Редактирование: Whole brain emulation (раздел)

= Overview =

The human brain occupies a volume of 1.5 liters. It has 85 billion neurons. It has 500 trillion synapses. For every neuron there are ten neuroglia, which provide structural and chemical support. Neuroglia may turn out to be necessary for a complete brain emulation, but are not necessary to imitate the phenomenology of spiking.

Each neuron has a soma, an spherical cell body that holds the organelles, an axon hillock from where the axon sprouts and begins branching. Action potentials (Signals) travel down the axon. Dendrites are the input side of neurons, there are many and they grow directly from the soma. Axons and dendrites (Or sometimes axons and cell bodies) intercept either at the terminal of the axon or at some point in its length, forming synaptic terminals or synapses ''en passant'', respectively.

[[File:Spikes real and fake.jpg|thumb|right|Which column of spikes belongs to a real rat's pyramidal neuron, and which is a simulation of the same?]]

These structures, grown on top of the other, form the many regions of the brain, which have somewhat discrete properties that form higher-level cognition.

[[File:Neuroscience of immortality.jpg|thumb|left|That's essentially the whole thing. Except for the immortality part.]]

There are many theories of mind, most of which are actually hypotheses of mind. The currently accepted theory is the theory that the mind is an emergent property of lower-level interactions, in the same way that a computer program is an emergent property of abstraction after abstraction above the machine code.

Note that all analogies between the computer and the brain are bound to fail. As John Searle said,

<blockquote>
Because we do not understand the brain very well we are constantly tempted to use the latest technology as a model for trying to understand it. In my childhood we were always assured that the brain was a telephone switchboard. ('What else could it be?') I was amused to see that Sherrington, the great British neuroscientist, thought that the brain worked like a telegraph system. Freud often compared the brain to hydraulic and electro-magnetic systems. Leibniz compared it to a mill, and I am told some of the ancient Greeks thought the brain functions like a catapult. At present, obviously, the metaphor is the digital computer.


- ''Minds, Brains and Science'', p.44</blockquote>

The brain is ''not'' a computer. The brain is the brain. Let this be a precedent for the rest of the article.