[extropy-chat] Question on computational power of brain

Eugen Leitl eugen at leitl.org
Wed Mar 14 20:39:59 UTC 2007

On Wed, Mar 14, 2007 at 12:17:02PM -0700, Jef Allbright wrote:

> We've seen estimates of the computational capacity of the human brain
> based on estimates of the number of synaptic connections and their
> nominal speed.  But this doesn't take into account an understanding of

The synapse is not the unit of neural computation. Pieces of dendritic
tree are, and as such I would take at least 10^6 active elements for each 

On another list, I estimated 10^23 ops on 10^17 sites (each about 10^2..10^3

> the usage patterns of those connections -- certainly they're not all
> working flat out.

There are metabolic limits on the amount of firing. But that's not
much of a limit, because you can't excise the circutry which isn't firing
right now, because it might (and will) later on.
> Given that we know the energy consumption of the brain, and (assuming
> we know) an efficiency factor for this biological machinery, can we
> arrive at a reality check for the effective, rather than total,
> ballpark computational equivalency?

If you only use 10% of your brain, does this mean you can make
an anatomic donation of the other 90% which is not active right now?
> Apologies in advance if I missed this elsewhere.

You probably haven't missed
> Comments from our resident neuro experts?

You can just page Anders, you know.

Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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