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 |