Koniocellular cell

Schematic diagram of the primate LGN. Koniocellular neurons not labeled, but are present between the layers.

A koniocellular cell (K-cell) is a neuron whose cell body is located in the koniocellular layer of the lateral geniculate nucleus (LGN) in primates, including humans. The koniocellular cells receive their input from bistratified retinal ganglion cells exiting the optic tract, and send their information via relay neurons in the optic radiation to the primary visual cortex.^[1][2] The koniocellular layers are located between the magnocellular and parvocellular layers, in thin interlaminar regions of the LGN. As part of a general pattern, K neurons form robust layers through the full representation of the visual hemifield.

Input to cells

The small-field bistratified retinal ganglion cells have their cell body in the retina, and extend their axons to the LGN. The first synapse in the central visual pathway is the bistratified cell with the koniocellular cell in the LGN. The LGN of primates, located in the thalamus, is a laminated structure with six distinct layers of neurons. The LGN receives the sensory input from the retinal ganglion cells, and divides the incoming information into the four dorsal parvocellular and two ventral magnocellular layers. The koniocellular layers are interspersed between the magnocellular and parvocellular layers. The visual information from the two eyes are kept separate at this point, and are not brought together until reaching the visual cortex.

Layers

Similar in physiology and connectivity to W cells in cat lateral geniculate nucleus, K cells form three pairs of layers in macaques.

• The middle pair relays input from short-wavelength cones to the cytochrome-oxidase blobs of primary visual cortex (V1), .
• The dorsal-most pair relays low-acuity visual information to layer I of V1.
• The ventral-most pair appears closely tied to the function of the superior colliculus.

Throughout each K layer are neurons that innervate extrastriate cortex and that are likely to sustain some visual behaviors in the absence of V1.^[3]

See also

• Magnocellular cell
• Parvocellular cell

References

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