MONOCULAR CORE ZONES AND BINOCULAR BORDER STRIPS IN PRIMATE STRIATE CORTEX REVEALED BY THE CONTRASTING EFFECTS OF ENUCLEATION, EYELID SUTURE, AND RETINAL LASER LESIONS ON CYTOCHROME-OXIDASE ACTIVITY

In primate striate cortex, geniculocortical afferents in layer IVc ter minate in parallel stripes called ocular dominance columns. We propose that this segregation of ocular inputs generates a related but distin ct columnar system of monocular core zones alternating with binocular border strips. Evidence for this functional parcellation was obtained by comparing the effects of enucleation, eyelid suture, and retinal la ser lesions on cytochrome oxidase (CO) activity in eight macaques. Enu cleation produced a high-contrast pattern of dark and light columns in layer IVc, corresponding precisely to the ocular dominance columns, w hereas eyelid suture produced a low-contrast pattern of thin dark colu mns alternating with wide pale columns. [H-3]Proline eye injection sho wed that the thin dark columns corresponded to the core zones of the o pen eye's ocular dominance columns. The wide pale columns resulted fro m loss of CO activity in the sutured eye's core zones and within both eyes' border strips. Loss of CO activity within both eyes' border stri ps suggested that these regions are binocular. To confirm our findings , we compared different CO patterns in the same cortex by making retin al laser lesions in four animals. They produced a CO pattern tantamoun t to ''focal'' enucleation, although contrast was low when laser damag e was confined to the outer retina. CO levels in cortical scotomas rem ained severely depressed for months after retinal lesions, even when t he other eye was enucleated. This observation provided little anatomic al support for the notion of topographic plasticity after visual deaff erentation. In a single human subject with macular degeneration, CO re vealed a low-contrast pattern of ocular dominance columns, resembling the pattern in monkeys with laser-induced photoreceptor damage.