Showing posts with label neuroscience. Show all posts
Showing posts with label neuroscience. Show all posts

Wednesday, June 28, 2017

Brain sex theories

Reframing sexual differentiation of the brain

20th century linear model for brain sex 

"For the past 50 years, the prevailing view of sexual differentiation of the brain has been a linear model in which chromosomal sex determines gonadal sex, which determines brain sex. (...) This iconic model based on the organizational/activational hypothesis14 has proved a sturdy framework for elucidating some, but not all, of the aspects of sexual differentiation of the brain."
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21st century model for brain sex

"Redefining sexual differentiation. In a twenty-first-century view of sexual differentiation of the brain, the importance of genetics and environment are incorporated along with the effects of hormones to provide a more nuanced portrayal of the types of variables that cause sex differences. Included in this view are the principles that hormones, sex chromosome genes and sex-specific environments have independent parallel differentiating effects that can interact with each other, often synergistically, to cause sex differences in the brain. However, there are also compensatory sex-specific variables that act to reduce sex differences rather than induce them. The result is that some aspects of male and female brain, behavior and physiology are unique from each other, whereas others are highly similar. Two important aspects of the redefined view are not illustrated here: sex differences are pervasive throughout the brain and not restricted to reproductively relevant neural circuits, and variability in the degree to which brain regions are masculinized or feminized in one individual results in a mosaic of relative maleness or femaleness and thereby greatly increases the variance between individuals of the same sex in a population."

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(McCarthy, Margaret M., and Arthur P. Arnold. "Reframing sexual differentiation of the brain." Nature neuroscience 14.6 (2011): 677-683.)




Sexual differentiation of the brain not only because of (prenatal) hormones, but also neuroimmunology and epigenetics

"Recent research in rodent models has led to dramatic shifts in our views of the mechanisms underlying the sexual differentiation of the brain. These include the surprising discoveries of a role for immune cells and inflammatory mediators in brain masculinization and a role for epigenetic suppression in brain feminization. How and to what degree these findings will translate to human brain development will be questions of central importance in future research in this field."
(McCarthy, Margaret M., Bridget M. Nugent, and Kathryn M. Lenz. "Neuroimmunology and neuroepigenetics in the establishment of sex differences in the brain." Nature Reviews Neuroscience (2017).)


Immune cells co-responsible for brain sex differentiation

"These studies demonstrate that immune cells in the brain interact with the nervous and endocrine systems during development, and are crucial for sexual differentiation of brain and behavior."
(Lenz, Kathryn M., et al. "Microglia are essential to masculinization of brain and behavior." Journal of Neuroscience 33.7 (2013): 2761-2772.)


AI detects differences between male and female brain rhythms

"The electric brain signals, measured by using EEG, of males and females show differences. The difference can't be detected by visual inspection, not even by the trained eye of a neurologist. A 'deep learning' computer is able to find it. (...) The main difference is in the 'beta activity', a frequency range between 20 and 25 Hz. These rhythms have to do with cognition and with tasks that are emotionally positive or negative. It is known from previous research that females are better capable of recognizing emotion: this could indicate a difference in beta activity. Within the context of this research project, this has not been elaborated further."
(University of Twente. "Male and female brain rhythms show differences." ScienceDaily. ScienceDaily, 15 February 2018.)


MRI shows significant differences in brain development between male and female fetuses

"However, models of relative growth accounting for global measures revealed a complex temporal form, with strikingly similar cortical development in males and females at lobe scales. In contrast, local cortical growth patterns and larger scale white matter volume and surface measures differed significantly between male and female. Many proportional differences were maintained during neurogenesis and over 18 weeks of growth. These indicate sex related sculpting of neuroanatomy begins early in development, before cortical folding, potentially influencing postnatal development."
(Studholme, C., Kroenke, C. D., & Dighe, M. (2020). Motion corrected MRI differentiates male and female human brain growth trajectories from mid-gestation. Nature Communications, 11(1), 1-16.)


Friday, July 29, 2016

Autism, Asperger's and prenatal testosterone

Introduction: why autism studies may shed light on the behavior of the general population

People with autism or Asperger's have been found to have a lower 2D:4D digit ratio than average, and to have been exposed to higher amounts of prenatal testosterone:

"We found that the 2D:4D ratios of children with autism, their siblings, fathers and mothers were lower than population normative values. Children with AS, who share the social and communicative symptoms of autism but have normal or even high IQ, had higher 2D:4D ratios than children with autism but lower ratios than population normative values."

(source: The 2nd to 4th digit ratio and autism, J T Manning PhD, S Baron-Cohen PhD, S Wheelwright MA and G Sanders PhD, Version of Record online: 2 MAR 2007, retrieved July 1st 2016)

"[The study result] suggests that [boys with higher levels of fetal testosterone] have a greater proclivity for "approach-related behaviors," such as fun-seeking and impulsivity. [...] For males, such behaviors are often heightened in teenage years and are found in extremes in many psychiatric conditions, such as [...] autism."

(source: Fetal Testosterone May Program Boys' Behavior, By Live Science Staff | November 5, 2012, retrieved 22/07/2016)

"fT (fetal Testosterone) levels were positively associated with higher scores on the CAST (Childhood Autism Spectrum Test) and AQ-Child (Child Autism Spectrum Quotient). This relationship was seen within sex as well as when the sexes were combined, suggesting this is an effect of fT rather than of sex per se. [...] These findings are consistent with the hypothesis that prenatal androgen exposure is related to children exhibiting more autistic traits."

(source: British Journal of Psychology (2009), 100, 1–22, Fetal testosterone and autistic traits, Bonnie Auyeung, Simon Baron-Cohen, Emma Ashwin, Rebecca Knickmeyer, Kevin Taylor, and Gerald Hackett)

"“We previously knew that elevated prenatal testosterone is associated with slower social and language development, better attention to detail, and more autistic traits. Now, for the first time, we have also shown that these steroid hormones are elevated in children clinically diagnosed with autism. [...] These new results are particularly striking because they are found across all the subgroups on the autism spectrum, for the first time uniting those with Asperger Syndrome, classic autism, or Pervasive Developmental Disorder Not-Otherwise-Specified.”"

(source: Elevated ‘Male Hormones’ During Fetal Development Linked With Autism, www.iflscience.com, retrieved 22/07/2016, referring to Molecular Psychiatry (2015) 20, 369–376; doi:10.1038/mp.2014.48; published online 3 June 2014,Elevated fetal steroidogenic activity in autism, S Baron-Cohen et al.)


"The Empathizing–Systemizing (E-S) theory of typical sex differences suggests that individuals may be classified based on empathy and systemizing. An extension of the E-S theory, the Extreme Male Brain (EMB) theory suggests that autistic people on average have a shift towards a more masculinized brain along the E-S dimensions. Both  theories have been investigated in small sample sizes, limiting their generalizability. Here we leverage two large datasets (discovery n = 671,606, including 36,648 autistic individuals primarily; and validation n = 14,354, including 226 autistic individuals) to investigate 10 predictions of the E-S and the EMB theories. In the discovery dataset, typical females on average showed higher scores on short forms of the Empathy Quotient (EQ) and Sensory Perception Quotient (SPQ), and typical males on average showed higher scores on short forms of the Autism Spectrum Quotient (AQ) and Systemizing Quotient (SQ). Typical sex differences in these measures were attenuated in autistic individuals. Analysis of “brain types” revealed that typical females on average were more likely to be Type E (EQ > SQ) or Extreme Type E and that typical males on average were more likely to be Type S (SQ > EQ) or Extreme Type S. In both datasets, autistic individuals, regardless of their reported sex, on average were “masculinized.” Finally, we demonstrate that D-scores (difference between EQ and SQ) account for 19 times more of the variance in autistic traits (43%) than do other demographic variables including sex. Our results provide robust evidence in support of both the E-S and EMB theories."
(Greenberg, David M., Varun Warrier, Carrie Allison, and Simon Baron-Cohen. "Testing the empathizing–systemizing theory of sex differences and the extreme male brain theory of autism in half a million people." Proceedings of the National Academy of Sciences (2018): 201811032.)



(see also Effects of (fetal) testosterone on brain and behavior)

Inversely, the (neurological) study of people with autism may give indications of how prenatal testosterone influences the human brain in general, also in those who have been exposed to levels lower than those found in persons on the autistic spectrum. Autistic people might be on the extreme end of high prenatal testosterone levels, while a significant portion of non-autistic ("neurotypical") people may exhibit traits which tend towards the autistic extremes (eg. low empathy, agression, systemizing versus empathizing, etc), without actually being so extreme, depending on prenatal testosterone levels.

General studies on autism

"Autistic phenotypes have been linked (...) to increased protein synthesis at synapses (Bourgeron, ), higher excitatory to inhibitory neurotransmission (Rubenstein and Merzenich, ), enhanced local compared to global processing and connectivity (Happé and Frith, ), a bias toward systemizing over empathizing (Baron-Cohen, ), and enhanced perceptual functioning (Mottron et al., ). These patterns and theories are not mutually exclusive (...)."

(Crespi, Bernard J. "Autism As a Disorder of High Intelligence." Frontiers in Neuroscience 10 (2016).)


Tendency of people with autism to partner with others on the spectrum may raise the condition's prevalence

"The tendency of people with autism to partner with others on the spectrum may raise the condition’s prevalence within families and across the population, according to a new study.

Researchers used genetic modeling to estimate the impact of this ‘nonrandom mating’ pattern among individuals with autism. The approach uses equations to deduce how genetic traits move through populations."

"People with autism are up to 11 times more likely than their typical peers to choose a partner on the spectrum."

(Partner preferences may contribute to autism prevalence, Spectrum, December 5 2016)


People with autism have more symmetrical brains

"[I]n typically developing young people, the right brain hemispheres had densely packed connections.

'This fits with the idea that the right hemisphere has a more integrative function, bringing together many kinds of information,' the team wrote in a summary of their research.

However, in the participants with ASD, these brain connections were more evenly distributed across both hemispheres.
[...]

MRI scans revealed that connections between white matter in the brains of young people with autism were more symmetrical across hemispheres. [...]

'The idea behind asymmetry in the brain is that there is a division of labor between the two hemispheres,' Müller said. 'It appears this division of labor is reduced in people with autism spectrum disorder.'

That lack of specialization could manifest itself in what Müller calls 'weak central coherence' — a concept best summed up in the idiom, 'not seeing the forest for the trees.' Many people with ASD are very good at seeing details but have difficulty putting it all together into a cohesive narrative, he explained."

(Brain Connections Show More Symmetry Between Hemispheres in People With Autism,
Neuroscience News, December 1, 2016)


Facial features of boys with autism and Asperger's



"White lines are statistically significantly increased in boys with autism spectrum disorder (ASD), and black lines are statistically significantly reduced in boys with ASD relative to typically developing (TD) boys."
(source: https://molecularautism.biomedcentral.com/articles/10.1186/2040-2392-2-15)



"Frontonasal prominences (FNP) and lateral nasal prominences (LNP) are shown in purple, maxillary prominences (MAX) are shown in blue, mandibular prominences (MAND) are shown in green and second branchial arch derivatives are shown in shades of pink." 
(source: https://molecularautism.biomedcentral.com/articles/10.1186/2040-2392-2-15)

"We found that essential autism in boys is associated with a distinctive facial phenotype characterized by an increased breadth of the mouth, orbits and upper face, combined with a flattened nasal bridge and reduced height of the philtrum [the divot below the nose, above the top lip] and maxillary [upper jawbone] region. [...]
[W]e found a narrowing of the intercanthic distance [distance between the inner corners of the eyes], or mild hypotelorism [distance between the eyes]. These findings are complementary in that we found an overall decrease in intercanthic distance, which potentially translates to decreased interpupillary distance, although we did not directly measure that distance.[...]
(source: Facial phenotypes in subgroups of prepubertal boys with autism spectrum disorders are correlated with clinical phenotypes, Kristina Aldridge e.a., Molecular Autism 2011, retrieved July 2nd 2016)

"Aldridge and colleagues found the following distinct differences between facial characteristics of children with autism and those of typically developing children:
Children with autism have a broader upper face, including wider eyes.
Children with autism have a shorter middle region of the face, including the cheeks and nose.
Children with autism have a broader or wider mouth and philtrum -- the divot below the nose, above the top lip."
(source: Autistic facial characteristics identified, ScienceDaily, october 21 2011, retrieved July 2nd 2016)

More Asperger's in maths, physics, engineering and computer science than in general population

"A recent survey of Cambridge undergraduates confirmed the belief that it is among the students of mathematics, physics, engineering and computer science that Asperger syndrome is most likely to be found."
(James, Ioan. "Singular scientists." Journal of the Royal Society of Medicine 96.1 (2003): 36-39.)


Current standard tests for detecting autism may miss autistic females

"Overall, the findings suggest that some autistic females may be missed by current diagnostic procedures."
(Ratto, Allison B., et al. "What About the Girls? Sex-Based Differences in Autistic Traits and Adaptive Skills." Journal of Autism and Developmental Disorders (2017): 1-14.)


Autistic traits are on a continuum in the wider community, with ASD representing an extreme end

"There is accumulating evidence that autistic traits are on a continuum in the wider community, with ASD representing an extreme end of the distribution."
(Tan, Diana Weiting, Murray T. Maybery, Michael W. Clarke, Renata Di Lorenzo, Melissa O. Evans, Michael Mancinone, Christina Panos, and Andrew JO Whitehouse. "No relationship between autistic traits and salivary testosterone concentrations in men from the general population." PloS one 13, no. 6 (2018): e0198779.)


Symptom severity in autism spectrum disorder is related to the frequency and severity of nausea and vomiting during pregnancy

"Impairments in social responsiveness in offspring, as indexed by SRS total score, significantly increased as a function of the frequency and severity of their mothers’ NVP [Nausea and vomiting during pregnancy], as did the level of language difficulties as indexed by the Global Communication Composite of the CCC-2.
The strong, positive association between increasing frequency and severity of NVP and ASD severity in offspring provides further evidence that exposure to an atypical hormonal environment during prenatal life may affect neurodevelopment and contribute to the ASD phenotype."
(Whitehouse, Andrew JO, Gail A. Alvares, Dominique Cleary, Alexis Harun, Angela Stojanoska, Lauren J. Taylor, Kandice J. Varcin, and Murray Maybery. "Symptom severity in autism spectrum disorder is related to the frequency and severity of nausea and vomiting during pregnancy: a retrospective case-control study." Molecular Autism 9, no. 1 (2018): 37.)


Criticism of the 'extreme male brain' theory as an explanation for autism

"The implication of this critical review of theory is that the concept of ‘the extreme male brain’ as a description or explanation of autism should be abandoned and replaced with the recognition that scores at any point on the AQ can be the product of a brain within either a male of female person. This allows the search for the biological basis, developmental causes and clinical correlates of autism to be broadened beyond that of differences between the sexes."
[...] ‘[E]ssentialism’ is the philosophical position which claims that things have a set of characteristics that makes them what they are. In the current context, essentialism would claim that there is such a thing as ‘maleness’ and that men deviating from this maleness are not truly male, rather than that such variation merely makes maleness more diverse."
(Ridley, Rosalind. "Some difficulties behind the concept of the ‘Extreme male brain’in autism research. A theoretical review." Research in Autism Spectrum Disorders 57 (2019): 19-27.)


Further support for extreme male brain theory concerning autism

"We demonstrated that females and males with ASD tended to follow the male pattern of developmental changes in interhemispheric connectivity, supporting the EMB theory of ASD."
(Kozhemiako, Nataliia, Vasily Vakorin, Adonay S. Nunes, Grace Iarocci, Urs Ribary, and Sam M. Doesburg. "Extreme male developmental trajectories of homotopic brain connectivity in autism." Human Brain Mapping, First published: 11 October 2018.)


High-functioning Autism (Asperger) associated with low 2D:4D in women and high 2D:4D in men

"Abstract
BACKGROUND:
The 'extreme male brain' theory suggests that autism spectrum disorder (ASD) is an extreme variant of male intelligence. However, somewhat paradoxically, many individuals with ASD display androgynous physical features regardless of gender.
AIMS:
To assess physical measures, supposedly related to androgen influence, in adults with and without ASD.
METHOD:
Serum hormone levels, anthropometry, the ratio of 2nd to 4th digit length (2D:4D) and psychiatric symptomatology were measured in 50 adults with high-functioning ASD and age- and gender-matched neurotypical controls. Photographs of face and body, as well as voice recordings, were obtained and assessed with respect to gender coherence, blindly and independently, by eight assessors.
RESULTS:
Women with ASD had higher total and bioactive testosterone levels, less feminine facial features and a larger head circumference than female controls. Men in the ASD group were assessed as having less masculine body characteristics and voice quality, and displayed higher (i.e. less masculine) 2D:4D ratios, but similar testosterone levels to controls. Androgynous facial features correlated strongly and positively with autistic traits measured with the Autism-Spectrum Quotient in the total sample. In males and females with ASD dehydroepiandrosterone sulfate did not decrease with age, in contrast to the control group.
CONCLUSIONS:
Women with ASD had elevated testosterone levels and several masculinised characteristics compared with controls, whereas men with ASD displayed several feminised characteristics. Our findings suggest that ASD, rather than being characterised by masculinisation in both genders, may constitute a gender defiant disorder."
(Bejerot, Susanne, Jonna M. Eriksson, Sabina Bonde, Kjell Carlström, Mats B. Humble, and Elias Eriksson. "The extreme male brain revisited: gender coherence in adults with autism spectrum disorder." The British Journal of Psychiatry 201, no. 2 (2012): 116-123.)


Many different neurological characteristics underly a common diagnosis of ASD

"Growing evidence shows that neural bases of ASDs cannot be pinpointed to specific regions of the brain, but that symptomatology is instead linked to atypical connectivity within and between functionally specialized brain networks (including ‘social brain’ networks). However, few neuroimaging findings have been widely replicated and no clear picture of the brain bases of sociocommunicative impairments in ASDs has emerged.
A main factor that has prevented consensus findings is etiological diversity. While diagnostic criteria focus on social deficits in ASDs, these probably result from the convergence of many different neurodevelopmental trajectories and many different causative factors."
(Müller, Ralph-Axel, and Inna Fishman. "Brain Connectivity and Neuroimaging of Social Networks in Autism." Trends in Cognitive Sciences (2018).)


Autism and neurological "rigidity"

"What does autism look like in the brain?A new study offers a fresh perspective on how autism works in the brain. Symptoms, the authors say, may be linked to persistent connections in the brain."
(What does autism look like in the brain?, Medical News Today, Published Tuesday 20 November 2018 By Maria Cohut, Fact checked by Paula Field)


Autism signs in ears and mouth form

"[M]inor malformations of the external ears -- notably posterior rotation, in which the top of the ear is tilted backward more than 15 degrees, are more common in children with autism than in typically developing children, children with mental retardation or siblings of children with autism. (...)
Child with autism is normal in appearance, at least to the untrained eye. But he has a few physical anomalies characteristic of the disorder. The corners of his mouth are low compared with the center of his upper lip, and the tops of his ears flop over (left). His ears are a bit lower than normal and have an almost square shape (right)."

(The Early Origins of Autism by Patricia M. Rodier, originally published in "Scientific American," February 2000)


Low fetal cortisol associated with ASD

"Fetal exposure to lower levels of maternal cortisol was associated with higher levels of ASD symptoms only among boys. The observed hypocortisolemic profile exhibited by these mothers may indicate a risk factor that precedes the stress of caregiving for a child with ASD and may not be solely a consequence of the stress of caregiving, as previously thought. These findings confirm the value of examining prenatal hormone exposures as predictors of ASD risk and support the premise that altered prenatal steroid exposures may play a role in the etiology of ASD."
(Ram, Sheena, Mariann A. Howland, Curt A. Sandman, Elysia Poggi Davis, and Laura M. Glynn. "Prenatal Risk for ASD: Fetal Cortisol Exposure Predicts Child Autism-Spectrum-Disorder Symptoms." Clinical Psychological Science (2018): 2167702618811079.)


39% more girls have Autism Spectrum Disorder than currently diagnosed

"The current study estimates that approximately 39 percent more girls should be diagnosed with ASD."
(Barnard-Brak, Lucy, David Richman, and M. Hasan Almekdash. "How many girls are we missing in ASD? An examination from a clinic-and community-based sample." Advances in Autism (2019).)


People with ASD have higher non-verbal than verbal skills; using abbreviated IQ-tests may misrepresent IQ

"The Fifth Edition of the Stanford-Binet Intelligence Scales (SB5; Roid, G. H. (2003). Stanford Binet intelligence scales (5th ed.). Itasca, IL: Riverside Publishing) is relatively new, with minimal published research on general populations and none with special populations. The present study provides information on the cognitive profiles of children with ASD (N=63) and on the whether the abbreviated battery is representative of the full scale. A high percentage of the children had significantly stronger nonverbal (vs. verbal) skills. This pattern was not related to Full Scale IQ, age or diagnostic subgroup. IQs derived from the abbreviated battery accounted for a large proportion of the variance in FSIQ relative to comparable abbreviated batteries. However, caution is warranted when using the abbreviated battery, as it misrepresents actual ability in a small percentage of cases."
(Coolican, Jamesie, Susan E. Bryson, and Lonnie Zwaigenbaum. "Brief report: Data on the Stanford–Binet intelligence scales in children with autism spectrum disorder." Journal of Autism and Developmental Disorders 38.1 (2008): 190-197.)


General neuroscience

Cognitive empathy can be learned, but erodes without continuous reinforcement

"Cognitive empathy can be learned [...] but the bad news is that it needs continuous reinforcement."
(Cundell, Diana R. "Culturing the Empathic Health Professional: Challenges and Opportunities." Healthcare Transformation 2.2 (2017): 71-83.)

Neurofeminism

"However, the outcome of research on differences between women and men in terms of linguistic abilities, spatial orientation, or mathematics—that is, of cognitive capacities in general—is by no means conclusive (Schmitz, 1999; Coluccia and Louse, 2004; Spelke, 2005; Mehl et al., 2007; Else-Quest et al., 2010; Lavenex and Lavenex, 2010; Fausto-Sterling et al., 2012a,b); neither are results on emotional or rational processing (Karafyllis, 2008) (...).
(...)
Feminist neuroscientists have uncovered inconsistent findings concerning sex differences and elaborated similarities between or variations within the gender groups, not only on the level of behavior and performance but also concerning their apparently biological sources, i.e., the brain networks and their functions (Frost et al., 1999; Blanch et al., 2004; Ulshöfer, 2008; Wallentin, 2009; Jordan-Young, 2010; Bluhm et al., 2012; Jordan-Young and Rumiati, 2012; Kuria, 2012; Roy, 2012; Vidal, 2012; Dussauge, 2014; Kaiser, 2014; Sommer et al., 2004, 2008).
(...)
 The concept of brain plasticity points out that brain structures and brain functions are not in any shape or form determined by evolution or remain unchanged during a life span. At birth, the brain is not at all branded or defined, and this network of nerve cells, neuronal fibers and their synapses is not ‘completely formed’ by genetic information.
(...)
The brain plasticity concept is important for deconstructing unilinear statements about a supposedly biological determination of behavior, attitudes, etc. In narrating plasticity stories, neurofeminist scholars mainly stress a return of genealogies of cause and effect, arguing that gendered social experiences and power relations impact the forming of the gendered brain’s structure and function more than vice versa (e.g., Vidal, 2012).
(...)
Modern neurodeterminism does not care whether brain structures and functions are innate or formed by experience, considering it to be irrelevant whether the individual brain is formed by nature or nurture.
(...)
There is an interesting ambivalence that is not articulated in current neurocultural discourse: while plasticity concepts are included in modern neurodeterminism up to the moment of measuring, they are dropped again when it comes to predicting future behavior. Although insisting on the forming of biological materiality from ‘outside’, neurocultural discourse is in danger of remaining connected to concepts that presume to predict behavior, thinking, and acting due to biological entities from ‘inside’. The impacts of these normative framings on cultural understandings, social practices, and governmental discourses are already the subject of critical analyses (Choudhury et al., 2009; Choudhury and Slaby, 2011). Neurofeminism must question the gender-based and intersected legitimations that are drawn from neurocultural discourse and practices, in particular because neuroscientific knowledge production can be used for various socio-political in- and exclusions (O’Connell, 2014).
(...)
One example of a critical examination of neurocultures is Höppner and Schmitz (2014) analysis which pursues the question of how the phenomenon of neuropharmacological enhancement is discussed in the German media. The analysis of 21 public media articles (published between 2006 and 2011 in four German online journals) shows that self-optimization of the brain with the help of neuropharmaceuticals is increasingly predicted as a universal strategy for success. Whereas success-oriented males tend to aim for the improvement of their rational skills, success-oriented-women should focus on regulating their self-confidence. Moreover, the articles once again manifest a hierarchized status quo of rational skills over emotional capacities and a different proficiency level that neuro-enhanced subjects could achieve depending on their gender. While women would need a continual consumption of neuro-enhancers in order to achieve a proficiency level similar to male capacities for a limited time, men should take neuro-enhancers only once a while to selectively enhance their supposedly high capacities (a result of their biological setup) to become the best within the group of the best men.
(...)
Since gendered conceptions and connotations shape individual actions, social practices, and social segregation, gender-sensitive analyses can help to assess the entanglements within and the outcomes of neuro-pedagogies in medial discourse, schools, and universities. More precisely, such approaches outline the interdependencies of bodily materiality, social experiences, and cultural norms by underpinning the alterability and interdependencies of brains, behavior, thinking, and acting throughout a person’s lifetime. In doing so, they suggest alternative concepts and settings for individual learning processes (e.g., Vidal, 2012; Just, 2014; Mead Vetter, 2014)."
(http://journal.frontiersin.org/article/10.3389/fnhum.2014.00546/full)

The brain does not work like a computer 

"No matter how hard they try, brain scientists and cognitive psychologists will never find a copy of Beethoven’s 5th Symphony in the brain – or copies of words, pictures, grammatical rules or any other kinds of environmental stimuli. The human brain isn’t really empty, of course. But it does not contain most of the things people think it does – not even simple things such as ‘memories’.[...]
We don’t store words or the rules that tell us how to manipulate them. We don’t create representations of visual stimuli, store them in a short-term memory buffer, and then transfer the representation into a long-term memory device. We don’t retrieve information or images or words from memory registers. Computers do all of these things, but organisms do not. [...]
A wealth of brain studies tells us, in fact, that multiple and sometimes large areas of the brain are often involved in even the most mundane memory tasks. When strong emotions are involved, millions of neurons can become more active.[...]
Misleading headlines notwithstanding, no one really has the slightest idea how the brain changes after we have learned to sing a song or recite a poem. But neither the song nor the poem has been ‘stored’ in it. The brain has simply changed in an orderly way that now allows us to sing the song or recite the poem under certain conditions. When called on to perform, neither the song nor the poem is in any sense ‘retrieved’ from anywhere in the brain, any more than my finger movements are ‘retrieved’ when I tap my finger on my desk. We simply sing or recite – no retrieval necessary. [...]
For any given experience, orderly change could involve a thousand neurons, a million neurons or even the entire brain, with the pattern of change different in every brain."
(source: "The Empty Brain", by Robert Epstein, senior research psychologist at the American Institute for Behavioral Research and Technology in California, published on Aeon, retrieved 26-7-2016)

Imagine a high fetal testosterone, low 2D:4D ratio brain, which in our hypothesis is highly rigid, interacting with the world. If change would just imply adapting a few data or algorithms, as the to-be-abandoned "the brain is like a computer"-model states, it would be able to handle this. But an extensive change throughout the whole brain, as a more realistic brain model implies, will be outright impossible or at least a painful experience. Maybe easier for such a brain to not adapt to the world, but adapt the world to itself - which at the surface corresponds with dogmatism and radicalism, and the kind of dictatorship we know of low 2D:4D ratio leaders like Mao and Stalin?

Do newborn babies imitate adults? New study says 'no', rekindling long-standing debate

"Professor Slaughter and her colleagues tested infant responses to a wide range of adult gestures at one, three, six and nine weeks of age. (...) 'To our surprise we did not find any evidence that babies imitated any of the gestures at any of the time points,' Professor Slaughter said."
​(source: abc.net.au, retrieved 17-5-2016)


Free will

"Using newer fMRI technology, Soon et al (2008) used a learning algorithm to predict "free will" decisions from brain activity about 7 seconds (and up to 10 seconds) prior to the subject reporting awareness of having made the decision. This experiment has been replicated in other labs: Presenter Marcus du Satoy undergoes it for the BBC documentary The Secret You (2009/2010), and remarks that there is something creepy about the radiologist being aware of his decision several seconds before even he is."


source: Predictive Experiments on Neuroscience of Free Will_, retrieved 18-5-2016)


Perception is constructed by the unconscious mind, then handed to consiousness

"But research shows that every perception we have is actually constructed by the unconscious mind, which then instantly hands it to consciousness. What the unconscious mind uses to do this constructing is largely sensory stimulations. We grasp this information with our senses, we process it with our brains unconsciously, and the product enters our consciousness."
("Spiritual emergency", adjunct professor psychiatrist James Carpenter, in Aeon, retrieved 11/8/2016)


Nucleus basalis, acetylcholine and new connections in the brain

"Our hunch that it’s easier to learn when you’re young isn’t completely wrong, or at least it has a real basis in neurology. However, the pessimistic assumption that learning somehow ‘stops’ when you leave school or university or hit thirty is at odds with the evidence. It appears that a great deal depends on the nucleus basalis, located in the basal forebrain. Among other things, this bit of the brain produces significant amounts of acetylcholine, a neurotransmitter that regulates the rate at which new connections are made between brain cells. This in turn dictates how readily we form memories of various kinds, and how strongly we retain them. When the nucleus basalisis ‘switched on’, acetylcholine flows and new connections occur. When it is switched off, we make far fewer new connections.
Between birth and the age of ten or eleven, the nucleus basalisis is permanently ‘switched on’. It contains an abundance of the neurotransmitter acetylcholine, and this means new connections are being made all the time. Typically this means that a child will be learning almost all the time — if they see or hear something once they remember it. But as we progress towards the later teenage years the brain becomes more selective. From research into the way stroke victims recover lost skills it has been observed that the nucleus basalis only switches on when one of three conditions occur: a novel situation, a shock, or intense focus, maintained through repetition or continuous application."
(Source: "Master of many trades", Robert Twigger, Aeon, 2016)

Ways to study intuitive (automatic, unintentional) empathy without relying on self-reports

"[W]e define intentional empathy as experience sharing that is consistent with a target person’s (i.e., the empathizer’s) focal intention, whatever that may be. By contrast, we conceptually define unintentional empathy as experience sharing that is inconsistent with a target person’s focal intention. Drawing upon conceptual analysis of intentionality within social cognition (Moors & De Houwer, 2006), we distinguish between weak and strong forms of unintentionality. Whereas weak unintentionality describes a process that starts spontaneously without any intention, here, we focus on a strong form of unintentional empathy: empathy that occurs despite intentions to the contrary. To date, no research has defined unintentional empathy with this conceptual precision nor examined unintentional empathy in this strong form.
[...]
To examine the distinction between intentional and unintentional empathy, we use implicit measurement and multinomial modeling. Implicit measures capture spontaneous evaluations while bypassing self-report (for review, see Wentura & Degner, 2010) and are useful for studying empathy, particularly given that people may be motivated to report being highly empathic (Paulhus & Reid, 1991).
[...]
To understand variation in empathy for pain, we created a new sequential priming task: the pain identification task (PIT). This task is modeled on similar sequential priming tasks used in social cognition research, such as the weapon identification task (Payne, 2001). Participants view successive prime and target images, each of which depicts experiences that are painful (i.e., hand pierced with needle) or non-painful (i.e., hand brushed with Q-tip). The task uses well-validated stimuli that people clearly judge as painful or non-painful (Lamm et al., 2007, 2010; Perry et al., 2010). Participants’ focal task is to judge the target experience as painful or non-painful while avoiding any influence of the primes (cf. Payne, 2001); responses are coded for accuracy. Thus, participants’ intentions are set in direct opposition to the influence of the primes."
(Cameron, C. Daryl, Victoria L. Spring, and Andrew R. Todd. "The empathy impulse: A multinomial model of intentional and unintentional empathy for pain." Emotion 17.3 (2017): 395.)


Neural synchronization between individuals

"Indeed, speaker–listener neural synchronization is associated with successful comprehension of a verbal message [...].
(...)
Finally, we assessed whether a self-reported tendency for empathy, that is, the disposition to catch others’ emotional states, would be associated with intersubject synchronization of brain activity. [Our findings suggest (...)] that activity within [the posterior middle temporal gyrus region] was most similar in participants who considered themselves as highly empathetic.
(...)
Catching emotions that other humans express—here in dynamic scenes resembling everyday life—is associated with intersubject synchronization of brain circuitries related to emotional, attentional, and mentalizing processes."
(Nummenmaa, Lauri, et al. "Emotions promote social interaction by synchronizing brain activity across individuals." Proceedings of the National Academy of Sciences 109.24 (2012): 9599-9604.)

"Brain-to-brain synchrony also reflected how much students liked the teacher and how much they liked each other."
(When Students Pay Attention in Class, Their Brains Are in Sync, Neuroscience News, Apr 27, 2017)


The psychopath's brain

"Many psychopaths show a distinctive pattern of brain activity, according to James Fallon, a UC Irvine School of Medicine neuroscientist who accidentally found out he may be one himself.
(...)
Here's a scan of a normal brain (top) and Fallon's brain (bottom). Notice that the normal scan shows much more activity (yellow and red) in the lower frontal lobe than Fallon's (mostly blue).
James Jim Fallon PET scanJames Fallon
The scans showed reduced activity in an area towards the center of the brain called the orbital cortex thought to play a role in regulating our emotions and impulses as well as morality and aggression.

Here's a set of brain scans of Fallon's family members. Again, you can see that Fallon's brain has large gaps in activity (black sections) in areas where his wife and children show normal (yellow and green) activity."

fallon brain scansJames Fallon
(Here's what a psychopath's brain looks like, Business Insider UK, jul.22, 2015)

"Scientists who scanned the brains of men convicted of murder, rape and violent assaults have found the strongest evidence yet that psychopaths have structural abnormalities in their brains. (...) 
The results showed that the psychopaths' brains had significantly less grey matter in the anterior rostral prefrontal cortex and temporal poles than the brains of the non-psychopathic offenders and non-offenders. 
These areas of the brain are important for understanding other people's emotions and intentions, and are activated when people think about moral behavior, the researchers said. 
Damage to these areas is linked with a lack of empathy, a poor response to fear and distress and a lack of self-conscious emotions such as guilt or embarrassment. 
Lindsay Thomson, a professor of forensic psychiatry at the University of Edinburgh who was not involved in this study, said Blackwood's findings add to evidence that psychopathy is a distinct neurodevelopmental brain disorder. Research shows that most violent crimes are committed by a small group of persistent male offenders with ASPD." (Anti-Social Personality Disorder)
(Study finds psychopaths have distinct brain structure, Reuters.com, may 7, 2012)


Neuromarketing adopts approach where behavior is rooted in genes and phsyiological processes

"Researchers of this approach consider our behaviors to be results of psychological processes embodied physiologically in the brain and nervous system. Thus, the biological influences may be rooted in our genes and shape the activities in our brain, and thus behaviors through actions on hormones and neurotransmitters. In this paradigm, our genotypes may be interpreted as a measure of individual differences, while brain activities may be observed and taken as more direct measures of the underlying psychological process."
(Chark R. (2018) Neuromarketing. In: Moutinho L., Sokele M. (eds) Innovative Research Methodologies in Management. Palgrave Macmillan, Cham)


Prenatal maternal anger stress causes neurobiological changes in offspring (with enhanced aggressive behaviors, reduced anxiety)


"Anger stressed maternal rats showed a significant increase in locomotion and aggression but a reduction in sucrose preference. Offspring subjected to pre-gestational anger stress displayed enhanced aggressive behaviors, reduced anxiety, and sucrose preference. Further, offspring subjected to pre-gestational stress showed significant impairments in the recognition index (RI) on the object recognition test and the number of platform crossings in the Morris water maze test. The monoaminergic system was significantly altered in pre-gestationally stressed offspring, and the expression of phosphorylated cyclic adenosine monophosphate response element binding protein (P-CREB), brain-derived neurotrophic factor (BDNF), and serotonin transporter (SERT) levels in pre-gestational stressed offspring were altered in some brain regions. (...) These findings suggest that anger stress before pregnancy could induce aggressive behaviors, cognitive deficits, and neurobiological alterations in offspring."
(Wei, Sheng, et al. "Impact of anger emotional stress before pregnancy on adult male offspring." Oncotarget 8.58 (2017): 98837.)


"Friends" are people with similar neural activity

"The researchers found that you can predict who people are friends with just by looking at how their brains respond to video clips. Friends had the most similar neural activity patterns, followed by friends-of-friends who, in turn, had more similar neural activity than people three degrees removed (friends-of-friends-of-friends).
(...)
The findings revealed that neural response similarity was strongest among friends, and this pattern appeared to manifest across brain regions involved in emotional responding, directing one's attention and high-level reasoning. Even when the researchers controlled for variables, including left-handed- or right-handedness, age, gender, ethnicity, and nationality, the similarity in neural activity among friends was still evident. The team also found that fMRI response similarities could be used to predict not only if a pair were friends but also the social distance between the two."
(Dartmouth College. "Your brain reveals who your friends are: Study illustrates how similar neural responses predict friendships." ScienceDaily. ScienceDaily, 30 January 2018.
Study: 
Carolyn Parkinson, Adam M. Kleinbaum, Thalia Wheatley. Similar neural responses predict friendship. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-017-02722-7)


Meditation does not significantly augment people's compassion or social connectedness, nor does it lower prejudice or agression

"Initial analysis indicated that meditation did have an overall positive impact. The researchers said meditation made people feel moderately more compassionate or empathic, compared to if they had done no other new emotionally-engaging activity.
However further analysis revealed that it played no significant role in reducing aggression or prejudice or improving how socially-connected someone was. The most unexpected result of this study, though, was that the more positive results found for compassion had important methodological flaws -- compassion levels in some studies only increased if the meditation teacher was also an author of the published report.
Overall, these results suggest that the moderate improvements reported by psychologists in previous studies may be the result of methodological weaknesses and biases, said the researchers."
(Coventry University. "Meditation has limited role in making you a better person, says study: For decades many people have claimed meditation can change how we behave towards others and make us more compassionate -- but new research suggests this is not the case.." ScienceDaily. ScienceDaily, 5 February 2018. )


‘Left-cradling bias’ linked to better social cognitive abilities in children

"Children who cradle dolls on the left show higher social cognitive abilities than those who do not, according to new research from City, University of London.
(...)
The study builds on previous knowledge of a 'left-cradling bias' -- the phenomenon that humans will typically cradle a baby on their left side, enabling both parent and child to keep the other in their left visual field -- which is unrelated to dominance of the use of right or left hand. Information from the left visual field is processed by the right hemisphere of the brain, which is associated with emotion and the perception of facial expression.
(...)
[Children] who showed this bias had a significantly higher social ability score compared with those who held the doll on the right."
(City, University of London. "‘Left-cradling bias’ linked to better social cognitive abilities in children." ScienceDaily. ScienceDaily, 9 July 2018. )