Hacker News Reader

Comment by pygy_ | Hacker News Reader

These attempts at brain simulation perplex me to no end.

Simulating a lump of tissue is definitely useful, it's when they start talking about simulating a complete brain that I get lost.

A brain doesn't happen overnight. It is the result of a long developmental process encompassing embryology, learning and experience acquisition.

How do they plan to wire the whole thing?

Micro- and macroscopic connections are well understood, it is the so-called meso-scale (in between) that is troublesome.

There will never be a non-destructive way to do extract the information of a live brain, and I'm not sure there will ever be a way to extract it at all. The current methods[0] allow to extract either the wiring or the genes expression.

[0] http://www.brain-map.org/

View on HN

Yup...people thought the Wright brothers should stick to building bicycles too. I mean how can a bicycle repairman replicate a mechanism that nature took a million years to develop in a bird? It was ridiculous. Couple years later they were watching them fly around in the air.

They use it to understand brain. So they wire it like the brain is wired.

If they simulate cortex, they wire arrange it into cortical columns (size of each column is between 50,000 and 100,000 neurons and there is over two million of them). Those columns have many different layers and neuron types. Understanding how cortical columns and minicolumns work is very important.

You made my point regarding small scale simulation, but completely missed the rest.

> So they wire it like the brain is wired.

As if anyone knew how to do that. Even assuming that you can do both accurate micro-tractography and extract cell-by cell epigenetic information out of a single column, you'd still be missing other cricial information like individual synaptic strength.

I'm not talking about cortico-thalamic connections (required to model epilepsy) inter-columnar connections, and whatever regulation happens in the white matter.

Relying on the probability distribution of connections as a crude approximation is useful, but far from the real deal.

> but far from the real deal.

Your real deal has nothing to do with current brain science and these simulations.

With these simulations, definitely, that was the point.

With current brain science, call me perplexed. Could detail were you think I'm off base?

Each neuron is growing, making decisions about it's environment, reacting to a multitude of neurotransmitters with a mulititude of complex reactions. Deciding where are when to make a new connection. If each node is a little computer system how do we even begin to emulate its probably extensive and convoluted 'programming.'

Reply on news.ycombinator.com