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Comment by bemmu | Hacker News Reader

The neocortex knows whether or not I’m popular, but it doesn’t care, because (on this view) it’s just a generic learning algorithm. The old brain cares very much whether I'm popular, but it’s too stupid to understand the world, so how would it know whether I’m popular or not?

"If I put my hand on this sugar, grab it, and move it to my mouth, then this other part of my brain will release reward chemicals" = good plan.

Concepts become abstracted over time, like "eat" as a shortcut for the above. "Popular" could be another shortcut for something like "many people will smile at me, and not hurt me, causing this other part of my brain to release reward chemicals and not punishment chemicals" = good plan.

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Yep.

What is so grossly wrong about Hawkins’ statement is that it implies that the “old brain” and the “new brain” could exist in separation, like modular units. This is BS. Most learning in the “new brain” would not work without the “old brain“ releasing neuromodulators. Neither would any sensory-motor loops work without intricate interaction of all different sorts of old, new and medium-aged brain parts.

Are neuromodulators released locally to a cortical column, i.e. with controlled spatial concentration?

I guess they must be, to have specific effects, but they always seem global when mentioned.

Locally, neuromodulators disperse through diffusion, unlike neurotransmitters which are hardly given a chance to travel far from the synaptic cleft they are released into, due to reuptake channels and enzymatic degradation.

But neurons that release neuromodulators innervate large portions of the brain; that is, when one such a neuron is active it releases neuromodulators all across the brain.

The mechanism how Neuromodulators can have specific effects in spite of their global delivery is one of the many open questions about brain function.

Part of the solution is that different neuron types respond differently to the same neuromodulator. Depending on the abundance of certain neuron types in a circuit, different circuits can also respond differently to the same neuromodulator.

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