Recent brain-imaging studies using PET scans and functional Magnetic Resonance imaging have increased our understanding of the areas of the brain involved with conscious experiences. Using such scans, we can now find what parts of the brain are active or inactive at any given time. For example when someone performs a specific action or has a specific mental process such as a feeling, there is increased glucose or oxygen uptake by the cells in a specific area of the brain. And we can find out what parts of the brain light up when people have certain feelings – for example when a person feels sad, what part of the brain lights up? This tells us that a particular pathway that is lighting up on the scanner is somehow involved in mediating that function.