Quantitative Changes in the Fibroarchitectonics of the Human Cortex from Birth to the Age of 12 Years

Abstract

Brains from 74 children aged from birth to 12 years were used to study fibroarchitectonic characteristics in topographically and functional diverse cortical zones (the temporal-parietal-occipital subregion, occipital, precentral, postcentral, and frontal areas) of the cerebral cortex; children aged up to 12 months were studied on the basis of one-month age intervals. Studies were performed by computer analysis of optical images on frontal sections stained with Nissl cresyl violet and silver nitrate impregnation by the modified Peters method. Data on the rate of increase in the thickness of radial bundles of fibers, the distances between bundles, and the age dynamics of the ratios of the specific volumes of neurons and fibers in fields 3, 4p, 6op, 17, 19, 37ac, 44, and 32/10 were obtained. These measurements showed that age-related transformation of fibroarchitectonics in fields of the sensorimotor, somatosensory, occipital, temporal-parietal-occipital, and frontal areas occurred at different times and with different intensities; the most significant changes were seen in the first 2-3 years of life, with changes continuing at a less intense level to age 9-12 years.

Functional connectivity and infant spatial working memory: A frequency band analysis

“…By 12 months of age, infants exhibit spatial WM processing with much longer delays (e.g., 10 s; Bell & Fox, ; Diamond, Prevor, Callender, & Druin, ). From a neuroanatomical perspective, during the first 2 years of life, there is considerable structural growth in the frontal axons and in the myelination of these projections (e.g., Deoni et al., ; Tsekhmistrenko, Vasil'eva, Shumeiko, & Vologirov, ). Thus, frontal structural connectivity likely limits frontal functional connectivity.…”

Measures of frontal functioning and the emergence of inhibitory control processes at 10 months of age

“…An examination of effect sizes reveals that the magnitude of difference between WM and WM+IC in EEG coherence was largest for medial frontal-temporal electrode pairs. This finding might reflect the regional differences in frontal axon growth and myelination (Deoni et al, 2011; Tsekhmistrenko et al, 2004) that are essential to executive processes.…”

“…Luna and Sweeney (2004) have proposed that changes in brain network dynamics (e.g., synaptic pruning, myelination) are essential to adult-like IC. During the first 2 years of postnatal development, there is considerable structural growth in the frontal axons and in the myelination of these projections (Deoni et al, 2011; Tsekhmistrenko et al, 2004), which contribute to more efficient neural communication. For instance, during the first year of postnatal development, the number of neurons in the frontal cortex decreases while the number of frontal axonal fibers increases (Tsekhmistrenko et al, 2004).…”

“…During the first 2 years of postnatal development, there is considerable structural growth in the frontal axons and in the myelination of these projections (Deoni et al, 2011; Tsekhmistrenko et al, 2004), which contribute to more efficient neural communication. For instance, during the first year of postnatal development, the number of neurons in the frontal cortex decreases while the number of frontal axonal fibers increases (Tsekhmistrenko et al, 2004). Likewise, glucose metabolism in the frontal cortex reaches adult levels at 12 months (Chugani et al, 1987), and a comparison of 7- and 13-month-olds revealed increased cerebral blood flow to the prefrontal cortex by 13 months (Wang et al, 2008).…”

“…Developmental cognitive neuroscientists have posited that the maturation of the frontal cortex and associated neural circuitry late in the first year underlies the emergence of higher order cognitive processes, such as executive functions (Colombo and Cheatham, 2006; Diamond, 1990b). Indeed, infants exhibit initial behavioral evidence of WM (i.e., active maintenance and manipulation of information) and IC (i.e., withholding of a prepotent response) near the end of the first year (Diamond, 1990a, 1990b) in conjunction with substantial maturation of the frontal cortex (Chugani et al, 1987; Deoni et al, 2011; Tsekhmistrenko et al, 2004). In the present study, we examined changes in 10-month-olds' frontal functioning during a WMIC task (i.e., A-not-B) by comparing psychophysiological measures during WM trials 1 and WM+IC trials.…”