Amplitude of low frequency fluctuations
Amplitude of Low Frequency Fluctuations and fractional Amplitude of Low Frequency Fluctuations are neuroimaging methods used to measure spontaneous fluctuations in BOLD-fMRI signal intensity for a given region in the resting brain. Whole-brain ALFF shows greater signal in posterior cingulate, precuneus, and medial prefrontal areas of the default mode network, but also in non-cortical areas near the ventricles, cisterns and large blood vessels. f/ALFF reduces the sensitivity of ALFF to physiological noise by taking the ratio of each frequency to the total frequency range. Both measures have been investigated as part of reliable biomarkers for many neurological conditions including schizophrenia, and ADHD.
