Abstract: Dynamics of resting-state functional magnetic resonance imaging (fMRI) provide a new window onto the organizational principles of brain function. Using state-of-the-art sparsity-driven deconvolution [1,2], we extract innovation-driven co-activation patterns (iCAPs) from resting-state fMRI [3]. The iCAPs’ maps are spatially overlapping and their activity-inducing signals temporally overlapping. Decomposing resting-state fMRI in terms of iCAPs reveals the rich spatiotemporal structure of functional components that dynamically assemble known resting-state networks. The temporal overlap between iCAPs is substantial, which confirms crosstalk happening at the fMRI timescale; on average, three to four iCAPs occur simultaneously in specific combinations that are consistent with their behaviour profiles according to BrainMap. Intriguingly, in contrast to conventional connectivity analysis, which suggests a negative correlation between fluctuations in the default-mode network (DMN) and task-positive networks, we instead find evidence for two DMN-related iCAPs consisting the posterior cingulate cortex that differentially interact with the attention network. These findings illustrate how conventional correlational approaches might be misleading in terms of how task-positive and -negative networks interact, and suggest that more detailed, dynamical decompositions can give more accurate descriptions of functional components of spontaneous activity.

1] F. I. Karahanoglu, I. Bayram, D. Van De Ville, “A Signal Processing Approach to Generalized 1D Total Variation”, IEEE Transactions on Signal Processing, vol. 59, no. 11, pp. 5265-5274, Nov. 2011. [2] F. I. Karahanoglu, C. Caballero Gaudes, F. Lazeyras, D. Van De Ville, “Total Activation: FMRI Deconvolution through Spatio-Temporal Regularization”, NeuroImage, vol. 73, pp. 121-134, 2013. [3] F. I. Karahanoglu, D. Van De Ville, “Transient Brain Activity Disentangles fMRI Resting-date Dynamics in Terms of Spatially and Temporally Overlapping Networks”, Nature Communications, vol. 6, p. 7751, 2015.