Awake ripples enhance emotional memory encoding in the human brain

Abstract

Enhanced memory for emotional experiences is hypothesized to depend on amygdala-hippocampal interactions during memory consolidation. Here we show using intracranial recordings from the human amygdala and the hippocampus during an emotional memory encoding and discrimination task increased awake ripples after encoding of emotional, compared to neutrally-valenced stimuli. Further, post-encoding ripple-locked stimulus similarity is predictive of later memory discrimination. Ripple-locked stimulus similarity appears earlier in the amygdala than in hippocampus and mutual information analysis confirms amygdala influence on hippocampal activity. Finally, the joint ripple-locked stimulus similarity in the amygdala and hippocampus is predictive of correct memory discrimination. These findings provide electrophysiological evidence that post-encoding ripples enhance memory for emotional events.

Hippocampal-prefrontal communication subspaces align with behavioral and network patterns in a spatial memory task

“…Given that we see a link between communication spaces and trajectory-specific position (Figure 2B, E), and several studies support links between task behavior and rhythms (Haegens et al 2014;Hyman et al 2005;Iwata, Kiyonari, and Imai 2017;Moberly et al 2018), we asked if there's any evidence that communication subspaces can be changed or modified by rhythmic activity. We primarily focused on theta and ripple oscillations given previous reports of relationships to memory-guided behavior (Benchenane et al 2010;Hasz and Redish 2020;Jadhav et al 2012;Jones and Wilson 2005a;Joo and Frank 2018;Sigurdsson et al 2010;Tang, Shin, and Jadhav 2021;Zhang et al 2024). It is unclear how and if these states relate to the alignment of activity to the communication subspace and the implied shared activity conducted therefrom.…”