Posts tagged fetal development
Articles and news from the latest research reports.
DHA during pregnancy does not appear to improve cognitive outcomes for children
Although there are recommendations for pregnant women to increase their intake of the omega-3 fatty acid docosahexaenoic acid (DHA) to improve fetal brain development, a randomized trial finds that prenatal DHA supplementation did not result in improved cognitive, problem-solving or language abilities for children at four years of age, according to the study in the May 7 issue of JAMA, a theme issue on child health. This issue is being released early to coincide with the Pediatric Academic Societies Annual Meeting.
Maria Makrides, B.Sc., B.N.D., Ph.D., of the South Australian Health and Medical Research Institute, Adelaide, Australia and colleagues conducted longer-term follow-up from a previously published study in which pregnant women received 800 mg/d of DHA or placebo. In the initial study, the researchers found that average cognitive, language, and motor scores did not differ between children at 18 months of age. For the follow-up study, outcomes were assessed at 4 years, a time point when any subtle effects on development should have emerged and can be more reliably assessed.
The majority (91.9 percent) of eligible families (DHA group, n = 313; control group, n = 333) participated in the follow-up. The authors found that measures of cognition, the ability to perform complex mental processing, language, and executive functioning (such as memory, reasoning, problem solving) did not differ significantly between groups.
"Our data do not support prenatal DHA supplementation to enhance early childhood development."
(Image: Shutterstock)
Babies learn to anticipate touch in the womb
Babies learn how to anticipate touch while in the womb, according to new research.
Using 4-d scans psychologists at Durham and Lancaster universities found, for the first time, that fetuses were able to predict, rather than react to, their own hand movements towards their mouths as they entered the later stages of gestation compared to earlier in a pregnancy.
The Durham-led team of researchers said that the latest findings could improve understanding about babies, especially those born prematurely, their readiness to interact socially and their ability to calm themselves by sucking on their thumb or fingers.
They said the results could also be a potential indicator of how prepared babies are for feeding.
The researchers carried out a total of 60 scans of 15 healthy fetuses at monthly intervals between 24 weeks and 36 weeks gestation.
Fetuses in the earlier stage of gestation more frequently touched the upper part and sides of their heads.
As the fetuses matured they began to increasingly touch the lower, more sensitive, part of their faces including their mouths.
By 36 weeks a significantly higher proportion of fetuses were observed opening their mouths before touching them, suggesting that later in pregnancy they were able to anticipate that their hands were about to touch their mouths, rather than reacting to the touch of their hands, the researchers said.
Increased sensitivity around a fetus’ mouth at this later stage of pregnancy could mean that they have more “awareness” of mouth movement, they added.
Previous theories have suggested that movement in sequence could form the basis for the development of intention in fetuses.
The researchers said their findings could potentially be an indicator of healthy development, as arguably fetuses who are delayed in this development due to illness, such as growth restriction, might not show the same behaviour observed during the study.
The research, published in the journal Developmental Psychobiology, involved eight girls and seven boys and the researchers noticed no difference in behaviour between boys and girls.
Lead author Dr Nadja Reissland, in the Department of Psychology, at Durham University, said: “Increased touching of the lower part of the face and mouth in fetuses could be an indicator of brain development necessary for healthy development, including preparedness for social interaction, self-soothing and feeding.
“What we have observed are sequential events, which show maturation in the development of fetuses, which is the basis for life after birth.
“The findings could provide more information about when babies are ready to engage with their environment, especially if born prematurely.”
Brian Francis, Professor of Social Statistics at Lancaster, added: “This effect is likely to be evolutionally determined, preparing the child for life outside the womb. Building on these findings, future research could lead to more understanding about how the child is prepared prenatally for life, including their ability to engage with their social environment, regulate stimulation and being ready to take a breast or bottle.”
The study builds on previous research by Durham and Lancaster into fetal development. Earlier this year another of their studies showed that unborn babies practise facial expressions in the womb in what is thought to be preparation for communicating after birth.
And in 2012 Dr Reissland published research showing that unborn babies yawn in the womb, suggesting that yawning is a developmental process which could potentially give doctors another index of a fetus’ health.
Researchers find caffeine during pregnancy negatively impacts mice brains
A team of European researchers has found that mice who consume caffeine while pregnant give birth to pups with negative changes to their brains. In their paper published in the journal Science Translational Medicine, the team reports on their findings after examining the brains of mice pups whose mothers were given caffeine during pregnancy.
Medical researchers have shown that drugs such as cocaine, heroin or even marijuana can have a negative impact on fetal development—in contrast most believe that moderate amounts of caffeine consumption during pregnancy is “safe” meaning it has little or no adverse impact on fetal development. This new study doesn’t change that view, but it does suggest that perhaps more research needs to be done.
In their study, the researchers administered the equivalent of 4 or 5 cups of coffee a day to pregnant mice—afterwards they studied the brains of the pups that were born. In so doing, they found that GABA neurons didn’t migrate during brain development to their proper location in the Hippocampus at the same rate as untreated mice. GABA neurons are responsible for controlling the flow of information in the brain. Subsequent tests found the treated pups to be more susceptible to seizures.
The team also found that if they allowed the treated pups to grow to adulthood, they tended to demonstrate problems with memory—instead of playing with new objects placed in their cages, for example, they were satisfied with playing with objects they already knew—a trait that is uncommon for mice. Autopsies of adult brains also showed fewer neurons in the Hippocampus.
The researchers point out that their results in mice are not necessarily applicable to humans and to reinforce that point another team of researchers also published a Focus piece in the same journal pointing out that there are significant differences in the developmental process of humans and mice fetuses and thus the study with mice has no real bearing on whether caffeine may or may not cause developmental problems with human babies.
Still, the results do indicate that perhaps more research should be done to find out if caffeine does indeed have an unknown negative impact on human fetal development.
Drinking alcohol during pregnancy affects learning and memory function in offspring?
Maternal alcohol consumption during pregnancy has detrimental effects on fetal central nervous system development. Maternal alcohol consumption prior to and during pregnancy significantly affects cognitive functions in offspring, which may be related to changes in cyclin-dependent kinase 5 because it is associated with modulation of synaptic plasticity and impaired learning and memory. Prof. Ruiling Zhang and team from Xinxiang Medical University explored the correlation between cyclin-dependent kinase 5 expression in the hippocampus and neurological impairments following prenatal ethanol exposure, and found that prenatal ethanol exposure could affect cyclin-dependent kinase 5 and its activator p35 in the hippocampus of offspring rats. These findings, which reported in the Neural Regeneration Research (Vol. 8, No. 18, 2013), propose new insights into the mechanisms underlying the role of ethanol exposure in central nervous system injuries, and provide a new strategy for treating the consequences of prenatal ethanol exposure.
E-tattoo monitors brainwaves and baby bump
Mind reading can be as simple as slapping a sticker on your forehead. An “electronic tattoo” containing flexible electronic circuits can now record some complex brain activity as accurately as an EEG. The tattoo could also provide a cheap way to monitor a developing fetus.
The first electronic tattoo appeared in 2011, when Todd Coleman at the University of California, San Diego, and colleagues designed a transparent patch containing electronic circuits as thin as a human hair. Applied to skin like a temporary tattoo, these could be used to monitor electrophysiological signals associated with the heart and muscles, as well as rudimentary brain activity.
To improve its usefulness, Coleman’s group has now optimised the placement of the electrodes to pick up more complex brainwaves. They have demonstrated this by monitoring so-called P300 signals in the forebrain. These appear when you pay attention to a stimulus. The team showed volunteers a series of images and asked them to keep track of how many times a certain object appeared. Whenever volunteers noticed the object, the tattoo registered a blip in the P300 signal.
The tattoo was as good as conventional EEG at telling whether a person was looking at the target image or another stimulus, the team told a recent Cognitive Neuroscience Society meeting in San Francisco.
The team is now modifying the tattoo to transmit data wirelessly to a smartphone, Coleman says. Eventually, he hopes the device could identify other complex patterns of brain activity, such as those that might be used to control a prosthetic limb.
For now, the group is focusing on optimising the tattoo for use in conditions such as depression and Alzheimer’s disease, each of which have characteristic patterns of neural activity. People with depression could wear the tattoo for an extended period, allowing it to help gauge whether medication is working. “The number one advantage is the medical ease of application,” says Michael Pitts of Reed College in Portland, Oregon.
Because its electronic components are already mass-produced, the tattoo can also be made very cheaply.
That means it might also lend itself to pregnancy monitoring in developing countries. With help from the Bill & Melinda Gates Foundation, Coleman’s group is working on an unobtrusive version of the tattoo that monitors signals such as maternal contractions and fetal heart rate.
How the brain folds to fit
During fetal development of the mammalian brain, the cerebral cortex undergoes a marked expansion in surface area in some species, which is accommodated by folding of the tissue in species with most expanded neuron numbers and surface area. Researchers have now identified a key regulator of this crucial process.
Different regions of the mammalian brain are devoted to the performance of specific tasks. This in turn imposes particular demands on their development and structural organization. In the vertebrate forebrain, for instance, the cerebral cortex – which is responsible for cognitive functions – is remarkably expanded and extensively folded exclusively in mammalian species. The greater the degree of folding and the more furrows present, the larger is the surface area available for reception and processing of neural information. In humans, the exterior of the developing brain remains smooth until about the sixth month of gestation. Only then do superficial folds begin to appear and ultimately dominate the entire brain in humans. Conversely mice, for example, have a much smaller and smooth cerebral cortex.
“The mechanisms that control the expansion and folding of the brain during fetal development have so far been mysterious,” says Professor Magdalena Götz, a professor at the Institute of Physiology at LMU and Director of the Institute for Stem Cell Research at the Helmholtz Center Munich. Götz and her team have now pinpointed a major player involved in the molecular process that drives cortical expansion in the mouse. They were able to show that a novel nuclear protein called Trnp1 triggers the enormous increase in the numbers of nerve cells which forces the cortex to undergo a complex series of folds. Indeed, although the normal mouse brain has a smooth appearance, dynamic regulation of Trnp1 results in activating all necessary processes for the formation of a much enlarged and folded cerebral cortex.
Levels of Trnp1 control expansion and folding
“Trnp1 is critical for the expansion and folding of the cerebral cortex, and its expression level is dynamically controlled during development,” says Götz. In the early embryo, Trnp1 is locally expressed in high concentrations. This promotes the proliferation of self-renewing multipotent neural stem cells and supports tangential expansion of the cerebral cortex. The subsequent fall in levels of Trnp1 is associated with an increase in the numbers of various intermediate progenitors and basal radial glial cells. This results in the ordered formation and migration of a much enlarged number of neurons forming folds in the growing cortex.
The findings are particularly striking because they imply that the same molecule – Trnp1 – controls both the expansion and the folding of the cerebral cortex and is even sufficient to induce folding in a normally smooth cerebral cortex. Trnp1 therefore serves as an ideal starting point from which to dissect the complex network of cellular and molecular interactions that underpin the whole process. Götz and her colleagues are now embarking on the next step in this exciting journey - determination of the molecular function of this novel nuclear protein Trnp1 and how it is regulated. (Cell 2013)
(Source: en.uni-muenchen.de)
When food is scarce, a smaller brain will do
A new study explains how young brains are protected when nutrition is poor. The findings, published on March 7th in Cell Reports, a Cell Press publication, reveal a coping strategy for producing a fully functional, if smaller, brain. The discovery, which was made in larval flies, shows the brain as an incredibly adaptable organ and may have implications for understanding the developing human brain as well, the researchers say.
The key is a carefully timed developmental system that ultimately ensures neural diversity at the expense of neural numbers.
"In essence, this study reveals an adaptive strategy allowing the reduction of the number of neurons produced in the face of sub-optimal nutritional conditions, while preserving their diversity," said Cedric Maurange of Aix-Marseille Université in France. "This is a survival strategy permitting the developing brain to produce the minimal set of neurons necessary to be functional, at the minimum energetic cost."
Most of the neurons in the human brain are produced well before birth, as the developing fetus grows and changes in the womb. But how the young brain copes with adversity is an unresolved question. If a mother doesn’t have enough food to eat, what happens to the brain of her baby?
To find out, Maurange and his colleagues looked to the fruit fly, a workhorse of biology. The much shorter lifespan of fruit flies means that they reach the equivalent of toddlerhood in just four days’ time.
Their developmental studies in the fly visual system reveal an early sensitivity to the availability of amino acids, ingredients that are the building blocks of proteins. They found that a fly with all the amino acids it needs ends up with a larger pool of neural stem cells than one lacking those nutrients. Later, when those neural stem cells start to produce the many different types of neurons, that nutrient sensitivity goes away. The end result is a brain that is functional but smaller. In some flies, the optic lobe contained 40 percent fewer neurons and still worked.
"We were surprised to realize that the optic lobe can have such a drastically reduced number of neurons under dietary restriction and yet remains functional," Maurange said.
The findings may help to explain well-documented patterns of brain growth in humans. The human brain is protected over other organs when nutrients are lacking late in fetal development, producing a brain that is large relative to organs such as the pancreas or intestine. But when nutrients are limited early in larval development, the brain remains small along with the rest of the body. Those growth patterns are known as asymmetric and symmetric intrauterine growth restriction (IUGR), respectively.
"Our work suggests new avenues to investigate how early nutrient restriction affects mammalian brain development and may help in understanding the mechanisms underlying symmetric and asymmetric IUGR in humans," Maurange said.
Prenatal Testosterone Levels Influence Later Response to Reward
New findings led by Dr. Michael Lombardo, Prof. Simon Baron-Cohen and colleagues at the University of Cambridge indicate that testosterone levels early in fetal development influence later sensitivity of brain regions related to reward processing and affect an individual’s susceptibility to engage in behavior, that in extremes, are related to several neuropsychiatric conditions that asymmetrically affect one sex more than the other.
Although present at low levels in females, testosterone is one of the primary sex hormones that exerts substantial influence over the emergence of differences between males and females. In adults and adolescents, heightened testosterone has been shown to reduce fear, lower sensitivity to punishment, increase risk-tasking, and enhance attention to threat. These effects interact substantially with context to affect social behavior.
This knowledge about the effects of testosterone in adolescence and adulthood suggests that it is related to influencing the balance between approach and avoidance behavior. These same behaviors are heightened in the teenage years and also emerge in extremes in many neuropsychiatric conditions, including conduct disorder, depression, substance abuse, autism, and psychopathy.
Scientists have long known that sex differences influence many aspects of psychiatric disorders, including age of disease onset, prevalence, and susceptibility. For example, according to the World Health Organization, depression is twice as common in women than men, whereas alcohol dependence shows the reverse pattern. In addition to many other factors, sex hormone levels are likely to be important factors contributing to sex differences in psychopathology.
However, research to date has mainly focused on sex hormone levels during adolescence and adulthood, when hormone levels are heightened and built upon substantial prior developmental experience. Sex hormone levels are also heightened during critical periods of fetal brain development, but the impact of such prenatal surges in sex hormone levels on subsequent adult brain and behavioral development has received relatively little attention.
"This study is the first to directly examine whether testosterone in fetal development predicts tendencies later in life to engage in approach-related behavior (e.g., fun-seeking, impulsivity, reward responsivity) and also how it may influence later brain development that is relevant to such behaviors," said first author Lombardo.
In this study, they tested a unique cohort of boys, 8-11 years of age, whose fetal testosterone had been previously measured from amniotic fluid at 13-20 weeks gestation. The boys were scanned with functional magnetic resonance imaging technology to assess changes in brain activity while viewing pictures of negative (fear), positive (happy), neutral, or scrambled faces.
They found that increased fetal testosterone predicted more sensitivity in the brain’s reward system to positively, compared to negatively, valenced facial cues. This means that reward-related brain regions of boys with higher fetal testosterone levels respond more to positive facial emotion compared to negative facial emotion than boys who with smaller levels of fetal testosterone.
In addition, increased fetal testosterone levels predicted increased behavioral approach tendencies later in life via its influence on the brain’s reward system. Lombardo explained, “This work highlights how testosterone in fetal development acts as a programming mechanism for shaping sensitivity of the brain’s reward system later in life and for predicting later tendency to engage in approach-related behaviors. These insights may be especially relevant to a number of neuropsychiatric conditions with skewed sex ratios and which affect approach-related behavior and the brain’s reward system.”
Dr. John Krystal, Editor of Biological Psychiatry, commented, “These remarkable data provide new evidence that hormonal exposures early in life can have lasting impact on brain function and behavior.”
(Source: alphagalileo.org)