One More Division — Heterochrony

Telencephalon Diencephalon Midbrain Hindbrain Cerebellum Outcome view:

Developmental cycle

Each active territory is still proliferating.

Relative cell output

4 units

Schematic progenitor descendants—not literal neuron counts.

Schedule consequence

Baseline

Change a stop time and rerun development.

What is being modeled?

Five already-patterned neural territories begin with the same simple rule: while proliferation is ON, divide once per developmental cycle; when the local stop signal arrives, differentiate and stop dividing.

The lever is timing.
One extra proliferative cycle doubles the relative output of that territory in this deliberately idealized model.

Real neurogenesis is asynchronous and is not a sequence of perfect whole-population doublings. The exponential rule is used here to make the consequence of developmental duration visible.

Stop proliferation after cycle…

Telencephalon

Diencephalon

Midbrain

Hindbrain

Cerebellum

Read the presets as experiments

Telencephalon +1 is a mosaic change: one territory runs longer and gains relative share.

All regions +1 is concerted: total output doubles but the proportions remain the same.

Hindbrain +2 shows that the same conserved plan can emphasize a different territory.

Mosaic schedule changes several clocks independently rather than moving one master clock.

Mormyrid cerebellum runs one dorsal hindbrain derivative far longer than everything else, as in the electric fish Mormyrus.

Baseline schedule. Press Play or Step. Watch each progenitor field stop at its own time, then compare the final colored outcome with the dashed baseline.