Lateral Geniculate Nucleus

Lateral Geniculate Nucleus

1. Layered structure- 6 stacked layers that are folded into a knee shape. This knee shape has 6 main layers with smaller in-between layers called K-cells (KONIOCELLULAR LAYERS)

2. The bottom two layers of the LGN are MAGNOCELLULAR LAYERS. The top four layers are PARVOCELLULAR LAYERS

3. Each layer of LGN receives input from only one eye. IE same layers receive input from contralateral eye, and some from ipsilateral eye

   • However- all layers receive their input from the contralateral visual world, as seen through contralateral or ipsilateral eye (NB crossover at the OPTIC CHAISM)

4. LGN layers also receive different kinds of input from the retina:

   • The bottom two layers (MAGNOCELLULAR) receive input from the M retinal GCs; the top four layers receive input from the P retinal GCs

5. From what we know about M and P cells, it is obvious that Magnocellular layers (M input) are important for motion detection. Whereas Parvocellular layers (P input) are important for fine details.

6. Each main layer in LGN contains a RETINOTOPIC MAP of half of the visual world. RM= laid out spatially like the retina itself; preserves spatial organization of light patterns in the world.

7. Striate cortex

   • Visual info finally reaches the striate cortex once it has left the LGN. The first destination within the primary visual cortex is the occipital lobe