Neural correlates of temporal auditory processing in developmental dyslexia during German vowel length discrimination: an fMRI study

This fMRI study investigated phonological vs. auditory temporal processing in developmental dyslexia by means of a German vowel length discrimination paradigm (Groth, Lachmann, Riecker, Muthmann, & Steinbrink, 2011). Behavioral and fMRI data were collected from dyslexics and controls while performing same-different judgments of vowel duration in two experimental conditions. In the temporal, but not in the phonological condition, hemodynamic brain activation was observed bilaterally within the anterior insular cortices in both groups and within the left inferior frontal gyrus (IFG) in controls, indicating that the left IFG and the anterior insular cortices are part of a neural network involved in temporal auditory processing. Group subtraction analyses did not demonstrate significant effects. However, in a subgroup analysis, participants performing low in the temporal condition (all dyslexic) showed decreased activation of the insular cortices and the left IFG, suggesting that this processing network might form the neural basis of temporal auditory processing deficits in dyslexia.     

“啊哈！”和“哈哈！”：顿悟与幽默的脑认知成分比较

作为人类智能的高级表现形式, 顿悟和幽默存在诸多共同之处。从认知和情感组成上看, 顿悟的非连续性、突发性、重构和惊讶, 对应于幽默的失谐、失谐探测、失谐消解和愉悦, 两者存在表征机制的重叠。神经机制的研究发现, 顿悟和幽默的心理事件都伴随着400 ms左右的额中央区负波(N400)以及前扣带回、顶颞叶联合区和前额叶等脑区的活动; 同时顿悟和幽默在P300成分以及海马、右侧前部颞上回等脑区活动上存在差异。未来可借鉴幽默的认知和情感成份的脑成像研究范式, 进一步探明顿悟过程的认知和情感组成。     

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.     

Factors affecting medial temporal lobe engagement for past and future episodic events: an ALE meta-analysis of neuroimaging studies

Remembering the past and envisioning the future are at the core of one's sense of identity. Neuroimaging studies investigating the neural substrates underlying past and future episodic events have been growing in number. However, the experimental paradigms used to select and elicit episodic events vary greatly, leading to disparate results, especially with respect to the laterality and antero-posterior localization of hippocampal and adjacent medial temporal activations (i.e., parahippocampal, entorhinal and perirhinal cortices, amygdala). Although a central concern in today's literature, the issue of hippocampal and medial temporal lobe laterality and antero-posterior segregation in past and future episodic events has not yet been addressed extensively. Using the activation likelihood estimation (ALE) procedure (Turkeltaub, Eden, Jones, & Zeffiro, 2002), we performed a meta-analysis of hippocampal and adjacent medial temporal coordinates extracted from neuroimaging studies examining past remembering and future envisioning. We questioned whether methodological choices could influence the laterality of activations, namely (1) the type of cue used (generic vs. specific), (2) the type of task performed (recognition vs. recall/imagine), (3) the nature of the information retrieved (episodic vs. "strictly" episodic events) and (4) the age of participants. We consider "strictly" episodic events as events which are not only spatio-temporally unique and personal like episodic events, but are also associated with contextual and phenomenological details. These four factors were compared two-by-two, generating eight whole-brain statistical maps. Results indicate that (1) specific cues tend to activate more the right anterior hippocampus compared to the use of generic cues, (2) recall/imagine tasks tend to recruit more the left posterior parahippocampal gyrus compared to recognition tasks, (3) (re/pre)experiencing strictly episodic events tends to activate more the bilateral posterior hippocampus compared to episodic events and (4) older subjects tend to activate more the right anterior hippocampus compared to younger subjects. Importantly, our results stress that strictly episodic events triggered by specific cues elicit greater left posterior hippocampal activation than episodic events triggered by specific cues. These findings suggest that such basic methodological choices have an impact on the conclusions reached regarding past and future (re/pre)experiencing and their neural substrates.     

Dual-tasking alleviated sleep deprivation disruption in visuomotor tracking: an fMRI study

Effects of dual-responding on tracking performance after 49-h of sleep deprivation (SD) were evaluated behaviorally and with functional magnetic resonance imaging (fMRI). Continuous visuomotor tracking was performed simultaneously with an intermittent color-matching visual detection task in which a pair of color-matched stimuli constituted a target and non-matches were non-targets. Tracking error means were binned time-locked to stimulus onset of the detection task in order to observe changes associated with dual-responding by comparing the error during targets and non-targets. Similar comparison was made with fMRI data. Our result showed that despite a significant increase in the overall tracking error post SD, from 20 pixels pre SD to 45 pixels post SD, error decreased to a minimum of about 25 pixels 0-6s after dual-response. Despite an overall reduced activation post SD, greater activation difference between targets and non-targets was found post SD in task-related regions, such as the left cerebellum, the left somatosensory cortex, the left extrastriate cortex, bilateral precuneus, the left middle frontal gyrus, and the left motor cortex. Our results suggest that dual-response helps to alleviate performance impairment usually associated with SD. The duration of the alleviation effect was on the order of seconds after dual-responding.     

1秒以上时距判断的ERP研究

以视觉呈现时距信号,采用时间泛化范式要求被试判断5种探测时距(1～4秒)与标准时距(2秒)之间的长度关系,并记录11名大学生在时距判断过程中的事件相关电位(ERP),继而探讨不同探测时距条件下CNV波幅特征变化以及左、右侧额叶在时距判断中的功能。结果发现:1秒、1.42秒以及2秒条件下,CNV波幅峰出现在探测时距结束点,2.84秒、4秒条件下,CNV波幅峰出现在大约2秒处(标准时距);CNV负性翻转至基线位置在1秒、1.42秒、2秒条件下随探测时距的增长而延后,而在2.84秒、4秒两种条件下无显著差异;左、右侧额叶处诱发的CNV波幅峰潜时在2.84秒、4秒探测时距条件下无显著差异,且均在2秒附近。这说明在1秒以上视时距判断中CNV波幅峰反映了基于记忆中标准时距的时距判断的决策过程;CNV负性翻转至基线位置与时距判断的决策阶段存在共变关系,CNV负性翻转至基线位置相当于负荷解脱过程中的一个由负翻正的转折点;左、右侧额叶均参与了时距脉冲累加过程。     

工作记忆训练诱发的神经可塑性——基于系列fMRI实验的脑区分布递减时空模型

工作记忆训练(Working Memory Training, WMT)诱发神经可塑性, 但其具体机制尚不明晰。为探索WMT改变正常人群大脑功能的时空特性, 以“扩展的智力顶额整合理论”和“神经效率假说”为依据, 采用逐层递进的5种方法, 分6个步骤来查究近20年来正常人群WMT的37篇fMRI文献。第一步, 用叙述性综述、频数分析和卡方检验法比较脑区激活模式和脑网络功能连接在WMT前后发生的改变, 发现WMT改变了大脑的5个联合区、7个宏观区和3个子区。其中, 额上回、顶下小叶和扣带回这3个子区各自激活减弱的报道文献数量多于其激活增强的, 且这种差异分别具有统计学意义。第二步, 采用激活似然估计法对其中26篇开展元分析, 发现大脑的3个子区激活减弱水平在WMT前后的差异具有统计学意义, 即额中回(BA6和8)、额上回(BA6)和前扣带回(BA24和32)。第三步, 综合定性和定量分析结果, 提出WMT脑区分布递减时空模型, 产生5个结果和讨论。第四步, 采用非参数检验进一步追踪WMT效应的调节因素, 发现训练的任务类型和时间分别对脑区激活的影响具有统计学意义。第五步, 针对正常人群WMT诱发神经可塑性的时空特性, 得出3个结论：第一, WMT改变了正常人群相应脑区的神经活动, 表现为减弱或增强, 但减弱更加突出, 且更新和较短时间的WMT倾向于诱发较多减弱; 第二, 这些神经活动变化主要发生在额顶叶联合区, 但也包括分别以颞叶、枕叶、扣带回及纹状体为主的联合区, 在一定范围内体现了整脑功能联合。这体现了WMT诱发神经可塑性的空间特性, 且符合“扩展的智力顶额整合理论”; 第三, 额中回、额上回、顶下小叶和扣带回(尤其前扣带回)这4个子区在激活减弱水平上重点展示了WMT神经可塑性的时间特性, 且符合“神经效率假说”, 恰好体现出“聪明的大脑更懒惰”。第六步, 指出WMT诱发神经可塑性的未来研究可能关注脑可塑性中的低活跃性、辨析额中回、额上回、顶下小叶和扣带回(尤其前扣带回)这4个子区在激活减弱水平上体现的时间特性、找寻训练减弱或增强大脑活动的综合性影响因素。     

Different types of working memory binding in epilepsy patients with unilateral anterior temporal lobectomy

The medial temporal lobe is an important structure for long-term memory formation, but its role in working memory is less clear. Recent studies have shown hippocampal involvement during working memory tasks requiring binding of information. It is yet unclear whether this is limited to tasks containing spatial features. The present study contrasted three binding conditions and one single-item condition in patients with unilateral anterior temporal lobectomy.A group of 43 patients with temporal lobectomy (23 left; 20 right) and 20 matched controls were examined with a working memory task assessing spatial relational binding (object–location), non-spatial relational binding (object–object), conjunctive binding (object–colour) and working memory for single items. We varied the delay period (3 or 6 s), as there is evidence showing that delay length may modulate working memory performance.The results indicate that performance was worse for patients than for controls in both relational binding conditions, whereas patients were unimpaired in conjunctive binding. Single-item memory was found to be marginally impaired, due to a deficit on long-delay trials only.In conclusion, working memory binding deficits are found in patients with unilateral anterior temporal lobectomy. The role of the medial temporal lobe in working memory is not limited to tasks containing spatial features. Rather, it seems to be involved in relational binding, but not in conjunctive binding. The medial temporal lobe gets involved when working memory capacity does not suffice, for example when relations have to be maintained or when the delay period is long.     

Temporospatial analysis of explicit and implicit processing of negative content during word comprehension

Although divergences between explicit and implicit processing of affective content during word comprehension have been reported, the underlying nature of those differences remains in dispute. Prior studies focused on either the timing or the spatial location of the effects. The present study examined the precise dynamics of the processing of negative words when attention is directed to affective content or to non-emotional properties by capitalizing on fine temporal resolution of the event-related potentials (ERPs) and recent advances in source localization. Tasks were used that required accessing knowledge about different semantic properties of negative and neutral words. In the direct task, participants’ attention was directed towards emotional information. By contrast, subjects had to decide whether the words’ referent could be touched or not in the indirect task. Regardless of being processed explicitly or implicitly, negative compared to neutral words were associated with more errors and greater key pressure responses. Electrophysiologically, affective processing was reflected in larger amplitudes to negative words in a late positive component (LPC) at the scalp level, and in increased activity in the pre-supplementary motor area (pre-SMA) at the voxel level. Interestingly, an interaction between emotion and type of task was observed. Negative words were associated with more errors, larger anterior distributed LPC amplitudes and increased activity in the posterior cingulate cortex (PCC) in the direct compared to the indirect task. This LPC effect was modulated by the concreteness of the words. Finally, a task effect was found in a posterior negativity around 220 ms, with enhanced amplitudes to words in the direct compared to the indirect task. The present results suggest that negative information contained in written language is processed irrespective of controlled attention is directed to it or not, but that this processing is reinforced in the former case.     

脑神经回路预警系统:研究社会公正的新视角

广义的预警系统不仅包含预警情境下脑神经回路的活动,还包括由其引发的一系列心理和行为反应。在面临威胁或不确定情境时,人们的公正判断经常无法用传统的公平理论来解释。预警系统的观点则认为,在预警情境下人们会检测到现实威胁与理想状态的差距,激活预警系统,并促使人们通过调整态度和行为来管理消极情绪或不确定性,从而影响到人们的公正判断和公正关心。一系列fMRI和ERP的研究表明,预警情境下的心理和行为主要与大脑前扣带回皮层的活动有关。预警系统通过冲突监测、情绪表征和整体调控过程,引发了人们对公正的关心,并导致在后续的公正判断过程中产生置换过程、首因效应和极端判断。