Effect of Task/Condition-Related Signal Variance on Functional Connectivity: An fMRI Simulation Study

Unal Sakoglu¹, Kushal Bohra¹

In this work, we study the effects of task-related signal variance differences to functional connectivity analysis using simulated fMRI signals. Considerable correlation was found between the functional connectivity and the standard deviations of the fMRI signals. This shows that functional connectivity differences are accompanied by systematic differences in the variance of the fMRI signal under different experimental tasks/conditions. This result highlights the need for caution in interpreting condition-dependent differences in functional connectivity analyses; one cannot rule out the possibility that the observed differences were merely a consequence of differences in the variance of the respective signal time-courses.