With PET scans and functional MRI, we can observe fluctuations in brain activity by measuring changes in blood flow and levels of nutrients. (scientificamerican.com)
It does so by measuring changes in blood - oxygen levels in different areas. (sciencedaily.com)
The consumer price index measures the change over time in the general price levels of goods and services that households require for the purpose of consumption. (ghanapoliticsonline.com)