Human brain development is a symphony in three movements

by Bill Hathaway
Human brain development is a symphony in three movements
Credit: Shutterstock

(Medical Xpress)—The human brain develops with an exquisitely timed choreography marked by distinct patterns of gene activity at different stages from the womb to adulthood, Yale researchers report in the Dec. 26 issue of the journal Neuron.

The Yale team conducted a large-scale analysis of in cerebral neocortex —an area of the brain governing perception, behavior, and cognition—at different stages of development. The analysis shows the general architecture of brain regions is largely formed in the first six months after conception by a burst of , which is distinct for specific regions of the neocortex. This rush is followed by a sort of intermission beginning in the third trimester of pregnancy. During this period, most genes that are active in specific brain regions are quieted—except for genes that spur connections between all neocortex regions. Then in late childhood and early adolescence, the genetic orchestra begins again and helps subtly shape neocortex regions that progressively perform more specialized tasks, a process that continues into adulthood.

The analysis is the first to show this "hour glass" sketch of development, with a lull in genetic activity sandwiched between highly complex patterns of gene expression, said Nenad Sestan, professor of neurobiology at Yale's Kavli Institute for Neuroscience and senior author of the study. Intriguingly, say the researchers, some of the same patterns of genetic activity that define this human "hour glass" sketch were not observed in developing monkeys, indicating that they may play a role in shaping the features specific to human brain development.

The findings emphasize the importance of the proper interplay between genes and environment in the child's earliest years after birth when the formation of synaptic connections between brain cells becomes synchronized, which shape how brain structures will be used later in life, said Sestan. For instance, disruptions of in synchronization of during child's earliest years have been implicated in autism.

Sestan says the human brain is more like a neighorhood, which is better defined by the community living within its borders than its buildings.

"The neighborhoods get built quickly and then everything slows down and the neocortex focuses solely on developing connections, almost like an electrical grid," said Sestan. "Later when these regions are synchronized, the neighborhoods begin to take on distinct functional identities like Little Italy or Chinatown."

Mihovil Pletikos, Andre ́ M.M. Sousa, and Goran Sedmak of Yale are co-lead authors of the study. Other Yale authors are Kyle A. Meyer, Ying Zhu, Feng Cheng, Mingfeng Li and Yuka Imamura Kawasawa.

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orti
3 / 5 (2) Dec 27, 2013
No miracle here. Just natural forces at work.
JVK
not rated yet Dec 27, 2013
The anonymous orti offers his OPINION with no concern about the obvious complexity of starting from niche construction in nematodes.

Many Families of C. elegans MicroRNAs Are Not Essential for Development or Viability http://www.scienc...09022143

Our genome-wide exon-resolution analysis of the mid-fetal human brain transcriptome revealed complex spatial patterns of gene expression and alternative exon usage, as well as coexpression networks, the vast majority of which have not been previously described. We have found that approximately 76% of well-annotated human genes are expressed at this crucial neurodevelopmental stage. At a conservative false discovery rate of 10−5, 33% of these are DEX and 28% are DAS (Figure 1B and Table S4). The vast majority of these genes have not previously been studied, emphasizing how little is known about the transcriptome of the human fetal brain. http://www.scienc...09002864
orti
5 / 5 (1) Dec 27, 2013
JVK,
Perhaps too much information does not always overcome too little understanding.
Me? I continue to be overjoyed by the events of circa. 1-30 AD.
JVK
not rated yet Dec 27, 2013
Thanks orti. Sarcasm is always hardest to understand in the context of one-liners.
davidivad
not rated yet Dec 28, 2013
was this just a rendered model of what they think is happening? I am supposing this on the idea of a biopsy and surely not a blood draw. I guess what I am asking for is by what method did they get their information.
JVK
not rated yet Dec 28, 2013
http://www.scienc...09002864 links to an earlier work by the senior author, which places this into the context of ecological variation that results in increasing organismal complexity via nutrient-dependent pheromone-controlled de novo gene creation: the holy grail of evolutionary biology.

Nutrient-dependent alternative splicings of pre-mRNA result in amino acid substitutions and altered transcription. This leads to the creation of new genes if the new genes stabilize the intercellular interactions and benefit organism-level thermoregulation.

The amino acid substitutions clearly differentiate all cell types in all individuals of all species.

That fact debunks the ridiculous theory that "Random mutations are the substrates on which directional natural selection acts." http://tech.group...ge/48229

The result of the amino acid substitutions is Mosaic Copy Number Variation in Human Neurons.
katesisco
not rated yet Dec 28, 2013
I was wondering if the sun's delayed reversal is not the reason for our slow degradation?
If Sol is an expended magnatar sun, the solar equatorial emissions may well have been the norm? An our self much more organized and coherent and focused under a solar equatorial emissive sun? The change from solar emissive to polar NASA associates with strong Earth weather so why not strong metastable changes in life? And not beneficial either.

Fossilized flowers for Algernon