The 2020 Drosophila connectome confirmed the ring-attractor architecture Zhang's 1996 theory predicted for head-direction coding, about 24 years later

Kechen Zhang's 1996 paper ("Representation of spatial orientation by the intrinsic dynamics of the head-direction cell ensemble: a theory," J. Neurosci. 16:2112–2126) proposed that an animal's sense of heading is held by a ring attractor: a ring of neurons in which a self-sustaining "bump" of activity marks the current head direction and slides around the ring as the animal turns. The bump is produced by short-range excitation plus long-range inhibition. In 1996 this was computational speculation — a dynamical model with no observed circuit behind it.

Turner-Evans et al. (2020, Neuron) mapped the relevant Drosophila connectome and found the predicted architecture physically present:

"Our results confirm that the Drosophila heading direction network contains the core components of a ring attractor while also revealing unpredicted structural features that might enhance the network's computational power."

The gap from theory (1996) to connectomic confirmation (2020) is roughly 24 years. The capture pairs this with the sound-localization case, claim-jeffress-1948-place-theory-waited-decades-for-anatomical-confirmation (a ~42-year gap), as two instances of the same evidentiary shape — a circuit theory that waits decades for the anatomy to catch up. The generalization is developed in claim-neural-circuit-theories-wait-decades-for-anatomical-confirmation.