
I thought this was interesting. It was just published in November. The link to  the full text  is below. It kind of goes along the lines of what was discussed  several months ago (maybe a year or more by now) on the ES list of the brain of a baby with DS  being normal or abnormal from the get-go.
Fetal Down Syndrome Brains Exhibit  Aberrant Levels of Neurotransmitters Critical for Normal Brain  Development
Nigel Whittle, MAppScia, Simone B. Sartori, PhDa, Mara Dierssen,  MD, PhDb, Gert Lubec, MDc and Nicolas Singewald, PhDa   BACKGROUND. In the  immature developing fetal brain, amino acids (such as -aminobutyric acid, and  taurine) and monoamines (serotonin, noradrenaline, and dopamine) act as  developmental signals or regulators. In subjects with Down syndrome,  dysfunctional brain development is evident from birth as reduction in brain  weight, as well as volume reductions in specific brain regions, and an altered  number of neurons, dendrites, and dendritic branching is observed. However,  mechanisms that underlie the observed dysfunctional brain development in Down  syndrome are not clear.   OBJECTIVES. Because diverse amino acids and  monoamines are critical for normal brain development, we wanted to determine  whether dysfunctional brain development observed in subjects with Down syndrome  is associated with altered brain amino acid and/or monoamine levels.    DESIGN/METHODS. We quantified tissue concentrations of diverse amino  acids, including -aminobutyric acid and taurine, and the monoamines serotonin,  noradrenaline, and dopamine in the frontal cortex of fetal Down syndrome tissue  at a gestational age of 20 weeks versus age-matched control aborted fetuses.    RESULTS. Fetal Down syndrome brains showed reductions in the levels of  serotonin, -aminobutyric acid, taurine, and dopamine in the frontal cortex. No  alteration in the levels of arginine, aspartate, glutamine, glutamate, glycine,  histidine, serine, or noradrenaline was observed.   CONCLUSIONS.  Serotonin, -aminobutyric acid, taurine, and dopamine are critical for the  acquisition of brain morphologic features, neuronal and glia proliferation, and  synapse formation. The detected reductions in the levels of these  neurotransmitters may indicate potential mechanisms for the observed  dysfunctional neuronal development in the Down syndrome fetal brain.  http://pediatrics.aappublications.org/cgi/content/full/120/6/e1465

















