Regensburg 2002 – scientific programme

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SYPH: Physik im Hirn - Physical Approaches to Brain Function

SYPH 1: Physik im Hirn - Physical Approaches to Brain Function

SYPH 1.4: Talk

Wednesday, March 13, 2002, 18:35–18:50, H2

Functional Connectivity revealed by Cross-Correlation Clustering — •Silke Dodel, Michael Herrmann und Theo Geisel — Max-Planck-Institut für Strömungsforschung, Bunsenstraße 10, 37073 Göttingen

We propose a deterministic method for cluster analysis based on cross-correlations and graph theoretical considerations which determines brain regions from fMRI data that can be considered as functionally connected. The method does not make any prior assumptions on the number of clusters and the results can be related to analytical findings from random graph theory.

The starting point is that two or more voxels could be considered as functionally connected if the temporal cross-correlation of their signal is high. To distinguish between clusters having equally high cross-correlations additional constraints from graph theory are used for the definition of clusters which implicitly determine the number of clusters as well. Both extreme graph theoretical cluster definitions reveal clusters reflecting identifyable influences on the data. By interpolating between the two extreme definitions the correlation structure of the functionally connected areas can be revealed. An extension of the method includes correlations with non-zero time lags to identify possibly causal relationships between brain regions.