Living organisms change from moment to moment along their internal laws and we can study them at different abstraction levels. ”Despite the extraordinary diversity and complexity of neuronal morphology and synaptic connectivity, the nervous systems adopts a number of basic principles”. [2] Although we will discuss their internal operation in terms of particular processes (the actual level depends on the process), here we classify the obvious results of observations according to the principles the foreword to this chapter mentions: how nature implements those ”basic rules” by more simple processes and states (which we can describe by using ordinary or extraordinary laws) and which events it provides for the observer (which we can use for staging those very complex ”signs of life”).
Fig. 1.4 illustrates our abstract view of a neuron, in this case as a ”stage machine”. Notice that the double circles are stages (states with event-defined periods) connected by bent arrows representing instant stage transitions, while at some other abstraction level we consider them as processes having a temporal course with their own event handling. Fundamentally, the system is circulating along the blue pathway, and maintains its state by using the black loops, but sometimes it takes the less common red pathways. It reveives its inputs cooperatively (controls the accepted amount of its external inputs from the upstream neurons by gating them by regulating a stage variable), furthermore it actively communicates the time of its state change (that is: not its state as assumed in the so called neural information theory) toward the downstream neurons in a process parallel with its mentioned activity.