Calibration of the Amplitude of FMRI Contrast (β) Using Fractional Volume of Gray Matter: The Spatial and Inter-Subject β Calibrations

Wanyong Shin¹, Hong Gu¹, Qihong Zou¹, Pradeep Kurup¹, Yihong Yang¹

The amplitude of BOLD contrast during brain activation (commonly called β) is widely used in fMRI study to monitor the neuronal activity. However, it is observed that β varies substantially over subjects, which is referred as inter-subject β variation. In this study, we propose a new calibrated fMRI method based on fractional volume of gray matter measurement using FRASIER method in which the spatial β variations and the inter-subject β variations are calibrated, and we show that the statistical power is significantly improved after the calibration in an fMRI study with a visual task.