Investigating white matter development in infancy and early childhood using myelin water faction and relaxation time mapping

Abstract

The elaboration of the myelinated white matter is essential for normal neurodevelopment, establishing and mediating rapid communication pathways throughout the brain. These pathways facilitate the synchronized communication required for higher order behavioral and cognitive functioning. Altered neural messaging (or ‘disconnectivity’) arising from abnormal white matter and myelin development may underlie a number of neurodevelopmental psychiatric disorders. Despite the vital role myelin plays, few imaging studies have specifically examined its maturation throughout early infancy and childhood. Thus, direct investigations of the relationship(s) between evolving behavioral and cognitive functions and the myelination of the supporting neural systems have been sparse. Further, without knowledge of the ‘normative’ developmental time-course, identification of early abnormalities associated with developmental disorders remains challenging. In this work, we examined the use of longitudinal (T1) and transverse (T2) relaxation time mapping, and myelin water fraction (MWF) imaging to investigate white matter and myelin development in 153 healthy male and female children, 3 months through 60 months in age. Optimized age-specific acquisition protocols were developed using the DESPOT and mcDESPOT imaging techniques; and mean T1, T2 and MWF trajectories were determined for frontal, temporal, occipital, parietal and cerebellar white matter, and genu, body and splenium of the corpus callosum. MWF results provided a spatio-temporal pattern in-line with prior histological studies of myelination. Comparison of T1, T2 and MWF measurements demonstrates dissimilar sensitivity to tissue changes associated with neurodevelopment, with each providing differential but complementary information.

Interactions between White Matter Asymmetry and Language during Neurodevelopment

“…Though not discussed in detail, leftward asymmetries in areas relevant here such as the anterior thalamus, mesial frontal cortex and rightward asymmetries in the anterior insula were also detected. These results are unlikely to be related to myelination, as this area is weakly myelinated in the infant age group investigated (Brody et al, 1987). Instead they may demonstrate asymmetries in the underlying fiber architecture, the structural foundation upon which myelination occurs.…”

“…Relationships described in adults have not specifically been shown with language, but with verbal recall (Catani et al, 2007), and asymmetry of tractographyderived streamlines in the arcuate showed a marked ceiling effect with a significant proportion of children showing 100% leftward asymmetry (i.e., no right arcuate fasciculus; Lebel and Beaulieu, 2009). Using fractional anisotropy, a measure of white matter fiber architecture, asymmetries in the arcuate fasciculus have been also shown in infants (Dubois et al, 2009).…”

“…Our results emphasize the critical role of subcortical structures in the architecture of early language development. This is perhaps unsurprising given that these structures are among the first to myelinate (Brody et al, 1987;Hasegawa et al, 1992). The areas reported here, part of cohesive thalamo-cortico-basal ganglial circuits (Alexander and Crutcher, 1990), are strongly associated with language ability (Barbas et al, 2013); the anterior thalamus especially in linguistic violation processing (Wahl et al, 2008) and the left caudate in language monitoring (Ali et al, 2010).…”

Perspective biopsychologique systémique des émotions de base1

“…Five basic emotions were retained in line with the five emotions related to neuronal circuits, which are defined in the literature, and these are the five circuits described by Panksepp as follows: aggressiveness (Rage, angry), stress (Fear-surprise), developed by LeDoux, reward (Seeking-joy), developed by Tassin, empathy (Panic-sadness), developed by Decety, and consciousness (consciousness-happiness), developed by Damasio. Several studies on myelination (Kinney, 1988, Parazzini, 2002, Deoni, 2012, Miller, 2012, andWelker, 2012) provide us with a scientific platform to determine the order of development of the neurohormonal circuits underlying basic emotions.…”

“…Plusieurs recherches sur la myélinisation (Kinney, 1988 ;Parazzini, 2002 ;Deoni, 2012), Miller, 2012et Welker 2012 Le cerveau fonctionne grâce à des circuits nerveux, hormonaux et immunitaires qui sont appelés circuits neurohormonaux. Ce sont des systèmes programmés à la base par les gènes qui se développent d'abord dans un environnement restreint, soit l'utérus de la mère, et par la suite dans un environnement social dès la naissance.…”