Brain complexity: forming cortex folds; new study (Introduction)

by David Turell , Sunday, July 05, 2020, 19:52 (1602 days ago) @ David Turell

A followup on previous studies:

https://cosmosmagazine.com/science/biology/understanding-how-brains-fold-and-misfold/

"In a pre-clinical study using animal models, a team led by Australia’s RMIT University identified the genes linked with the development of the two types of brain folds – inward and outward – in the brain’s grey matter.

"Writing in the journal Cerebral Cortex, they report finding differences in both genetic expression and neuron shape during the folding process.

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"The researchers say previous studies have focussed on white matter or looked at animals with smooth brains rather than folded ones, largely overlooking grey matter. Grey matter is made up of neuron bodies and their connecting arms; white matter comprises the neurons’ long nerve fibres and their protective layer of fat.

"The latest evidence suggests grey matter in the developing brain expands faster than white matter, creating mechanical instability that leads to brain folding. The resulting “hill” and “valley” folds follow a similar pattern in all folded brains of the same species.

"Tolcos and colleagues investigated the genetic and microstructural differences in future grey matter, the cortical plate, in the parts of the brain just beneath the “hills” and “valleys”. These areas were analysed at three points of development: when the brain was smooth, semi-folded and fully folded.

“'We found some genes have higher expression in regions that fold outward and lower expression in regions that fold inwards. Other genes reverse this pattern,” says RMIT’s Sebastian Quezada Rojas.

“'Together, these genetic expression patterns might explain why the cortical folding pattern is so consistent between individuals of the same species.”

"These genetic differences are also correlated with changes in grey matter neurons, with the study finding variations in the number of arms – or dendrites – that neurons grow in these regions during the folding process.

“'We believe the regions that fold outward and inward are programmed to behave differently, and the shape of the neurons affects the way these areas fold,” Quezada Rojas says."

Comment: The old idea that rapid growth forced the folding is incorrect. These folds are purposely planned. More evidence of purposeful design.