Parental lying thwarted both their children and researchers

This 2017 German human study explored the relationship between birth stress and handedness. The authors summarized previous research which, among other points, estimated epigenetic contributions to handedness as great as 75%.

The study hit a snag in its reliance on the sixty participants (average age 24) completing, with the assistance of their parents and medical records, a 24-item questionnaire of maternal health problems during pregnancy, substance use during pregnancy, and birth complications. The subjects didn’t provide accurate information. For example:

  • Only one of the subjects reported maternal alcohol use during pregnancy. An expected number would have been 26.
  • None of the subjects reported maternal mental illness during pregnancy. An expected number would have been at least 7.

The subjects’ parents willingly misled their children about facts of their child’s important earliest development periods. This is unethical to the children in that once it is recognized, it diminishes or destroys the society among family members. This study’s example is also of general interest to anyone who values not being lied to, like me.

As I mentioned on the Welcome page, lies and omissions ruin the standard scientific methodology of surveying parents and caregivers. The absence of evidence greatly increased the difficulty for researchers in determining causes of epigenetic effects still present in the subjects’ lives.

The parental lying is again unethical in that it diminished or destroyed the society between the sources of information – the research subjects – and the users of the information. It adversely affected anyone who values evidence-based research. The research hypothesis itself was worthwhile based on the prior studies cited and elsewhere such as Is what’s true for a population what’s true for an individual?.

http://www.tandfonline.com/doi/full/10.1080/1357650X.2017.1377726 “DNA methylation in candidate genes for handedness predicts handedness direction” (not freely available)

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Genetic imprinting, sleep, and parent-offspring conflict

This 2016 Italian review subject was the interplay of genetic imprinting and sleep regulation:

“Sleep results from the synergism between at least two major processes: a homeostatic regulatory mechanism that depends on the accumulation of the sleep drive during wakefulness, and a circadian self-sustained mechanism that sets the time for sleeping and waking throughout the 24-hour daily cycle.

REM sleep apparently contravenes the restorative aspects of sleep; however, the function of this ‘paradoxical’ state remains unknown. Although REM sleep may serve important functions, a lack of REM sleep has no major consequences for survival in humans; however, severe detrimental effects have been observed in rats.

Opposite imprinting defects at chromosome 15q11–13 are responsible for opposite sleep phenotypes as well as opposite neurodevelopmental abnormalities, namely the Prader-Willi syndrome (PWS) and the Angelman syndrome (AS). Whilst the PWS is due to loss of paternal expression of alleles, the AS is due to loss of maternal expression.

Maternal additions or paternal deletions of alleles at chromosome 15q11–13 are characterized by temperature control abnormalities, excessive sleepiness, and specific sleep architecture changes, particularly REM sleep deficits. Conversely, paternal additions or maternal deletions at chromosome 15q11–13 are characterized by reductions in sleep and frequent and prolonged night wakings.

The ‘genomic imprinting hypothesis of sleep’ remains in its infancy, and several aspects require attention and further investigation.”

http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1006004 “Genomic Imprinting: A New Epigenetic Perspective of Sleep Regulation”


A commenter to the review referenced a 2014 study Troubled sleep: night waking, breastfeeding, and parent–offspring conflict that received several reactions, including one by the same commenter. Here are a few quotes from the study author’s consolidated response:

“‘Troubled sleep’ had two major purposes. The first was to draw attention to the oppositely perturbed sleep of infants with PWS and AS and explore its evolutionary implications. The involvement of imprinted genes suggests that infant sleep has been subject to antagonistic selection on genes of maternal and paternal origin with genes of maternal origin favoring less disrupted sleep.

My second major purpose was a critique of the idea that children would be happier, healthier and better-adjusted if we could only return to natural methods of child care. This way of thinking is often accompanied by a belief that modern practices put children at risk of irrevocable harm. The truth of such claims is ultimately an empirical question, but the claims are sometimes presented as if they had the imprimatur of evolutionary biology. This appeal to scientific authority often seems to misrepresent what evolutionary theory predicts: that which evolves is not necessarily that which is healthy.

Why should pregnancy not be more efficient and more robust than other physiological systems, rather than less? Crucial checks, balances and feedback controls are lacking in the shared physiology of the maternal–fetal unit.

Infant sleep may similarly lack the exquisite organization of systems without evolutionary conflict. Postnatal development, like prenatal development, is subject to difficulties of evolutionarily credible communication between mothers and offspring.”

The author addressed comments related to attachment theory:

“Infants are classified as having insecure-resistant attachment if they maintain close proximity to their mother after a brief separation while expressing negative emotions and exhibiting contradictory behaviors that seem to both encourage and resist interaction. By contrast, infants are classified as having insecure-avoidant attachment if they do not express negative emotion and avoid contact with their mother after reunion.

Insecure-avoidant and insecure-resistant behaviors might be considered antithetic accommodations of infants to less responsive mothers; the former associated with reduced demands on maternal attention, the latter with increased demands. A parallel pattern is seen in effects on maternal sleep. Insecure-avoidant infants wake their mothers less frequently, and insecure-resistant infants more frequently, than securely attached infants.

Parent–child interactions are transformed once children can speak. Infants with more fragmented sleep at 6 months had less language at 18 and 30 months. Infants with AS have unconsolidated sleep and never learn to speak. The absence of language in the absence of expression of one or more MEGs [maternally expressed imprinted genes] is compatible with a hypothesis in which earlier development of language reduces infant demands on mothers.”

Regarding cultural differences:

“China, Taiwan and Hong Kong have both high rates of bed-sharing and high rates of problematic sleep compared with western countries. Within this grouping, however, more children sleep in their own room but parents report fewer sleep problems in Hong Kong than in either China or Taiwan. Clearly, cultural differences are significant, and the causes of this variation should be investigated, but the differences cannot be summarized simply as ‘west is worst’.

The fitness [genetic rather than physical fitness] gain to mothers of an extra child and the benefits for infants of longer IBIs [interbirth intervals] are substantial. These selective forces are unlikely to be orders of magnitude weaker than the advantages of lactase persistence, yet the selective forces associated with dairying have been sufficient to result in adaptive genetic differentiation among populations. The possibility of gene–culture coevolution should not be discounted for behaviors associated with infant-care practices.”

Regarding a mismatch between modern and ancestral environments:

“I remain skeptical of a tendency to ascribe most modern woes to incongruence between our evolved nature and western cultural practices. We did not evolve to be happy or healthy but to leave genetic descendants, and an undue emphasis on mismatch risks conflating health and fitness.

McKenna [a commenter] writes ‘It isn’t really nice nor maybe even possible to fool mother nature.’ Here I disagree. Our genetic adaptations often try to fool us into doing things that enhance fitness at costs to our happiness.

Our genes do not care about us and we should have no compunction about fooling them to deliver benefits without serving their ends. Contraception, to take one obvious example, allows those who choose childlessness to enjoy the pleasures of sexual activity without the fitness-enhancing risk of conception.

Night waking evolved in environments in which there were strong fitness costs from short IBIs and in which parents lacked artificial means of birth-spacing. If night waking evolved because it prolonged IBIs, then it may no longer serve the ends for which it evolved.

Nevertheless, optimal infant development might continue to depend on frequent night feeds as part of our ingrained evolutionary heritage. It could also be argued that when night waking is not reinforced by feeding, and infants sleep through the night, then conflict within their genomes subsides. Infants would then gain the benefit of unfragmented sleep without the pleiotropic costs of intragenomic conflict. Plausible arguments could be presented for either hypothesis and a choice between them must await discriminating evidence.”


Commenters on the 2014 study also said:

[Crespi] The profound implications of Haig’s insights into the roles of evolutionary conflicts in fetal, infant and maternal health are matched only by the remarkable absence of understanding, appreciation or application of such evolutionary principles among the research and clinical medical communities, or the general public.

[Wilkins] A mutation may be selected for its effect on the trait that is the basis of the conflict, but that mutation also likely affects other traits. In general, we expect that these pleiotropic effects to be deleterious: conflict over one trait can actually drive other traits to be less adapted. Natural selection does not necessarily guarantee positive health outcomes.

[McNamara] Assuming that AS/REM is differentially influenced by genes of paternal origin then both REM properties and REM-associated awakenings can be better explained by mechanisms of genomic conflict than by traditional claims that REM functions as an anti-predator ‘sentinel’ for the sleeping organism.

[Hinde] Given this context of simultaneous coordination and conflict between mother and infant, distinguishing honest signals of infant need from self-interested, care-extracting signals poses a challenge.

Use it or lose it: the interplay of new brain cells, age, and activity

This 2015 German review was of aging and activity in the context of adult neurogenesis:

“Adult neurogenesis might be of profound functional significance because it occurs at a strategic bottleneck location in the hippocampus.


Age-dependent changes essentially reflect a unidirectional development in that everything builds on what has occurred before. In this sense, aging can also be seen as continued or lifelong development. This idea has limitations but is instructive with regard to adult neurogenesis, because adult neurogenesis is neuronal development under the conditions of the adult brain.

The age-related alterations of adult neurogenesis themselves have quantitative and qualitative components. So far, most research has focused on the quantitative aspects. But there can be little doubt that qualitative changes do not simply follow quantitative changes (e.g., in cell or synapse numbers), but emerge on a systems level and above when an organism ages. With respect to adult neurogenesis, only one multilevel experiment including morphology and behavior has been conducted, and, even in that study, only three time points were investigated.

In old age, adult neurogenesis occurs at only a small fraction of the level in early adulthood. The decline does not seem to be ‘regulated’ but rather the by-product of many age-related changes of other sorts.


From a behavioral level down to a synaptic level, activity increases adult neurogenesis. This regulation does not seem to occur in an all-or-nothing fashion but rather influences different stages of neuronal development differently. Both cell proliferation and survival are influenced by or even depend on activity.

The effects of exercise and environmental enrichment are additive, which indicates that increasing the potential for neurogenesis is sufficient to increase the actual use of the recruitable cells in the case of cognitive stimulation. Physical activity would not by itself provide specific hippocampus-relevant stimuli that induce net neurogenesis but be associated with a greater chance to encounter specific relevant stimuli.


Adult hippocampal neurogenesis might contribute to a structural or neural reserve that if appropriately trained early in life might provide a compensatory buffer of brain plasticity in the face of increasing neurodegeneration or nonpathological age-related functional losses. There is still only limited information on the activity-dependent parameters that help to prevent the age-dependent decrease in adult neurogenesis and maintain cellular plasticity.

The big question is what the functional contribution of so few new neurons over so long periods can be. Any comprehensive concept has to bring together the acute functional contributions of newly generated, highly plastic neurons and the more-or-less lasting changes they introduce to the network.”

I’ve quoted quite a lot, but there are more details that await your reading. A few items from the study referenced in the first paragraph above:

“The hippocampus represents a bottleneck in processing..adult hippocampal neurogenesis occurs at exactly the narrowest spot.

We have derived the theory that the function of adult hippocampal neurogenesis is to enable the brain to accommodate continued bouts of novelty..a mechanism for preparing the hippocampus for processing greater levels of complexity.”


The role of the hippocampus in emotion was ignored as it so often is. The way to address many of the gaps mentioned by the author may be to Advance science by including emotion in research.

For example, from the author’s The mystery of humans’ evolved capability for adults to grow new brain cells:

“Adult neurogenesis is already effective early in life, actually very well before true adulthood, and is at very high levels when sexual maturity has been reached. Behavioral advantages associated with adult neurogenesis must be relevant during the reproductive period.”

When human studies are designed to research how “behavioral advantages associated with adult neurogenesis must be relevant” what purpose does it serve to exclude emotional content?

http://cshperspectives.cshlp.org/content/7/11/a018929.full “Activity Dependency and Aging in the Regulation of Adult Neurogenesis”

Empathy, value, pain, control: Psychological functions of the human striatum

This 2016 US human study found:

“A link between existing data on the anatomical and physiological characteristics of striatal regions and psychological functions.

Because we did not limit our metaanalysis to studies that specifically targeted striatal function, our results extend previous knowledge of the involvement of the striatum in reward-related decision-making tasks, and provide a detailed functional map of regional specialization for diverse psychological functions, some of which are sometimes thought of as being the exclusive domain of the PFC [prefrontal cortex].”

The analysis led to dividing the striatum into five segments:

Ventral striatum (VS):

  • Stimulus Value
  • Terms such as “reward,” “losses,” and “craving”
  • The most representative study reported that monetary and social rewards activate overlapping regions within the VS.
  • Together with the above finding of a reliable coactivation with OFC [orbitofrontal cortex] and ventromedial PFC, this finding suggests a broad involvement of this area in representing stimulus value and related stimulus-driven motivational states.

Anterior caudate (Ca) Nucleus:

  • Incentive Behavior
  • Terms such as “grasping,” “reaching,” and “reinforcement”
  • The most representative study reported a stronger blood-oxygen level-dependent (BOLD) response in this region during trials in which participants had a chance of winning or losing money in a card guessing game, in comparison to trials where participants merely received feedback about the accuracy of their guess.
  • This result suggests a role in evaluating the value of different actions, contrasting with the above role of the VS in evaluating the value of stimuli.

Posterior putamen (Pp):

  • Sensorimotor Processes
  • Terms such as “foot,” “noxious,” and “taste”
  • The most representative study reported activation of this region in response to painful stimulation at the back of the left hand and foot of participants. Anatomically, the most reliable and specific coactivation is with sensorimotor cortices, and the posterior and midinsula and operculum (secondary somatosensory cortex SII) in particular, some parts of which are specifically associated with pain.
  • Together, these findings suggest a broad involvement of this area in sensorimotor functions, including aspects of their affective qualities.

Anterior putamen (Pa):

  • Social- and Language-Related Functions
  • Terms such as “read,” “vocal,” and “empathic”
  • The most representative study partially supports a role of this area in social- and language-related functions; it reported a stronger activation of the Pa in experienced singers, but not when novices were singing.
  • It is coactivated with frontal areas anterior to the ones coactivated with the Pp, demonstrating topography in frontostriatal associations. These anterior regions have been implicated in language processes.

Posterior caudate (Cp) Nucleus:

  • Executive Functions
  • Terms such as “causality,” “rehearsal,” and “arithmetic”
  • The representative study reported this region to be part of a network that included dorsolateral PFC and ACC, which supported inhibitory control and task set-shifting.
  • These results suggest a broad, and previously underappreciated, role for the Cp in cognitive control.

The authors presented comparisons of the above striatal segments with other analyses of striatal zones.


One of the coauthors was the lead researcher of the 2015 Advance science by including emotion in research. The current study similarly used a coactivation view rather than a connectivity paradigm of:

“Inferring striatal function indirectly via psychological functions of connected cortical regions.”

Another of the coauthors was a developer of the system used by the current study and by The function of the dorsal ACC is to monitor pain in survival contexts, and he provided feedback to those authors regarding proper use of the system.


The researchers’ “unbiased, data-driven approach” had to work around the cortical biases evident in many of the 5,809 human imaging studies analyzed. The authors referred to the biases in statements such as:

“The majority of studies investigating these psychological functions report activity preferentially in cortical areas, except for studies investigating reward-related and motor functions.”

The methods and results of research with cortical biases influenced the study’s use of:

“Word frequencies of psychological terms in the full text of studies, rather than a detailed analysis of psychological tasks and statistical contrasts.”

http://www.pnas.org/content/113/7/1907.full “Regional specialization within the human striatum for diverse psychological functions”

How brains mature during critical periods

This 2015 German rodent study found:

“Once silent synapses are consolidated in any neural circuit, initial experience-dependent functional optimization and critical periods end.

Silent synapses are thought to be immature, still-developing excitatory synapses.”

The number of silent synapses related to visual processing was measured at ~50% at eye opening. Visual experience reduced this to 5% or less by adulthood in the study’s control group. Removing a protein in the subjects’ hippocampus silenced the synapses back up to ~50%, even in adults.

Critical periods are:

“Characterized by the absolute requirement for experience in a restricted time window for neural network optimization.

Although some functions can be substantially ameliorated after the CP [critical period], they are rarely optimally restored.”

Two human studies were cited on critical periods in second-language and musical skills development.

The researchers generalized their findings as:

“Experience-dependent unsilencing of silent synapses constitutes an important general maturational process during CPs of cortical development of different functional domains and suggest an interplay with inhibitory circuits in regulating plasticity.”

http://www.pnas.org/content/112/24/E3131.full “Progressive maturation of silent synapses governs the duration of a critical period”

Differing characteristics of languages shape people’s brains differently

This 2015 Chinese study found that the differing characteristics of the Chinese and English languages shape people’s brains differently:

“Our results revealed that, although speech processing is largely carried out in the common left hemisphere classical language areas (Broca’s and Wernicke’s areas) and anterior temporal cortex, speech comprehension across different language groups depends on how these brain regions interact with each other.”

For an informed discussion of the study and related issues, visit http://languagelog.ldc.upenn.edu/nll/?p=17949 and comments.

We can infer from the Would you deprive your infant in order to be in a researcher’s control group? study that this shaping process begins during womb life.

http://www.pnas.org/content/112/10/2972.full “Cross-language differences in the brain network subserving intelligible speech”

Would you deprive your infant in order to be in a researcher’s control group?

This 2015 Harvard study found that exposing extremely premature babies to sounds of their mothers enlarged their auditory cortex.

The lead researcher stated:

“Our findings do not prove that the brains of these babies are necessarily better, and we cannot conclude that they will end up with no developmental disabilities.

We don’t know the advantages of having a bigger auditory cortex.”

It’s too bad that studies like this one have to take deprived infants and further deprive them for use as a control group. I suppose it’s possible that the control group members’ development could just be shifted, similar to the Maternal depression and antidepressants epigenetically change infant language development study.

However, given the findings of the Our early experiences are maintained and unconsciously influence us for years, if not indefinitely study, it’s also possible that the last trimester of womb life is a critical period for a child’s auditory cortex. If timely development doesn’t take place within the environment provided by the mother, there may not be another period to fully catch up on growth and learning, even given the effects of neural plasticity.

http://www.pnas.org/content/112/10/3152.full “Mother’s voice and heartbeat sounds elicit auditory plasticity in the human brain before full gestation”