SAMpower Version 3

Description: SAMpower computes the Hilbert envelope of power for continuous data and outputs a 3D+time image. It does not compute event-related power (for which see, SAM3d/SAM3dc, SAM4d/SAM4dc, or SAMersc). SAMpower is intended for use in connectivity studies of the correlation of the envelope of power among voxels -- e.g., by using ICA or the AFNI, function "Instacorr".

SAMpower applies the beamformer coefficients to the filtered MEG data (specified by ImageBand) to compute the estimated source time-series. It then applies the Hibert transform to obtain the envelope of power. This is followed by a lowpass filter (specified by SmoothBand) and resampling at the interval specified by TimeStep. The smoothed resampled Hilbert envelope of power is written out to each voxel.

Usage:

SAMpower -r <dataset_name> -m <parameter_file_name> -v

The -r flag is followed by the dataset name (with or without the .ds suffix). The -m flag is followed by the parameter file name without the .param suffix. The -v argument specifies verbose output — else SAMpower works silently.

The required parameter file keywords for SAMpower are:

Optional keywords include:

Examples parameters for imaging the Hilbert envelope of beta-band power in Taliarach space on an 8mm grid:

NumMarkers 0
CovBand 4.0 50.0
ImageBand 14.0 30.0
SmoothBand 0.0 5.0
XBounds -12 12
YBounds -9 9
ZBounds -2 15
ImageStep 0.5
ImageFormat TLRC 8.0
Mask /data2/Mask8mm.nii
ImageMetric Power
CovType GLOBAL
MRIDirectory /data1/mri
ImageDirectory /data1/Rest/Images
TimeStep 0.1
RemoveBaseline BYVOXEL