Jacco A. De Zwart1, Peter van Gelderen1, Jeff H. Duyn1
1Advanced MRI, LFMI, NINDS, National Institutes of Health, Bethesda, MD, United States
In low-noise situations the correlation between two signals is underestimated, an effect known as attenuation of correlation. This work shows that this well-established effect can lead to significant underestimation of cross-correlation in resting-state fMRI, where often the ratio between the neurogenic fluctuation of interest and noise level is less than 10. Correction of the cross-correlation value for this effect is well established and straightforward if the noise level is known.