The postnatal development of the association projection from visual cortical area 17 to area 18 in the cat

Abstract

The postnatal development of the association projection from area 17 to area 18 was studied in normal and binocularly deprived kittens between 1 and 28 days of age, using retrograde transport of horseradish peroxidase conjugated with wheat germ agglutinin. The positions of injection sites in the visual cortex, defined in relation to the borders of visual areas 17, 18, and 19 located in Nissl- and cytochrome oxidase-stained sections, were confirmed by observing the patterns of labeling of cells in the lateral geniculate nucleus. The association projection is present and is arranged at least roughly topographically from birth onward; at all ages it arises from cells in both the superficial layers (II, III, and the upper part of IV) and the deep layers (V and VI). In older kittens (20 days or more), however, the origin of the pathway is principally from the upper layers, as in adult cats, whereas in younger animals the projection arises roughly equally from cells in superficial and deep laminae. Initially, the association neurons in area 17 are distributed uniformly along each lamina. Periodic clustering of labeled cells in the upper layers can just be discerned at 10 days, and this patchiness has reached its adult clarity by 20 days, at which stage the projection from the lower layers is greatly diminished. Binocular deprivation until the age of 28 days did not prevent these developmental changes in the projection. Various controls established that the patterns of labeling seen in this study were not due to direct spread of tracer into area 17, to uptake of tracers by fibers-of-passage, or to transcellular transport via the thalamus.

Development of Y‐axon innervation of cortical area 18 in the cat.

“…This division is slightly less distinct in the kitten. (A recent report by Price & Blakemore (1985) indicates that staining for cytochrome oxidase facilitates these areal distinctions in the neonate although this was not attempted in the present study. )…”

“…Does a similar process occur at the geniculocortical level or does the Y-innervation of area 18 develop by a retractive process as has been suggested for the geniculocortical innervation of area 17 (LeVay et al 1978) and for a variety of other projections to kitten visual cortex (Innocenti, Fiore & Cemoniti, 1977;Koppel & Innocenti, 1983;Price & Blakemore, 1985)?…”

Analysis of connectivity in the cat cerebral cortex

“…Olson and Lawler (1987). Paula- Barbossa'et al (1975), PereziBas et al (1985), Porter (1991) : Porter and Sakamoto (1988), Price and Blakemore (1985), Price (1985), Price and Zumbroich (1989), Reinoso-Suarez (1984), Reinoso-Suarez and Roda (1985). Rosenquist (1985), Rouiller et al (1990Rouiller et al ( , 1991, Room and Groenewegen (1986a,b), Room et al (1985), Russchen (1982), Sherk (1986), Shipp and Grant (1991), Squatrito et al (1981a-c), Symonds and Rosenquist (1984a,b), Updike (1982Updike ( , 1986, Van Groen and Lopes da Silva (1986), , Van Groen and Wyss (1988), Vedovato (1978), Waters et al (1982), Winguth and Winer (1989), Witter and Groenewegen (1984, 1986a), Witteret al (1986, Yamaguchi et al (1982).…”

Interareal coordination of columnar architectures during visual cortical development

“…Intriguingly, however, in neonates of many species interareal connectivity is more widespread than in the mature brain (6), raising the possibility that interareal interactions across larger regions of the developing brain also contribute to the specification of individual functional areas. In fact, the visual cortex of neonatal kitten receives projections not only from other visual cortical areas (23,24) but also from auditory, somatosensory, and motor cortex areas (25)(26)(27). Even after exuberant interareal connections have been pruned during the first month of life, the density of interareal connections is often similar to that of intraareal connections (28,29).…”