PATTERN OF OCULAR DOMINANCE COLUMNS AND CYTOCHROME-OXIDASE ACTIVITY IN A MACAQUE MONKEY WITH NATURALLY-OCCURRING ANISOMETROPIC AMBLYOPIA

Unilateral eyelid suture, a model for amblyopia induced by congenital cataract, produces shrinkage of the deprived eye's ocular dominance co lumns in the striate cortex. Loss of geniculocortical projections are thought to account for the poor vision in the amblyopic eye. It is unc ertain whether ocular dominance columns become shrunken in other forms of amblyopia. we examined the striate cortex in a pigtailed macaque w ith natural anisometropia discovered at age 5 months. Amblyopia in the left eye was documented at 1 year by behavioral testing. At age 6 yea rs, the left eye was injected with [H-3]proline and the striate cortex was processed for autoradiography and cytochrome oxidase (GO). The oc ular dominance columns in layer IVc labelled with [H-3]proline were no rmal. CO staining showed a novel pattern of thin dark bands in layer I V. These bands occupied the core zones at the center of the ocular dom inance columns. Their appearance resulted from relative loss of CO act ivity along the borders of the ocular dominance columns, regions speci alized for binocular processing. These findings indicate that not all forms of amblyopia are accompanied by shrinkage of ocular dominance co lumns. The unusual pattern of CO staining in layer IVc reflected a sub tle alteration in metabolic activity which may have resulted from impa irment of binocular function in anisometropic amblyopia.