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Using direct recordings from human MTL neurons during sleep, Staresina et al. reveal that neuronal firing and communication—thought to underlie synaptic plasticity and learning—are controlled by coupled slow oscillations, spindles and ripples.

The memory function of sleep relies on the coordination of slow oscillations and spindles. Here the authors show that respiration is associated with the emergence and interplay of these sleep rhythms, and that this coupling is linked to memory reactivation.

New memory traces are believed to be reactivated and reorganized during sleep, mediated by the fine-tuned temporal interplay of neocortical slow oscillations, thalamo-cortical spindles and hippocampal ripples. The authors used intracranial recordings in humans to provide, for the first time, direct evidence for a systematic interaction of these oscillations in the human hippocampus.

Sleep after learning helps to strengthen new memories. Here, the authors link this memory benefit to the reactivation of learning experiences when two endogenous sleep rhythms—slow oscillations and sleep spindles—coincide.

The hippocampus is involved both in episodic memory recall and scene processing. Here, the authors show that hippocampal neurons first process scene cues before coordinating memory-guided pattern completion in adjacent entorhinal cortex.

By tracking brain activity in both normal subjects and in epilepsy patients, the authors demonstrate that there are differences in the time courses of activation to a memory task in the perirhinal cortex and the hippocampus. These results suggest differentiated roles for these two areas during memory tasks.

Kolibius et al. show that individual neurons in the human hippocampus code for particular episodic memories.

Using single-neuron recordings in patients with epilepsy, Kunz et al. show that stimulus-specific neurons activate together during hippocampal ripples when humans encode and retrieve associative memories.

The hippocampus is a central memory hub and exhibits prominent theta oscillations. Here the authors show that oscillations are visible in behavior when decisions depend on memory, paralleled by theta phase synchronization in hippocampal recordings.

Michelmann and colleagues investigated how humans search for information in episodic memory. Using MEG, the authors show fast, forward-directed memory replay, with speed changing flexibly depending on the task.

While the contribution of sharp wave ripples in memory consolidation and decision-making is established in rodent models, our understanding of their role in human memory is incomplete. Here, the authors discuss common methodological challenges in detecting, analyzing, and reporting sharp wave ripples, then they suggest practical solutions to distinguish them from other high-frequency events

Cox et al. investigate communication between the hippocampus and neocortex during sleep using invasive electroencephalography from human patients. They characterize the oscillations exhibiting interregional coordination and identify an important orchestrating role for hippocampal slow oscillations.