Coupled ripple oscillations between the medial temporal lobe and neocortex retrieve human memory

Coupled ripples in memory Short-lived, high-frequency oscillations in the brain called ripples have been implicated as substrates for memory formation. There is, however, little evidence linking ripple activity with awake memory retrieval in humans. Vaz et al. analyzed intracranial recordings in human subjects (see the Perspective by Gelinas). They found that ripple oscillations in the brain's medial temporal lobe were coupled with ripple oscillations in the temporal cortex. This coupling was enhanced just before successful memory retrieval. During successful retrievals with ripples, patterns of oscillations were recapitulated across multiple electrodes, consistent with the initial encoding. The observation that ripple oscillations occur before successful memory retrieval suggests that they may play a mechanistic role in the retrieval process. Science , this issue p. 975 ; see also p. 927