Impact of negative affectively charged stimuli and response style on cognitive-control-related neural activation: An ERP study

The canonical AX-CPT task measures two forms of cognitive control: sustained goal-oriented control (“proactive” control) and transient changes in cognitive control following unexpected events (“reactive” control). We modified this task by adding negative and neutral International Affective Picture System (IAPS) pictures to assess the effects of negative emotion on these two forms of cognitive control. Proactive and reactive control styles were assessed based on measures of behavior and electrophysiology, including the N2 event-related potential component and source space activation (Low Resolution Tomography [LORETA]). We found slower reaction-times and greater DLPFC activation for negative relative to neutral stimuli. Additionally, we found that a proactive style of responding was related to less prefrontal activation (interpreted to reflect increased efficiency of processing) during actively maintained previously cued information and that a reactive style of responding was related to less prefrontal activation (interpreted to reflect increased efficiency of processing) during just-in-time environmentally triggered information. This pattern of results was evident in relatively neutral contexts, but in the face of negative emotion, these associations were not found, suggesting potential response style-by-emotion interaction effects on prefrontal neural activation.     

汉语口语韵律的作用及其神经机制

汉语是一种声调语言, 在口语韵律表达中存在独特的特点。本项目利用汉语不同于非声调语言的特点, 探讨已有研究中尚未澄清的问题, 即汉语声调在早期自动加工中对语义激活的作用, 以及在不同认知阶段中, 汉语声调和语调加工的神经机制。这些问题是当前的研究热点, 但仍存在着各种分歧和激烈的争论。本项目拟采用ERP方法, 结合LORETA源定位技术, 通过不同的实验范式考察以下内容：(1)在早期自动加工过程中, 汉语声调对词汇语义激活的作用; (2)在早期阶段, 汉语声调和语调加工的大脑激活模式; (3)在晚期阶段, 汉语声调和语调加工的大脑激活模式。对这些问题的考察将有助于澄清当前的激烈争论, 拓展以往基于非声调语言研究建立的口语加工理论的适用范围, 为完善言语认知加工的理论模型提供新的实验证据。     

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.     

Perceptual visual grouping under inattention: electrophysiological functional imaging

Two types of perceptual visual grouping, differing in complexity of shape formation, were examined under inattention. Fourteen participants performed a similarity judgment task concerning two successive briefly presented central targets surrounded by task-irrelevant simple and complex grouping patterns. Event-related potentials (ERPs) were recorded from 22 scalp electrodes and source current density estimations were conducted for the net response to the task-irrelevant background patterns, using low-resolution electromagnetic tomography (LORETA). Although participants’ subjective reports indicated that neither type of organization induced awareness, electrophysiological results showed they both evoked significant activation in occipital, parieto-temporal and frontal brain areas. Behavioral results demonstrated that only grouping of the simple pattern arose under inattention. In contrast to the complex pattern, the processing of the simple pattern was associated with an initially longer latency and higher activation beginning at 130 ms. These results support the distinction of grouping patterns differing in complexity of shape formation.     

汉语语调早期加工的脑机制

采用ERP方法, 结合LORETA源定位分析技术, 考察了汉语语调早期自动加工的脑机制。结果发现： (1)对于附着在二声调汉字后的语调, 无论以单字词的形式, 还是以句子的形式呈现, 都没有诱发MMN; (2)当过滤掉实验刺激的言语信息后, 词音高和句子音高条件均诱发了MMN, 且这两个条件下的MMN波幅差异不显著; (3)LORETA分析发现, 句子音高条件在右半球顶叶的多个区域存在显著激活。该结果拓展了以往的研究结论, 为声学假设提供了证据。     

Higher-order activity beyond the word level: cortical dynamics of simple transitive sentence comprehension

Slow electrophysiological effects, which fluctuate throughout the course of a sentence, independent of transient responses to individual words, have been reported. However, this type of activity has scarcely been studied, and with only limited use of electrophysiological information, so that the brain areas in which these variations originate have not been clearly identified. To improve this state of affairs, a principal component analysis and a modern source analysis algorithm (LORETA) were applied to the slow activity underlying transitive sentence reading. Four components explained 97.3% of the variance. Of key interest was a slow variation that occurred throughout the entire sentence but peaked with the appearance of the verb. The main solution for this component was localized in prefrontal and temporal regions presumably involved in semantic sentence processing. This constitutes empirical evidence for cortical activity--related to semantic processes thought to be involved in thematic role assignment--developing throughout the sentence but presenting a conspicuous maximum with the appearance of the verb. This finding also highlights the central role of verb information in the understanding of transitive sentences.