Growing neurite. Each neuron starts as a single point and grows outward, reaching toward target points scattered across the screen. When a branch has no target left nearby, it stops, or splits into two new branches.
Synapse. When two branches from different neurons meet, they connect. That connection point is marked in gold.
Signal pulse. Once neurons are connected, a signal starts at one neuron and travels along the network, crossing every synapse it reaches. The amber dot moving along the lines is that signal: an action potential, the same kind of electrical impulse a real neuron sends to the ones it's wired to. It travels at a speed based on distance, so nearby connections light up first.