AM

AM is calculated as the average amplitude and the standard deviation of the mean-subtracted time series. The AM represents the strength of time series’ temporal fluctuation, which is similar to ALFF/fALFF.

_images/am.png
  • mask: could be whole brain mask or gray matter mask.
  • id index: identifier to find unique string for each subject
  • filetype: files in the filetype will be searched in input directories.
  • 4D nifti files: if the input data is 4D, check this item. Otherwise uncheck.
  • input dirs: directories can be input either using a *.txt file or spm select window.
  • mean temporal ampilitude: calculate absolute value of detrended and demeaned time series.
  • standard deviation: calculate standard deviation of time series
  • variation: calculate variation of time series
  • normalize transform: in output file, a suffix of _m means the output is divided by mean intensity in the mask; a suffix of _z means the output is subtracted by mean intensity and divided by standard deviation.
  • out dir: output directory for saving results.
  • Buttons:
    • S: Save parameters of the current panel to a *.mat file. The *.mat can be further loaded for the panel or be used in a script processing.
    • L: Load parameters from *.mat for the current panel.
    • ?: Help information.
  • Reference:
  1. Liu Y, Yu C, Zhang X, Liu J, Duan Y, Alexander-Bloch AF, et al. Impaired long distance functional connectivity and weighted network architecture in Alzheimer’s disease. Cereb Cortex 2014; 24(6): 1422-35.