The biochemical processes inside the brain of an infant can be mapped with a medical imaging technique that has permitted scientists for the first time to view how the human brain matures.
Researchers at UCLA, studying nine newborns who had suffered seizures and four older children with psychomotor disturbances, used positron emission tomography (PET) to trace how the children metabolized certain chemicals in the brain.
"For the first time we can visualize maturational changes of the newborn brain. No tool before has been able to do that," said Dr. Harry Chugani, an assistant professor of pediatrics and neurology.
PET technology involves introducing radioactive isotopes into the patient's body. A scanner sensitive to the material traces the substances and produces images on a screen that can be deciphered by the use of computers.
Chugani said because the isotopes are short-lived, they pose no danger to the children being studied.
The technique permits researchers to measure the biochemical processes of the brain by the energy its cells burn. The energy is primarily supplied by a combination of oxygen and the simple sugar glucose.
The radioisotopes also emit energy particles that are incorporated into the molecules of oxygen and glucose, allowing scientists to trace their passage and metabolism in the brain.
The babies in the study were followed over a period of 14 months and all were ultimately found to have normal neurological development.
The older children, who in addition to psychomotor problems also suffered mental retardation and low IQs, showed glucose utilization similar to that of the infants, Chugani said.
Results of the study indicate that glucose metabolism in retarded children strongly correlates with that of babies during a period when infants are exhibiting such behavior as grasping at about 3 months old.
Shows How Brain Matures
The PET scans, however, showed progressive changes in glucose utilization by various regions of the brain in the newborns, providing a clear picture of how each area of the brain matures.
Glucose metabolism, the study found, increased with age as sensory-motor activity developed.
Chugani said the study also showed that regional glucose uptake in newborns during a period when non-purposeful limb movements are common resembles glucose utilization in the brains of adults suffering Huntington's chorea.
That genetic disorder, which usually appears around the age of 35, is characterized by involuntary jerky movements of the arms and legs. The victim usually has an irregular gait and suffers dementia during the course of the disease, for which there is no cure.
Chugani said the PET studies also have promising potential in the evaluation of brain-impaired children because the images can uncover areas of disturbance that lead to developmental delay or learning disability.