What this does is integration. What SON and PVN does is to send signals for hormone secretion and motivated behavior

Magnocellular (M) Pathway: Specialized for fast movement, depth perception, and large-scale contrast. It uses large cells with fast signal transmission, but it is colorblind and has low spatial resolution.

Parvocellular (P) Pathway: Specialized for high-resolution detail, color vision (such as red/green), and pattern recognition. It transmits signals more slowly using smaller cells and works best with stationary or slow-moving objects.

See chapter 6

Enables BOTH rapid autonomic reflexes AND higher-order interoception, homeostatic regulation and motivated behavior

That's why the nucleus ambiguus is located on the ventral plate.

Historically, anatomists often divided the brain according to visible anatomy—shape, location, cell appearance, boundaries seen under the microscope, and so on. Evo-devo gives scientists another kind of evidence: which developmental regulatory genes are expressed in which regions.

These are different ways allometry can manifest