Can posthypnotic suggestions boost updating in working memory? Behavioral and ERP evidence

Reduced generalization of reward among individuals with subthreshold depression: Behavioral and EEG evidence

Altered stimulus generalization has been well-documented in anxiety disorders; however, there is a paucity of research investigating this phenomenon in the context of depression. Depression is characterized by impaired reward processing and heightened attention to negative stimuli. It is hypothesized that individuals with depression exhibit reduced generalization of reward stimuli and enhanced generalization of loss stimuli. Nevertheless, no study has examined this process and its underlying neural mechanisms. In the present study, we recruited 25 participants with subthreshold depression (SD group) and 24 age-matched healthy controls (HC group). Participants completed an acquisition task, in which they learned to associate three distinct pure tones (conditioned stimuli, CSs) with a reward, a loss, or no outcome. Subsequently, a generalization session was conducted, during which similar tones (generalization stimuli, GSs) were presented, and participants were required to classify them as a reward tone, a loss tone, or neither. The results revealed that the SD group exhibited reduced generalization errors in the early phase of generalization, suggesting a diminished ability to generalize reward-related stimuli. The event-related potential (ERP) results indicated that the SD group exhibited decreased generalization of positive valence to reward-related GSs and heightened generalization of negative valence to loss-related GSs, as reflected by the N1 and P2 components. However, the late positive potential (LPP) was not modulated by depression in reward generalization or loss generalization. These findings suggested that individuals with subthreshold depression may have a blunted or reduced ability to generalize reward stimuli, shedding light on potential treatment strategies targeting this particular process.

Using hypnotic suggestion in the rehabilitation of working memory capacity after acquired brain injury: study protocol for a randomized controlled trial

OBJECTIVES

Establishment of effective evidence-based interventions in rehabilitation of working memory (WM) deficits after acquired brain injury (ABI) is sorely needed. Despite robust evidence for the efficiency of clinical hypnosis in a wide range of clinical conditions, and improved understanding of mechanisms underlying its effects, the potential of clinical hypnosis in cognitive rehabilitation is underexplored. A recent study has shown large effects of hypnotic suggestion on WM capacity following ABI. This randomized controlled trial aims to evaluate and explore the replicability of these findings and examine the generalization of treatment effects. The study will also explore possible mechanisms of change.

METHODS

Ninety patients will be recruited from the Sunnaas Rehabilitation Hospital. Inclusion criteria are nonprogressive ABI, minimum 12-month post-injury, ongoing WM deficits, and age between 18 and 67 years. Patients will be randomized to either (a) an intervention group receiving four weekly 1-h sessions with induction and hypnosis, (b) an active control group receiving four weekly 1-h sessions of induction and mindfulness, or (c) a passive control group without intervention. The targeted procedure consists of suggestions about enhancing WM functions, for example through the instantiation of preinjury WM capacity in the present using age regression or through visualizations of brain plasticity. The non-targeted suggestions contain no explicit mention of ABI- or WM-related abilities. Each participant will be assessed at baseline, immediately after intervention, and 6 months after baseline. The primary outcome is the WM index from WAIS-IV and self- and informant-reported WM subscale from BRIEF-A, a questionnaire exploring executive functioning in everyday life. Secondary outcomes include a cognitive composite score derived from tests measuring processing speed, executive functions, learning capacity and memory, and self-reported measures of emotional distress, quality of life, and community integration. Exploratory measures include self-rated ABI and WM-related self-efficacy.

DISCUSSION

Rehabilitation of impaired WM after ABI has hitherto yielded limited transfer effects beyond the training material, i.e., improvement effects on everyday WM capacity, and clinical trials of new interventions are thus warranted. Long-standing empirical evidence demonstrates that hypnosis is an effective therapeutic technique in a wide range of conditions, and recent exploratory research has suggested a high efficacy of hypnosis in improving WM capacity in patients with ABI. However, these extraordinary findings need replication in studies applying scientifically rigorous designs. If successful, our ambition is to provide recommendations and materials to implement hypnotic suggestion as an adjunct treatment following ABI. Study findings may inform future studies exploring the use of clinical hypnosis in other areas of rehabilitation, such as mild TBI, and in other neurological conditions where WM deficit is prominent.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05287542. Registered on March 2022 PROTOCOL VERSION: Protocol version 2.0, December 2023.

Childhood trauma and violent behavior in adolescents are differentially related to cognitive-emotional deficits

Introduction

Converging neurobiological and epidemiological evidence indicates that exposure to traumatic events in the early stages of development, that is, adverse childhood experiences (ACEs), negatively affects the likelihood of being involved in violent behavior later in life. These problems are hypothesized to be mediated by the disruption of executive functions, in particular, the ability to inhibit inappropriate actions. Here we aimed to distinguish the contribution of inhibition in non-emotional and emotional situations (i.e., emotion regulation) and assessed the modulating influence of stress, testing Nairobi county high school students in a two-experiment study.

Methods

In Experiment 1, neutral and emotional inhibition, working memory, and fluid intelligence were measured alongside questionnaires about ACE and violent behavior. Experiment 2 replicated these relations in an independent sample and assessed whether they would be aggravated after acute experimentally induced stress.

Results

Experiment 1 results showed that ACE was positively related to both non-emotional and emotional inhibition; in contrast, violent behavior was only associated with deficient emotional inhibition. Experiment 2 findings showed that stress did not significantly affect the relation of ACE to non-emotional inhibition and emotion regulation; however, it increased deficits of violent participants in their ability to down-regulate emotions.

Discussion

Together, results suggest that deficits in emotion regulation, especially under stressful conditions, are more critical than impairments in non-emotional inhibition in predicting violent behavior in victims of childhood trauma. These findings open perspectives toward more targeted research and interventions.

The nature and persistence of the effects of posthypnotic suggestions on food preferences: The final report of an online study

The persistence of food preferences, which are crucial for diet-related decisions, is a significant obstacle to changing unhealthy eating behavior. To overcome this obstacle, the current study investigates whether posthypnotic suggestions (PHSs) can enhance food-related decisions by measuring food choices and subjective ratings. After assessing hypnotic susceptibility in Session 1, at the beginning of Session 2, a PHS was delivered aiming to increase the desirability of healthy food items (e.g., vegetables and fruit). After the termination of hypnosis, a set of two tasks was administrated twice, once when the PHS was activated and once deactivated in counterbalanced order. The task set consisted of rating 170 pictures of food items, followed by an online supermarket where participants were instructed to select enough food from the same item pool for a fictitious week of quarantine. After 1 week, Session 3 mimicked Session 2 without renewed hypnosis induction to assess the persistence of the PHS effects. The Bayesian hierarchical modeling results indicate that the PHS increased preferences and choices of healthy food items without altering the influence of preferences in choices. In contrast, for unhealthy food items, not only both preferences and choices were decreased due to the PHS, but also their relationship was modified. That is, although choices became negatively biased against unhealthy items, preferences played a more dominant role in unhealthy choices when the PHS was activated. Importantly, all effects persisted over 1 week, qualitatively and quantitatively. Our results indicate that although the PHS affected healthy choices through resolve, i.e., preferred more and chosen more, unhealthy items were probably chosen less impulsively through effortful suppression. Together, besides the translational importance of the current results for helping the obesity epidemic in modern societies, our results contribute theoretically to the understanding of hypnosis and food choices.

The response set theory of hypnosis reconsidered: toward an integrative model

Irving Kirsch is a leading figure in the field of psychological science who has advanced our understanding of hypnosis in key respects that have withstood the tests of time and replication. We honor his prodigious contributions over his distinguished career and extend his response expectancy theory in an integrative model that encompasses predictive coding. We review the construct of expectancies that he articulated and championed for decades and extended in response set theory. We propose novel hypotheses to align his innovative contributions with the most current findings in psychological science and to acknowledge the heuristic value of his work. We especially focus on (I) how the response set theory can be conceptualized in terms of the predictive coding model and (II) psycho-social constructs that need to be considered to better understand the effects of expectancies on hypnotic phenomena in an open and evidence-based integrative model of hypnosis.

A comparative experimental study of visual brain event-related potentials to a working memory task: virtual reality head-mounted display versus a desktop computer screen

Virtual reality head mounted display (VR HMD) systems are increasingly utilised in combination with electroencephalography (EEG) in the experimental study of cognitive tasks. The aim of our investigation was to determine the similarities/differences between VR HMD and the computer screen (CS) in response to an n-back working memory task by comparing visual electrophysiological event-related potential (ERP) waveforms (N1/P1/P3 components). The same protocol was undertaken for VR HMD and CS with participants wearing the same EEG headcap. ERP waveforms obtained with the VR HMD environment followed a similar time course to those acquired in CS. The P3 mean and peak amplitudes obtained in VR HMD were not significantly different to those obtained in CS. In contrast, the N1 component was significantly higher in mean and peak amplitudes for the VR HMD environment compared to CS at the frontal electrodes. Significantly higher P1 mean and peak amplitudes were found at the occipital region compared to the temporal for VR HMD. Our results show that successful acquisition of ERP components to a working memory task is achievable by combining VR HMD with EEG. In addition, the higher amplitude N1/P1 components seen in VR HMD indicates the potential utility of this VR modality in the investigation of early ERPs. In conclusion, the combination of VR HMD with EEG/ERP would be a useful approach to advance the study of cognitive function in experimental brain research.

Deployment dynamics of hypnotic anger modulation

To understand the role that attention plays in the deployment timeline of hypnotic anger modulation, we composed an Attentional Blink paradigm where the first and second targets were faces, expressing neutral or angry emotions. We then suppressed the salience of angry faces through a "hypnotic numbing" suggestion. We found that hypnotic suggestion only attenuated the emotional salience of the second target (T2). By implementing drift-diffusion decision modelling, we also found that hypnotic suggestion mainly affected decision thresholds. These findings suggest that hypnotic numbing resulted from belated changes in response strategy. Interestingly, a contrast against non-hypnotized participants revealed that the numbing suggestion had the instruction-like feature of incorporating emotional valence into the attentional task-set. Together, our results portray hypnotic anger modulation as a two-tiered process: first, hypnotic suggestion alters the attentional task-set; second, provided processing and response preparation are not interrupted, a hypnotizability-dependent response based on said altered task-set is produced through late cognitive control strategies.