Music listening and stress recovery in healthy individuals: A systematic review with meta-analysis of experimental studies.

Effective stress recovery is crucial to prevent the long-term consequences of stress exposure. Studies have suggested that listening to music may be beneficial for stress reduction. Thus, music listening stands to be a promising method to promote effective recovery from exposure to daily stressors. Despite this, empirical support for this opinion has been largely equivocal. As such, to clarify the current literature, we conducted a systematic review with meta-analysis of randomized, controlled experimental studies investigating the effects of music listening on stress recovery in healthy individuals. In fourteen experimental studies, participants (N = 706) were first exposed to an acute laboratory stressor, following which they were either exposed to music or a control condition. A random-effects meta-regression with robust variance estimation demonstrated a non-significant cumulative effect of music listening on stress recovery g = 0.15, 95% CI [-0.21, 0.52], t(13) = 0.92, p = 0.374. In healthy individuals, the effects of music listening on stress recovery seemed to vary depending on musical genre, who selects the music, musical tempo, and type of stress recovery outcome. However, considering the significant heterogeneity between the modest number of included studies, no definite conclusions may currently be drawn about the effects of music listening on the short-term stress recovery process of healthy individuals. Suggestions for future research are discussed.

Defensive freezing and its relation to approach-avoidance decision-making under threat.

Successful responding to acutely threatening situations requires adequate approach-avoidance decisions. However, it is unclear how threat-induced states-like freezing-related bradycardia-impact the weighing of the potential outcomes of such value-based decisions. Insight into the underlying computations is essential, not only to improve our models of decision-making but also to improve interventions for maladaptive decisions, for instance in anxiety patients and first-responders who frequently have to make decisions under acute threat. Forty-two participants made passive and active approach-avoidance decisions under threat-of-shock when confronted with mixed outcome-prospects (i.e., varying money and shock amounts). Choice behavior was best predicted by a model including individual action-tendencies and bradycardia, beyond the subjective value of the outcome. Moreover, threat-related bradycardia (high-vs-low threat) interacted with subjective value, depending on the action-context (passive-vs-active). Specifically, in action-contexts incongruent with participants' intrinsic action-tendencies, stronger bradycardia related to diminished effects of subjective value on choice across participants. These findings illustrate the relevance of testing approach-avoidance decisions in relatively ecologically valid conditions of acute and primarily reinforced threat. These mechanistic insights into approach-avoidance conflict-resolution may inspire biofeedback-related techniques to optimize decision-making under threat. Critically, the findings demonstrate the relevance of incorporating internal psychophysiological states and external action-contexts into models of approach-avoidance decision-making.

Eye-Movement Intervention Enhances Extinction via Amygdala Deactivation.

Improving extinction learning is essential to optimize psychotherapy for persistent fear-related disorders. In two independent studies (both n = 24), we found that goal-directed eye movements activate a dorsal frontoparietal network and transiently deactivate the amygdala (η p2 = 0.17). Connectivity analyses revealed that this downregulation potentially engages a ventromedial prefrontal pathway known to be involved in cognitive regulation of emotion. Critically, when eye movements followed memory reactivation during extinction learning, it reduced spontaneous fear recovery 24 h later (η p2 = 0.21). Stronger amygdala deactivation furthermore predicted a stronger reduction in subsequent fear recovery after reinstatement (r = 0.39). In conclusion, we show that extinction learning can be improved with a noninvasive eye-movement intervention that triggers a transient suppression of the amygdala. Our finding that another task which taxes working memory leads to a similar amygdala suppression furthermore indicates that this effect is likely not specific to eye movements, which is in line with a large body of behavioral studies. This study contributes to the understanding of a widely used treatment for traumatic symptoms by providing a parsimonious account for how working-memory tasks and goal-directed eye movements can enhance extinction-based psychotherapy, namely through neural circuits (e.g., amygdala deactivation) similar to those that support cognitive control of emotion.SIGNIFICANCE STATEMENT Fear-related disorders represent a significant burden on individual sufferers and society. There is a high need to optimize treatment, in particular via noninvasive means. One potentially effective intervention is execution of eye movements following trauma recall. However, a neurobiological understanding of how eye movements reduce traumatic symptoms is lacking. We demonstrate that goal-directed eye-movements, like working-memory tasks, deactivate the amygdala, the core neural substrate of fear learning. Effective connectivity analyses revealed amygdala deactivation potentially engaged dorsolateral and ventromedial prefrontal pathways. When applied during safety learning, this deactivation predicts a reduction in later fear recovery. These findings provide a parsimonious and mechanistic account of how behavioral manipulations taxing working memory and suppressing amygdala activity can alter retention of emotional memories.

Motor imagery: a window into the mechanisms and alterations of the motor system.

Motor imagery is a widely used paradigm for the study of cognitive aspects of action control, both in the healthy and the pathological brain. In this paper we review how motor imagery research has advanced our knowledge of behavioral and neural aspects of action control, both in healthy subjects and clinical populations. Furthermore, we will illustrate how motor imagery can provide new insights in a poorly understood psychopathological condition: conversion paralysis (CP). We measured behavioral and cerebral responses with functional magnetic resonance imaging (fMRI) in seven CP patients with a lateralized paresis of the arm as they imagined moving the affected or the unaffected hand. Imagined actions were either implicitly induced by the task requirements, or explicitly instructed through verbal instructions. We previously showed that implicitly induced motor imagery of the affected limb leads to larger ventromedial prefrontal responses compared to motor imagery of the unaffected limb. We interpreted this effect in terms of greater self-monitoring of actions during motor imagery of the affected limb. Here, we report new data in support of this interpretation: inducing self-monitoring of actions of both the affected and the unaffected limb (by means of explicitly cued motor imagery) abolishes the activation difference between the affected and the unaffected hand in the ventromedial prefrontal cortex. Our results show that although implicit and explicit motor imagery both entail motor simulations, they differ in terms of the amount of action monitoring they induce. The increased self-monitoring evoked by explicit motor imagery can have profound cerebral consequences in a psychopathological condition.

Childhood abuse in patients with conversion disorder.

OBJECTIVE: Despite the fact that the assumption of a relationship between conversion disorder and childhood traumatization has a long history, there is little empirical evidence to support this premise. The present study examined this relation and investigated whether hypnotic susceptibility mediates the relation between trauma and conversion symptoms, as suggested by Janet's autohypnosis theory of conversion disorder. METHOD: A total of 54 patients with conversion disorder and 50 matched comparison patients with an affective disorder were administered the Structured Trauma Interview as well as measures of cognitive (Dissociative Experiences Scale) and somatoform (20-item Somatoform Dissociation Questionnaire) dissociative experiences. RESULTS: Patients with conversion disorder reported a higher incidence of physical/sexual abuse, a larger number of different types of physical abuse, sexual abuse of longer duration, and incestuous experiences more often than comparison patients. In addition, within the group of patients with conversion disorder, parental dysfunction by the mother-not the father-was associated with higher scores on the Dissociative Experiences Scale and the Somatoform Dissociation Questionnaire. Physical abuse was associated with a larger number of conversion symptoms (Structured Clinical Interview for DSM-IV Axis I Disorders). Hypnotic susceptibility proved to partially mediate the relation between physical abuse and conversion symptoms. CONCLUSIONS: The present results provide evidence of a relationship between childhood traumatization and conversion disorder.

Changes in PTSD patients' narratives during prolonged exposure therapy: a replication and extension.

Following E. B. Foa, C. Molnar, and L. Cashman (1995), narrative changes from the first to the last exposure session were compared for improved and nonimproved PTSD patients on fragmentation, organization, internal, and external events. Improved (n = 8) and nonimproved (n = 12) patients did not differ regarding changes in fragmentation or organized thoughts. However, improved patients showed a greater decrease in disorganized thoughts during treatment. Furthermore, all patients, independent of improvement, showed significant changes in the same direction; a decrease in disorganized thoughts and external events and an increase in internal events. Although previous results were partly replicated, it is concluded that narrative changes may be due to exposure treatment itself rather than to changes in memory representation.

Motor initiation and execution in patients with conversion paralysis.

Motor initiation and motor execution in four patients with conversion paralysis were investigated in a non-affected motor modality (speech). In line with the hypothesis of dissociated control in conversion disorder [Cognit. Neuropsychiatry 8 (1) (2001) 21] motor initiation, but not response duration, was expected to be impaired. The motor initiation times (reaction time: RT) and motor execution times (response duration: RD) were compared on four RT-tasks that required the production of a verbal response: a simple choice RT-task, a mental letter rotation task, and an implicit and an explicit mental hand rotation task. Because conversion disorder is expected to primarily involve an impairment in the initiation of movement, we expected the following task characteristics to uniquely affect RT and not RD: type of instruction (implicit versus explicit instructed imagery), angle of rotation, and target arm (affected versus non-affected arm). The results indeed showed the task characteristics to significantly affect the participants' RT and not their RD. It was concluded that conversion paralysis is associated with a specific impairment in the explicit initiation of processes with a spatial and motor component.

Hypnotic susceptibility in patients with conversion disorder.

Conversion disorder has been associated with hypnotic susceptibility for over a century and is currently still believed to be a form of autohypnosis. There is, however, little empirical evidence for the relation between hypnotic susceptibility and conversion symptoms. The authors compared 50 patients with conversion disorder with 50 matched control patients with an affective disorder on measures of hypnotic susceptibility, cognitive dissociation, and somatoform dissociation. Conversion patients were significantly more responsive to hypnotic suggestions than control patients. In addition, conversion patients showed a significant correlation between hypnotic susceptibility and the number of conversion complaints. These results provide the first evidence of a relationship between hypnotic susceptibility and the presence and number of conversion symptoms.

Motor imagery during hypnotic arm paralysis in high and low hypnotizable subjects.

Previous research suggests that conversion disordered patients with hand/arm paralysis exhibit slowed reaction times for mental hand-rotation tasks that correspond to their affected arm when the tasks are explicitly instructed and not when they are implicitly cued. Because of the many similarities between hypnotic phenomena and conversion symptoms, the authors tested whether similar motor imagery impairment would occur among normal high hypnotizable subjects when paralysis is suggested. Nine high and 8 low hypnotizable subjects were administered an implicit and an explicit mental hand-rotation task during hypnotically suggested paralysis of the right arm. On the implicit task, there were no significant reaction time (RT) differences between highs and lows. On the explicit task, only highs showed a significantly larger RT increase per degree of rotation with the paralyzed arm, compared to the normal arm. These preliminary findings suggest that the motor imagery impairment observed in conversion paralysis can be induced in highs using hypnosis.