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brain development

Zika and Birth Defects: The Evidence Mounts

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Zike virus infection

Caption: Human neural progenitor cells (gray) infected with Zika virus (green) increased the enzyme caspase-3 (red), suggesting increased cell death.
Credit: Sarah C. Ogden, Florida State University, Tallahassee

Recently, public health officials have raised major concerns over the disturbing spread of the mosquito-borne Zika virus among people living in and traveling to many parts of Central and South America [1]. While the symptoms of Zika infection are typically mild, grave concerns have arisen about its potential impact during pregnancy. The concerns stem from the unusual number of births of children with microcephaly, a very serious condition characterized by a small head and damaged brain, coinciding with the spread of Zika virus. Now, two new studies strengthen the connection between Zika and an array of birth defects, including, but not limited to, microcephaly.

In the first study, NIH-funded laboratory researchers show that Zika virus can infect and kill human neural progenitor cells [2]. Those progenitor cells give rise to the cerebral cortex, a portion of the brain often affected in children with microcephaly. The second study, involving a small cohort of women diagnosed with Zika virus during their pregnancies in Rio de Janeiro, Brazil, suggests that the attack rate is disturbingly high, and microcephaly is just one of many risks to the developing fetus. [3]


If I Only Had a Brain? Tissue Chips Predict Neurotoxicity

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Image of neurons, glial cells, and nuclei

Caption: 3D neural tissue chips contain neurons (green), glial cells (red), and nuclei (blue). To take this confocal micrograph, developing neural tissue was removed from a chip and placed on a glass-bottom Petri dish.
Credit: Michael Schwartz, Dept.  of Bioengineering, University of Wisconsin-Madison

A lot of time, money, and effort are devoted to developing new drugs. Yet only one of every 10 drug candidates entering human clinical trials successfully goes on to receive approval from the Food and Drug Administration (FDA) [1]. Many would-be drugs fall by the wayside because they prove toxic to the brain, liver, kidneys, or other organs—toxicity that, unfortunately, isn’t always detected in preclinical studies using mice, rats, or other animal models. That explains why scientists are working so hard to devise technologies that can do a better job of predicting early on which chemical compounds will be safe in humans.

As an important step in this direction, NIH-funded researchers at the Morgridge Institute for Research and University of Wisconsin-Madison have produced neural tissue chips with many features of a developing human brain. Each cultured 3D “organoid”—which sits comfortably in the bottom of a pea-sized well on a standard laboratory plate—comes complete with its very own neurons, support cells, blood vessels, and immune cells! As described in Proceedings of the National Academy of Sciences [2], this new tool is poised to predict earlier, faster, and less expensively which new or untested compounds—be they drug candidates or even ingredients in cosmetics and pesticides—might harm the brain, particularly at the earliest stages of development.


Sound Advice: High School Music Training Sharpens Language Skills

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Band InstrumentsWhen children enter the first grade, their brains are primed for learning experiences, significantly more so, in fact, than adult brains. For instance, scientists have documented that musical training during grade school produces a signature set of benefits for the brain and for behavior—benefits that can last a lifetime, whether or not people continue to play music.

Now, researchers at Northwestern University, Evanston, IL, have some good news for teenagers who missed out on learning to play musical instruments as young kids. Even when musical training isn’t started until high school, it produces meaningful changes in how the brain processes sound. And those changes have positive benefits not only for a teen’s musical abilities, but also for skills related to reading and writing.


Autism Architecture: Unrolling the Genetic Blueprint

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An array of childrenWe know that a combination of genetic and environmental factors influence a child’s risk of autism spectrum disorder (ASD), which is a diverse group of developmental brain conditions that disrupt language, communication, and social interaction. Still, there remain a great many unknowns, including the crucial issues of what proportion of ASD risk is due to genes and what sorts of genes are involved. Answering such questions may hold the key to expanding our understanding of the disorder—and thereby to devising better ways to help the millions of Americans whose lives are touched by ASD [1].

Last year, I shared how NIH-funded researchers had identified rare, spontaneous genetic mutations that appear to play a role in causing ASD. Now, there’s additional news to report. In the largest study of its kind to date, an international team supported by NIH recently discovered that common, inherited genetic variants, acting in tandem with each other or with rarer variants, can also set the stage for ASD—accounting for nearly half of the risk for what’s called “strictly defined autism,” the full-blown manifestation of the disorder. And, when the effects of both rare and common genetic variants are tallied up, we can now trace about 50 to 60 percent of the risk of strictly defined autism to genetic factors.


A Blueprint for Brain Development

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Brain image

Caption: An image generated by whole-brain diffusion tensor tractography, one of a variety of innovative techniques used to create the 3-D gene expression atlas of the developing human brain.
Credit: Allen Institute for Brain Science and Bruce Fischl, Massachusetts General Hospital

There is mounting evidence that predisposition to autism, schizophrenia, and many other devastating brain disorders may begin in the womb when genes are turned on or off at the wrong time during early brain development. But because our current maps of the developing brain are not nearly as detailed or dynamic as we would like, it has been a major challenge to identify and understand the precise roles of these genes.

So, I’m pleased to report that NIH-funded researchers at the Allen Institute for Brain Science in Seattle have produced a comprehensive 3-D map that reveals the activity of some 20,000 genes in 300 brain regions during mid-prenatal development [1]. While this is just the first installment of what will be an atlas of gene activity covering the entire course of human brain development, this rich trove of data is already transforming the way we think about neurodevelopmental disorders.


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