That TED talk took an unexpected left turn in the last third which made an interesting subject ten times as fascinating. Thanks so much for sharing it.
To be honest I expected something way overhyped but her research looks really good. They take a bunch of relatively simple physical measurements and come up with a mathematical model that can explain the relationship between them. They even make physical models of the process:
>"Our model incorporates the known mechanics and organization of elongating axonal fibers (26, 27), as described in the supplementary materials. It predicts that from a purely physical perspective, A_G, A_E, and T are related by the power law T^1/2 x A_G = k x A_E^5/4. (The exponent 5/4 is the only value for which the constant k is adimensional.)
[... to supplements ...]
To test our model, we made paper balls of sheets of A4 office paper of different
surface areas and thickness by dividing sheets in half in a geometric series, and stacking
different numbers of sheets before crumpling them. Once each crumpled paper ball
relaxed, its diameter was measured along the three principal orthogonal axes and used to
calculate the exposed surface area of the equivalent ellipsoid. The folding index for each
paper ball was calculated as the ratio between the total surface area of the unfolded paper
and the equivalent surface area of the crumpled paper ball."
As should be expected from useful science, their new way of looking at things make the world seem less complex. All too often bio/etc seems to move in the opposite direction:
>"The finding that cortical folding scales universally across clades, species, individuals, and parts of the same cortex implies that the single mechanism based on the physics of minimization of effective free energy of a growing surface subject to inhomogeneous bulk stresses applies across cortical development and evolution. This is in stark contrast to previous conclusions that different mechanisms regulated folding at different levels (7); such conclusions may reflect the traditional emphasis on the relationship between folding degree and brain volume (1, 8), which is indeed diverse across orders, across species, and across individuals of a same species (6, 8)."
Really enjoyed this. I got my doctorate in neurophys at a time when the 10 glia/1 neuron in the human brain was accepted dogma, but with little experimental support. The numerous glia were viewed as little more than passive electrical insulation around neural axons.
Great to see somebody with a curious mind, a blender, a microscope and nuclear-specific stains give us a much richer, more complex description and light a new pathway for further work. Brava!
For example, there’s no truth to the idea that
the brain is half android and half artist, with
a left hemisphere dedicated to logic and analytical
thinking and a right hemisphere for intuition and
creativity.
But! Each hemisphere does tend to sequester different specialties, as is evidenced by stroke victims, no?
Yes, I believe you are referencing Wernicke’s and Broca’s aphasia — which may occur after a stroke depending on which hemisphere was affected. But different specialties in the brain does not enforce the idea that the left part is logical and right part is creative.
This kind of speaks to a premise discussed later on in the article regarding the manner in which the gist of interesting trivia tends to drift as time passes, the longer trivia is in play and the greater currency it gains among laymen and non-experts.
Starting with the words:
In a decades-long game of telephone [...]
The article points to an effect in the field of neuroscience that is not unlike The Murray Gell-Mann Amnesia Effect.
The author segues, apparently unselfconsciously, from a critique of unverified notions that became accepted as if established fact, to uncritically accepting a number of speculative extrapolations from these results. Those speculations are interesting, well-founded and plausible, but not yet verified.
The fact that an important discovery was recently made by puréeing brains indicates how incomplete our knowledge of them is.
Pretty amazing to think that our position at the top of the food chain is as tenuous as a change in diet. I hope no one ever starts cooking for dolphins.
I wonder how many generations of "cooking (for) dolphins" you'd need in order for a drastic brain evolution to occur. Probably not enough to provide them with cooked meals, you'd probably also have to progressively increase the mental difficulty of obtaining the food.
The most fascinating part of the article was the tidbit about how fire was a potential factor in the differentiation of humans and other primates. If the theory holds true, then society perhaps has a greater impact on our evolution than previously thought — as the use of fire is not something in our genes but taught to us by others.
I may be over looking some complexity here, but to me the least obvious part in the process is the coloring.
The rest just makes sense. If you want a total average, mix everything together.
To distinguish between neurons and glia, Herculano-
Houzel injected the vials with a chemical dye that
would make all nuclei fluoresce blue under ultraviolet
light, and then with another dye to make the nuclei of
neurons glow red.
You mean that part? It’s about differentiating support infrastructure from the actual cellular operators responsible for cognitive brain function.
Summary: She liquefies the brains to measure the numbers of nuclei, thus accurately extrapolating the numbers of each type of cell in the brain, which was hard to do with previous methods due to the differnet concentrations of types of cells in the brain.
https://www.nybooks.com/articles/2016/11/24/86-billion-neuro...
And a TED talk:
https://www.ted.com/talks/suzana_herculano_houzel_what_is_so...