ON/OFF organization in the cat lateral geniculate nucleus: sublaminae vs. columns

The hypothesis was tested that ON and OFF cells in the A layers of the cat's lateral geniculate nucleus (l.g.n.) form separate ON and OFF columns, and new evidence for their sublaminar distributions is presented. Evidence for columns was sought in previously published results from 184 electrode tracks oriented parallel to the layers and in new experiments, based on multiple, closely spaced electrode tracks oriented vertically to the layers. The tracks parallel to the layers were analyzed in two ways. First, the distances between cells of like-sign and unlike-sign were measured. Second, the signs of response of cells above and below one another, from pairs of tracks made simultaneously in the same layer, were compared. The analyses, which included computer simulations of the experiments based on columnar and noncolumnar models, provided no evidence for columns. The results from the closely spaced, vertical tracks also failed to show columns but confirmed that the organization of ON and OFF cells in the layers is fundamentally sublaminar.