SLEEP DEPRIVATION AND INTERFERENCE BY EMOTIONAL DISTRACTERS Sleep Deprivation and Interference by Emotional Distracters

1305 Emotional Distractibility during Sleep Deprivation—Chuah et al EMOTION IS A DOUBLE-EDGED SWORD THAT CAN ENHANCE1-3 OR HINDER COGNITION,4-6 DEPENDING ON THE CONTEXT IN WHICH EMOTIONAL STIMULI are encountered. The emotive content of pictures may enhance our attention and memory, particularly when task-relevant.7-9 However, task-irrelevant, emotion-laden stimuli are also potent distracters, often reducing the recall of neutral memoranda presented earlier.10,11 Distraction by negative emotional events is postulated to result from the interaction of two neural systems, a “hot, affective” ventral system and a “cold, executive” dorsal system.10,12,13 Negative emotional stimuli increase maintenance-related activity within the ventral system, which includes the amygdala and the ventrolateral prefrontal cortex (vlPFC). Concurrently, these stimuli attenuate activation of the dorsal executive system, which includes the dorsolateral prefrontal cortex (dlPFC) and the lateral parietal cortex (LPC). Sleep deprivation can also impair attention and memory,14-19 and its growing prevalence,20 especially among “knowledge workers,” motivates a detailed exploration of its impact on human behavior. Several behavioral and imaging studies have examined the effects of sleep deprivation on attention,17,18,21 memory,22-24 and emotion processing.25,26 However, less is known about how these elements interact with each other and, in particular, how emotional stimuli can affect memory by serving as distracters in sleep deprived persons. An understanding of the neural mechanisms underpinning this effect could help reduce adverse outcomes in health care settings, shift work, and military operations. Given earlier observations concerning the greater efficacy of negative emotional distracters compared to neutral distracters,10,11 it is possible that emotional distracters could also have a greater impact on working memory in sleep deprived persons. This would underscore the value of maintaining emotional neutrality in workplaces where critical decisions are made by sleep deprived individuals, for example, in intensive care units. In studying the neural mechanisms underlying the effects of negative distraction on memory, we focused on the amygdala, as it is known to mediate the effect of emotional stimuli on attention and memory.27-29 Additionally, sleep deprivation has been shown to elevate amygdala activation in response to aversive emotional targets26 as well as reduce the functional connectivity between the amygdala and a medial frontal region associated with emotional regulation. Analyses of functional connectivity between the amygdala and other neural structures also suggest that emotional stimuli may be processed in a manner that facilitates more robust recollection in spite of sleep deprivation.30 In light of these findings, we predicted that (1) working memory would be impaired following sleep deprivation and that emotional distracters would be more effective than neutral distracters; (2) declines in the ability to maintain neutral memoSLEEP DEPRIVATION AND INTERFERENCE BY EMOTIONAL DISTRACTERS