Final answer:
To evaluate metabolic activity in neurons, scientists can utilize fluorodeoxyglucose (18-FDG) and observe the metabolically active neurons on a PET scan. 18-FDG, a radiolabeled glucose molecule, accumulates in active neurons, highlighting them on the scan. BrdU, another compound, is used for identifying new neurons but does not indicate metabolic activity.
Step-by-step explanation:
To assess which neurons are most metabolically active, scientists can use a technique involving the injection of a radiolabeled compound such as fluorodeoxyglucose (18-FDG). This compound is a glucose molecule modified with the radioactive isotope fluorine-18.
When injected, 18-FDG accumulates in metabolically active neurons, making them visible on positron emission tomography (PET) scans as bright "hot spots". The PET scan can thereby provide a map of neuronal activity by tracking the metabolic consumption of glucose, a primary energy source for cells.
Bromodeoxyuridine (BrdU) is another compound that can be used to identify new neurons as it incorporates into the DNA of cells in the S phase of the cell cycle. However, it doesn't reflect the metabolic activity of neurons but is useful in identifying the presence of newly generated neurons via immunohistochemistry and fluorescent microscopy techniques.