What is a functional MRI?

Functional magnetic resonance imaging (fMRI) is a non-invasive brain imaging technique that measures changes in blood flow in the brain. These changes in blood flow are thought to be related to changes in neural activity, so fMRI can be used to map out the brain areas that are involved in different cognitive processes.

fMRI works by measuring the changes in the magnetic properties of blood when it is oxygenated and deoxygenated. Oxygenated blood is slightly more magnetic than deoxygenated blood, so when blood flows into an area of the brain that is active, the magnetic field in that area will increase. This change in the magnetic field can be detected by an MRI scanner and used to create images of the brain that show the areas that are active.

fMRI is a powerful tool for studying the brain, and it has been used to investigate a wide range of cognitive processes, including perception, memory, language, and decision-making. fMRI has also been used to study the effects of brain damage and disease, such as stroke and Alzheimer's disease.

Here is a more detailed explanation of how fMRI works:

1. A person lies down in an MRI scanner, and a strong magnetic field is applied to their head. This magnetic field causes the protons in the water molecules in the brain to align with the field.

2. A radiofrequency pulse is then applied to the head, which causes the protons to flip their spins. This creates a magnetic field that is opposite to the original magnetic field.

3. The magnetic field created by the protons then decays, and this decay is measured by the MRI scanner. The rate of decay is different for oxygenated and deoxygenated blood, so the MRI scanner can create images of the brain that show the areas that are active.

fMRI is a safe and painless procedure, and it is widely used in research and clinical settings.