title: Group imaging of task-related changes in cortical synchronisation using nonparametric permutation testing.
abstract: 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.
authors.affiliation: The Wellcome Trust Laboratory for MEG Studies, Neurosciences Research Institute, Aston University, Birmingham B4 7ET, England, UK. k.d.singh@aston.ac.uk
authors.forename: Krish D
authors.initials: KD
authors.lastname: Singh
authors.forename: Gareth R
authors.initials: GR
authors.lastname: Barnes
authors.forename: Arjan
authors.initials: A
authors.lastname: Hillebrand
mesh_terms: D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology*; D003344:Cortical Synchronization; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008280:Magnetics; D015225:Magnetoencephalography; D008297:Male; D008432:Mathematical Computing; D009039:Motion Perception / Q000502:physiology; D009415:Nerve Net / Q000502:physiology; D016011:Normal Distribution; D009778:Occipital Lobe / Q000502:physiology; D009949:Orientation / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D012984:Software; D018709:Statistics, Nonparametric; D013702:Temporal Lobe / Q000502:physiology