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The title and article are not clearly written IMHO. What they mean is that the brain has more molecular switches than the number of transistors (switches) of al

by mrb 16y ago

The title and article are not clearly written IMHO. What they mean is that the brain has more molecular switches than the number of transistors (switches) of all computers. Some numbers: * 1.25e14 synapses in a brain * they discovered each synapse has 1000 molecular switches * so 1.25e17 molecular switches in a brain * a post-2005 CPU has 1e8 transistors or so (2010 CPUs barely hit 1e9 transistors) * I estimate 1e9 computers on earth * so 1e17 transistors in all CPUs * 1.25e17 > 1e17 so the statement is right

pygy_ 16y ago
There are 1.25e14 synapses in the cerebral cortex. The total number is higher still (the cerebellum is heavilly wired too), but I don't know by how much.
- a-priori 16y ago
  According to Wikipedia[1], citing [2], the human brain has 'as many as' a quadrillion (10e15) synapses. I presume this includes the entire central nervous system (including the cerebral cortex, cerebellum, and subcortical structures). [1] http://en.wikipedia.org/wiki/Human_brain http://en.wikipedia.org/wiki/Human_brain [2] http://www.ncbi.nlm.nih.gov/pubmed/8527499 http://www.ncbi.nlm.nih.gov/pubmed/8527499 Edit: I just skimmed that paper, and it doesn't look like a reliable source. It's an estimate based on a mathematical analysis, and the authors say "We emphasize that these conclusions are preliminary, based as they are on an incomplete database and simplified models of the brain". I also don't see where the Wikipedia article gets the 10e15 number.
AngryParsley 16y ago
While comparing apples and oranges, they neglected to mention the speed of the "molecular switches." The fastest neurons fire at around 200Hz. Most fire at around 20Hz. Transistors are around 100,000,000 times faster. Oh and circuits conduct signals at 0.5c while neurons are lucky to go at 0.000001c (300 meters/sec).
- Shorel 16y ago
  This really puts the book 'True Names' in perspective. May be the mailman could be a fast thinker.
- phlux 16y ago
  True, but our brains absorb massive amounts of information and process it in parallel whereas it is much more serial for computers.
  - AngryParsley 16y ago
    All parallel tasks can be efficiently serialized on a fast CPU but not all serial tasks can be efficiently parallelized on many slow CPUs. From http://lesswrong.com/lw/k5/cached_thoughts/ http://lesswrong.com/lw/k5/cached_thoughts/ : Can you imagine having to program using 100Hz CPUs, no matter how many of them you had? You'd also need a hundred billion processors just to get anything done in realtime.
pointernil 16y ago
I think the number of neurons should not be missed in those calculations.
- pmiller2 16y ago
  This deserves a few more upvotes. There's some ongoing research to determine the role glial cells have in that wonderful computation we call "thought." See, for example this interview: http://www.scientificamerican.com/article.cfm?id=the-root-of-thought-what http://www.scientificamerican.com/article.cfm?id=the-root-of... .

by mrb 16y ago

pygy_ 16y ago

There are 1.25e14 synapses in the cerebral cortex. The total number is higher still (the cerebellum is heavilly wired too), but I don't know by how much.

a-priori 16y ago
According to Wikipedia[1], citing [2], the human brain has 'as many as' a quadrillion (10e15) synapses. I presume this includes the entire central nervous system (including the cerebral cortex, cerebellum, and subcortical structures). [1] http://en.wikipedia.org/wiki/Human_brain http://en.wikipedia.org/wiki/Human_brain [2] http://www.ncbi.nlm.nih.gov/pubmed/8527499 http://www.ncbi.nlm.nih.gov/pubmed/8527499 Edit: I just skimmed that paper, and it doesn't look like a reliable source. It's an estimate based on a mathematical analysis, and the authors say "We emphasize that these conclusions are preliminary, based as they are on an incomplete database and simplified models of the brain". I also don't see where the Wikipedia article gets the 10e15 number.

AngryParsley 16y ago

While comparing apples and oranges, they neglected to mention the speed of the "molecular switches." The fastest neurons fire at around 200Hz. Most fire at around 20Hz. Transistors are around 100,000,000 times faster. Oh and circuits conduct signals at 0.5c while neurons are lucky to go at 0.000001c (300 meters/sec).

Shorel 16y ago
This really puts the book 'True Names' in perspective. May be the mailman could be a fast thinker.
phlux 16y ago
True, but our brains absorb massive amounts of information and process it in parallel whereas it is much more serial for computers.
- AngryParsley 16y ago
  All parallel tasks can be efficiently serialized on a fast CPU but not all serial tasks can be efficiently parallelized on many slow CPUs. From http://lesswrong.com/lw/k5/cached_thoughts/ http://lesswrong.com/lw/k5/cached_thoughts/ : Can you imagine having to program using 100Hz CPUs, no matter how many of them you had? You'd also need a hundred billion processors just to get anything done in realtime.

pointernil 16y ago

I think the number of neurons should not be missed in those calculations.

pmiller2 16y ago
This deserves a few more upvotes. There's some ongoing research to determine the role glial cells have in that wonderful computation we call "thought." See, for example this interview: http://www.scientificamerican.com/article.cfm?id=the-root-of-thought-what http://www.scientificamerican.com/article.cfm?id=the-root-of... .