[laotzu]

Ah, forgive my ignorance. But when you speak of amplitude and frequency, you are referring to wave-like phenomenon correct? Are not waves binary, or "black and white" in the sense that they go up and down and that the these two dualities are relative and dependent on each other for their definition?

[Jtsummers]

They aren't binary. They don't have two values, they have a multitude of values (theoretically infinite if it's truly continuous and not stepped between the minimum and maximum).

If neurons only responded to each other at the min and max value (or a couple thresholds/ranges rather than strictly matching values), then it could be seen as binary. But they respond differently along the range of their inputs to produce a range of outputs, so not binary.

[jsprogrammer]

Their outputs may also differ over time when given the 'same input'.

[JoeAltmaier]

Right! They are stateful and can even have variable gain/time constants etc.