The 11th J.A.F. Stevenson memorial lecture. Blobs and color vision

When the monkey striate cortex is stained for the mitochondrial enzyme cytochrome oxidase a polka-dot pattern of patches or blobs is observed in layers 2 and 3 and more faintly in layers 5 and 6. In the macaque these blobs are aligned along the centers of ocular dominance columns. Cells within blobs lack the orientation selectivity and instead have the simpler concentric center-surround fields common in geniculate cells. Blob cells are specifically concerned with color and in particular with maintaining color constancy despite marked changes in the spectral content of the light source.