Figure 3. .
Dynamic core-periphery structure. (A) Top: Cartoon representing the core-periphery organization of the network with core nodes colored in blue and peripheral nodes in red. Bottom: Histogram of the values of the instantaneous weighted coreness Ci(t) of each neuron at each time of a recording: The most frequent values of (t) are close to 0 (red dot), hence coreness values typical of peripheral nodes, whereas coreness values of core nodes, Ci(t) ∼ 1 are rare (blue dot). (B) Histograms of instantaneous weighted coreness values of the neurons in several individual time-frames (every 60 s). The different histograms show that the picture of a majority of neurons with low coreness value and few neurons with high coreness hold at all times. The core-periphery organization of the information sharing network is thus persistent in time. (C) Plot of the temporal evolution of the weighted coreness (t) of each node i in a specific recording: The green line highlights the evolution of the coreness of the node with highest average coreness 〈Cw(t)〉max (time average over the whole recording); the purple line corresponds to the node whose coreness fluctuates the most (node of maximum variance of (t)). We show below this plot a cartoon of the core-periphery organization of the network, where we illustrate how the former node steadily belongs to the core, while the latter node evolves several times from the core to the periphery and back. (D) Plots of the core filling factor (top and center panels) and of the core filling fraction (bottom) of the different layers of hippocampus (HPC) and medial entorhinal cortex (mEC). The core filling factor of each layer is the percentage of nodes of each layer that are located in the core (nodes above the 95th percentile of coreness values). In the bottom panel, the green line represents the separation between the fraction of core nodes located either in the mEC layers (orange) or in the HPC (blue): the core filling fraction. The cartoon below the core filling fraction plot illustrates how the neurons that belong to the core at different times can be located in different anatomical structures.