memory encoding
Research Papers
16 Aberrant emotional memory encoding in a transdiagnostic sample of patients with intrusive memories
Emotion can affect the way in which experiences are stored in our memory. The dual representation account proposes that traumatic events may be encoded as fragmented sensory-perceptual details without a broader conceptual organisation. This can result in involuntary retrieval of perceptual information triggered by environmental cues without the associated context – a phenomenon referred to as intrusive memories.Currently, it is unknown whether individuals who experience intrusive memories have an underlying vulnerability to aberrant memory encoding, which may lead to the onset or maintenance of symptoms.In Experiment 1, we examined memory recall for neutral and negative images in a transdiagnostic sample of patients with intrusive memories (N = 36), compared to healthy controls (N = 44). Clinical diagnoses in the patient sample included Post-Traumatic Stress Disorder, Major Depressive Disorder, Social Anxiety Disorder, Generalised Anxiety Disorder, Panic Disorder and Other Specified Feeding or Eating Disorders. We excluded participants currently taking psychotropic medication. At encoding, participants viewed neutral, negative and mixed valence image pairs. In the test phase, participants were presented with cues and, if recognised, were asked to recall the associated image. We found a significant group effect, with patients demonstrating impaired item memory for negative images [F(1,280) = 4.435, p = 0.036], relative to healthy controls. This group difference might suggest that individuals with intrusive memories experienced greater sensitivity to negative stimuli, leading to disruptions in memory encoding. Recent work highlights attention maintenance on threat and high levels of threat-related emotional arousal in anxiety- and fear-related disorders which may be one factor driving the disruption to item memory observed in our clinical population.For Experiment 2, in a separate sample of healthy participants (N = 18) we measured eye-tracking behaviour during the encoding phase of the same task. Healthy participants showed greater item memory [F(3, 136 = 2.893, p = 0.0377] and avoidance of fixation [F(1, 110) = 4.898, p = 0.029] on highly arousing, negative stimuli relative to neutral. This might suggest that a shift in attention away from negative stimuli prevents item memory impairments for emotional information.Our future work will identify biological factors driving attentional biases and higher emotional arousal in clinical populations.
View Full Paper →About Sleep's Role in Memory
Over more than a century of research has established the fact that sleep benefits the retention of memory. In this review we aim to comprehensively cover the field of “sleep and memory” research by providing a historical perspective on concepts and a discussion of more recent key findings. Whereas initial theories posed a passive role for sleep enhancing memories by protecting them from interfering stimuli, current theories highlight an active role for sleep in which memories undergo a process of system consolidation during sleep. Whereas older research concentrated on the role of rapid-eye-movement (REM) sleep, recent work has revealed the importance of slow-wave sleep (SWS) for memory consolidation and also enlightened some of the underlying electrophysiological, neurochemical, and genetic mechanisms, as well as developmental aspects in these processes. Specifically, newer findings characterize sleep as a brain state optimizing memory consolidation, in opposition to the waking brain being optimized for encoding of memories. Consolidation originates from reactivation of recently encoded neuronal memory representations, which occur during SWS and transform respective representations for integration into long-term memory. Ensuing REM sleep may stabilize transformed memories. While elaborated with respect to hippocampus-dependent memories, the concept of an active redistribution of memory representations from networks serving as temporary store into long-term stores might hold also for non-hippocampus-dependent memory, and even for nonneuronal, i.e., immunological memories, giving rise to the idea that the offline consolidation of memory during sleep represents a principle of long-term memory formation established in quite different physiological systems.
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