Explanation of fraternal birth order effect on sexual orientation.

A number of studies have by now confirmed that the probability of a boy growing up to be gay increases for each older brother born to the same mother, the so-called fraternal birth order (FBO) effect. Between 15% and 29% of gay men owe their sexual orientation to this effect. Bogaert et al. now present direct biochemical evidence indicating that the increased incidence of homosexuality in males with older brothers results from a progressive immunization of the mother against a male-specific cell-adhesion protein that plays a key role in cell–cell interactions, specifically in the process of synapse formation. Here are the details:

Significance

Gay men have, on average, a greater number of older brothers than do heterosexual men, a well-known finding within sexual science. This finding has been termed the fraternal birth order effect. Strong scientific interest in sexual orientation exists because it is a fundamental human characteristic, and because its origins are often the focal point of considerable social controversy. Our study is a major advance in understanding the origins of sexual orientation in men by providing support for a theorized but previously unexamined biological mechanism—a maternal immune response to a protein important in male fetal brain development—and by beginning to explain one of the most reliable correlates of male homosexuality: older brothers.

Abstract

We conducted a direct test of an immunological explanation of the finding that gay men have a greater number of older brothers than do heterosexual men. This explanation posits that some mothers develop antibodies against a Y-linked protein important in male brain development, and that this effect becomes increasingly likely with each male gestation, altering brain structures underlying sexual orientation in their later-born sons. Immune assays targeting two Y-linked proteins important in brain development—protocadherin 11 Y-linked (PCDH11Y) and neuroligin 4 Y-linked (NLGN4Y; isoforms 1 and 2)—were developed. Plasma from mothers of sons, about half of whom had a gay son, along with additional controls (women with no sons, men) was analyzed for male protein-specific antibodies. Results indicated women had significantly higher anti-NLGN4Y levels than men. In addition, after statistically controlling for number of pregnancies, mothers of gay sons, particularly those with older brothers, had significantly higher anti-NLGN4Y levels than did the control samples of women, including mothers of heterosexual sons. The results suggest an association between a maternal immune response to NLGN4Y and subsequent sexual orientation in male offspring.

Benefits of talking to yourself.

Talking to ourselves either internally or out loud we can switch from 1st person voice (I can do this) to second person (you can do this) or third person voice (Deric can do this). Kristin Wong does a piece pointing to several studies showing that this motivational self talk can lessen anxiety and improve performance. Focusing on the self from the distanced perspective of a third person, even though that person is you, enhances objectivity. Speaking the name of a familiar object out loud enhances its subsequent identification among random items. The work cited concluded that motivational self-talk works best on tasks based on speed, strength and power, while instructional self-talk works best with tasks that involved focus, strategy and technique.

Old brains come uncoupled in sleep.

From Helfrich et al.:

Highlights

•Precise coupling of NREM (Non-rapid-eye-movement) slow waves and spindles dictates memory consolidation 

•Aging impairs slow wave-spindle coupling, leading to overnight forgetting 

•Age-related atrophy in mPFC (medial prefrontal cortex) predicts the failure of such coupling and thus memory

Summary

The coupled interaction between slow-wave oscillations and sleep spindles during non-rapid-eye-movement (NREM) sleep has been proposed to support memory consolidation. However, little evidence in humans supports this theory. Moreover, whether such dynamic coupling is impaired as a consequence of brain aging in later life, contributing to cognitive and memory decline, is unknown. Combining electroencephalography (EEG), structural MRI, and sleep-dependent memory assessment, we addressed these questions in cognitively normal young and older adults. Directional cross-frequency coupling analyses demonstrated that the slow wave governs a precise temporal coordination of sleep spindles, the quality of which predicts overnight memory retention. Moreover, selective atrophy within the medial frontal cortex in older adults predicted a temporal dispersion of this slow wave-spindle coupling, impairing overnight memory consolidation and leading to forgetting. Prefrontal-dependent deficits in the spatiotemporal coordination of NREM sleep oscillations therefore represent one pathway explaining age-related memory decline.

How to detect that someone is sick.

Alexsson et al. do a study suggesting that you should look first for droopy eyelids and corners of the mouth, then also check for pale skin and lips, how puffy their faces look, eye redness, and tiredness. Here is their abstract:

Detection and avoidance of sick individuals have been proposed as essential components in a behavioural defence against disease, limiting the risk of contamination. However, almost no knowledge exists on whether humans can detect sick individuals, and if so by what cues. Here, we demonstrate that untrained people can identify sick individuals above chance level by looking at facial photos taken 2 h after injection with a bacterial stimulus inducing an immune response (2.0 ng kg−1 lipopolysaccharide) or placebo, the global sensitivity index being d′ = 0.405. Signal detection analysis (receiver operating characteristic curve area) showed an area of 0.62 (95% confidence intervals 0.60–0.63). Acutely sick people were rated by naive observers as having paler lips and skin, a more swollen face, droopier corners of the mouth, more hanging eyelids, redder eyes, and less glossy and patchy skin, as well as appearing more tired. Our findings suggest that facial cues associated with the skin, mouth and eyes can aid in the detection of acutely sick and potentially contagious people.

Figure - Averaged images of 16 individuals (eight women) photographed twice in a cross-over design, during experimentally induced (a) acute sickness and (b) placebo. Images made by Audrey Henderson, MSc, St Andrews University, using Psychomorph. Here, 184 facial landmarks were placed on each image before composites displaying the average shape, colour and texture were created

A Two-System Framework for understanding fear and anxiety.

LeDoux and Pine note that extensive study and understanding of how mammalian brains, including our own, detect and respond to threats has not led to significant improvements in clinical treatments. Their open source article suggests that a conceptual reframing is needed to distinguish two classes of responses elicited by threats. The graphics in the article provide useful summaries:

Tremendous progress has been made in basic neuroscience in recent decades. One area that has been especially successful is research on how the brain detects and responds to threats. Such studies have demonstrated comparable patterns of brain-behavior relationships underlying threat processing across a range of mammalian species, including humans. This would seem to be an ideal body of information for advancing our understanding of disorders in which altered threat processing is a key factor, namely, fear and anxiety disorders. But research on threat processing has not led to significant improvements in clinical practice. The authors propose that in order to take advantage of this progress for clinical gain, a conceptual reframing is needed. Key to this conceptual change is recognition of a distinction between circuits underlying two classes of responses elicited by threats: 1) behavioral responses and accompanying physiological changes in the brain and body and 2) conscious feeling states reflected in self-reports of fear and anxiety. This distinction leads to a “two systems” view of fear and anxiety. The authors argue that failure to recognize and consistently emphasize this distinction has impeded progress in understanding fear and anxiety disorders and hindered attempts to developmore effective pharmaceutical and psychological treatments. The two-system view suggests a new way forward.

Demonstrating reciprocity on a global scale.

In this age that seems characterized by increasing domestic and international chaos, I like to pass on any work that shows potential buffering or stability in our complex political and economic systems. Here is a contribution from Frank et al.; the open source article has useful graphics describing cooperation and reciprocity around the world:

Reciprocity stabilizes cooperation from the level of microbes all the way up to humans interacting in small groups, but does reciprocity also underlie stable cooperation between larger human agglomerations, such as nation states? Famously, evolutionary models show that reciprocity could emerge as a widespread strategy for achieving international cooperation. However, existing studies have only detected reciprocity-driven cooperation in a small number of country pairs. We apply a new method for detecting mutual influence in dynamical systems to a new large-scale data set that records state interactions with high temporal resolution. Doing so, we detect reciprocity between many country pairs in the international system and find that these reciprocating country pairs exhibit qualitatively different cooperative dynamics when compared to nonreciprocating pairs. Consistent with evolutionary theories of cooperation, reciprocating country pairs exhibit higher levels of stable cooperation and are more likely to punish instances of noncooperation. However, countries in reciprocity-based relationships are also quicker to forgive single acts of noncooperation by eventually returning to previous levels of mutual cooperation. By contrast, nonreciprocating pairs are more likely to exploit each other’s cooperation via higher rates of defection. Together, these findings provide the strongest evidence to date that reciprocity is a widespread mechanism for achieving international cooperation.

Forget about major life extension - Aging is a fundamental feature of multicellular life

Nelson and Masel, present a theoretical argument summarized by Wagner in his brief essay on their paper. From Wagner:

Paul Nelson and Joanna Masel present a theoretical result showing that aging in multicellular organisms is inevitable. The argument is as simple as it is powerful. Cellular senescence is a well-known consequence of the second law of thermodynamics, due to mutations, epigenetic misregulation, and protein misfolding. Molecular accidents in a cell can happen and they consequently do happen. In unicellular organisms, life is maintained because of natural selection against senescent cells and, thus, at the population level life can continue potentially indefinitely. However, in multicellular organisms, competition among cells has been killed to ensure cooperation among cells and thus the integrity of the organism. Breakdown of cooperation and unchecked competition among cells is known as cancer. Cooperation, and thus limited competition among cells, leads to the accumulation of senescent cells, while competition among cells kills the organism because of a breakdown of cooperation.

The result presented by Nelson and Masel... is a negative theoretical prediction based on very few but fundamental features of reality: senescence is a consequence of the second law of thermodynamics (molecular accidents and degradation are inevitable); senescence can be countered by natural selection; but natural selection among cells undermines cooperation among the cells of a multicellular organism. Thus, the multicellular organism is doomed either by senescence or cancer. The fact that this result is a negative prediction, like those of Gödel in mathematics, also explains why it can have a law-like certainty. It does not depend on contingent evolved properties of organisms but only on those which are intrinsic to life itself, namely that organisms are physical systems subject to the limits of thermodynamics, natural selection, and the need for cooperation among the cells in multicellular organisms.

Exercise alters the microbiome, enhancing immune function.

Reynolds points to interesting work by Allen et al. showing that exercise by lean, but not obese, subjects enhances microbial production of short chain fatty acids that suppress tissue irritation and inflammation in the colon as well as the rest of the body. These short fatty acids also boost metabolism and dampen the insulin resistance that is a precursor to diabetes.

Memories are stored by the extracellular matrix surrounding brain cells.

Fascinating work from Thompson et al., who show that degrading the extracellular matrix structure with local injections into visual cortex area 2L of bacterial enzyme chondroitinase ABC can abolish a remote visual fear memory:

Significance

Perineuronal nets (PNNs), a type of extracellular matrix only found in the central nervous system, wraps tightly around the cell soma and proximal dendrites of a subset of neurons. The PNNs are long-lasting structures that restrict plasticity, making them eligible candidates for memory processing. This work demonstrates that PNNs in the lateral secondary visual cortex (V2L) are essential for the recall of a remote visual fear memory. The results suggest a role of extracellular molecules in storage and retrieval of memories.

Abstract

Throughout life animals learn to recognize cues that signal danger and instantaneously initiate an adequate threat response. Memories of such associations may last a lifetime and far outlast the intracellular molecules currently found to be important for memory processing. The memory engram may be supported by other more stable molecular components, such as the extracellular matrix structure of perineuronal nets (PNNs). Here, we show that recall of remote, but not recent, visual fear memories in rats depend on intact PNNs in the secondary visual cortex (V2L). Supporting our behavioral findings, increased synchronized theta oscillations between V2L and basolateral amygdala, a physiological correlate of successful recall, was absent in rats with degraded PNNs in V2L. Together, our findings suggest a role for PNNs in remote memory processing by stabilizing the neural network of the engram.

The narcissism epidemic is dead?

An interesting piece from Wetzel et al., who find no evidence for a commonly reported narcissism epidemic over the past 10-20 years, based on the perception that today’s popular culture encourages individuals to engage in self-inflation:

Are recent cohorts of college students more narcissistic than their predecessors? To address debates about the so-called “narcissism epidemic,” we used data from three cohorts of students (1990s: N = 1,166; 2000s: N = 33,647; 2010s: N = 25,412) to test whether narcissism levels (overall and specific facets) have increased across generations. We also tested whether our measure, the Narcissistic Personality Inventory (NPI), showed measurement equivalence across the three cohorts, a critical analysis that had been overlooked in prior research. We found that several NPI items were not equivalent across cohorts. Models accounting for nonequivalence of these items indicated a small decline in overall narcissism levels from the 1990s to the 2010s (d = −0.27). At the facet level, leadership (d = −0.20), vanity (d = −0.16), and entitlement (d = −0.28) all showed decreases. Our results contradict the claim that recent cohorts of college students are more narcissistic than earlier generations of college students.

Figure: Difference between latent means estimated in partial-invariance models as a function of cohort and trait. The means of the 1990s cohort were constrained to 0 for model identification. Mean differences between the 1990s and the 2000s cohorts and between the 1990s and 2010s cohorts can be interpreted as standard deviations. Error bars show ±1 SE of the estimated mean difference.

The temporal organization of perception.

Ronconi et al. do interesting work suggesting that whether we perceive two visual stimuli as being separate events or a single event depends on a precise relationship between specific temporal window durations and specific brain oscillations measured by EEG (alpha oscillations (8–10 Hz)and theta oscillations (6–7 Hz):

Incoming sensory input is condensed by our perceptual system to optimally represent and store information. In the temporal domain, this process has been described in terms of temporal windows (TWs) of integration/segregation, in which the phase of ongoing neural oscillations determines whether two stimuli are integrated into a single percept or segregated into separate events. However, TWs can vary substantially, raising the question of whether different TWs map onto unique oscillations or, rather, reflect a single, general fluctuation in cortical excitability (e.g., in the alpha band). We used multivariate decoding of electroencephalography (EEG) data to investigate perception of stimuli that either repeated in the same location (two-flash fusion) or moved in space (apparent motion). By manipulating the interstimulus interval (ISI), we created bistable stimuli that caused subjects to perceive either integration (fusion/apparent motion) or segregation (two unrelated flashes). Training a classifier searchlight on the whole channels/frequencies/times space, we found that the perceptual outcome (integration vs. segregation) could be reliably decoded from the phase of prestimulus oscillations in right parieto-occipital channels. The highest decoding accuracy for the two-flash fusion task (ISI = 40 ms) was evident in the phase of alpha oscillations (8–10 Hz), while the highest decoding accuracy for the apparent motion task (ISI = 120 ms) was evident in the phase of theta oscillations (6–7 Hz). These results reveal a precise relationship between specific TW durations and specific oscillations. Such oscillations at different frequencies may provide a hierarchical framework for the temporal organization of perception.

Facebook admits its sociopathic side. Are social media the drug epidemic of our times?

An article by Farhad Manjoo notes that Facebook itself has pointed to work by Shakya and Christakis showing that overall the use of Facebook is negatively associated with well-being. From Shakya and Christakis:

For example, a 1-standard-deviation increase in “likes clicked” (clicking “like” on someone else's content), “links clicked” (clicking a link to another site or article), or “status updates” (updating one's own Facebook status) was associated with a decrease of 5%–8% of a standard deviation in self-reported mental health.

At the same time, work by Burke and Kraut suggests the effect of Facebook use on well-being depends on whether communication is passive (clicking "like" or on links) or more meaningful and active (actually engaging in back and forth conversations with friends important to the user). The latter use improves people's scores on well-being.

The ongoing debate is a useful one, particularly in light of suggestions that social media are a major drug epidemic of our times, addicting us to “short-term, dopamine-driven feedback loops” that “are destroying how society works.”

How early stress exposure influences adult decision making.

From Birn et al.:

Individuals who have experienced chronic and high levels of stress during their childhoods are at increased risk for a wide range of behavioral problems, yet the neurobiological mechanisms underlying this association are poorly understood. We measured the life circumstances of a community sample of school-aged children and then followed these children for a decade. Those from the highest and lowest quintiles of childhood stress exposure were invited to return to our laboratory as young adults, at which time we reassessed their life circumstances, acquired fMRI data during a reward-processing task, and tested their judgment and decision making. Individuals who experienced high levels of early life stress showed lower levels of brain activation when processing cues signaling potential loss and increased responsivity when actually experiencing losses. Specifically, those with high childhood stress had reduced activation in the posterior cingulate/precuneus, middle temporal gyrus, and superior occipital cortex during the anticipation of potential rewards; reduced activation in putamen and insula during the anticipation of potential losses; and increased left inferior frontal gyrus activation when experiencing an actual loss. These patterns of brain activity were associated with both laboratory and real-world measures of individuals’ risk taking in adulthood. Importantly, these effects were predicated only by childhood stress exposure and not by current levels of life stress.

Pax Technica - the new web of world government

Some clips from an Op-Ed piece by Roger Cohen:

...the puzzle remains. A year of Trump and the world has not veered off a precipice. Is there some 21st century iteration of Adam Smith’s “invisible hand” that explains this equilibrium?

One stab at defining such an invisible force that I find persuasive has been offered by Philip Howard, a professor of Internet Studies at Oxford University. He has coined the term “Pax Technica” to define the vast web of internet-connected devices that, together, create a network of stability.

Just as Smith’s “invisible hand” alluded to the unobservable market forces that lead to equilibrium in a free market, so Howard’s Pax Technica (the title of a book he wrote) evokes the cumulative stabilizing effect of the tens of billions of connected devices forming the Internet of Things (IoT). There is, simply put, too much connection in the world today to allow space for outright destruction, even emanating from Trump.

Implicit in this theory is a radical reordering of the nature of power. Pax Romana, Pax Britannica and Pax Americana depended on the military might of sovereign governments. Pax Technica shifts the source of stability to what Howard calls an “empire of connected things.” National authorities are less influential than supranational connected platforms and the private corporations behind them.

Under Pax Technica, there will be advocates of open systems and closed ones. There will be fierce competitions for influence. There will be nationalist and nativist reactions against the supranational apparent across the world today. There will be a reordering of societies — and possibly their increasing fragmentation — as Facebook traps people in what Chamath Palihapitiya, a former Facebook executive, recently called “short-term, dopamine-driven feedback loops.”

But there will also be the hard-to-measure investment of every owner of those billions of devices in a world of connectedness of which war is the enemy. Trump has come to power at a moment when power is increasingly passing out of the hands of governments. That may be even more reassuring than his incompetence.

Palihapatiya suggested Facebook has forged a world of “no civil discourse, no cooperation, misinformation.” Trump, of course, reflects that. But I think Facebook, on balance, also limits the devastation he can wreak.