Abstract #1600

Impact of the Global Average in Resting State Functional Connectivity: Quantification of Anti-Correlations

Felix Carbonell¹, Pierre Bellec², Amir Shmuel¹

¹Montreal Neurological Institute, Montreal, Quebec, Canada; ²Centre de recherche de l'institut de Griatrie de Montral

In the current work we introduce the notion of Impact of the Global Average in Functional Connectivity (IGAFC) for quantifying the sensitivity of seed-based correlation analysis to the inclusion of the global average signal as a confounding effect. The IGAFC index is defined as the correlation between the GA and the BOLD at a particular voxel times the correlation between the GA and the seed time course of interest. This definition enables the calculation of a threshold at which the impact of the GA would be large enough to artificially introduce negative correlations.