Influence of Motor Cortex Stimulation During Motor Training on Neuroplasticity as a Potential Therapeutic Intervention

Rehabilitation options to promote neuroplasticity may be enhanced when patients are engaged in motor practice during repetitive transcranial magnetic stimulation (rTMS). Twelve participants completed 3 separate sessions: motor practice, motor practice with rTMS, and rTMS only: motor practice consisted of 30 isometric contractions and subthreshold rTMS was 30, 3-s trains at 10 Hz. Assessments included the Box and Block Test (BBT), force steadiness (10% of the maximum voluntary contraction), and TMS (cortical excitability, intracortical inhibition, and intracortical facilitation). Participants significantly increased BBT scores following the combined condition. Force steadiness improved after all 3 conditions (p < .05). TMS outcomes depended on intervention condition with significant increases in facilitation following the motor practice plus rTMS condition. All interventions influenced motor control, yet are likely modulated differently when combining motor practice plus rTMS. These results help guide the clinical utility of rTMS as an intervention to influence motor control.     

对人类不良记忆的修饰：来自记忆再巩固的证据

已经巩固的长时记忆被再次提取后, 进入一个记忆的不稳定期, 在此过程中, 记忆可被更新、强化、削弱甚至抹除, 这个过程称为再巩固。人类不良记忆再巩固研究揭示记忆激活后口服普萘洛尔(propranolol)或进行消退训练可削弱或抹除不良情绪记忆, 此过程中涉及杏仁核、海马、前额叶皮层等脑区的参与及其构成的神经环路的调控。当前临床上利用再巩固原理可通过药物治疗、行为干预或无创脑部刺激的方法改变不良记忆。然而, 由于其形成过程复杂并受多种因素影响, 未来研究应尽可能模拟临床中人类不良记忆形成的复杂环境, 深入探讨再巩固“边界问题”, 推动实验室研究向临床应用的转化。     

基于非侵入性脑刺激的认知增强：方法、伦理和应用

作为人类追求卓越的方式之一,基于非侵入性脑刺激的认知增强成为众多学科和公众关注的问题。首先阐述了非侵入性脑刺激的两种主要技术手段(经颅磁刺激和经颅直流刺激)的技术原理及其在提升健康个体认知功能上的应用,并分析了这两种技术可能带来的安全、自主选择、公平等伦理问题,最后总结了该认知增强技术在体育和军事等两个具体领域的应用。未来可进一步提高技术手段的深部脑区刺激能力及该增强技术的持续和真实效果。     

Predicting remembering and forgetting of autobiographical memories in children and adults: a 4-year prospective study

Preservation and loss to forgetting of autobiographical memories is a focus in both the adult and developmental literatures. In both, there are comparative arguments regarding rates of forgetting. Children are assumed to forget autobiographical memories more rapidly than adults, and younger children are assumed to forget more rapidly than older children. Yet few studies can directly inform these comparisons: few feature children and adults, and few prospectively track the survival of specific autobiographical memories over time. In a 4-year prospective study, we obtained autobiographical memories from children 4, 6, and 8 years, and adults. We tested recall of different subsets of the events after 1, 2, and 3 years. Accelerated rates of forgetting were apparent among all child groups relative to adults; within the child groups, 4- and 6-year-olds had accelerated forgetting relative to 8-year-olds. The differences were especially pronounced in open-ended recall. The thematic coherence of initial memory reports also was a significant predictor of the survival of specific memories. The pattern of findings is consistent with suggestions that the adult distribution of autobiographical memories is achieved as the quality of memory traces increases (here measured by thematic coherence) and the rate of forgetting decreases.     

Evidence that an episodic mode of thinking facilitates encoding of perceptually rich memories for naturalistic events relative to a gist-based mode of thinking

ABSTRACT

Several studies have demonstrated that an episodic specificity induction (ESI) can influence cognitive abilities that involve episodic processes at retrieval. To better understand the downstream implications of an “episodic mode of thinking,” we investigate whether an ESI influences encoding of new events. In a between-subjects design, participants were given an ESI or gist (control) induction. In an ostensibly unrelated task, participants then were shown film clips of naturalistic events. After a filled delay, participants were given a surprise memory test, which required narrative recollection of the film clips. Participants who received the ESI generated narratives that contained more perceptual details specifically. Relative to gist thinking, an episodic mode of thinking appears to facilitate encoding of perceptually rich memories for naturalistic events.     

Episodic memory effects of gamma frequency precuneus transcranial magnetic stimulation in Alzheimer's disease: A randomized multiple baseline study

Episodic memory decline is the prominent neuropsychological feature of typical Alzheimer's Disease (AD), for which current treatments have a limited clinical response. Recently, gamma entrainment therapy has been used as a non-invasive treatment in AD, providing evidence that it may have the potential to alleviate brain pathology and improve cognitive function in AD patients. At the same time, the precuneus (PC) has been recognized as a key area involved in AD related memory deficits and as a key node of the Default Mode Network. This study aimed to investigate the effectiveness of a 40 Hz Transcranial Magnetic Stimulation (TMS) intervention, delivered bilaterally to the precuneus for 10 days, in improving the patients' episodic memory performance. Secondary outcome variables investigated included general cognitive function, semantic and spatial memory, as well as attention and executive function. A concurrent multiple baseline design across five cases was employed. Four patients completed the study. Visual analysis combined with effect size indices were used to evaluate changes across phases. An increase in the average level of immediate recalled words was observed in three out of four patients. Effect size indices indicated significant improvement of attention skills in two patients. No treatment effect was observed for semantic and visual memory, or for executive function. An immediate treatment effect was observed in all patients' general cognitive function as assessed with the Alzheimer's Disease Assessment Scale (mean reduction of 5 points), which was maintained and improved further three months post-treatment. The neuropsychological evaluations indicated improved performance three months post-treatment in immediate and delayed recall, attention, phonological verbal fluency, anxiety, and neuropsychiatric symptoms. This study provides preliminary evidence for the efficacy of a novel non-pharmacological treatment using gamma-band TMS in addressing cognitive dysfunction in AD.     

行为干预情绪记忆再巩固：从实验室到临床转化

重新激活已经储存的记忆会重返暂时不稳定的状态, 需要经历重新稳定, 称为记忆再巩固。在这期间可以通过多种行为手段破坏、强化或更新原始记忆痕迹, 这为开发一种革命性的情绪记忆障碍治疗方法开辟了道路。然而, 即使在简单的实验模型中引发记忆再巩固的条件也是复杂的, 这给临床转化带来了困难与挑战。未来研究可以设置更具生态效应的基础模型, 寻求引发以及干预再巩固的最佳方式, 从神经生理、细胞分子层面进一步深化其内在机理研究。     

工作记忆刷新及其训练效应——经颅直流电刺激的作用

工作记忆刷新是执行功能的重要成分之一。以往研究结合n-back任务和经颅直流电刺激（transcranial direct current stimulation ,tDCS）技术探究刷新能力,发现tDCS技术能够一定程度上增强刷新训练效果并引起大脑神经元相关活动的变化,其增强效果能够维持一定的时间,且能够迁移到其他认知任务之中。但tDCS的干预效果在各项研究中存在一定的差异性。其作用效果会受到训练任务与训练方式、电流强度、电极布局和训练时间间隔等因素的影响。未来研究可以探索tDCS结合刷新训练的最佳刺激参数,以获得最优化的干预效果。     

Out of one's mind: a study of involuntary semantic memories

The study of memories that pop into one's mind without any conscious attempt to retrieve them began only recently. While there are some studies on involuntary autobiographical memories (e.g., ) research on involuntary semantic memories or mind-popping is virtually non-existent. The latter is defined as an involuntary conscious occurrence of brief items of one's network of semantic knowledge. The recall of these items (e.g., a word, a name, a tune) is not accompanied by additional contextual information and/or involvement of self-a standard feature of involuntary autobiographical memories. The paper reports several diary and questionnaire studies which looked into the nature and frequency of occurrence of these memories. The data show that people do experience involuntary semantic memories which tend to occur without any apparent cues while being engaged in relatively automatic activities. Possible mechanisms of involuntary semantic memories are discussed (e.g., very long-term priming), and the results of the study provide information on the possible duration of the priming effects in everyday life. Related theoretical and methodological issues and future avenues of research in this neglected area are outlined.     

The psychological distance of memories: Examining causal relations with mood and self-esteem in young,middle-aged and older adults

Three studies examined the self-enhancement function of autobiographical memory (measured with subjective temporal distance of memories). Participants recalled a memory of an attained and a failed goal and rated the subjective distance between each memory and the present. Study 1 showed that young adults with higher self-esteem felt closer to memories of attained goals and farther from failure memories than those with lower self-esteem. In Study 2, young, middle-aged and older adults with higher self-esteem felt closer to success memories, whereas self-esteem was unrelated to the temporal distance of failure memories. In both studies, feeling closer to success memories (and far from failure) led to enhanced mood. In Study 3, state self-esteem was experimentally manipulated. The manipulation had no effect on young and older adults, but middle-aged adults whose self-esteem was decreased, felt closer to success memories than failure memories. Results are discussed in relation to the temporal self-appraisal theory.     

The association of personal semantic memory to identity representations: insight into higher-order networks of autobiographical contents

Identity representations are higher-order knowledge structures that organise autobiographical memories on the basis of personality and role-based themes of one’s self-concept. In two experiments, the extent to which different types of personal semantic content are reflected in these higher-order networks of memories was investigated. Healthy, young adult participants generated identity representations that varied in remoteness of formation and verbally reflected on these themes in an open-ended narrative task. The narrative responses were scored for retrieval of episodic, experience-near personal semantic and experience-far (i.e., abstract) personal semantic contents. Results revealed that to reflect on remotely formed identity representations, experience-far personal semantic contents were retrieved more than experience-near personal semantic contents. In contrast, to reflect on recently formed identity representations, experience-near personal semantic contents were retrieved more than experience-far personal semantic contents. Although episodic memory contents were retrieved less than both personal semantic content types to reflect on remotely formed identity representations, this content type was retrieved at a similar frequency as experience-far personal semantic content to reflect on recently formed identity representations. These findings indicate that the association of personal semantic content to identity representations is robust and related to time since acquisition of these knowledge structures.     

The very same thing: Extending the object token concept to incorporate causal constraints on individual identity

The contributions of feature recognition, object categorization, and recollection of episodic memories to the re-identification of a perceived object as the very same thing encountered in a previous perceptual episode are well understood in terms of both cognitive-behavioral phenomenology and neurofunctional implementation. Human beings do not, however, rely solely on features and context to re-identify individuals; in the presence of featural change and similarly-featured distractors, people routinely employ causal constraints to establish object identities. Based on available cognitive and neurofunctional data, the standard object-token based model of individual re-identification is extended to incorporate the construction of unobserved and hence fictive causal histories (FCHs) of observed objects by the pre-motor action planning system. It is suggested that functional deficits in the construction of FCHs are associated with clinical outcomes in both autism spectrum disorders and later-stage stage Alzheimer's disease.     

Brain regions involved in subprocesses of small-space episodic object-location memory: a systematic review of lesion and functional neuroimaging studies

Object-location memory (OLM) enables us to keep track of the locations of objects in our environment. The neurocognitive model of OLM (Postma, A., Kessels, R. P. C., & Van Asselen, M. (2004). The neuropsychology of object-location memory. In G. L. Allen (Ed.), Human spatial memory: Remembering where (pp. 143–160). Mahwah, NJ: Lawrence Erlbaum, Postma, A., Kessels, R. P. C., & Van Asselen, M. (2008). How the brain remembers and forgets where things are: The neurocognition of object-location memory. Neuroscience & Biobehavioral Reviews, 32, 1339–1345. doi:10.1016/j.neubiorev.2008.05.001) proposes that distinct brain regions are specialised for different subprocesses of OLM (object processing, location processing, and object-location binding; categorical and coordinate OLM; egocentric and allocentric OLM). It was based mainly on findings from lesion studies. However, recent episodic memory studies point to a contribution of additional or different brain regions to object and location processing within episodic OLM. To evaluate and update the neurocognitive model of OLM, we therefore conducted a systematic literature search for lesion as well as functional neuroimaging studies contrasting small-space episodic OLM with object memory or location memory. We identified 10 relevant lesion studies and 8 relevant functional neuroimaging studies. We could confirm some of the proposals of the neurocognitive model of OLM, but also differing hypotheses from episodic memory research, about which brain regions are involved in the different subprocesses of small-space episodic OLM. In addition, we were able to identify new brain regions as well as important research gaps.     

Remembering all that and then some: Recollection of autobiographical memories after a 1-year delay

We have previously shown that repeated retrievals of remote autobiographical memories over the course of one month led to an overall increase in reported detail (Nadel, Campbell, & Ryan, 2007). The current study examined the retrieval of those same memories 1 year later in order to determine whether the level of detail remained stable or whether the memories returned to their original state. Participants reported even more details than they had recalled at least 1 year earlier, including new details that were reported for the first time. This finding was consistent across both multiple and single retrieval conditions, suggesting that the critical factor leading to the increase in recall was the passage of time. These findings provide evidence for long-term effects of repeated retrieval on memory content.     

More to it than meets the eye: how eye movements can elucidate the development of episodic memory

The ability to recognise past events along with the contexts in which they occurred is a hallmark of episodic memory, a critical capacity. Eye movements have been shown to track veridical memory for the associations between events and their contexts (relational binding). Such eye-movement effects emerge several seconds before, or in the absence of, explicit response, and are linked to the integrity and function of the hippocampus. Drawing from research from infancy through late childhood, and by comparing to investigations from typical adults, patient populations, and animal models, it seems increasingly clear that eye movements reflect item–item, item–temporal, and item–spatial associations in developmental populations. We analyse this line of work, identify missing pieces in the literature and outline future avenues of research, in order to help elucidate the development of episodic memory.     

Networks of self-defining memories as a contributing factor to emotional openness

Emotional openness is characterised by a capacity to tolerate threatening self-relevant material and an interest towards new emotional situations. We investigated how specific networks of memories could be an important contributing factor to emotional openness. At Phase 1, participants completed measures of personality traits and emotional intelligence, described a self-defining memory, provided other memories associated with it, and rated the valence of each of their memories. A score assessing the complexity of this memory network, comprising the number of memories reported and their valence diversity, was created. Two weeks later, in laboratory, participants watched an anxiety-inducing film and took part in an interview assessing their emotional openness to the film. They completed a cognitive task before and after the film to measure ego depletion. Controlling for traits and emotional intelligence, memory network complexity was positively associated with emotional openness and negatively with ego depletion. The mental organisation of self-defining memories thus appears to be a critical factor contributing to emotional openness.     

Why people rehearse their memories: Frequency of use and relations to the intensity of emotions associated with autobiographical memories

People may choose to rehearse their autobiographical memories in silence or to disclose their memories with other people. This paper focuses on five types of memory rehearsal: involuntary rehearsal, rehearsal to maintain an event memory, rehearsal to re-experience the emotion of an event, rehearsal to understand an event, or rehearsal for social communication. A total of 337 participants recalled event memories, provided estimates of how often each event was rehearsed and for what reason, and rated the affective characteristics of the events. Rehearsal frequency was highest for social communication and lowest for rehearsals aimed at understanding events. For many rehearsal types, rehearsal was more frequent for positive than negative events. Frequently rehearsed events tended to show less affective fading. The pattern changed when events were socially rehearsed. For positive events, increased social rehearsal was related to a reduction in affective fading. For negative events, increased social rehearsal was associated with increased affective fading.     

Memory specificity as a risk factor for suicidality in non-affective psychosis: The ability to recall specific autobiographical memories is related to greater suicidality

A difficulty in recalling specific autobiographical memories has been noted as a risk factor for suicidal behaviour. However, the relationship between memory specificity and suicide has not previously been investigated in those with non-affective psychosis. It was predicted that in this group, more specific memory recall would be associated with an increased risk of suicide. This is because such specific memories are likely to be associated with greater levels of distress and negative affect than less specific memories. This prediction contradicts the prevailing belief that lower memory specificity is associated with greater suicidality. Sixty participants with schizophrenia spectrum disorders were recruited, 40 of whom reported past suicide attempts. Analyses showed suicide attempters recalled a greater proportion of specific memories, whilst controlling for trait anxiety and depressive symptoms. These results supported the main hypothesis, and suggest non-specific memory may have adaptive qualities in individuals with psychosis.     

The reminiscence bump without memories: The distribution of imagined word-cued and important autobiographical memories in a hypothetical 70-year-old

The reminiscence bump is the disproportionate number of autobiographical memories dating from adolescence and early adulthood. It has often been ascribed to a consolidation of the mature self in the period covered by the bump. Here we stripped away factors relating to the characteristics of autobiographical memories per se, most notably factors that aid in their encoding or retention, by asking students to generate imagined word-cued and imagined ‘most important’ autobiographical memories of a hypothetical, prototypical 70-year-old of their own culture and gender. We compared the distribution of these fictional memories with the distributions of actual word-cued and most important autobiographical memories in a sample of 61–70-year-olds. We found a striking similarity between the temporal distributions of the imagined memories and the actual memories. These results suggest that the reminiscence bump is largely driven by constructive, schematic factors at retrieval, thereby challenging most existing theoretical accounts.