Cortical Up-States as a General Leitmotif

We have discussed above the slow oscillation of sleep and some of its physiological properties, particularly including its robustness and the grouping of faster rhythms on the intracellular up-states. We will argue that these recurring states of neuronal depolarization and increased firing, often with superimposed faster network oscillations, are a hallmark of cortical activity. In this chapter we will illustrate how up-states occur in cortical structures – sometimes recurring, sometimes in isolation – in a number of regions and physiological contexts. An overview of the examples will give the reader an idea of the broad spectrum of up-states.