Monoclonal antibody that identifies subsets of neurones in the central visual system of monkey and cat

Striking correlations between structure and function are found in the visual cortex of Old World primates. These include the co-localization of glutamic acid decarboxylase (GAD, the biosynthetic enzyme of the inhibitory neurotransmitter, gamma-aminobutyric acid) with the mitochondrial enzyme, cytochrome oxidase (CO) in functionally distinct subcompartments of ocular dominance columns. We report here immunocytochemical studies with a monoclonal antibody (CAT 301) showing that the antibody recognizes an uncharacterized antigen on surfaces of some neurones in certain layers of the monkey striate cortex (area 17), and in certain parts of the cat and monkey dorsal lateral geniculate nuclei (LGN). Patches of immunocytochemically stained neurones and neuropil, apparent in layers III, IVB and VI of the striate cortex of normal monkeys, become even more clearly delineated in animals from which one eye has been removed. The antibody-stained patches in the three layers line up radially with one another in lines passing through the centres of ocular dominance columns (demonstrable by CO staining in layers IVA and IVC). In layers III and VI the patches coexist with CO-positive patches and, in the horizontal dimension, both antibody and CO-positive patches are aligned to form rows. Stained neurones in the monkey LGN are primarily in the magnocellular layers and in the cat LGN are confined to laminae A and A1, the inter-laminar plexuses, the perigeniculate nucleus and the medial inter-laminar nucleus. The antigen we have localized is associated with particular cell populations, some of which may correspond to a specific, physiological class.