It seems we are using terms meant for manufactured items that probably don't apply to the brain. Neurons do what neurons do, regardless of the label. You can model them (in sufficient approximation) using both analog and digital means. If forced to classify neurons with "analog versus digital", I'd say they resemble our analog machinery more than our digital machines. A cup of coffee may change the "calculations" our brain makes, which is not a typical feature of our digital machines (unless they have what we'd call a defect).