From the Cover: Unlocking adults’ implicit statistical learning by cognitive depletion

Human learning is supported by multiple neural mechanisms that maturate at different rates and interact in mostly cooperative but also sometimes competitive ways. We tested the hypothesis that mature cognitive mechanisms constrain implicit statistical learning mechanisms that contribute to early language acquisition. Specifically, we tested the prediction that depleting cognitive control mechanisms in adults enhances their implicit, auditory word-segmentation abilities. Young adults were exposed to continuous streams of syllables that repeated into hidden novel words while watching a silent film. Afterward, learning was measured in a forced-choice test that contrasted hidden words with nonwords. The participants also had to indicate whether they explicitly recalled the word or not in order to dissociate explicit versus implicit knowledge. We additionally measured electroencephalography during exposure to measure neural entrainment to the repeating words. Engagement of the cognitive mechanisms was manipulated by using two methods. In experiment 1 (n = 36), inhibitory theta-burst stimulation (TBS) was applied to the left dorsolateral prefrontal cortex or to a control region. In experiment 2 (n = 60), participants performed a dual working-memory task that induced high or low levels of cognitive fatigue. In both experiments, cognitive depletion enhanced word recognition, especially when participants reported low confidence in remembering the words (i.e., when their knowledge was implicit). TBS additionally modulated neural entrainment to the words and syllables. These findings suggest that cognitive depletion improves the acquisition of linguistic knowledge in adults by unlocking implicit statistical learning mechanisms and support the hypothesis that adult language learning is antagonized by higher cognitive mechanisms.

Human learning is thought to be supported by the interactions between two basic memory systems of the brain, namely declarative and nondeclarative memory (1). Declarative memory is characterized by voluntary, explicit, attention-based processes, such as recall and recognition of facts/events, and is mediated by medial-temporal lobe and prefrontal cortex structures (2). Nondeclarative memory, also referred to as procedural memory, on the other hand is part of implicit memory and includes the acquisition of a heterogeneity of skills, habits, and procedures. It is mediated by basal ganglia, cerebellar, and neocortical structures, as well as parts of the prefrontal cortex [e.g., Broca''s area (3–5)].Accumulating evidence supports a competitive relationship between these two memory systems during human skill learning. Suppression of the declarative memory system by interventions like repetitive transcranial magnetic stimulation (TMS), distraction tasks, alcohol consumption, hypnosis, intake of benzodiazepines, or cognitive fatigue, can actually enhance performance in implicit, perceptual-motor learning tasks such as the serial-reaction time task (6–11) or intuitive reasoning tasks (12). These findings suggest that higher-level cognitive functions associated with declarative memory and supported by the prefrontal cortex can interfere with behavior that is naturally driven by implicit learning processes (13). However, it remains unresolved whether competing memory systems also affect implicit statistical learning abilities that are critical for the early, rapid acquisition of language in infants (14). This is an important question, as it could explain why infants and children pick up languages with less effort than adults (cf “What don’t we know?”) (15).Language acquisition involves many different memory and learning processes that are dependent on both procedural and declarative memory (2, 16). The first step for infants acquiring language is to gain knowledge about the phonological structure in one’s spoken language system, the probabilistic constraints on how speech sounds combine (i.e., phonotactic learning), and the segments of continuous speech (i.e., word forms) (17). Word form learning takes place already in the first 12 months of life and is an important precursor to vocabulary acquisition (i.e., mapping form to meaning) and more complex language acquisition (e.g., grammar) later in development (18). In the present study, we focus on statistical learning mechanisms that contribute to word segmentation and thus novel word form learning in the early stages of language acquisition.Statistical learning is generally known as the ability to pick up on patterns in the environment through extraction of frequent regularities and distributional properties. The term was first introduced in the field of cognitive psychology by the work of Saffran, Aslin, and Newport (1996) (19), who demonstrated that infants of only 8-mo-old can extract word boundaries and segment novel word forms from a continuous stream of speech sounds with no other cue than the transitional probabilities between syllables. Later, this learning was also demonstrated in older children and adults (20, 21) and across different domains (e.g., music and grammar) or modalities (e.g., auditory, visual, and motor) (22, 23), indicating that statistical learning is a largely continuous and domain-general learning mechanism for skill acquisition across the human life span.In a typical statistical learning experiment, participants are repeatedly exposed to patterned stimuli such as consonant strings from an artificial grammar, or recurrent syllable triplets. Learning is then typically assessed postexposure by using a two-alternative forced-choice recognition task in which triplets from the exposure stream are pitted against foils. Participants have to indicate which of the two triplets sounded most familiar, and above-chance accuracy is taken as indication of learning. Since statistical learning occurs without any instruction or intention to learn, it is often assumed to result in implicit memory representations (24). This view is also supported by the evidence that statistical learning occurs in infants and even in sleeping neonates (25). However, in recent work, Batterink and colleagues demonstrated that even without intention to learn, adults acquire mainly explicit knowledge of the novel word forms during statistical learning (26–29). This can be derived from the observation that participants’ performance was above chance when they were confident remembering the triplet but at chance when they were unconfident. Knowledge is implicit when participants lack awareness of what they have learned. This means that if participants perform also above chance when they are unconfident, knowledge is inferred to be implicit (30). In contrast, if they perform at chance level when confidence is low, no implicit knowledge is gained. Although statistical learning may produce additional implicit knowledge that cannot be assessed by the recognition and memory judgement tasks (e.g., ref. 28), Batterink’s earlier findings show that adults store the acquired word knowledge mainly in the explicit memory system.We and others have proposed that cognitive development and maturation of the prefrontal areas negatively affect language acquisition, such as word form or grammar learning (31–35). For instance, we showed that children outperform adults on the Hebb repetition learning paradigm (32, 33), a memory paradigm in which participants are asked to immediately recall syllable sequences that consist of hidden repeated word forms. Interestingly, in a follow-up study, we found that cognitive depletion by TMS to the left dorsolateral prefrontal cortex (DLPFC), an area closely related to declarative memory and cognitive control, enhanced Hebb performance in adult participants (34). This suggests that late-developing prefrontal cognitive mechanisms can induce changes in efficiently acquiring sequential language information from the environment, a finding that is largely in line with previously reported evidence in skill learning (13). Recently, we corroborated this idea further by showing enhanced phonotactic constraint learning in adults under cognitive fatigue (35). Based on these findings, we hypothesize that the higher cognitive control system could reduce access to implicit memory processes in adults, thereby making them less efficient in language acquisition relative to infants and children. This idea is in line with the well-known less-is-more hypothesis that attributes developmental changes in language acquisition, such as phonology and grammar, to maturational changes in attention and memory capacities (36–38). In our previous work, participants were explicitly asked to memorize (34) or produce (35) syllable sequences and thus exposure to the novel language was not passive, or “infant like.” Moreover, we did not separate implicit and explicit memory representations. Thus it remains unresolved how higher-order cognitive functions affect acquisition of implicit linguistic knowledge during passive listening to continuous speech using statistical learning mechanisms that support infant language acquisition (23, 39).The aim of the current study was to directly address this question using the auditory statistical learning paradigm. In particular, we aimed to determine whether a temporary depletion of the higher cognitive control system, using two different interventions, can unlock adults’ implicit statistical learning processes that serve infant word segmentation. To investigate this, we exposed young adults to continuous streams of syllables with, unknown to them, repeating three-syllable pseudowords, while watching a silent film. In the first experiment, inhibitory continuous theta-burst stimulation was used to induce a long-lasting disruption in left DLPFC or a control site prior to exposure, similar to the method used in Smalle et al., 2017 (34). In the second experiment, participants first performed an effortful dual working-memory task under high– or low–cognitive-load( HCL and LCL, respectively) conditions, which induces cognitive fatigue that hampers subsequent cognitive performance (7, 35, 40), or did not perform a cognitive load task prior to the language exposure (control or no-load condition). Our primary measure of statistical learning was the offline recognition of the hidden words, which was assessed 15 min after exposure. This was combined with a memory judgement procedure, which measured how confident the participants were that they remembered the hidden words. This task dissociates explicit versus implicit memory representations (e.g., refs. 27–29, 41). In both experiments, electroencephalography (EEG) was also measured during the 20-min language exposure in order to investigate an online perceptual component as second independent measure of statistical learning. Research has shown that the steady-state response of the brain shows a decrease at the frequency of individual syllables and an increase at the rhythm of three-syllable words while listening to continuous sound streams that consist of repeating three-syllable structures. This shift in neural entrainment indicates online statistical learning of novel words as a function of auditory exposure (29). Overall, we predicted that TMS-induced disruption of the DLPFC (in experiment 1) and cognitive fatigue (in experiment 2) would enhance statistical language learning and especially strengthen implicit memory representations for the hidden novel words.     

Diagnostic value of eye movement and vestibular function tests in patients with posterior circulation infarction

Objective: To evaluate the diagnostic value of eye movements and vestibular function tests in PCI patients.

Methods: Thirty-eight PCI patients and 31 patients with unilateral vestibular neuritis (UVN) were enrolled and underwent eye movement tests and vestibular function tests (spontaneous nystagmus [SN], head-shaking nystagmus [HSN]).

Results: The rates of eye movement abnormality were 78.9% and 41.9% in PCI and UVN patients, respectively. The positive rate of SN and HSN were, respectively, 41.2% and 43.8% in cerebellar infarction patients, 33.3% and 66.7% in medullary infarction patients, and 100.0% and 86.2% in UVN patients. The horizontal direction of SN and HSN coincided with the affected side in cerebellar infarction patients, and the healthy side in UVN patients, which coincided with the healthy side and the affected side, respectively in medullary infarction patients. The horizontal direction of HSN was bidirectional nystagmus in 16.0% (4/25) of UVN patients.

Conclusions and significance: Eye movement and vestibular function tests contribute to the early diagnosis of PCI. The horizontal direction of SN and HSN are consistently toward the affected side in cerebellar infarction patients and the healthy side in UVN patients, in contrast to medullary infarction patients, and deserve further investigations.     

Prognostic factors of facial nerve function after vestibular schwannoma removal via translabyrinthine approach

Background: Prediction of facial function is a major concern when proposing surgery for patients with vestibular schwannoma (VS).

Aims/objectives: To evaluate postoperative facial function of patients who underwent operation of VS via a translabyrinthine approach (TL), and to analyze factors that influence facial functions.

Material and methods: A total of 91 VS patients, who were operated via a TL approach, between March 1997 and December 2016, were analyzed. Demographics, tumor-related factors, and operative findings were collected. Facial function was assessed according to the House-Brackmann (HB) grading system before surgery, immediately after surgery, and 1-, 3-, 6-months, and 1 year after surgery.

Results: In cases of patients that had a tumor that extended to the CPA, an unsatisfactory facial outcome was noted in 12 (30.0%) patients. FN outcomes after tumor removal depend on tumor size (p?=?.040). Among FN-related factors, only the FN recovery timing was correlated with facial outcomes (p?=?.030). Univariable and multivariable analysis revealed that tumor size and the timing of FN recovery were significant as favorable prognostic factors for good facial outcomes.

Conclusions and significance: Tumor size and the FN recovery timing are significant prognostic factors of facial outcome in VS patients who underwent operations via a TL approach.     

经皮穴位电刺激对无痛胃肠镜检查后恶心呕吐的影响

目的 观察经皮穴位电刺激(TEAS)双侧足三里穴(ST36)、脾俞穴(BL20)及大陵穴(PC7)对预防无痛胃肠镜检查后恶心呕吐的影响。方法 选择行无痛胃肠镜检查患者159例,男72例,女87例,年龄25～64岁,BMI 18～28 kg/m²,ASAⅠ或Ⅱ级。采用随机数字表法将患者分为两组：TEAS组(T组,n=80)和对照组(C组,n=79)。麻醉诱导前T组给予TEAS双侧ST36、BL20及PC7 20 min; C组仅在相应穴位予电极片贴敷不行电刺激。两组麻醉诱导均采用丙泊酚1.5 mg/kg复合舒芬太尼0.1μg/kg,并根据检查中患者情况追加丙泊酚0.5 mg/kg。记录患者苏醒后30 min头晕、恶心呕吐发生情况。记录检查中最低HR、SBP、DBP和苏醒后30 min的SBP、DBP。记录患者、麻醉科医师满意情况及患者留观时间。结果 与C组比较,T组检查后恶心呕吐发生率明显降低(P<0.05),检查中最低SBP明显升高(P<0.05),患者和麻醉科医师满意度明显升高(P<0.05),留观时间明显缩短(P<0.05)。结论 经皮...     

四磨汤加低频脉冲电治疗对剖宫术产妇排气、泌乳量及子宫复旧的影响

目的观察四磨汤加低频脉冲电治疗对剖宫术产妇排气、泌乳量及子宫复旧的影响。方法选择剖宫术后产妇114例,随机分为A组(四磨汤 低频脉冲电治疗组)38例,B组(四磨汤组)36例,C组(常规治疗组)40例。四磨汤在术后6 h口服,每次20 mL。脉冲电治疗在术后6~8 h腰骶部进行,观察3组排气、泌乳和子宫复旧情况。结果肛门排气和术后第3日泌乳量A、B组均优于C组(P<0.01),子宫复旧情况A组优于B、C组(P<0.01),B、C组比较无统计学意义(P>0.05)。结论四磨汤和低频脉冲电治疗分别对剖宫术后产妇肛门排气和泌乳量有促进作用,低频脉冲治疗能有效促进子宫收缩,四磨汤和低频脉冲电治疗联合应用可使剖宫术后产妇肛门排气提前,泌乳量增加,子宫复旧良好。     

高频重复经颅磁刺激对缺血性脑卒中后中枢性面瘫的效果北大核心CSCD

目的探讨高频重复经颅磁刺激(rTMS)在缺血性脑卒中后中枢性面瘫中的应用价值。方法 2020年6月至2021年6月,选取在徐州市中心医院康复科住院的脑卒中后中枢性面瘫患者54例,随机分为对照组(n=27)和试验组(n=27)。两组均给予常规康复治疗,包括药物治疗和面部肌群康复训练。试验组加患侧初级运动皮质5 Hz rTMS治疗,对照组在同一治疗部位予以相同参数的假刺激治疗。治疗前、治疗4周后分别采用修订版House-Brackmann分级系统(HBGS-2)、Sunnybrook面部分级量表、静息时双侧嘴角至人中下中心点的水平距离差、最大努力示齿时双侧嘴角至下颌中切牙交点的水平距离差和伸舌时舌中线偏离面部正中线的角度对患者进行面神经功能评价。结果两组各脱落1例。治疗前,两组HBGS-2评分、Sunnybrook面部分级量表评分、静息时双侧嘴角至人中下中心点的水平距离差、最大努力示齿时双侧嘴角至下颌中切牙交点的水平距离差和伸舌时舌中线偏离面部正中线的角度均无显著性差异(P>0.05);治疗后两组各项评价指标均显著改善(|t|>8.987, P<0.001),且试验组均明显优于对照组(t>2.939, P<0.01)。结论患侧初级运动皮质5 Hz rTMS对改善缺血性脑卒中后中枢性面瘫患者面神经功能有积极作用。     

指部徒手感觉刺激前后脑卒中偏瘫患者手指屈、伸肌张力及超声剪切波弹性成像的变化北大核心CSCD

目的观察指部徒手感觉刺激(MDSS)前后脑卒中患者偏瘫侧手指屈、伸肌张力以及超声剪切波弹性成像(SWE)的变化规律。方法2020年4月至6月,选取在安徽医科大学第二附属医院康复医学科住院的51例脑卒中偏瘫患者,对偏瘫侧5个手指的甲床、末节指骨两侧进行MDSS,刺激强度为能引起伸指但不致明显疼痛的最小强度,两次刺激间隔5~10 s。分别于MDSS前、MDSS后即刻采用改良Ashworth量表(MAS)评估偏瘫侧指浅屈肌、指深屈肌、拇长屈肌、指伸肌肌张力,低肌张力记作-1级;同时以SWE技术检测上述四组肌群中的剪切波速度(SWV)。结果MDSS后,脑卒中患者四组肌群的MAS评级均显著降低(|Z|>2.843,P<0.001)。各肌群初始MAS评级为0和-1时,MDSS前后SWV均无显著性差异(t<1.052,P>0.05)。各肌群初始MAS评级为1~3时,MDSS后SWV均降低(t>2.672,P<0.05)。MDSS前后各肌群SWV与MAS评级均呈正相关(r>0.334,P<0.05)。结论MDSS可有效、迅速、安全地降低脑卒中患者偏瘫侧手部肌群痉挛并促进主动伸指。SWE可客观、定量评估脑卒中偏瘫患者手部肌群肌张力。     

经颅直流电刺激结合任务导向性训练改善脑卒中患者上肢运动功能的静息态fMRI研究

目的:探讨经颅直流电刺激结合任务导向性训练对脑卒中患者静息态低频振幅(ALFF)的影响,以探讨该疗法的作用机制。方法:招募15例慢性期脑卒中偏瘫患者和15名健康受试者。治疗组每天接受20min t DCS结合60min任务导向性训练,5次/周,共4周。治疗组于治疗前和治疗4周后采用Fugl-Meyer量表上肢部分(Fugl-Meyer assessment of upper extremity,FMA-UE)、Brotez手功能测试和f MRI进行评估。健康组仅进行首次f MRI检查,不进行任何干预。结果:4周康复干预结束后,治疗组患者FMA-UE、Brotez评分均较治疗前明显提高(P0.05)。与健康对照组相比,试验组治疗前ALFF减弱的脑区有右侧颞上回、右侧中央前回,而试验组治疗后ALFF减弱的脑区有右侧颞上回、右侧中央前回、左侧楔叶;试验组治疗前后比则发现,治疗后患者ALFF增高的脑区为右侧小脑前叶。结论:经颅直流电刺激结合任务导向性训练对静息态脑自发性活动产生显著影响,小脑前叶ALFF的增强可能是这种联合干预促进脑卒中患者运动功能恢复的神经机制。     

电刺激联合生物反馈疗法在产后女性性功能障碍治疗中的疗效分析

目的:观察电刺激联合生物反馈疗法在产后女性性功能障碍治疗中的临床疗效。方法:以106例2015年6月至2016年6月期间于本院就诊治疗产后女性性功能障碍的患者资料作为研究资料,随机等分为常规疗法组(53例)和联合疗法组(53例)。常规疗法组采取常规盆底肌肉锻炼法治疗,联合疗法组在常规盆底肌肉锻炼法治疗基础上应用电刺激联合生物反馈疗法治疗,比较分析两组产妇治疗前后的SAS评分、SDS评分和后盆底肌肉肌力评级情况,并分析两组产妇治疗后性功能障碍情况。结果:治疗后两组产妇在SAS评分和SDS评分上均显著下降,治疗后联合疗法组产妇的SAS评分和SDS评分显著低于常规疗法组(P0.05);治疗后两组产妇的后盆底肌肉肌力评级均有所提高,且联合疗法组提高更为明显,比较差异具有统计学意义(P0.05);治疗后联合疗法组产妇性欲望、性交时间、性高潮频率、阴道湿润度、性满足感和性频率诊断得分均显著高于常规疗法组,而性交疼痛感显著低于常规疗法组(P0.05);治疗后联合疗法组的治疗总有效率为96.23%,显著高于常规疗法组的79.25%,两组间比较具有显著的统计学差异(P0.05)。结论:电刺激联合生物反馈疗法相较于常规盆底肌肉锻炼法治疗产后女性性功能障碍疗效更为显著,可显著改善产妇性功能障碍,可提升产后女性性功能障碍患者的SAS评分、SDS评分和后盆底肌肉肌力评级,提升产后女性性生活质量,值得临床推广。