Mammalian cortex (well, in the species that have been studied closely) has both laminar and columnar structures. If you are interested in the biology side of t

Mammalian cortex (well, in the species that have been studied closely) has both laminar and columnar structures. If you are interested in the biology side of things, take a look at http://hubel.med.harvard.edu/book/bcontex.htm Caveat: it's pretty old, and is probably not quite right in a number of ways. But IMHO still a reasonable lay-person's introduction to what we know about the organization of the early visual pathway. (Whether this has got anything to do with ML, I'm not in a position to say.)