Altered predictive control during memory suppression in PTSD

Event-related potentials associated with cognitive control in adolescents exposed to complex childhood trauma

ABSTRACTBackground: Complex childhood trauma (CCT), characterized by repeated and prolonged exposure to adverse experiences, disrupts cognitive, emotional, and neural development. Adolescence, a critical developmental period, is particularly vulnerable to these effects, with CCT increasing the risk of psychopathologies, including post-traumatic stress disorder (PTSD). Despite this, the neurophysiological underpinnings of trauma-related deficits in cognitive control remain insufficiently explored, particularly in the developing brains of children and adolescents. This study aimed to investigate the neurophysiological markers of cognitive control in adolescents with CCT using event-related potential (ERP) components to propose an electrophysiological phenotype associated with CCT, as a vulnerability for PTSD.Methods: Twenty adolescents with CCT and 40 age- and gender-matched healthy controls performed a cued GO/NOGO task. ERP components - contingent negative variation (CNV), NoGo-N2, and NoGo-P3 - were analysed alongside behavioural measures such as omission and commission errors and reaction time, using a preregistered protocol. Statistical analysis included Mann-Whitney tests and cluster-based permutation tests for ERP comparisons.Results: Adolescents with CCT showed significant impairments in both proactive (reduced CNV amplitudes) and reactive (diminished NoGo-N2 and NoGo-P3 amplitudes) control mechanisms. Behaviourally, the CCT group exhibited higher omission errors and shorter reaction times than controls. Exploratory analysis revealed reduced amplitudes in the visual negativity (VN) component, suggesting disruptions in predictive processing. Latent component analysis identified ERP markers with potential diagnostic utility, linking deficits to key neural circuits associated with cognitive control and predictive processing.Conclusion: Study findings highlight significant impairments in cognitive control mechanisms and disrupted predictive processing in adolescents with CCT, emphasizing the importance of addressing trauma-related neural deficits during adolescence. Given that CCT is a significant risk factor for PTSD, the study provides insights into shared neurobiological pathways, supporting the development of targeted interventions. ERP markers like CNV, NoGo-N2, NoGo-P3, and VN show promise for improving diagnostic precision and monitoring therapeutic outcomes in trauma-exposed youth.

Pathological forgetting from a predictive processing perspective

Recent research suggests that natural forgetting is beneficial, allowing the brain to prioritize relevant information and disregard the irrelevant, thus aiding decision-making and mental health. Conversely, pathological conditions may arise from disruptions in these memory control processes. Without adequate memory control capacities, individuals can suffer from conditions like PTSD or addiction (where unwanted or addiction-related memories persist) on one end of the scale, to conditions such as dementia, Parkinson's disease or traumatic brain injury, which are characterised by heightened rates of forgetting on the other side. This review will explore the concept of predictive processing as a potential mechanism underlying pathological forgetting. It will summarise the neurobiological basis of predictive processing and how it influences what we remember or forget. As evident in the emerging literature, this has distinct implications for understanding pathological forgetting in psychological disorders. Finally, this review will highlight therapeutic interventions that have recently targeted predictive processes and consequently improved symptoms related to forgetting, suggesting translational applications for treatment approaches in these conditions.

Plasticity of human resilience mechanisms

The hippocampus's vulnerability to trauma-induced stress can lead to pathophysiological disturbances that precipitate the development of posttraumatic stress disorder (PTSD). The mechanisms of resilience that foster remission and mitigate the adverse effects of stress remain unknown. We analyzed the evolution of hippocampal morphology between 2016/2017 and 2018/2019, as well as the memory control mechanisms crucial for trauma resilience. Participants were individuals exposed to the 2015 Paris terrorist attacks (N = 100), including chronic (N = 34) and remitted (N = 19) PTSD, and nonexposed (N = 72). We found that normalization of inhibitory control processes, which regulate the resurgence of intrusive memories in the hippocampus, not only predicted PTSD remission but also preceded a reduction in traumatic memories. Improvement in control mechanisms was associated with the interruption of stress-induced atrophy in a hippocampal region that includes the dentate gyrus. Human resilience to trauma is characterized by the plasticity of memory control circuits, which interacts with hippocampal neuroplasticity.

Narration of a collective traumatic event according to the presence of PTSD and considering the social function

Introduction

Individuals suffering from PTSD recount the traumatic event using perceptual, emotional and sensory details. Memorization and recall of individual events are influenced by the individual's social function, i.e., what they are willing and able to share about themselves with others and the society. While the influence of PTSD on narratives has been studied, few studies have measured the effect of social function on the link between PTSD and narrative.

Objectives

The aim was to measure trauma narratives of the terrorist attacks of November 13, 2015, according to the presence of PTSD and considering the social function (civil or professional) at the time of exposure.

Methods

Thirty-seven civilians (including 16 women and 21 men) and 22 first responders (including 7 women and 15 men) exposed to the terrorist attacks of November 13, 2015, in France recounted their experiences. Textometric analyses were carried out to characterize the narrative lexicons of the 4 groups (civilians with PTSD; civilians without PTSD, first responders with PTSD; first responders without PTSD).

Results

The narratives of civilians with or without PTSD contain emotional details of the event. The narratives of first responders with and without PTSD contain details of intervention and team. The narratives of civilians and first responders with PTSD contain elements of social and family contacts. The narratives of civilians and first responders without PTSD contains elements of collective control and aid. Civilians with PTSD mostly use the "I" in narratives, while first responders without PTSD mostly use the "we" narrative and the notion of colleague.

Conclusion

Trauma narratives of individuals exposed to the same collective traumatic event who have developed PTSD are characterized by information about social and family contexts. Trauma narratives of individuals without PTSD show a sense of control and collective support. Associated with PTSD, the social function during the event influences the narrative, involving self-centered statements (first person singular, individual reactions) for exposed civilians, and allo-centered statements (colleagues, victims) for exposed professionals. This study underlines the importance of considering the inclusion of reference to the social group to which one belongs when testifying about peritraumatic experiences to others.

The Index of Intrusion Control (IIC): Capturing individual variability in intentional intrusion control in the laboratory

Intrusive memories can be downregulated using intentional memory control, as measured via the Think/No-Think paradigm. In this task, participants retrieve or suppress memories in response to an associated reminder cue. After each suppression trial, participants rate whether the association intruded into awareness. Previous research has found that repeatedly exerting intentional control over memory intrusions reduces their frequency. This decrease is often summarised with a linear index, which may miss more complex patterns characterising the temporal dynamics of intrusion control. The goal of this paper is to propose a novel metric of intrusion control that captures those dynamic changes over time as a single index. Results from a mega-analysis of published datasets revealed that the change in intrusion frequencies across time is not purely linear, but also includes non-linear dynamics that seem best captured by a log function of the number of suppression attempts. To capture those linear and non-linear dynamics, we propose the Index of Intrusion Control (IIC), which relies on the integral of intrusion changes across suppression attempts. Simulations revealed that the IIC best captured the linear and non-linear dynamics of intrusion suppression when compared with other linear or non-linear indexes of control, such as the regression slope or Spearman correlation, respectively. Our findings demonstrate how the IIC may therefore act as a more reliable metric to capture individual differences in intrusion control, and examine the role of non-linear dynamics characterizing the conscious access to unwanted memories.

Differences in predictive factors for post-traumatic stress disorder encompassing partial PTSD and full PTSD: a cross-sectional study among individuals exposed to the November 13, 2015 Paris attacks

Background

When faced with a surge of physically injured individuals, especially following a traumatic event like an attack, frontline practitioners prioritize early triage. Detecting potential psychological injuries soon after such events remains challenging. Some individuals might develop post-traumatic stress disorder (PTSD) according to DSM-V criteria. Others may exhibit PTSD symptoms without meeting full diagnostic criteria, termed partial or sub-syndromal PTSD, a less-explored area in literature. This study aims to identify predictive factors for both full and partial PTSD.

Method

In a cohort of victims of the 2015 Paris attacks, multinomial logistic regressions explored predictive factors for partial or full PTSD status 8 to 18 months post-attacks. Analyses considered pre, peri, and posttraumatic factors chosen from literature review and univariate analysis within each group.

Results

Within the cohort, 50 individuals showed no signs of PTSD, 35 experienced partial PTSD, and 30 presented with full PTSD. After logistic regression, risk factors associated with full PTSD included a history of trauma (OR = 1.30, CI [1.02-1.66], p < 0.05), the intensity of peri-traumatic physical reactions (OR = 1.22, CI [1.09-1.36], p < 0.001), the difficulties in suppressing intrusive thoughts (OR = 1.11, CI [1.02-1.21], p < 0.013). Only the intensity of peri-traumatic physical reactions emerged as a risk factor for partial PTSD (OR = 1.13, [CI 1.02-1.24], p < 0.001).

Discussion

This study revealed that a history of trauma, the intensity of peri-traumatic physical reactions (e.g., tachycardia, trembling, flushes, numbness.), and the difficulties in suppressing intrusive thoughts constitute risk factors for the development of full PTSD. Moreover, the study identified that only the intensity of peri-traumatic physical reactions emerged as a risk factor for partial PTSD. These findings seem to underscore the significance of peri-traumatic experiences in influencing the development of post-traumatic stress symptoms.

Conclusion

This study emphasizes the significance of examining peri-traumatic reactions in PTSD development, suggesting its potential as a straightforward screening tool for post-traumatic stress disorder. It also underscores the influence of prior traumatic experiences, before de novo traumatization, in shaping vulnerability to PTSD and illuminates the crucial role of compromised control of intrusive thoughts that could perpetuate PTSD.

Increase in physiological inhibitory control results in better suppression of unwanted memories

Forgetting or suppressing a memory with unwanted content is just as important as remembering a desirable one. In addition to emphasizing the role of inhibitory control in memory suppression processes, neuropsychological studies have indicated that an intentional inhibition targeting a brain area may exert its inhibitory effects in seemingly unrelated areas through a common inhibitory network. In this study, we aimed to investigate whether the suppression of unwanted memories can be strengthened by recruiting an inhibitory task that can be simultaneously performed with a memory suppression task. Therefore, we manipulated the level of urinary urgency-induced inhibition of participants (N = 180) and test its effect on the suppression of unwanted memories using a Think/No-Think (T/NT) task. The results of our study indicated that individuals with high levels of urinary urgency demonstrated greater memory suppression compared to those with low urinary urgency. Findings and their implications are discussed within the context of cognitive and clinical perspectives, and recommendations are made for future research.

Musical experience prior to traumatic exposure as a resilience factor: a conceptual analysis

Resilience mechanisms can be dynamically triggered throughout the lifecourse by resilience factors in order to prevent individuals from developing stress-related pathologies such as posttraumatic stress disorder (PTSD). Some interventional studies have suggested that listening to music and musical practice after experiencing a traumatic event decrease the intensity of PTSD, but surprisingly, no study to our knowledge has explored musical experience as a potential resilience factor before the potential occurrence of a traumatic event. In the present conceptual analysis, we sought to summarize what is known about the concept of resilience and how musical experience could trigger two key mechanisms altered in PTSD: emotion regulation and cognitive control. Our hypothesis is that the stimulation of these two mechanisms by musical experience during the pre-traumatic period could help protect against the symptoms of emotional dysregulation and intrusions present in PTSD. We then developed a new framework to guide future research aimed at isolating and investigating the protective role of musical experience regarding the development of PTSD in response to trauma. The clinical application of this type of research could be to develop pre-trauma training that promotes emotional regulation and cognitive control, aimed at populations at risk of developing PTSD such as healthcare workers, police officers, and military staffs.

Peritraumatic physical symptoms and the clinical trajectory of PTSD after a terrorist attack: a network model approach

Introduction: Following a mass casualty event, such as the Paris terrorist attacks of 13 November 2015, first responders need to identify individuals at risk of PTSD. Physical peritraumatic symptoms involving the autonomic nervous system may be useful in this task.Objective: We sought to determine the trajectory of physical response intensity in individuals exposed to the Paris terrorist attacks using repeated measures, and to examine its associations with PTSD. Using network modelling, we examined whether peritraumatic physical symptom associations differed by PTSD status.Methods: Physical reactions were assessed using the Subjective Physical Reactions Scale at three time points: peritraumatic by retrospective recall, then current at one year (8-18 months) and three years (30-42 months) after the attacks. Interaction networks between peritraumatic physical reactions were compared according to PTSD status.Results: On the one hand, the reported intensity of physical reactions was significantly higher in the PTSD group at all time points. On the other hand, using the dynamic approach, more robust positive interactions between peritraumatic physical reactions were found in the PTSD group one and three years after the attacks. Negative interactions were found in the no-PTSD group at one year. Peritraumatic physical numbness was found to be the most central network symptom in the PTSD group, whereas it was least central in the no-PTSD group.Discussion: Network analysis of the interaction between peritraumatic physical subjective responses, particularly physical numbness, may provide insight into the clinical course of PTSD. Our knowledge of the brain regions involved in dissociation supports the hypothesis that the periaqueductal grey may contribute to the process leading to physical numbing.Conclusions: Our findings highlight the role of peritraumatic somatic symptoms in the course of PTSD. Peritraumatic physical numbness appears to be a key marker of PTSD and its identification may help to improve early triage.

Attentional capture mediates the emergence and suppression of intrusive memories

Intrusive memories hijack consciousness and their control may lead to forgetting. However, the contribution of reflexive attention to qualifying a memory signal as interfering is unknown. We used machine learning to decode the brain's electrical activity and pinpoint the otherwise hidden emergence of intrusive memories reported during a memory suppression task. Importantly, the algorithm was trained on an independent attentional model of visual activity, mimicking either the abrupt and interfering appearance of visual scenes into conscious awareness or their deliberate exploration. Intrusion of memories into conscious awareness were decoded above chance. The decoding accuracy increased when the algorithm was trained using a model of reflexive attention. Conscious detection of intrusive activity decoded from the brain signal was central to the future silencing of suppressed memories and later forgetting. Unwanted memories require the reflexive orienting of attention and access to consciousness to be suppressed effectively by inhibitory control.

Memory Sins in Applied Settings: What Kind of Progress?

Over two decades ago, I proposed that memory errors could be classified into seven basic categories or sins (Schacter, 1999, 2001), comprising three sins of omission (transience, absentmindedness, and blocking) and four sins of commission (misattribution, suggestibility, bias, and persistence). In the past two decades, much has been learned about the nature and basis of the memory sins. Here, I assess the extent of progress that has been made during that time regarding applied implications of five of the sins: transience, absentmindedness, misattribution, suggestibility, and persistence. The manifestations of these sins have been examined in a variety of applied settings, including educational, clinical, legal, and technological domains. I argue that considerable progress has been made in characterizing the impact of memory sins in each domain, identify gaps in and limitations of our current knowledge, and briefly consider how these developments bear on broad questions regarding the reliability of human memory.

Trauma and Remembering: From Neuronal Circuits to Molecules

Individuals with posttraumatic stress disorder (PTSD) experience intrusions of vivid traumatic memories, heightened arousal, and display avoidance behavior. Disorders in identity, emotion regulation, and interpersonal relationships are also common. The cornerstone of PTSD is altered learning, memory, and remembering, regulated by a complex neuronal and molecular network. We propose that the essential feature of successful treatment is the modification of engrams in their unstable state during retrieval. During psychedelic psychotherapy, engrams may show a pronounced instability, which enhances modification. In this narrative review, we outline the clinical characteristics of PTSD, its multifaceted neuroanatomy, and the molecular pathways that regulate memory destabilization and reconsolidation. We propose that psychedelics, acting by serotonin-glutamate interactions, destabilize trauma-related engrams and open the door to change them during psychotherapy.

Altered predictive control during memory suppression in PTSD

Aberrant predictions of future threat lead to maladaptive avoidance in individuals with post-traumatic stress disorder (PTSD). How this disruption in prediction influences the control of memory states orchestrated by the dorsolateral prefrontal cortex is unknown. We combined computational modeling and brain connectivity analyses to reveal how individuals exposed and nonexposed to the 2015 Paris terrorist attacks formed and controlled beliefs about future intrusive re-experiencing implemented in the laboratory during a memory suppression task. Exposed individuals with PTSD used beliefs excessively to control hippocampal activity during the task. When this predictive control failed, the prediction-error associated with unwanted intrusions was poorly downregulated by reactive mechanisms. This imbalance was linked to higher severity of avoidance symptoms, but not to general disturbances such as anxiety or negative affect. Conversely, trauma-exposed participants without PTSD and nonexposed individuals were able to optimally balance predictive and reactive control during the memory suppression task. These findings highlight a potential pathological mechanism occurring in individuals with PTSD rooted in the relationship between the brain’s predictive and control mechanisms.

It remains unclear how predictions of future threat affect memory recall, specifically in the case of post-traumatic stress disorder (PTSD). Here, the authors combined computational modeling and brain connectivity analyses to show that individuals with PTSD have exaggerated predictive control and reduced reactive control in a memory suppression task.