In sync: gamma oscillations and emotional memory.

Drew B Headley,Denis Paré

doi:10.3389/fnbeh.2013.00170

Drew B Headley, Denis Paré

Open Access

https://doi.org/10.3389/fnbeh.2013.00170

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Abstract

Emotional experiences leave vivid memories that can last a lifetime. The emotional facilitation of memory has been attributed to the engagement of diffusely projecting neuromodulatory systems that enhance the consolidation of synaptic plasticity in regions activated by the experience. This process requires the propagation of signals between brain regions, and for those signals to induce long-lasting synaptic plasticity. Both of these demands are met by gamma oscillations, which reflect synchronous population activity on a fast timescale (35–120 Hz). Regions known to participate in the formation of emotional memories, such as the basolateral amygdala, also promote gamma-band activation throughout cortical and subcortical circuits. Recent studies have demonstrated that gamma oscillations are enhanced during emotional situations, coherent between regions engaged by salient stimuli, and predict subsequent memory for cues associated with aversive stimuli. Furthermore, neutral stimuli that come to predict emotional events develop enhanced gamma oscillations, reflecting altered processing in the brain, which may underpin how past emotional experiences color future learning and memory.

Highlights

Emotions are layered upon the stream of sensations that we experience throughout our lives
Attention, which figures prominently in several cognitive models of emotional behavior (e.g., Mather and Sutherland, 2011), enhances gamma oscillations and their coordinating abilities. These findings provide the basis for hypothesizing that the salience of emotional memory depends, in part, on the enhanced strength of gamma oscillations induced by emotional experience
While a plethora of factors likely contribute to this deficit, increased gamma power may be one of them, which raises the question: how does this fit into the relationship between gamma oscillations and emotional memory? One explanation is that factors that enhance memory, such as level of arousal, can become impairing if they exceed a certain level, creating a socalled “inverted-U” relationship between their magnitude and behavioral performance (Yerkes and Dodson, 1908). At this juncture it is worth noting that while this review focuses on gamma oscillations in the neocortex and amygdala, they have been extensively investigated in the hippocampus, a structure implicated in learning and memory

Summary

INTRODUCTION

Emotions are layered upon the stream of sensations that we experience throughout our lives Beyond being merely another event in an experience, they shape the quality, vividness, and persistence of what is remembered. The neural processes that support emotional memory should exhibit similar properties to emotional memory itself. Gamma oscillations are observed in numerous studies of emotional memory and processing As reviewed below, they are generated during circumstances that incite emotional arousal and are enhanced by stimuli that predict affective events. Much evidence indicates that gamma oscillations predict subsequent memory for emotional experiences, and the accompanying neuroplasticity. This is not to say that gamma oscillations in particular support emotional memory, but that understanding why emotional events have such a profound impact on memory requires an appreciation of how they engage gamma oscillations

BACKGROUND

CONCLUSIONS