question: job of a neuron

[Wolfram]

Kalman Rubinson <kr4 at nyu.edu> wrote:

>A neurons sums,
> temporally and spatially, all the signals impinging on it and fires an
> output signal or signals depending on the inputs and the membrane
> properties of the neuron.

Is that true? A neuron sums the signals impinging? Or does it any
other operation on it? Maybe multiplicating, processing them as
vectors or something like that? No, that isn't a joke - just a
verifying question (see below).

If that is true - one further question: It should be impossible -
only looking to the output signal of the outputting neuron (A) -
to determine which of its input neurons (B) gave A _what_ signal
or _how_ it "looked like". Right? 

Yes, I know that it's impossible to get the summands ot of a given
sum. Because of that i am asking so detailed, if neurons, in fact,
just do summing up the incoming signals. Just to verify that i
didn't miss a point.

-- 

best regards, 
Wolfram