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Polarising and depolarising decide on the charge (positive or negative). This charge may vary within a single neuron but that charge has to reach a certain threshold before a signal is passed to the next neuron. This passing of signals is either happening or it isn't. In this sense the brain is digital.

What may be called analogue, I suppose, is the way a neuron builds up and releases a charge. For the brain to be fully analogue neurons must be in a constant state of connection with each other and it's just the power, or frequency that varies. We know that this firing isn't a constant stream and so while the reactions within a neuron may be analogue, the firing and non-firing is digital.

In summary, you cannot really say whether a brain is digital or not. It all depends on the specific function you're referring to.

[quote]The brain isn't digital at all, it doesn't work in an on/off fashion but on a homeostatic balance between inhibition and dis-inhibition.[/quote]

I never said the brain was digital, I said the way neurons either fire, or do not fire is digital (more accurately analogous to digital) .

[quote]If action potentials were anything like 'bits' of data then you would see them as square waves on the scope.[/quote]

The firing of a neuron is a bit of data. You didn't see it as a 'block' because the graph, no doubt, was just to measure the polarisation/depolarisation over time. As polarisation isn't instantaneous it will show as a wave when measured in milliseconds. Another graph which would show the amount of ions being positively charged no doubt would show little steps, or blocks, rising and falling just like digital information rising and falling at any one time. Don't let the way you measured the data influence how it's happening, for you only measured what was happening.

I reiterate: neurons or either firing or they're not firing; this, I think makes them a good analogy when talking of digital code.

Reggie Perrin,
This debate is getting interesting and now we have hypothesis and antithesis and I for one will learn by synthesis. Yes we have the eye lenses to record visual imagery, the ear-microphones to record the audio but we we have something no computer, digital or analogue has yet to my knowledge, and I would love to be proved wrong on this point, olfactory recording!
Mike Freeman.

A good discussion and with all this talk of nerves like wires and brains like computers, analogue or digital, I am surprised that no-one ever suggested that Homo Sapiens might be bio-machines!
Mike Freeman.