Cortical flow: Investigating the spatiotemporal dynamics of the brain

Magneto- and electro-encephalography (MEG/EEG) offer probably the best trade-off between a superlative time resolution and a fair spatial one. At the scale of sensors, MEG/EEG signals reflect the global dynamic of the brain whereas sources imaging through inverse problem provide more regional behaviors. In both case, the data can be seen as spatiotemporal structures from which we can features such as optical flow, reflecting the amount of changes in the sequence of brain activations. After having recalled the theoretical basis of the so-called cortical flow, we present two applications in different experimental paradigms. We first show that our tool yields a temporal sequencing of brain events at a global scale. At last we focus on more local neural behaviors occurring in the visual cortex.