Time meets space: brain dynamics drive spatial topography

Unlike the brains faster frequencies, the exact role of its more powerful infraslow frequencies (ISF, 0.01 - 0.1Hz) in information processing remains poorly understood. Do and how ISF process information? We investigate information processing and related temporal dynamics of ISF in resting and task state fMRI. To quantify information, we apply the Lempel-Ziv complexity (LZC), a measure of signal compression indexing information. The LZC is combined with direct measurement of the dynamics of ISF themselves, namely their power spectral density by median frequency (MF). We demonstrate the following: (I) topographical differences in resting state between higher- and lower-order networks, showing statistically lower LZC in the former; (II) task-related changes in LZC; (III) modulation of LZC associated with MF changes, with low and high MF resting-state values correlated with different degrees of LZC change. In sum, we provide evidence that ISF carry and process information as mediated through their temporal dynamics.