Light sleep versus slow wave sleep in memory consolidation:a question of global versus local processes?

Contains fulltext : 135488.pdf (publisher's version ) (Closed access)Sleep is strongly involved in memory consolidation, but its role remains unclear. 'Sleep replay', the active potentiation of relevant synaptic connections via reactivation of patterns of network activity that occurred during previous experience, has received considerable attention. Alternatively, sleep has been suggested to regulate synaptic weights homeostatically and nonspecifically, thereby improving the signal:noise ratio of memory traces. Here, we reconcile these theories by highlighting the distinction between light and deep nonrapid eye movement (NREM) sleep. Specifically, we draw on recent studies to suggest a link between light NREM and active potentiation, and between deep NREM and homeostatic regulation. This framework could serve as a key for interpreting the physiology of sleep stages and reconciling inconsistencies in terminology in this field

Initial Investigation of the Effects of an Experimentally Learned Schema on Spatial Associative Memory in Humans

Contains fulltext : 139952.pdf (publisher's version ) (Open Access

Action boosts episodic memory encoding in humans via engagement of a noradrenergic system

We are constantly interacting with our environment whilst we encode memories. However, how actions influence memory formation remains poorly understood. Goal-directed movement engages the locus coeruleus (LC), the main source of noradrenaline in the brain. Noradrenaline is also known to enhance episodic encoding, suggesting that action could improve memory via LC engagement. Here we demonstrate, across seven experiments, that action (Go-response) enhances episodic encoding for stimuli unrelated to the action itself, compared to action inhibition (NoGo). Functional magnetic resonance imaging, and pupil diameter as a proxy measure for LC-noradrenaline transmission, indicate increased encodingrelated LC activity during action. A final experiment, replicated in two independent samples, confirmed a novel prediction derived from these data that emotionally aversive stimuli, which recruit the noradrenergic system, modulate the mnemonic advantage conferred by Go-responses relative to neutral stimuli. We therefore provide converging evidence that action boosts episodic memory encoding via a noradrenergic mechanism

Effectiveness of Emotional Memory Reactivation vs Control Memory Reactivation Before Electroconvulsive Therapy in Adult Patients With Depressive Disorder A Randomized Clinical Trial:A Randomized Clinical Trial

Importance: Although electroconvulsive therapy (ECT) is often effective, approximately half of patients with depression undergoing ECT do not benefit sufficiently, and relapse rates are high. ECT sessions have been shown to weaken reactivated memories. The effect of emotional memory retrieval on cognitive schemas remains unknown. Objective: To assess whether emotional memory retrieval just before patients receive ECT sessions weakens underlying cognitive schemas, improves ECT effectiveness, increases ECT response, and reduces relapse rates. Design, Setting, and Participants: In this multicenter randomized clinical trial conducted from 2014 to 2018 in the departments of psychiatry in 3 hospitals in the Netherlands, 72 participants were randomized 1:1 to 2 parallel groups to receive either emotional memory reactivation (EMR-ECT) or control memory reactivation (CMR-ECT) interventions before ECT sessions. The Hamilton Depression Rating Scale (HDRS [total score range: 0-52, with 0-7 indicating no depression and ≥24 indicating severe depression]) was used to measure symptoms of depression during and after ECT, with a 6-month follow-up period. Participants were between ages 18 and 70 years with a primary diagnosis of unipolar major depressive disorder (MDD) according to the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition, Text Revision) and in whom ECT was indicated. Data analysis was performed from July to November 2019. Interventions: EMR-ECT or CMR-ECT interventions prior to ECT sessions. Main Outcomes and Measures: Depression scores and relapse rates within 6 months were assessed with the HDRS and analyzed using logistic and linear multiple regression analyses. Results: A total of 66 patients (mean [SD] age, 49.3 [12.3] years; 39 [59.1%] women) were randomized to the EMR-ECT group (n = 32) or the CMR-ECT group (n = 34). Regardless of the memory intervention, 42.4% (28 of 66) of patients responded (≥50% decrease of symptom severity on the HDRS). Of patients who responded, 39.3% (11 of 28) relapsed within 6 months. Remission rates (CMR-ECT group, 29.4% [10 of 34] vs EMR-ECT group, 25.0% [8 of 32]; P = .58), mean (SD) HDRS scores after the ECT course (CMR-ECT group, 14.6 [8.6] vs EMR-ECT group, 14.9 [8.8]; P = .88), total mean (SD) number of required ECT sessions for response (CMR-ECT group, 14.9 [7.9] vs EMR-ECT group, 15.6 [7.3]; P = .39), and relapse rates (CMR-ECT group, 46.7% [7 of 15] vs EMR-ECT group, 30.8% [4 of 13]; P = .33) were not significantly altered by the intervention. Conclusions and Relevance: Study findings suggest that the EMR-ECT intervention just before patient receipt of ECT for depression did not improve effectiveness, increase speed of response, or reduce relapse rates after the ECT course compared with patients receiving CMR-ECT. Trial Registration: Trialregister.nl Identifier: NL4289

Blocking human fear memory with the matrix metalloproteinase inhibitor doxycycline

Learning to predict threat is a fundamental ability of many biological organisms, and a laboratory model for anxiety disorders. Interfering with such memories in humans would be of high clinical relevance. On the basis of studies in cell cultures and slice preparations, it is hypothesised that synaptic remodelling required for threat learning involves the extracellular enzyme matrix metalloproteinase (MMP) 9. However, in vivo evidence for this proposal is lacking. Here we investigate human Pavlovian fear conditioning under the blood-brain barrier crossing MMP inhibitor doxycyline in a pre-registered, randomised, double-blind, placebo-controlled trial. We find that recall of threat memory, measured with fear-potentiated startle 7 days after acquisition, is attenuated by ~60% in individuals who were under doxycycline during acquisition. This threat memory impairment is also reflected in increased behavioural surprise signals to the conditioned stimulus during subsequent re-learning, and already late during initial acquisition. Our findings support an emerging view that extracellular signalling pathways are crucially required for threat memory formation. Furthermore, they suggest novel pharmacological methods for primary prevention and treatment of posttraumatic stress disorder.Molecular Psychiatry advance online publication, 4 April 2017; doi:10.1038/mp.2017.65

Eradicating war memories: neuroscientific reality and ethical concerns

Traumatic memories of war can result in mental disorders such as post-traumatic stress disorder (PTSD). PTSD is characterized by intrusive trauma memories and severe stress responses with devastating personal and societal consequences. Current treatments teach patients to regulate trauma memories, but many experience a return of symptoms even after initially successful treatment. Neuroscience is discovering ways to permanently modify trauma memories and prevent the return of symptoms. Such memory modification techniques (MMTs) have great clinical potential but also important ethical, legal and social implications. In this article, the authors describe PTSD, the role of memory in PTSD, its effects on the brain, and the limitations of current treatment methods. Then, the state of the art of the neuroscience of MMTs is presented. Within this realistic scientific framework the authors will discuss the ethical, legal and social implications of MMTs for the treatment of war-induced PTSD, especially in a military population. Three major sets of issues will be focused on: safety and social justice concerns, concerns about threats to authenticity and identity, and the possible legal and moral duties to retain certain memories. Finally, the article concludes that within scientific reality, concerns are limited and do not outweigh the potential benefits of developing treatments for patients

Memory modification as treatment for PTSD: neuroscientific reality and ethical concerns

Exposure to traumatic events can trigger mental disorders, such as posttraumatic stress disorder (PTSD). People with PTSD are haunted by intrusive traumatic memories that evoke severe fear responses, causing great suffering. Members of the armed forces are at an increased risk of experiencing traumatic events and therefore developing PTSD. Current treatments teach patients to regulate trauma memories, but many experience a return of symptoms even after initially successful treatment. Neuroscientific research is discovering ways to permanently modify trauma memories and prevent the return of symptoms. Such memory modification techniques (MMTs) have great clinical potential but also important ethical, legal, and social implications (ELSI). This chapter provides an overview of how traumatic memories contribute to PTSD, current treatment methods, their limitations, and the state-of-the-art of MMTs. Then, drawing on these neuroscience insights, the chapter discusses some ELSI of utilizing MMTs to treat PTSD in military populations. The focus is on three major sets of issues: safety and social justice concerns, concerns about threat to authenticity and identity, and possible legal and moral duties to retain certain memories. The chapter concludes that, within current scientific reality, concerns are often overstated and do not outweigh the potential benefit to develop treatments for patients

Structural brain abnormalities common to posttraumatic stress disorder and depression

Background: Posttraumatic stress disorder (PTSD) and major depression are reliably associated with reductions in brain volume in markedly similar areas. To our knowledge, no volumetric studies have directly contrasted these conditions. We investigated which, if any, grey matter reductions would be uniquely associated with each disorder. We also investigated more subtle independent effects: specifically, correlations between brain volume and self-report measures of psychopathology. Methods: We obtained structural magnetic resonance imaging scans from participants with PTSD, major depression and healthy controls exposed to trauma. Participants completed standardized self-report measures of anxiety and depression. We used voxel-based morphometry, applying the DARTEL algorithm within SPM5 to identify associated volumetric changes. Results: We enrolled 24 patients with PTSD, 29 with major depression and 29 controls in our study. The clinical groups had regions of markedly smaller volume compared with the control group, particularly in prefrontal areas, but did not differ from each other. Greater self-reported anxiety was inversely related to volume in several areas, particularly the inferior temporal cortex, among patients with PTSD, but was associated with some volume increases in patients with major depression. Greater self-reported depression showed similar but weaker effects, being inversely related to brain volume in patients with PTSD but positively related to volume in the cuneus and precuneus of those with major depression. Limitations: To maintain the representativeness of the sample, patients with PTSD were not excluded if they had typical comorbid conditions, such as depression. Patients were not all medication-free, but we controlled for group differences in antidepressant use in the analyses. Conclusion: We identified commonalities in areas of brain volume in patients with PTSD and those with major depression, suggesting that existing findings concerning reductions in prefrontal areas in particular may not be specific to PTSD but rather related to features of the disorder that are shared with other conditions, such as depression. More subtle differences between patients with PTSD and those with major depression were represented by distinct structural correlates of self-reported anxiety and depression