TL;DR: Noisy timing makes STDP thrash. In Part 1 we added uncertainty intervals. This post takes it to the next level and uses uncertainty as a signal to determine how much each neuron is willing to learn. When things are noisy, neurons freeze up. When the signal is good, they keep learning. No global tuning required. The Barn Owl Problem A barn owl hunts in darkness. It finds a mouse by comparing when a sound reaches its left ear versus its right ear (interaural time difference). The difference is on the order of microseconds. From that little difference, its brain computes a bearing and the owl dives.