Group imaging of task-related changes in cortical synchronisation using nonparametric permutation testing

Neuroimage. 2003 Aug;19(4):1589-601. doi: 10.1016/s1053-8119(03)00249-0.


Synthetic aperture magnetometry (SAM) is a nonlinear beamformer technique for producing 3D images of cortical activity from magnetoencephalography data. We have previously shown how SAM images can be spatially normalised and averaged to form a group image. In this paper we show how nonparametric permutation methods can be used to make robust statistical inference about group SAM data. Data from a biological motion direction discrimination experiment were analysed using both a nonparametric analysis toolbox (SnPM) and a conventional parametric approach utilising Gaussian field theory. In data from a group of six subjects, we were able to show robust group activation at the P < 0.05 (corrected) level using the nonparametric methods, while no significant clusters were found using the conventional parametric approach. Activation was found using SnPM in several regions of right occipital-temporal cortex, including the superior temporal sulcus, V5/MT, the fusiform gyrus, and the lateral occipital complex.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Cerebral Cortex / physiology*
  • Cortical Synchronization*
  • Female
  • Fourier Analysis
  • Humans
  • Image Processing, Computer-Assisted*
  • Imaging, Three-Dimensional*
  • Magnetics*
  • Magnetoencephalography*
  • Male
  • Mathematical Computing*
  • Motion Perception / physiology
  • Nerve Net / physiology
  • Normal Distribution
  • Occipital Lobe / physiology
  • Orientation / physiology
  • Pattern Recognition, Visual / physiology*
  • Psychomotor Performance / physiology
  • Software
  • Statistics, Nonparametric*
  • Temporal Lobe / physiology