Changes in volume, surface estimate, three-dimensional shape and total number of neurons of the human primary visual cortex from midgestation until old age

Abstract

Macroscopic features such as volume, surface estimate, thickness and caudorostral length of the human primary visual cortex (Brodman's area 17) of 46 human brains between midgestation and 93 years were studied by means of camera lucida drawings from serial frontal sections. Individual values were best fitted by a logistic function from midgestation to adulthood and by a regression line between adulthood and old age. Allometric functions were calculated to study developmental relationships between all the features. The three-dimensional shape of area 17 was also reconstructed from the serial sections in 15 cases and correlated with the sequence of morphological events. The sulcal pattern of area 17 begins to develop around 21 weeks of gestation but remains rather simple until birth, while it becomes more convoluted, particularly in the caudal part, during the postnatal period. Until birth, a large increase in cortical thickness (about 83% of its mean adult value) and caudorostral length (69%) produces a moderate increase in cortical volume (31%) and surface estimate (40%) of area 17. After birth, the cortical volume and surface undergo their maximum growth rate, in spite of a rather small increase in cortical thickness and caudorostral length. This is due to the development of the pattern of gyrification within and around the calcarine fissure. All macroscopic features have reached the mean adult value by the end of the first postnatal year. With aging, the only features to undergo significant regression are the cortical surface estimate and the caudorostral length. The total number of neurons in area 17 shows great interindividual variability at all ages. No decrease in the postnatal period or in aging could be demonstrated.

Correlated Size Variations in Human Visual Cortex, Lateral Geniculate Nucleus, and Optic Tract

“…A similar interindividual variation was detected when V1 volume measurements were combined for corresponding hemispheres of 14 brains (range, 7769 -14213 mm 3 ; mean ϭ 10770 mm 3 ). These values are somewhat higher than those reported by Murphy (1985) and Leuba and Kraftsik (1994). The area and volume of V1 within a hemisphere were found to correlate closely (r ϭ 0.81; p Ͻ 0.001).…”

“…In the early part of this century, several researchers showed that the surface area of V1 differs markedly among normal human subjects (Smith, 1904(Smith, , 1906Brodmann, 1909;Putnam 1926;Filiminoff, 1932). These findings were extended by Stensaas et al (1974), who found, in a more comprehensive analysis, that the range of this interindividual variation in V1 area is approximately threefold (for comparable results in V1 volume, see Murphy, 1985;Klekamp et al, 1991;Leuba and Kraftsik, 1994). An equally striking result has been obtained by measurements of the human lateral geniculate nucleus (LGN), which shows a two-to threefold range in volume among individuals (Zworykin, 1980(Zworykin, , 1981.…”

“…Scale bar, 2 mm. correlation between overall hemisphere mass and the size of these several components of the visual system (also see Leuba and Kraftsik, 1994) (Table 3).…”

Light microscopic quantification of morphological changes during aging in neurons and glia of the rat parietal cortex

“…These findings clearly suggest that the degree and extent of the aging process vary between different regions (Haug et al, 1984;Rogers and Bloom, 1985), species (Morgan et al, 1987), and even strains McNelly, 1979, 1981) and individuals (Leuba and Kraftsik, 1994). The purpose of the present study was to analyze quantitatively the cytoarchitecture of the somatosensory cortex of the aging rat, with particular attention to cortical volume, neuronal and glial density, and area and shape of the neuronal soma and nucleus.…”

Accurate prediction of V1 location from cortical folds in a surface coordinate system

“…The calcarine sulcus is one of the first cortical folds to appear, presenting at about 16 weeks gestational age (Chi et al, 1977). V1 can be delineated cytoarchitecturally via differences in the development of the deep cortical layers after 20 or 21 weeks of gestation (Leuba and Kraftsik, 1994). In contrast, V1 does not begin the process of myelination until birth, and may take up to four years to become fully myelinated (Yakovlev and Lecours, 1967;Welker, 1990).…”