- The LGN is a part of the thalamus that transmits visual information
- Receives information from the optic tract
- Sends information to the occipital lobe
- Some axons terminate in the primary visual cortex of the occipital lobe-- these are called optic radiations

Lateral geniculate nucleus (LGN)

- The LGN is made of six main layers 
- All layers contain concentric receptive fields
- The four outer (dorsal) layers are made of small cells (parvocellular)
- The two inner (ventral) layers are made of large cells (magnocellular)

Layers of the LGN

- Light always hyper polarizes photoreceptors (rods and cones)
- Hyperpolarization causes the photoreceptors to release less glutamate
- Decreased glutamate release excites some retinal neurons and inhibits others

Excitatory and inhibitory feedback to retinal neurons

Neurons in the retina and LGN have receptive fields that consist of a circular central area and a ring around it.

University of Michigan - Ann Arbor

- Sensory stimulus region and features that elicit a neuronal response
- Provides information about the function of a cell
- Neurons at different levels of the visual systems have different receptive fields, and therefore, different functions in vision

Receptive fields of visual system

Breedlove, S. & Watson, N. (2017). Behavioral neuroscience, eighth edition. Oxford University Press.

Behavioral Neuroscience 8th Edition

Concentric receptive fields of retinal and lateral geniculate nucleus (LGN) neurons

- Neurons in the visual cortex require more specific stimulation than neurons of the LGN
- Different groups of neurons here have different receptive fields
- Some respond best to movement, some to lines in a particular orientation, and many others

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