Well the most accurate description would not be digital or analogue in the same terms as we discuss.

Sure the output of a neuron is a digital signal with two discrete values, on and off. Receptors (with the exception of the eyes and some other things) do not give off analogue signals. They do the same thing as neurons, a probabilistic-discretized output encodes the analogue input.

Again, basically a neuron uses a binary output state (spike or no spike) to transmit an analogue probability encoding the sum of its inputs.