Probably discrete, but a related question is what constitutes the discrete element? Science just discovered that it's not just neuron synapses as previously believed. Recent discoveries with snails show that reflexive 'memories' are transferrable from one snail to another via injection, so our synapse only model was likely incomplete for at least simpler organisms: https://www.cnn.com/2018/05/17/health/snail-memory-rna-scien...