Gray matter development

Central nervous system myelin is enriched in certain lipids. Table 4-1 lists the composition of bovine, rat, and human myelin compared to bovine and human white matter, human gray matter, and rat whole brain [1] (see Ch. 3). While there are no absolutely myelin-specific lipids, cerebroside (galactosyl ceramide) is the most typical of myelin. With the exception of early development,... 

Another commercially available product containing naturally occurring marine products is Formulaid , produced by Martek Biosciences as a nutritional supplement for infant formulas. Formulaid contains two fatty acids, arachidonic acid (ARA) and docosahexaenoic acid (DHA), extracted from a variety of marine microalgae. ARA and DHA are the most abundant polyunsaturated fatty acids found in breast milk, and they are the most important fatty acids used in the development of brain gray matter. They are especially desirable for use in infant formulas because they come from nonmeat sources and can be advertised as vegetarian additives to the product. 

In humans and other more developed animals, most nerve cells are located in the brain and in the spinal cord, which together make up the central nervous system. The brain acts to process and integrate information. It is composed of several parts, the thinking portion of which is composed of two hemispheres at the top and front of the brain, called the cerebrum. This part of the brain is covered with a thin layer of gray matter called the cerebral cortex. 

Another marine product undergoing development is docosahexaenoic acid (DHA), developed via fermentation of a microalgae. DHA is a major component in human gray matter and is important for normal healthy development in infants. Various groups, such as the World Health Organization, have recommended DHA s inclusion in infant formulas at levels similar to those found in human milk. DHA is presently used in Belgium and Holland and is expected to gain approval in the United States. 

Lead tends to accumulate in the kidneys, the brain (i.e., the gray matter and various nuclei), and the skeleton. Lead can cross the placenta and has been shown to accumulate in the developing child. Prolonged exposure to lead (>4 weeks) in young children can lead to the accumulation of lead in the growth plates at the end of the long bones. 

In this chapter, our intent is to review the rapid changes that take place in the cerebral cortex of n-3 fatty acid-deficient monkeys when their diet is subsequently supplied with ample dietary n-3 fatty acids. Juvenile rhesus monkeys who had developed n-3 fatty acids deficiency since intrauterine life were repleted with a fish-oil diet rich in n-3 fatty acids, DHA, and 20 5n-3 (eicosapentaenoic acid, EPA). The fatty acid composition was determined for the lipid classes of plasma and erythrocytes and for the phospholipid classes and molecular species of frontal cortex samples obtained from serial biopsies and at the time of autopsy. From these analyses, the half-lives ofDHA and EPA in the phospholipids of plasma, erythrocytes, and cerebral cortex were estimated. The deficient brain rapidly regained a normal or even supernormal content ofDHA with a reciprocal decline in n-6 fatty acids, demonstrating that the fatty acids of the gray matter of the brain turn over with relative rapidity under the circumstances of these experiments. 

In the same decade, five dialysis patients developed dyspraxia and seizures at a dialysis center in Denver, Colorado (Alfrey et al. 1972). Investigators suspected a contaminant in the tap water used for dialysis but did not suspect aluminum until their second study in 1976 found increased aluminum in the gray matter of 12 subjects with dialysis dementia (DD) (Alfrey et al. 1976). Two fields of research then merged with additional data from occupational exposures to focus on aluminum s putative role as a cause of dementing illnesses. 

MRI studies of adolescent autistic children show increases in thickness of the cerebral cortex (gray matter) in specific areas of the brain coupled with decreases in thickness of fiber tracts (white matter) leading in and out of those and other areas.63 This provokes the idea that a combination of developmentally enlarged cortex and reduced white matter may be the structural basis of autism. But it s also possible that the anatomical differences may be a consequence of autistic behavior rather than a basis, since the development of the brain continues throughout childhood. 

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