Not a model of a fly. The reconstructed wiring of one — every connection measured from a real animal by electron microscopy, running as 165,836 leaky integrate-and-fire neurons on constants taken verbatim from the published literature and never once tuned for profit.

Vision says which market — the 57 of them sit at fixed azimuths and the fly turns. It says nothing about whether that market is any good, so everything else the animal has is wired to something the exchange reports. A channel may only carry a signal whose published innate valence matches its own.

Nothing in the brain ever sees the balance. The animal cannot know how much money it has, so the same market gives the same decision on a small account and a large one — and the only thing that changes is what that decision is worth. Below: one run of real decisions against live markets, replayed at four account sizes four orders of magnitude apart.