Abstract #3544

Inter-Subject Correlations Between Resting-State Spontaneous Fluctuations & Fractional Volume of Gray Matter

Qihong Zou^1,2, Wanyong Shin^1,3, Hong Gu¹, Xiujuan Geng¹, Wang Zhan⁴, Yufeng Zang², Yihong Yang¹

¹Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, United States; ²State Key Laboratory of Cognitive Neuroscience & Learning, Beijing Normal University, Beijing, China, People's Republic of; ³Imaging Institute, Cleveland Clinic, Cleveland, OH, United States; ⁴Center of Imaging for Neurodegenerative Diseases, University of California San Francisco, San Francisco, CA, United States

Fractional amplitude of low-frequency fluctuations (fALFF) has been used to measure the strength of spontaneous fluctuations of resting-state fMRI signal. However, its underlying mechanisms and inter-subject variations are unknown. In this study, voxel-wise correlations between fALFF and fractional volume of gray matter (fv,GM) across subjects are investigated. Our results show that fALFF and fv,GM are positively correlated over large parts of the brain and fv,GM can be used as a covariate to remarkably reduce inter-subject variations. These findings suggest that fALFF is related to tissue fraction and its inter-subject variations can be reduced by including fv,GM in group analyses.