|
|
|
ComponentsOther Links:Brain ConnectionStuff for Kids Webvision More on LGN Created By:Rhoda LeeFrank Lardi Anna Tran Justine Yau |
THE LATERAL GENICULATE NUCLEUSThe lateral geniculate nucleus (LGN) is the subcortical area that deals with vision; it is a layered structure with cells that respond to form, motion, and color. Fibres from the optic nerve
enter the LGN where the process of co-ordinating vision from the two eyes starts.
"Geniculate" means knee-shaped,
The outer 4 layers are composed of small cells, and correspondingly, receive inputs from the small ganglion cells of the retina referred to as the P ganglion cells; these cells dominate the fovea, are colour sensitive, and are "fine-grained", meaning their receptive fields are small enough that they can pick up a high level of detail. These layers are called the parvocellular layers. The two most ventral layers are referred to as the magnocellular layers and are composed of large cells which receive their input from large ganglion cells referred to as the M ganglion cells. These cells receive information from a wide radius of bipolar cells. They are mostly found in the peripheral retina, are insensitive to colour, and are "coarse-grained," meaning they are relatively insensitive to detail. Their main asset is that they are sensitive to motion. Therefore it is evident that two types of information, motion vs. colour and form, are kept in separate layers in the LGN; these being the magnocellular and parvocellular layers, respectively.
To the cortex... |
and it is a pretty accurate description of the LGN. The lateral geniculate nucleus consists of six layers with each alternating layer receiving inputs from a different
eye: 3 layers for the left eye and 3 layers for the right.
