2.3. Preprocessing

Here we provide a description of how motion correction was performed and how we obtained homogeneous image intensity in the acquired images.

in vivo occipital and whole-brain T1-w images were corrected for head movement between scan acquisitions using the 3dAllineate function in AFNI (http://afni.nimh.nih.gov), using 6 degrees of freedom and imposing wsinc5 as the last interpolation step (Table 1). After motion correction, images of the same FOV were averaged together to increase SNR. PD images were resampled to the corresponding T1-w space and blurred with a Gaussian smoothing kernel (full width half-max=12 mm). T1-w images were divided by the blurred PD images of the corresponding FOV to correct for field inhomogeneities [3]. Subsequently, data were resampled for laminar analysis and for surface analysis (the latter only for whole brain images).

Motion correction results for the occipital scan and whole brain scan. For each scan and participant the largest motion detected between multiple acquisitions is reported (in mm).