title: An improved approach to detection of amplitude of low-frequency fluctuation (ALFF) for resting-state fMRI: fractional ALFF.
abstract: Most of the resting-state functional magnetic resonance imaging (fMRI) studies demonstrated the correlations between spatially distinct brain areas from the perspective of functional connectivity or functional integration. The functional connectivity approaches do not directly provide information of the amplitude of brain activity of each brain region within a network. Alternatively, an index named amplitude of low-frequency fluctuation (ALFF) of the resting-state fMRI signal has been suggested to reflect the intensity of regional spontaneous brain activity. However, it has been indicated that the ALFF is also sensitive to the physiological noise. The current study proposed a fractional ALFF (fALFF) approach, i.e., the ratio of power spectrum of low-frequency (0.01-0.08 Hz) to that of the entire frequency range and this approach was tested in two groups of resting-state fMRI data. The results showed that the brain areas within the default mode network including posterior cingulate cortex, precuneus, medial prefrontal cortex and bilateral inferior parietal lobule had significantly higher fALFF than the other brain areas. This pattern was consistent with previous neuroimaging results. The non-specific signal components in the cistern areas in resting-state fMRI were significantly suppressed, indicating that the fALFF approach improved the sensitivity and specificity in detecting spontaneous brain activities. Its mechanism and sensitivity to abnormal brain activity should be evaluated in the future studies.
authors.affiliation: State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, PR China.
authors.forename: Qi-Hong
authors.initials: QH
authors.lastname: Zou
authors.forename: Chao-Zhe
authors.initials: CZ
authors.lastname: Zhu
authors.forename: Yihong
authors.initials: Y
authors.lastname: Yang
authors.forename: Xi-Nian
authors.initials: XN
authors.lastname: Zuo
authors.forename: Xiang-Yu
authors.initials: XY
authors.lastname: Long
authors.forename: Qing-Jiu
authors.initials: QJ
authors.lastname: Cao
authors.forename: Yu-Feng
authors.initials: YF
authors.lastname: Wang
authors.forename: Yu-Feng
authors.initials: YF
authors.lastname: Zang
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001921:Brain / Q000098:blood supply* / Q000502:physiology; D001931:Brain Mapping; D002648:Child; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D012146:Rest / Q000502:physiology*; D013997:Time Factors
chemical_list: D010100:Oxygen