Glossary
Resting-state fMRI
What is resting-state fMRI?
Resting-state functional magnetic resonance imaging (fMRI) studies brain activity while a person is not performing an explicit experimental task. It measures fluctuations in the blood-oxygen-level-dependent (BOLD) signal, an indirect measure related to neural activity.
How it works
Resting-state fMRI identifies correlated fluctuations in the BOLD signal without an explicit task. These patterns help researchers study large-scale networks, including the default mode, salience, executive control, visual, and motor networks. The measurement of these patterns depends on acquisition, analysis and participant factors, including movement. Quietly lying in a scanner does not make the brain idle.
A motor-network research example
In the foundational study by Biswal and colleagues (1995), researchers first identified sensorimotor regions activated during hand movement. They then examined signal fluctuations recorded at rest. Slow fluctuations in these regions were correlated with one another and with signals in other regions associated with motor function.
Correlation here means that two recorded signals tend to vary together over time. For example, a rise in one region’s signal may tend to accompany a rise in another’s. That statistical relationship is called functional connectivity; it does not, by itself, show that one region directly causes activity in the other or identify a physical nerve connection. The important observation was that coordinated signals could be measured even without an ongoing movement task.
Research and clinical interpretation
A researcher can compare connectivity patterns across groups or sessions. A difference associated with depression in a study would still need separate validation before it could diagnose an individual patient.
Why it matters
Resting-state fMRI supports research on intrinsic functional organization.