Global and local nature of cortical slow waves

Explaining the macroscopic activity of a recorded neuronal population from its known microscopic properties still poses a great challenge, not just because of the many local agents that shape the output of a circuit, but due to the impact of long-range connections from other brain regions. Here we use a computational model to explore how local and global components of a network shape the Slow Wave Activity (SWA). We performed a sensitivity analysis of multiple cellular and synaptic features in models of isolated and connected networks. This allowed us to explore how the interaction of local properties and long-range connections shape the SWA of a population and its neighbors, as well as how the sequential propagation of active “Up” states lead to the emergence of preferred modes of propagation. We described relevant features of cortical Up states that are modulated by “stiff” combinations of parameters of the local circuit as opposed to other that are sensitive to the level of excitability of the whole network and the input coming from neighbor populations. We found that while manipulations in the synaptic excitatory/inhibitory balance can create local changes, cellular components that modulate the excitability or adaptation of a population have a long-range effect that leads to changes in neighbor populations too. Additionally, our simulations guided in vivo experiments that showed how heterogeneities in excitability between cortical areas can determine the directionality of travelling waves during SWA. We expect these results to motivate future research exploring and comparing cortical circuits through the analysis of their Up states.