Estimating Directions of Information Flow between Cortical Activities Using Phase-Slope Index

Abstract

AbstractThis paper reports our preliminary experiments on analyzing the direction of information flow between cortical activities. Our analysis method combines the Champagne source reconstruction algorithm, with the phase slope index (PSI) analysis, which was proposed by Nolte et al.. We applied the source PSI analysis to MEG data measured with a hand grasping. The Champagne algorithm reconstructed source time courses for the VOI, and the PSI was then computed between all voxel locations and a seed point set at ipsilateral primary motor area. Our PSI analysis shows that the contralateral primary motor area has a large negative PSI value, indicating a good agreement with our physiological knowledge that the contralateral primary motor area is first activated and the ipsilateral primary motor area is activated later. Our analysis also shows that several areas in cerebellum have fairly large positive PSI values, suggesting that the information flows from the contralateral primary motor area to cerebellum via the ipsilateral primary motor area. Consistent results were obtained from two data sets: the one measured with subject’s left-hand grasping and the other with subject’s right-hand grasping.Keywordsfunctional connectivityinformation flowflow directioncross-spectral matrixphase-slope index