The Koniocellular Pathway in Primate Vision

Abstract

A neurochemically distinct population of koniocellular (K) neurons makes up a third functional channel in primate lateral geniculate nucleus. As part of a general pattern, K neurons form robust layers through the full representation of the visual hemifield. 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 primay visual cortex (V1), the dorsal-most pair relays low-acuity visual information to layer I of V1, and 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. These data show that several pathways exist from retina to V1 that are likely to process different aspects of the visual scene along lines that may remain parallel well into V1.

Colour vision deficiency

“…4 The koniocellular layers in turn project to the lower echelons of layers 3 and 4A of the primary visual cortex, whereas the parvocellular layers project to layer 4Cb. 2 …”

Aging of human short-wave cone pathways

“…Recently, an S-cone OFF signal has been shown to provide input to a melanopsin-containing retinal ganglion cell (16). Although the retinal circuits originating from the S cones are controversial, it is known that their signals are carried by ganglion cell axons that project to distinct sublaminae (the koniocellular layers) in the LGN (17), which, in turn, project to cytochrome oxidase blobs in layers 2 and 3 of primary visual cortex (18,19).…”

Geniculocortical relay of blue-off signals in the primate visual system

“…A smaller proportion of neurons in the retina and LGN shows blue-on responses, as a result of excitatory input arising in short-wavelength-sensitive (S) cones (1)(2)(3)(4)(5). Blue-on ganglion cells in the retina show a distinct bistratified morphology (5), and blue-on signals reach the visual cortex via the koniocellular/intercalated layers of the LGN (6,7). Unlike cells in the parvocellular (PC) and ventral (magnocellular) layers, the constituent cells of koniocellular pathways show diverse functional properties and widespread cortical terminations and are considered to have arisen early in the evolutionary history of the visual system (7)(8)(9).…”

“…Blue-on ganglion cells in the retina show a distinct bistratified morphology (5), and blue-on signals reach the visual cortex via the koniocellular/intercalated layers of the LGN (6,7). Unlike cells in the parvocellular (PC) and ventral (magnocellular) layers, the constituent cells of koniocellular pathways show diverse functional properties and widespread cortical terminations and are considered to have arisen early in the evolutionary history of the visual system (7)(8)(9). The blue-on koniocellular cells thus have been considered as part of a primordial pathway for color vision (10).…”