Correlations between brain regions require removal of shared physiological noise.

Evidence

Since resting state connectivity is based upon correlations between activity in relevant channels, it is important to carefully remove any aspects of the data (such as fluctuations from heartbeat, breathing, or from movement artifacts that are present in all channels) that would produce a correlation but is not related to neural activity. These processing steps to remove unwanted signals from the data included: minimizing regional drift using a discrete cosine transform; removing global drift using PCA ‘denoising’ techniques, low-pass filtering (0.08 Hz) to remove heart and breathing fluctuations. — Dijk, Pim van, Physiology, Psychoacoustics and…, 4292

Categorization

• XREF: The confound of shared systemic physiology inflating functional connectivity is central to resting-state fMRI method debates; connects to how any correlated-signal metric must contend with common-source artifacts.