Comment by computerdork | Hacker News Reader

Comment by computerdork | Hacker News Reader

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am no expert in brain development, still have read about evolution. I like aspects of the way you mentioned this, but seems that putting cortex separately from fish brain isn't quite right. As you mentioned, the cortex is simply a part of the fish brain that evolved much (much, much) larger than a fish's. Maybe:

Fish Brain = brain stem + small cortex (+ other parts of brain)

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 (evolved into)
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      V

Human Brain = brain stem + gigantic cortex (+ other parts of brain)

Sorry, know this is splitting hairs, but just thought it a useful distinction to make.

That's not quite right - a fish does not have a cortex.

The pallium of a fish and mammal are structured differently. A fish's (& bird's) pallium has a clustered (aka "nuclear") organization, while a mammal's has a mostly layered organization which is what is referred to as the cortex.

There is also more to a brain than just brainstem + pallium. In a vertebrate it's brainstem (aka hindbrain) + midbrain + forebrain, with the pallium being part of the forebrain.

Ah, I stand corrected:) Maybe a better diagram might be to merge our ideas:

Fish Brain = brain stem + pallium + other parts of brain[1]

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 (evolved into)
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      V

Human Brain = brain stem + gigantic cortex(which directly evolved from the pallium) + other parts of brain[1]

Good to know:)

[1] Am using "other parts of the brain" to cover any parts of the brain not covered by the brain stem and cortex

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