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Cluster Probability fMRI Smoothness
This plot shows the measured and theoretical smoothness of
an fMRI data set after low pass filtering. As shown in the
plot, the measured smoothness within the brain region
varies about the theoretical value.
The measured smoothness is numerically estimated as the determinate
of the variance-covariance matrix of the difference images
of temporally adjacent image slices. See equation 6 in
The theoretical value of 0.47 is based on a Gaussian LPF
with an image space FWHM
= 1.76 pixels (N = 64, K space radius = 16).
See equation 8 in the implementation
Data from Wei Chen (I_MF_CB_8Hz_TR_2s.fid).
Jinhu Xiong, et al.
``Clustered Pixels Analysis for Functional MRI
Activation Studies of the Human Brain''
Human Brain Mapping, 3:287-301(1995).