Top Highlights

• These observations highlight the importance of CA3 inhibition for ripple generation, while pre-ripple responses indicate a long and orchestrated ripple initiation process in the awake state.
• Recent in vitro studies have also emphasized the importance of inhibitory neurons in ripple initiation (Bazelot et al., 2016; Ellender et al., 2010; Schlingloff et al., 2014), while other studies suggested that area CA2 and a special class of CA3 cells play a key role in ripple initiation (Hunt et al., 2018; Oliva et al., 2016).
• Whole-cell recordings in awake animals have opened a window to understanding the interplay between collective network activity and membrane potential (Vm) dynamics of hippocampal neurons, which can reveal the nature and timing of synaptic inputs and subthreshold changes that are invisible to extracellular recordings.

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