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Most animals have smooth brains. The brains of humans (and a handful of animals we consider pretty intelligent – dolphins, chimps, elephants, pigs) start out smooth in the early days of gestation and get more and more wrinkled through infancy.

A wrinkled brain makes sense - folding means you can have a really big cortex but the different parts of the brain won’t be as far apart. But how do brains become wrinkled? Is it programmed somehow - does some genetic code determine the pattern of folds?

A new study from Harvard says no - its just simple physics. They created a 3D model of a smooth fetal brain and coated it with an elastomer gel “cortex.” When they immersed this brain in a special solution, the gel swelled, mimicking brain growth.

Lo and behold, the brain began to buckle, creating folds similar to size, shape and location of a real brain.

Image credit: Mahadevan Lab/Harvard SEAS

Expression of combinations of three different fluorescent proteins in a mouse brain produced ten different colored neurons. Individual neurons in a mouse brain appear in different colors in a fluorescence microscope. This “Brainbow” method enables many distinct cells within a brain circuit to be viewed at one time. 

youtube

This was a really interesting video that anyone should watch if they need a clarification on the differences introverts and extroverts have. :)

re: Brain Folds; submission by theioniansea

My understanding of why brain folds are important for intelligence is not just that it allows more interconnectivity of neurons, but that it allows for more efficient interconnectivity of neurons. The problem with intelligence is that you want your brain to be able to process specific types of problems very quickly and very reliably. For this you need modularity of neurons, i.e. areas of the brain in which lots of neurons work on the same types of problems very efficiently. These modular processing units are areas on the surface of the brain, the grey matter. The problem with this, however, is you also want ease of interconnectivity - all these disparate processing areas have to be able to communicate very quickly. So you need pretty direct connections through long axons, which create the white matter (the lipid component of myelin on the axons leads to the lighter colour). This structure is mirrored in the two types of neurons, the Golgi I neurons which have very long axons that allow information to travel quickly between two destinations and Golgi II neurons which have very short axons and mostly let information travel within the grey matter. As I understand it, the folding of grey matter of the brain allows you to have lots of surface area, which increases ability for modular processing power, but doesn’t increase the distance information travels through the axons in the white matter, preserving processing speed.

There’s some interesting research on how ratios of intracortical to intercortical connections in the human neocortex (~ 9:1) suggest that the human brain might function like a small world network, one of the most efficient structures for increasing both modular processing power and long range interconnectivity.

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Hey theioniansea,

Thanks for writing!

The idea of modularity - that it helps devote a certain section to certain tasks - is something I’ve wondered about, but the rest of the brain can effectively have ‘sections’ and doesn’t seem to need those wrinkles. (And how are they really ‘sections’? If I crumple a piece of paper, it’ll appear to have sections but it’s still just a continuous sheet. Would a neuron think any differently of neocortex brain folds? =/  )

I liked the points you raised (and will think about it more) but still don’t see how they wouldn’t be just as effective if the outer cortex was just as thick but simply smooth. (And it seems to me it would enable faster and increased connections since you wouldn’t need to relay messages around the folds, but simply through it in a straight line.

Imagine the brain as a park, and the neural paths as walking paths. If you’re trying to move across the park quickly, wouldn’t you prefer a straight line instead of meandering around?

Is it possible the folds and wrinkles - esp after seeing the story that it might just be physics which cause the folds - might not really have a purpose, but may simply be a result of physical forces or side-effects of other evolutionary adaptations?

But my brain is working, digesting this answer (and I’m reading some articles on it - though most just say “more surface area!” without much explanation). The interconnectivity aspect is growing on me, but I’m gonna chew that some more.
Please feel free to send my your insights. I, for one, definitely appreciate it.

He finds me.

He climbs in my car sopping wet and we sit.
And I stare.

“I didn’t want you to have to see me like this.”

He says,


“I didn’t have to. I chose to be here.”
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Since I get asked a lot about where to learn more about the human brain and behaviour, I’ve made a masterpost of books, websites, videos and online courses to introduce yourself to that piece of matter that sits between your ears.

Books

  • The Brain Book  by Rita Carter
  • The Pyschology Book (a good starter book)  by DK
  • Thinking, Fast and Slow  by Daniel Kahneman
  • Quiet: The Power of Introverts in a World That Can’t Stop Talking  by Susan Cain
  • The Man Who Mistook His Wife for a Hat  by Oliver Sacks
  • The Brain: The Story of You  by David Eagleman
  • The Brain That Changes Itself: Stories of Personal Triumph from the Frontiers of Brain Science  by Norman Doidge
  • This Is Your Brain on Music  by Daniel Levitin
  • The Autistic Brain by Richard Panek and Temple Grandin (highly reccomended)
  • Sapiens: A Brief History of Humankind  by Yuval Noah Harari (not really brain-related, but it is single handedly the best book I have ever read)

Websites

Videos & Youtube Channels

Online Courses