Research ArticleBrain Development

Cross-Hemispheric Functional Connectivity in the Human Fetal Brain

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Science Translational Medicine  20 Feb 2013:
Vol. 5, Issue 173, pp. 173ra24
DOI: 10.1126/scitranslmed.3004978

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Connecting the Dots on Normal Brain Development

Functional connections between different areas of the human brain develop and mature over time. Abnormalities in such connections have been implicated in many common disorders, ranging from developmental problems such as attention deficit hyperactivity disorder and autism to adult-onset diseases such as schizophrenia and Alzheimer’s disease. Abnormal patterns of brain connections likely originate during in utero development, but it is difficult to determine what happens in the brain during the prenatal period in healthy fetuses. Imaging studies of premature neonates have shed some light on this problem, but any infant born prematurely is no longer in a physiological environment for normal brain development, and anything that caused a premature delivery could have also changed the pattern of connections in the infant’s brain. Imaging of healthy full-term neonates can also help map the patterns of infant brain connectivity, but knowing the state of an infant’s brain at the time of birth is not enough to determine the developmental trajectory that it took in utero.

Now, Thomason and colleagues used resting-state functional magnetic resonance imaging (MRI) to map the brain connections of 25 healthy singleton fetuses between 24 and 39 weeks of gestation. Their imaging data confirmed the presence of bilateral functional connections in the fetal brain, as well as regional connections within each hemisphere. As expected, the connection pattern varied with the age of the fetus, such that connection strength increased as the fetuses approached full term.

Further research will be needed to determine how abnormal brain connectivity patterns evolve over time, and how they differ from the healthy infant patterns presented here. In addition, the quality of prenatal MRI data is still limited by fetal movement, and future improvements in MRI technology will be required to address this problem and refine the process of fetal MRI imaging. The current report by Thomason et al. provides a foundation for such future studies and presents a map of fetal brain connections that can serve as a starting point for research in this field.