What is Functional connectivity?
Functional connectivity refers to the statistical correlation of neural activity between spatially separate brain regions. When two regions consistently activate together, they are said to be functionally connected, suggesting they work as part of a coordinated network.
How it works
Functional connectivity is measured using fMRI by correlating the time series of blood-oxygen-level-dependent (BOLD) signals across brain regions. It reveals the brain’s network architecture without requiring participants to perform any task (resting-state functional connectivity). Altered functional connectivity patterns are biomarkers for psychiatric and neurological conditions: depression shows hyperconnectivity within the default mode network, while schizophrenia shows disrupted frontotemporal connectivity.
Applied example
Resting-state fMRI reveals that even when a person lies quietly in the scanner, their brain’s activity patterns are organized into consistent networks. Regions within the default mode network show correlated activity fluctuations, indicating ongoing coordinated processing even during apparent rest.
Why it matters
Functional connectivity reveals the brain’s network organization, showing that cognitive functions emerge from coordinated activity across distributed regions rather than from isolated brain areas.
