Enhancing cognition by affecting memory reconsolidation

Split-Second Unlearning: Developing a Theory of Psychophysiological Dis-ease

Psychophysiological “stress” underpins many conditions including anxiety, depression, phobias, chronic fatigue syndrome and non-specific musculoskeletal pain such as fibromyalgia. In this article we develop an understanding of chronic psychophysiological stress from a psychological educational perspective, by drawing on supporting evidence that significant emotional events in early life (traumatic and benign) can influence health and well-being later in life. We suggest that traumatic events instigate psychophysiological “stress” responses and the formation of emotional memory images (EMIs) within very short time frames, i.e., “split-second learning.” Once formed these emotional memories are triggered in daily living “re-playing” psychophysiological stress responses, resulting in chronic psychophysiological “dis-ease.” We describe a novel therapeutic approach to scan clients for mannerisms signifying a subconscious “freeze-like” stress response that involves the client as a curious observer within their own experience, feeding back the non-verbal cues as they arrive in the moment. By breaking down the observable fragments of their split-second Pavlovian response to the trigger, clients can detach their EMI from the psychophysiology stress response, i.e., “split-second unlearning.” Our split-second unlearning model recognizes the EMI as a barrier to moving forward and needs to be unlearned before the client can become naturally adaptive again. We argue that this approach places the client at the center of the work without the need of getting bogged down in a life-long narrative.

The serotonergic and alpha-1 adrenergic receptor modulator ACH-000029 ameliorates anxiety-like behavior in a post-traumatic stress disorder model

Post-traumatic stress disorder (PTSD) is a severe chronic mental illness that develops in individuals exposed to life-threatening trauma and is characterized by hyperarousal, flashbacks and nightmares. The serotonergic (5-HT) and noradrenergic (NE) systems are deeply involved in the pathogenesis of PTSD. We have previously reported a novel anxiolytic compound, ACH-000029, that modulates 5-HT and α1-adrenergic receptors and induces acute anxiolytic-like effects in rodents. Here, we investigated the potential of ACH-000029 to prevent anxiety-like behavior in the single prolonged stress (SPS) PTSD model. Mice were subjected to the SPS procedure, followed by a 7-day treatment with ACH-000029 and, for comparison, with the α1-adrenergic antagonist prazosin. Animals were behaviorally assessed using social interaction, elevated plus maze and open field tests. Interestingly, treatment with ACH-000029 but not with prazosin ameliorated the SPS-induced sociability impairment and anxiety-like behavior. The brain-wide c-fos mapping, used as a surrogate for brain activity, indicated the brain structures that were altered by SPS and putatively involved in the anxiolytic-like effect of ACH-000029. The SPS protocol produced long-lasting impairment of regions involved in stress-anxiety response, such as the amygdala, prefrontal cortex, globus pallidus and superior colliculus. ACH-000029 treatment reversed the SPS-induced c-fos changes in the globus pallidus, lateral septum and entorhinal cortex and exclusively modulated c-fos levels in subregions from the retrosplenial cortex, cerebellum, superior colliculus and ventromedial hypothalamus. These results support the hypothesis that the dual regulation of 5-HT and α1-adrenergic receptors is required to alleviate PTSD symptoms and suggest a possible role of ACH-000029 as a PTSD treatment.

The surprising subtleties of changing fear memory: a challenge for translational science

Current pharmacological and psychological treatments for disorders of emotional memory only dampen the affective response while leaving the original fear memory intact. Under adverse circumstances, these original memories regain prominence, causing relapses in many patients. The (re)discovery in neuroscience that after reactivation consolidated fear memories may return to a transient labile state, requiring a process of restabilization in order to persist, offers a window of opportunity for modifying fear memories with amnestic agents. This process, known as memory reconsolidation, opens avenues for developing a revolutionary treatment for emotional memory disorders. The reconsolidation intervention challenges the dominant pharmacological and psychological models of treatment: it is only effective when the amnestic drug is given in conjunction with memory reactivation during a specific time window, and a modification of cognitive processes is a boundary condition for changing fear. Notwithstanding the dramatic effects of targeting memory reconsolidation in the laboratory (i.e. proof of principle), the greatest hurdle to overcome is that the success of the manipulation depends on subtle differences in the reactivation procedure. These experimental parameters cannot be easily controlled in clinical practice. In harnessing the clinical potential of memory reconsolidation, a heuristic for bi-directionally translating behavioural neuroscience and clinical science is proposed.

This article is part of a discussion meeting issue ‘Of mice and mental health: facilitating dialogue between basic and clinical neuroscientists’.

Can Memories of Traumatic Experiences or Addiction Be Erased or Modified? A Critical Review of Research on the Disruption of Memory Reconsolidation and Its Applications

Recent research suggests that the mere act of retrieving a memory can temporarily make that memory vulnerable to disruption. This process of "reconsolidation" will typically restabilize the neural representation of the memory and foster its long-term storage. However, the process of reconsolidating the memory takes time to complete, and during this limited time window, the original memory may be modified either by the presentation of new information or with pharmacological agents. Such findings have prompted rising interest in using disruption during reconsolidation as a clinical intervention for anxiety, posttraumatic stress, and substance use disorders. However, "boundary conditions" on memory reconsolidation may pose significant obstacles to clinical translation. The aim of this article is to critically examine the nature of these boundary conditions, their neurobiological substrates, and the potential effect they may have on disruption of reconsolidation as a clinical intervention. These boundary conditions also highlight potential constraints on the reconsolidation phenomenon and suggest a limited role for memory updating consistent with evolutionary accounts of associative learning for threat and reward. We conclude with suggestions for future research needed to elucidate the precise conditions under which reconsolidation disruption may be clinically useful.

Counterconditioning During Reconsolidation Prevents Relapse of Cocaine Memories

Relapse to drug abuse is often caused by exposure to drug-associated cues that evoke craving. Therefore, disruption of the cue-drug memory can prevent relapse. Memories destabilize and become temporarily labile upon their retrieval, and re-stabilize in a process termed reconsolidation. Pharmacological disruption of reconsolidation prevents relapse in animal models, yet may evoke side effects. Therefore, behavioral procedures capable of preventing cue-induced craving and relapse are extremely valuable. Aversion therapies, in which drug-paired cues are re-associated (counterconditioned) with aversive consequences, have limited success, because the previous cue-drug memory may recover, triggering relapse. Here, we prevented the memory recovery and relapse to cocaine seeking by applying aversive counterconditioning during memory reconsolidation. Mice were trained to seek cocaine in a conditioned place preference procedure. The cocaine-associated compartment was then counterconditioned with lithium chloride (LiCl)-induced malaise, preceded by a brief exposure to the compartment (memory retrieval). Relapse was assessed in a reinstatement test. We found that aversive counterconditioning conducted shortly after memory retrieval (during reconsolidation) induced a long-lasting prevention of relapse to cocaine seeking. However, mice relapsed when counterconditioned without, before, or long after memory retrieval, or when receiving LiCl without place counterconditioning. Our findings suggest that post-retrieval aversive counterconditioning leads to relapse prevention, possibly by replacing the cue-drug with a cue-aversion memory, thereby the cue ceases to evoke craving. Moreover, we found that a similar memory replacement procedure prevented relapse of conditioned place aversion. Hence, this novel procedure can also prevent relapse of aversive memories, providing a safe approach to alter various maladaptive behaviors.

Dizocilpine (MK-801) impairs learning in the active place avoidance task but has no effect on the performance during task/context alternation

The prevention of engram interference, pattern separation, flexibility, cognitive coordination and spatial navigation are usually studied separately at the behavioral level. Impairment in executive functions is often observed in patients suffering from schizophrenia. We have designed a protocol for assessing these functions all together as behavioral separation. This protocol is based on alternated or sequential training in two tasks testing different hippocampal functions (the Morris water maze and active place avoidance), and alternated or sequential training in two similar environments of the active place avoidance task. In Experiment 1, we tested, in adult rats, whether the performance in two different spatial tasks was affected by their order in sequential learning, or by their day-to-day alternation. In Experiment 2, rats learned to solve the active place avoidance task in two environments either alternately or sequentially. We found that rats are able to acquire both tasks and to discriminate both similar contexts without obvious problems regardless of the order or the alternation. We used two groups of rats, controls and a rat model of psychosis induced by a subchronic intraperitoneal application of 0.08mg/kg of dizocilpine (MK-801), a non-competitive antagonist of NMDA receptors. Dizocilpine had no selective effect on parallel/sequential learning of tasks/contexts. However, it caused hyperlocomotion and a significant deficit in learning in the active place avoidance task regardless of the task alternation. Cognitive coordination tested by this task is probably more sensitive to dizocilpine than spatial orientation because no hyperactivity or learning impairment was observed in the Morris water maze.

Propranolol for the treatment of anxiety disorders: Systematic review and meta-analysis

The effects of propranolol in the treatment of anxiety disorders have not been systematically evaluated previously. The aim was to conduct a systematic review and meta-analysis of randomised controlled trials, addressing the efficacy of oral propranolol versus placebo or other medication as a treatment for alleviating either state or trait anxiety in patients suffering from anxiety disorders. Eight studies met the inclusion criteria. These studies concerned panic disorder with or without agoraphobia (four studies, total n = 130), specific phobia (two studies, total n = 37), social phobia (one study, n = 16), and posttraumatic stress disorder (PTSD) (one study, n = 19). Three out of four panic disorder trials qualified for pooled analyses. These meta-analyses found no statistically significant differences between the efficacy of propranolol and benzodiazepines regarding the short-term treatment of panic disorder with or without agoraphobia. Also, no evidence was found for effects of propranolol on PTSD symptom severity through inhibition of memory reconsolidation. In conclusion, the quality of evidence for the efficacy of propranolol at present is insufficient to support the routine use of propranolol in the treatment of any of the anxiety disorders.

Effects of propranolol on fear of dental extraction: study protocol for a randomized controlled trial

Background

Undergoing an extraction has been shown to pose a significantly increased risk for the development of chronic apprehension for dental surgical procedures, disproportionate forms of dental anxiety (that is, dental phobia), and symptoms of post-traumatic stress. Evidence suggests that intrusive emotional memories of these events both induce and maintain these forms of anxiety. Addressing these problems effectively requires an intervention that durably reduces both the intrusiveness of key fear-related memories and state anxiety during surgery. Moreover, evidence suggests that propranolol is capable of inhibiting “memory reconsolidation” (that is, it blocks the process of storing a recently retrieved fear memory). Hence, the purpose of this trial is to determine the anxiolytic and fear memory reconsolidation inhibiting effects of the ß-adrenoreceptor antagonist propranolol on patients with high levels of fear in anticipation of a dental extraction.

Methods/Design

This trial is designed as a multicenter, randomized, placebo-controlled, two-group, parallel, double-blind trial of 34 participants. Consecutive patients who have been referred by their dentist to the departments of oral and maxillofacial surgery of a University hospital or a secondary referral hospital in the Netherlands for at least two tooth and/or molar removals and with self-reported high to extreme fear in anticipation of a dental extraction will be recruited. The intervention is the administration of two 40 mg propranolol capsules 1 hour prior to a dental extraction, followed by one 40 mg capsule directly postoperatively. Placebo capsules will be used as a comparator. The primary outcome will be dental trait anxiety score reduction from baseline to 4-weeks follow-up. The secondary outcomes will be self-reported anxiety during surgery, physiological parameters (heart rate and blood pressure) during recall of the crucial fear-related memory, self-reported vividness, and emotional charge of the crucial fear-related memory.

Discussion

This randomized trial is the first to test the efficacy of 120 mg of perioperative propranolol versus placebo in reducing short-term (“state”) anxiety during dental extraction, fear memory reconsolidation, and lasting dental (“trait”) anxiety in a clinical population. If the results show a reduction in anxiety, this would offer support for routinely prescribing propranolol in patients who are fearful of undergoing dental extractions.

Trial registration

ClinicalTrials.gov identifier: NCT02268357, registered on 7 October 2014. The Netherlands National Trial Register identifier: NTR5364, registered on 16 August 2015.

Post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) occurs in 5-10% of the population and is twice as common in women as in men. Although trauma exposure is the precipitating event for PTSD to develop, biological and psychosocial risk factors are increasingly viewed as predictors of symptom onset, severity and chronicity. PTSD affects multiple biological systems, such as brain circuitry and neurochemistry, and cellular, immune, endocrine and metabolic function. Treatment approaches involve a combination of medications and psychotherapy, with psychotherapy overall showing greatest efficacy. Studies of PTSD pathophysiology initially focused on the psychophysiology and neurobiology of stress responses, and the acquisition and the extinction of fear memories. However, increasing emphasis is being placed on identifying factors that explain individual differences in responses to trauma and promotion of resilience, such as genetic and social factors, brain developmental processes, cumulative biological and psychological effects of early childhood and other stressful lifetime events. The field of PTSD is currently challenged by fluctuations in diagnostic criteria, which have implications for epidemiological, biological, genetic and treatment studies. However, the advent of new biological methodologies offers the possibility of large-scale approaches to heterogeneous and genetically complex brain disorders, and provides optimism that individualized approaches to diagnosis and treatment will be discovered.