Barlow & Levick's 1965 divisive-inhibition model of retinal direction selectivity waited about 46 years for the 2011 connectomic wiring diagram that confirmed it

Horace Barlow and W. R. Levick's 1965 paper, "The mechanism of directionally selective units in rabbit's retina" (J. Physiol. 178(3):477–504), proposed that direction-selective retinal ganglion cells (DSGCs) compute their preferred direction through spatially asymmetric inhibition rather than through any observed wiring. A 2012 review states the resulting two-component account: "Facilitation in the preferred direction... acts multiplicatively to enhance spiking..., whereas asymmetric inhibition in the null direction... acts divisively to suppress spiking." At proposal this was a functional/computational model with no synaptic substrate behind it — the same evidentiary posture as claim-jeffress-1948-place-theory-waited-decades-for-anatomical-confirmation and claim-drosophila-connectome-confirmed-zhang-1996-ring-attractor.

The structural confirmation came in 2011. Briggman, Helmstaedter & Denk (Nature 471:183–188) combined two-photon calcium imaging with serial block-face electron microscopy to reconstruct the DS circuit at synaptic resolution. The 2012 review describes it as "a study that was a technical tour-de-force" and reports the quantitative asymmetry:

"The DSGCs received 11 times as many putative synapses from null-side SACs than from preferred-side SACs, consistent with the conclusion that the putative synapses provide the substrate for null-direction GABAergic inhibition."

The gap from theory (1965) to wiring diagram (2011) is roughly 46 years — the longest of the four cases the vault now tracks, and a third independent circuit (after auditory brainstem and insect head-direction) in which a purely computational model waited on the instrument that could test it. The pattern is drawn together in claim-neural-circuit-theories-wait-decades-for-anatomical-confirmation; its limits are examined in claim-circuit-theory-vindication-lacks-denominator-survivorship-not-ruled-out. The same Horace Barlow authored the vault's claim-barlow-1961-efficient-coding-removes-sensory-redundancy.