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

neurosciencesystems-neurosciencedirection-selectivityretinaconnectomicstheory-confirmation-lagdelayed-vindicationhorace-barlowhistory-of-science

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.