Mapping Infant Brain Myelination with Magnetic Resonance Imaging

Abstract

Myelination, the elaboration of myelin surrounding neuronal axons, is essential for normal brain function. The development of the myelin sheath enables rapid synchronized communication across the neural systems responsible for higher order cognitive functioning. Despite this critical role, quantitative visualization of myelination in vivo is not possible with current neuroimaging techniques including diffusion tensor and structural magnetic resonance imaging (MRI). Although these techniques offer insight into structural maturation, they reflect several different facets of development, e.g., changes in axonal size, density, coherence, and membrane structure; lipid, protein, and macromolecule content; and water compartmentalization. Consequently, observed signal changes are ambiguous, hindering meaningful inferences between imaging findings and metrics of learning, behavior or cognition. Here we present the first quantitative study of myelination in healthy human infants, from 3 to 11 months of age. Using a new myelin-specific MRI technique, we report a spatiotemporal pattern beginning in the cerebellum, pons, and internal capsule; proceeding caudocranially from the splenium of the corpus callosum and optic radiations (at 3-4 months); to the occipital and parietal lobes (at 4 -6 months); and then to the genu of the corpus callosum and frontal and temporal lobes (at 6 -8 months). Our results also offer preliminary evidence of hemispheric myelination rate differences. This work represents a significant step forward in our ability to appreciate the fundamental process of myelination, and provides the first ever in vivo visualization of myelin maturation in healthy human infancy.

Affective and non-affective touch evoke differential brain responses in 2-month-old infants

“…At birth, the nervous system of the infant is immature since the myelination process is not finished (Eyre, 1992;Deoni et al, 2011), which means that the discriminative sense of touch probably lacks the specificity it has in adults. However, the unmyelinated system, which is evolutionarily older and encompasses temperature, pain and CT afferents (Uvn€ as-Moberg, 2012), may already be in place.…”

Visual Pathway for the Optokinetic Reflex in Infant Macaque Monkeys

“…The further maturation of NOT-DTN response properties seen as increase in peak activity, shortening of visual latencies and strengthening of the input of the ipsilateral eye leading to an improvement of the mhOKR during nasotemporal stimulation can probably be attributed to the maturation of cortical areas and their projections to the NOT-DTN. The long time course might correspond to the prolonged process of myelination and local circuit formation in primate cortex as revealed histologically and with magnetic resonance imaging (Rodman, 1994;Condé et al, 1996;Gogtay et al, 2004;Kourtzi et al, 2006;Malkova et al, 2006;Deoni et al, 2011). Interestingly, area MT like primary sensory areas shows adult-like immunohistochemistry within the first postnatal month (Bourne and Rosa, 2006).…”

Prenatal Stress Alters the Development of Socioemotional Behavior and Amygdala Neuron Excitability in Rats

“…A late-developing brain center for socioemotional control (Giedd et al, 1996;Deoni et al, 2011), the amygdala is implicated in the pathophysiology of neurodevelopmental psychiatric disorders (Quirk and Gehlert, 2003;Amaral et al, 2008;Benes, 2010;Felix-Ortiz and Tye, 2014). Adult amygdala function and emotional behavior are altered by PS (Weinstock, 2008;Sadler et al, 2011), and several studies have identified effects of PS on the developing amygdala (Kraszpulski et al, 2006;Laloux et al, 2012).…”