A novel method is presented which enables the anatomical localization of stochastic phase resetting processes of neuronal populations non-invasively with magnetoencephalography (MEG). The cerebral current source (CCS) density is reconstructed from the measured MEG signals with magnetic field tomography [1]. Univariate and bivariate stochastic phase resetting analysis [2-4] is applied to the CCS. In this way transient phenomena like stimulus-locked cross-trial (CT) response clustering, i.e. switching between different responses across trials, as well as stimulus-locked transient synchronization/desynchronization are detected. In contrast, standard data analysis tools applied across trials relative to stimulus onset, such as CT averaging, CT standard deviation, and CT cross-correlation, fail in detecting these processes and lead to severe misinterpretations and artifacts. The talk is about the theoretical background of the novel method, and first experimental results obtained with standard visual stimulation paradigms.
 

[1] A.A. Ioannides et al., Inverse Problems 6 (1990) 523.

[2] P.A. Tass, Europhys. Lett. 59 (2002) 199.

[3] P.A. Tass, Chaos 13 (2003) 364.

[4] P.A. Tass, Phys. Rev. E (2003) in press, May