/ Dr. Silvia Maier
How is MRI used to examine decisions?
How do researchers interpret MRI data and how is MRI used to examine decisions? Read answers to the most common questions concerning MRI in this blogpost and learn more about how you can support this research project.
"BOLD" MRI measures oxygen consumption in the brain
Brain research takes advantage of the fact that nerve cells need oxygen in order to work. The oxygen is transported by the red blood pigment hemoglobin. The hemoglobin molecule has an iron atom in the middle. When oxygen is transported, the iron atom is shielded by the hemoglobin. But once the oxygen is consumed, the iron atom is no longer shielded and creates a slight disturbance in the basic magnetic field of the scanner, which can be measured. When examined by means of the BOLD signal ("blood oxygen level dependent"), the brain regions involved in the solution of a given task can be displayed.
How do researchers interpret this oxygen consumption signal?
The temporal coincidence of the brain signal and the task is the key to a better understanding of the brain: at a certain point in time, the scanner starts recording brain activity. At the same time, a computer begins to show the task that the test subjects are to solve. In the analysis, both recordings are combined and the measured oxygen consumption in all areas of the brain is interpreted in light of the task at hand. With these analyzes, hypotheses can be made about which brain regions deal with risk (i.e., where oxygen consumption increases when risky tasks are solved) or which deal with the expected reward (i.e., which consume more oxygen when more attractive rewards are shown). Such local hypotheses provided by the MRI examination can later be further tested in other studies using other neuroscientific techniques to find out whether the suspected brain regions must really be causally and necessarily involved in a thought process.