allows dynamic tracer studies of brain–heart and brain–gut interactions.

Friday, February 07, 2020

Economic Inequality increases desire for a strong leader.

From Sprong et al., studies very relevant to the current political climate in the U.S., and worldwide:
Societal inequality has been found to harm the mental and physical health of its members and undermine overall social cohesion. Here, we tested the hypothesis that economic inequality is associated with a wish for a strong leader in a study involving 28 countries from five continents (Study 1, N = 6,112), a study involving an Australian community sample (Study 2, N = 515), and two experiments (Study 3a, N = 96; Study 3b, N = 296). We found correlational (Studies 1 and 2) and experimental (Studies 3a and 3b) evidence for our prediction that higher inequality enhances the wish for a strong leader. We also found that this relationship is mediated by perceptions of anomie, except in the case of objective inequality in Study 1. This suggests that societal inequality enhances the perception that society is breaking down (anomie) and that a strong leader is needed to restore order (even when that leader is willing to challenge democratic values).

Wednesday, February 05, 2020

Resilient misinformation in a crisis

From Carey et al.:
Disease epidemics and outbreaks often generate conspiracy theories and misperceptions that mislead people about the risks they face and how best to protect themselves. We investigate the effectiveness of interventions aimed at combating false and unsupported information about the Zika epidemic and subsequent yellow fever outbreak in Brazil. Results from a nationally representative survey show that conspiracy theories and other misperceptions about Zika are widely believed. Moreover, results from three preregistered survey experiments suggest that efforts to counter misperceptions about diseases during epidemics and outbreaks may not always be effective. We find that corrective information not only fails to reduce targeted Zika misperceptions but also reduces the accuracy of other beliefs about the disease. In addition, although corrective information about the better-known threat from yellow fever was more effective, none of these corrections affected support for vector control policies or intentions to engage in preventive behavior.

Monday, February 03, 2020

How much are we misled by inauthentic internet content? Perhaps not much...

Bail et al. analyze data describing attitudes and online behaviors of Republican and Democratic Twitter users from late 2017 and find no evidence that interaction with Russian troll accounts (operated by the Russian Internet Research Agency, IRA) had a effect on political attitudes and behaviors. Their abstract:
There is widespread concern that Russia and other countries have launched social-media campaigns designed to increase political divisions in the United States. Though a growing number of studies analyze the strategy of such campaigns, it is not yet known how these efforts shaped the political attitudes and behaviors of Americans. We study this question using longitudinal data that describe the attitudes and online behaviors of 1,239 Republican and Democratic Twitter users from late 2017 merged with nonpublic data about the Russian Internet Research Agency (IRA) from Twitter. Using Bayesian regression tree models, we find no evidence that interaction with IRA accounts substantially impacted 6 distinctive measures of political attitudes and behaviors over a 1-mo period. We also find that interaction with IRA accounts were most common among respondents with strong ideological homophily within their Twitter network, high interest in politics, and high frequency of Twitter usage. Together, these findings suggest that Russian trolls might have failed to sow discord because they mostly interacted with those who were already highly polarized. We conclude by discussing several important limitations of our study—especially our inability to determine whether IRA accounts influenced the 2016 presidential election—as well as its implications for future research on social media influence campaigns, political polarization, and computational social science.

Friday, January 31, 2020

Universality and diversity in human song

In the same vein as the previous post on cultural variation and universal structures in music, another massive research collective reports on their study of universality and diversity in human music, emphasizing different dimensions of experience. They provide interactive graphic tools providing detailed descriptions and samples of songs. The tools pointed to in this and the previous MindBlog post give readers access hundreds (probably thousands) of different music samples, and their variety is astonishing. Here is a summary description done by Science magazine:
It is unclear whether there are universal patterns to music across cultures. Mehr et al. examined ethnographic data and observed music in every society sampled (see the Perspective by Fitch and Popescu). For songs specifically, three dimensions characterize more than 25% of the performances studied: formality of the performance, arousal level, and religiosity. There is more variation in musical behavior within societies than between societies, and societies show similar levels of within-society variation in musical behavior. At the same time, one-third of societies significantly differ from average for any given dimension, and half of all societies differ from average on at least one dimension, indicating variability across cultures.

Wednesday, January 29, 2020

What music makes us feel - 13 cross cultural categories

From Cowen et al.:
(Be sure to check out their striking visualization of the data. By moving the cursor about the screen you can listen to the different emotional categories of music, each differently color coded).

Significance
Do our subjective experiences when listening to music show evidence of universality? And if so, what is the nature of these experiences? With data-driven methodological and statistical approaches, we examined the feelings evoked by 2,168 music excerpts in the United States and China. We uncovered 13 distinct types of experiences that people across 2 different cultures report in listening to music of different kinds. Categories such as “awe” drive the experience of music more so than broad affective features like valence. However, emotions that scientists have long treated as discrete can be blended together. Our results provide answers to long-standing questions about the nature of the subjective experiences associated with music.
Abstract
What is the nature of the feelings evoked by music? We investigated how people represent the subjective experiences associated with Western and Chinese music and the form in which these representational processes are preserved across different cultural groups. US (n = 1,591) and Chinese (n = 1,258) participants listened to 2,168 music samples and reported on the specific feelings (e.g., “angry,” “dreamy”) or broad affective features (e.g., valence, arousal) that they made individuals feel. Using large-scale statistical tools, we uncovered 13 distinct types of subjective experience associated with music in both cultures. Specific feelings such as “triumphant” were better preserved across the 2 cultures than levels of valence and arousal, contrasting with theoretical claims that valence and arousal are building blocks of subjective experience. This held true even for music selected on the basis of its valence and arousal levels and for traditional Chinese music. Furthermore, the feelings associated with music were found to occupy continuous gradients, contradicting discrete emotion theories. Our findings, visualized within an interactive map (https://www.ocf.berkeley.edu/∼acowen/music.html) reveal a complex, high-dimensional space of subjective experience associated with music in multiple cultures. These findings can inform inquiries ranging from the etiology of affective disorders to the neurological basis of emotion.

Monday, January 27, 2020

Repeated fake headlines feel more moral

In a bit of work relevant to the current impeachment drama Effron and Raj find that repeatedly viewing a false headline increases approval and reduces perceptions of how unethical it is to share it with others:
People may repeatedly encounter the same misinformation when it “goes viral.” The results of four main experiments (two preregistered) and a pilot experiment (total N = 2,587) suggest that repeatedly encountering misinformation makes it seem less unethical to spread—regardless of whether one believes it. Seeing a fake-news headline one or four times reduced how unethical participants thought it was to publish and share that headline when they saw it again—even when it was clearly labeled as false and participants disbelieved it, and even after we statistically accounted for judgments of how likeable and popular it was. In turn, perceiving the headline as less unethical predicted stronger inclinations to express approval of it online. People were also more likely to actually share repeated headlines than to share new headlines in an experimental setting. We speculate that repeating blatant misinformation may reduce the moral condemnation it receives by making it feel intuitively true, and we discuss other potential mechanisms that might explain this effect.

Friday, January 24, 2020

Altruistic behaviors relieve physical pain.

From Wang et al., the fascinating observation that altruistic behavior diminishes both acute and chronic pain by damping activity in brain areas responsible for subjective pain.

Significance
For centuries, scientists have pondered why people would incur personal costs to help others and the implications for the performers themselves. While most previous studies have suggested that those who perform altruistic actions receive direct or indirect benefits that could compensate for their cost in the future, we offer another take on how this could be understood. We examine how altruistic behaviors may influence the performers’ instant sensation in unpleasant situations, such as physical pain. We find consistent behavioral and neural evidence that in physically threatening situations acting altruistically can relieve painful feelings in human performers. These findings shed light on the psychological and biological mechanisms underlying human prosocial behavior and provide practical insights into pain management.
Abstract
Engaging in altruistic behaviors is costly, but it contributes to the health and well-being of the performer of such behaviors. The present research offers a take on how this paradox can be understood. Across 2 pilot studies and 3 experiments, we showed a pain-relieving effect of performing altruistic behaviors. Acting altruistically relieved not only acutely induced physical pain among healthy adults but also chronic pain among cancer patients. Using functional MRI, we found that after individuals performed altruistic actions brain activity in the dorsal anterior cingulate cortex and bilateral insula in response to a painful shock was significantly reduced. This reduced pain-induced activation in the right insula was mediated by the neural activity in the ventral medial prefrontal cortex (VMPFC), while the activation of the VMPFC was positively correlated with the performer’s experienced meaningfulness from his or her altruistic behavior. Our findings suggest that incurring personal costs to help others may buffer the performers from unpleasant conditions.

Wednesday, January 22, 2020

Childhood deprivation alters adult brains despite subsequent environmental enrichment.

A sobering study from Mackes et al:  

Significance
Millions of children worldwide live in nonfamilial institutions. We studied impact on adult brain structure of a particularly severe but time-limited form of institutional deprivation in early life experienced by children who were subsequently adopted into nurturing families. Institutional deprivation was associated with lower total brain volume in a dose-dependent way. Regionally specific effects were seen in medial prefrontal, inferior frontal, and inferior temporal areas. Deprivation-related alterations in total brain volume were associated with lower intelligence quotient and more attention deficit/hyperactivity disorder symptoms; alterations in temporal volume seemed compensatory, as they were associated with fewer attention deficit/hyperactivity disorder symptoms. We provide evidence that early childhood deprivation is related to alterations in adult brain structure, despite environmental enrichment in intervening years.
Abstract
Early childhood deprivation is associated with higher rates of neurodevelopmental and mental disorders in adulthood. The impact of childhood deprivation on the adult brain and the extent to which structural changes underpin these effects are currently unknown. To investigate these questions, we utilized MRI data collected from young adults who were exposed to severe deprivation in early childhood in the Romanian orphanages of the Ceaușescu era and then, subsequently adopted by UK families; 67 Romanian adoptees (with between 3 and 41 mo of deprivation) were compared with 21 nondeprived UK adoptees. Romanian adoptees had substantially smaller total brain volumes (TBVs) than nondeprived adoptees (8.6% reduction), and TBV was strongly negatively associated with deprivation duration. This effect persisted after covarying for potential environmental and genetic confounds. In whole-brain analyses, deprived adoptees showed lower right inferior frontal surface area and volume but greater right inferior temporal lobe thickness, surface area, and volume than the nondeprived adoptees. Right medial prefrontal volume and surface area were positively associated with deprivation duration. No deprivation-related effects were observed in limbic regions. Global reductions in TBV statistically mediated the observed relationship between institutionalization and both lower intelligence quotient (IQ) and higher levels of attention deficit/hyperactivity disorder symptoms. The deprivation-related increase in right inferior temporal volume seemed to be compensatory, as it was associated with lower levels of attention deficit/hyperactivity disorder symptoms. We provide compelling evidence that time-limited severe deprivation in the first years of life is related to alterations in adult brain structure, despite extended enrichment in adoptive homes in the intervening years.

Monday, January 20, 2020

What is your biological age? A problem with the epigenetic clock approach.

Having already sent off blood samples to 23andMe and Helix, mainly out of curiosity over possible genome details relevant to my health (Apparently I might be slightly less inclined to dementia issues and more inclined to heart issues), I couldn't resist sending off yet another blood sample to myDNAge, for a test based on Horvath's epigenetic aging clock. The test analyzes DNA methylation patterns of over 2,000 loci on the human genome to give an 'accurate' biological age prediction. I hoped to confirm my smug opinion that my biological age is ~ 10 years less than my chronological age.

I have not yet received a result that might confirm my opinion, but any result I get (after laying out $300 for the test) is now called into question by El Khoury et al. (open source), who show that both the Horvath clock model ,as well as another model by Hannum, systematically underestimate age in tissues from older people. The testing data used in generating this clock did not have a large representation of tissue from elderly individuals, and closer analysis of such date shows a divergence from Horvath's extrapolated line. Details of the analysis are in the open source paper. Here is the summary:

The age prediction properties of both Horvath and Hannum DNA methylation clock models begin to degrade as subjects enter old age. This is at least partly due to saturation, i.e., DNA methylation proportion at some loci approaching 0 or 1, and confounding with the effects of other age-related processes will also play a role. It is likely that this could be ameliorated with additional loci and/or further refined modeling of the currently used set. Association tests using age acceleration should incorporate age as a covariate (as should those using DNA methylation values for individual loci) to avoid spurious associations.

Update on post.....I emailed mydnage.com about this issue, and got the following response:
Dear Deric,
We observed the phenomena mentioned in the recent publication entitled “Systematic underestimation of the epigenetic clock and age acceleration in older subjects” 4 years ago. Our algorithms that are optimized for sample type (optimized either to whole blood or urine) have already took this factor in consideration. In short, your result will not be influenced.

Friday, January 17, 2020

The Mind-Body problem - How our brain talks to stress systems in our body.

Dun et al. use a neuronal pathway tracking technique to show how different brain areas link to the adrenal medulla to connect its activity (secretion of epinephrine (adrenaline), norepinephrine (noradrenaline), and a small amount of dopamine) to how we think and feel.:
Which regions of the cerebral cortex are the origin of descending commands that influence internal organs? We used transneuronal transport of rabies virus in monkeys and rats to identify regions of cerebral cortex that have multisynaptic connections with a major sympathetic effector, the adrenal medulla. In rats, we also examined multisynaptic connections with the kidney. In monkeys, the cortical influence over the adrenal medulla originates from 3 distinct networks that are involved in movement, cognition, and affect. Each of these networks has a human equivalent. The largest influence originates from a motor network that includes all 7 motor areas in the frontal lobe. These motor areas are involved in all aspects of skeletomotor control, from response selection to motor preparation and movement execution. The motor areas provide a link between body movement and the modulation of stress. The cognitive and affective networks are located in regions of cingulate cortex. They provide a link between how we think and feel and the function of the adrenal medulla. Together, the 3 networks can mediate the effects of stress and depression on organ function and provide a concrete neural substrate for some psychosomatic illnesses. In rats, cortical influences over the adrenal medulla and the kidney originate mainly from 2 motor areas and adjacent somatosensory cortex. The cognitive and affective networks, present in monkeys, are largely absent in rats. Thus, nonhuman primate research is essential to understand the neural substrate that links cognition and affect to the function of internal organs.

Wednesday, January 15, 2020

You ideal job can be predicted by your social media behavior.

So...are occupational guidance counselors going to be replaced by social media algorithms? From Kern et al.: 

Significance
Employment is thought to be more enjoyable and beneficial to individuals and society when there is alignment between the person and the occupation, but a key question is how to best match people with the right profession. The information that people broadcast online through social media provides insights into who they are, which we show can be used to match people and occupations. Findings have implications for career guidance for new graduates, disengaged employees, career changers, and the unemployed.
Abstract
Work is thought to be more enjoyable and beneficial to individuals and society when there is congruence between one’s personality and one’s occupation. We provide large-scale evidence that occupations have distinctive psychological profiles, which can successfully be predicted from linguistic information unobtrusively collected through social media. Based on 128,279 Twitter users representing 3,513 occupations, we automatically assess user personalities and visually map the personality profiles of different professions. Similar occupations cluster together, pointing to specific sets of jobs that one might be well suited for. Observations that contradict existing classifications may point to emerging occupations relevant to the 21st century workplace. Findings illustrate how social media can be used to match people to their ideal occupation.

Monday, January 13, 2020

An alternative neural mechanism for treating anxiety disorders through safety signal learning.

In these times of political polarization all over the world, over one third of all people experience anxiety disorders, in which circumstances frequently are taken to be more threatening than they actually are. This makes understanding the inhibition of emotional over-reactivity an important goal of brain research. Meyer et al. make a significant contribution by identifying a pathway that engages the ventral hippocampus for the attenuation of threat responses through conditioned inhibition using neurons that are more active to safety and compound cues than threat cues. This pathway might be a target for therapeutic approaches. Their summaries:  

Significance
Although fear can contribute to survival, difficulty regulating threat responses can interfere with goal-directed activities and is the hallmark of anxiety disorders. These disorders are the most common psychiatric illnesses, affecting up to one-third of the population. In parallel studies across species, we identify a pathway that engages the ventral hippocampus for the attenuation of threat responses through conditioned inhibition. Conditioned inhibition relies on the specific involvement of ventral hippocampal neurons projecting to the prelimbic cortex in mice and homologous ventral hippocampal–dorsal anterior cingulate cortex functional connectivity in humans. These findings highlight a pathway for the inhibition of fear with the potential to enhance interventions for anxiety disorders by targeting an alternative neural circuitry through safety signal learning.
Abstract
Heightened fear and inefficient safety learning are key features of fear and anxiety disorders. Evidence-based interventions for anxiety disorders, such as cognitive behavioral therapy, primarily rely on mechanisms of fear extinction. However, up to 50% of clinically anxious individuals do not respond to current evidence-based treatment, suggesting a critical need for new interventions based on alternative neurobiological pathways. Using parallel human and rodent conditioned inhibition paradigms alongside brain imaging methodologies, we investigated neural activity patterns in the ventral hippocampus in response to stimuli predictive of threat or safety and compound cues to test inhibition via safety in the presence of threat. Distinct hippocampal responses to threat, safety, and compound cues suggest that the ventral hippocampus is involved in conditioned inhibition in both mice and humans. Moreover, unique response patterns within target-differentiated subpopulations of ventral hippocampal neurons identify a circuit by which fear may be inhibited via safety. Specifically, ventral hippocampal neurons projecting to the prelimbic cortex, but not to the infralimbic cortex or basolateral amygdala, were more active to safety and compound cues than threat cues, and activity correlated with freezing behavior in rodents. A corresponding distinction was observed in humans: hippocampal–dorsal anterior cingulate cortex functional connectivity—but not hippocampal–anterior ventromedial prefrontal cortex or hippocampal–basolateral amygdala connectivity—differentiated between threat, safety, and compound conditions. These findings highlight the potential to enhance treatment for anxiety disorders by targeting an alternative neural mechanism through safety signal learning.

Friday, January 10, 2020

Great graphics - a review of cerebral cortex structure/folding from mice to humans.

I pass on this open source review article for the small number of MindBlog readers who might find it useful in their teaching. The summary color graphics of increasingly larger vertebrate brains (Mouse, Marmosett, Macaque, Chimpanzee, Human) show overall appearance and cell number, myelin patterns, and cortical parcellations. Here is the technical abstract:
Advances in neuroimaging and neuroanatomy have yielded major insights concerning fundamental principles of cortical organization and evolution, thus speaking to how well different species serve as models for human brain function in health and disease. Here, we focus on cortical folding, parcellation, and connectivity in mice, marmosets, macaques, and humans. Cortical folding patterns vary dramatically across species, and individual variability in cortical folding increases with cortical surface area. Such issues are best analyzed using surface-based approaches that respect the topology of the cortical sheet. Many aspects of cortical organization can be revealed using 1 type of information (modality) at a time, such as maps of cortical myelin content. However, accurate delineation of the entire mosaic of cortical areas requires a multimodal approach using information about function, architecture, connectivity, and topographic organization. Comparisons across the 4 aforementioned species reveal dramatic differences in the total number and arrangement of cortical areas, particularly between rodents and primates. Hemispheric variability and bilateral asymmetry are most pronounced in humans, which we evaluated using a high-quality multimodal parcellation of hundreds of individuals. Asymmetries include modest differences in areal size but not in areal identity. Analyses of cortical connectivity using anatomical tracers reveal highly distributed connectivity and a wide range of connection weights in monkeys and mice; indirect measures using functional MRI suggest a similar pattern in humans. Altogether, a multifaceted but integrated approach to exploring cortical organization in primate and nonprimate species provides complementary advantages and perspectives.

Wednesday, January 08, 2020

Brain aging reduced by elevating acetyl-CoA levels.

Acetyl coenzyme A (acetyl-CoA) is a central molecule in the energy metabolism of mitochondria in our cells. Currais et al. show that two Alzheimer's disease (AD) drug candidates known to reduce cognitive decline in a mouse model of AD increase acetyl-CoA levels and preserve mitochondrial function. Here is their technical abstract:
Because old age is the greatest risk factor for dementia, a successful therapy will require an understanding of the physiological changes that occur in the brain with aging. Here, two structurally distinct Alzheimer's disease (AD) drug candidates, CMS121 and J147, were used to identify a unique molecular pathway that is shared between the aging brain and AD. CMS121 and J147 reduced cognitive decline as well as metabolic and transcriptional markers of aging in the brain when administered to rapidly aging SAMP8 mice. Both compounds preserved mitochondrial homeostasis by regulating acetyl-coenzyme A (acetyl-CoA) metabolism. CMS121 and J147 increased the levels of acetyl-CoA in cell culture and mice via the inhibition of acetyl-CoA carboxylase 1 (ACC1), resulting in neuroprotection and increased acetylation of histone H3K9 in SAMP8 mice, a site linked to memory enhancement. These data show that targeting specific metabolic aspects of the aging brain could result in treatments for dementia.

Monday, January 06, 2020

The quiet brains of athletes

An interesting study by Kraus and collaborators shows that athletes have larger responses to specified sounds than non-athletes, due to a reduction in their level of background neural noise. Their brains are not as noisy as those of non-athletes. From their abstract:
Playing sports has many benefits, including boosting physical, cardiovascular, and mental fitness. We tested whether athletic benefits extend to sensory processing—specifically auditory processing—as measured by the frequency-following response (FFR), a scalp-recorded electrophysiological potential that captures neural activity predominately from the auditory midbrain to complex sounds...We measured FFRs to the speech syllable “da” in 495 student-athletes across 19 Division I teams and 493 age- and sex-matched controls and compared them on 3 measures of FFR amplitude: amplitude of the response, amplitude of the background noise, and the ratio of these 2 measures.
Athletes have larger responses to sound than nonathletes, driven by a reduction in their level of background neural noise...These findings suggest that playing sports increases the gain of an auditory signal by turning down the background noise. This mode of enhancement may be tied to the overall fitness level of athletes and/or the heightened need of an athlete to engage with and respond to auditory stimuli during competition.
Such a study cannot distinguish whether being an athlete changed the young people’s brains or whether they succeeded as athletes because they were better at sound processing from the start. Further work might resolve this, as well as determining whether older people can reshape their sound processing by becoming active.

Friday, January 03, 2020

Anti-immigration sentiment does not correlate with local democraphic changes.

Hill et al. analyze election results and demographic measures for almost 32,000 precincts in the states of Florida, Georgia, Michigan, Nevada, Ohio, Pennsylvania, and Washington. Influxes of non-citizen immigrants correlated with vote shift away from the anti-immigration candidate (Trump) in the 2016 election. A commentary by Enos notes, however that:
....If ethnic minority populations are segregated and those voters without day-to-day contact continue to react negatively against the minority group, then even a local positive correlation between diversity and liberal politics may not lead to long-term harmony for a society...if increasing diversity affects political outcomes, the relationship can point in two consequentially different directions: toward increased diversity liberalizing politics or toward increased diversity causing a reactionary backlash.
From Hill et al.:

Significance
In recent years, advanced industrial democracies have grown more ethnically and racially diverse. This increasing diversity has the potential to reshape voting behavior in those countries, in part because majority groups may react by shifting support toward anti-immigration candidates and parties. This paper considers whether local demographic changes in the United States were associated with pro-Republican shifts between 2012 and 2016, when the Republican presidential candidate was especially outspoken in opposition to immigration. By showing that demographic changes were not associated with shifts toward the Republican, this research indicates that local demographic changes are not on their own increasing support for anti-immigration candidates.
Abstract
Immigration and demographic change have become highly salient in American politics, partly because of the 2016 campaign of Donald Trump. Previous research indicates that local influxes of immigrants or unfamiliar ethnic groups can generate threatened responses, but has either focused on nonelectoral outcomes or analyzed elections in large geographic units, such as counties. Here, we examine whether demographic changes at low levels of aggregation were associated with vote shifts toward an anti-immigration presidential candidate between 2012 and 2016. To do so, we compile a precinct-level dataset of election results and demographic measures for almost 32,000 precincts in the states of Florida, Georgia, Michigan, Nevada, Ohio, Pennsylvania, and Washington. We employ regression analyses varying model specifications and measures of demographic change. Our estimates uncover little evidence that influxes of Hispanics or noncitizen immigrants benefited Trump relative to past Republicans, instead consistently showing that such changes were associated with shifts to Trump’s opponent.

Wednesday, January 01, 2020

Increased emotional reactivity in men with high hair testosterone concentrations.

As I was scanning the table of contents of the latest issue of the journal "Social Cognitive and Affective Neuroscience" the article whose abstract I pass on below jumped out at me. (This is because I feel more emotional and sexual when my androgen levels reach their highest point in a monthly cycle, with lower points in the cycle correlating with lower motivation and anhedonia.) From Klein et al.:
Testosterone has been linked to alterations in the activity of emotion neurocircuitry including amygdala, orbitofrontal cortex (OFC) and insula and diminished functional amygdala/prefrontal coupling. Such associations have only ever been studied using acute measures of testosterone, thus little is known about respective relationships with long-term testosterone secretion. Here, we examine associations between hair testosterone concentration (HTC), an index of long-term cumulative testosterone levels and neural reactivity during an emotional passive viewing task using functional magnetic resonance imaging (fMRI). Forty-six men viewed negative, positive and neutral pictures in the MRI. HTCs were assessed from 2 cm hair segments. The emotional paradigm elicited neural activation in the amygdala, insula and OFC. HTCs were associated with increased reactivity to negative pictures in the insula and increased reactivity to positive pictures in the OFC. We show an association of long-term testosterone levels with increased emotional reactivity in the brain. These results suggest a heightened emotional vigilance in individuals with high trait testosterone levels.