Lateral Geniculate Nucleus - Structure

Structure

Both the left and right hemisphere of the brain have a lateral geniculate nucleus, named so for its resemblance to a bent knee (genu is Latin for "knee"). In many primates, including humans and macaques, it has layers of cell bodies with layers of neuropil in between, in an arrangement something like a club sandwich or layer cake, with cell bodies of LGN neurons as the "cake" and neuropil as the "icing". In humans and macaques the LGN is normally described as having six distinctive layers. The inner two layers, 1 and 2, are called the magnocellular layers, while the outer four layers, 3, 4, 5, and 6, are called parvocellular layers. An additional set of neurons, known as the koniocellular sublayers, are found ventral to each of the magnocellular and parvocellular layers. This layering is variable between primate species, and extra leafleting is variable within species.