Using Corticomuscular and Intermuscular Coherence to Assess Cortical Contribution to Ankle Plantar Flexor Activity During Gait

The present study used coherence and directionality analyses to explore whether the motor cortex contributes to plantar flexor muscle activity during the stance phase and push-off phase during gait. Subjects walked on a treadmill, while EEG over the leg motorcortex area and EMG from the medial gastrocnemius and soleus muscles was recorded. Corticomuscular and intermuscular coherence were calculated from pair-wise recordings. Significant EEG–EMG and EMG–EMG coherence in the beta and gamma frequency bands was found throughout the stance phase with the largest coherence towards push-off. Analysis of directionality revealed that EEG activity preceded EMG activity throughout the stance phase until the time of push-off. These findings suggest that the motor cortex contributes to ankle plantar flexor muscle activity and forward propulsion during gait.     

Rostro‐caudal and dorso‐ventral gradients in medial and lateral prefrontal cortex during cognitive control of affective and cognitive interference

Characterizing the anatomical substrates of major brain functions such as cognition and emotion is of utmost importance to the ongoing efforts of understanding the nature of psychiatric ailments and their potential treatment. The aim of our study was to investigate how the brain handles affective and cognitive interferences on cognitive processes. Functional magnetic resonance imaging investigation was performed on healthy individuals, comparing the brain oxygenation level dependent activation patterns during affective and cognitive counting Stroop tasks. The affective Stroop task activated rostral parts of medial prefrontal cortex (PFC) and rostral and ventral parts of lateral PFC, while cognitive Stroop activated caudal parts of medial PFC and caudal and dorsal parts of lateral PFC. Our findings suggest that the brain may handle affective and cognitive interference on cognitive processes differentially, with affective interference preferentially activating rostral and ventral PFC networks and cognitive interference activating caudal and dorsal PFC networks.     

The representation of category typicality in the frontal cortex and its cross-linguistic variations

When asked to judge the membership of typical (e.g., car) vs. atypical (e.g., train) pictures of a category (e.g., vehicle), native English (N = 18) and native Chinese speakers (N = 18) showed distinctive patterns of brain activity despite showing similar behavioral responses. Moreover, these differences were mainly due to the amount and pervasiveness of category information linguistically embedded in the everyday names of the items in the respective languages, with important differences across languages in how pervasive category labels are embedded in item-level terms. Nonetheless, the left inferior frontal gyrus and the bilateral medial frontal gyrus are the most consistent neural correlates of category typicality that persist across languages and linguistic cues. These data together suggest that both cross- and within-language differences in the explicitness of category information have strong effects on the nature of categorization processes performed by the brain.     

Predicting language: MEG evidence for lexical preactivation

It is widely assumed that prediction plays a substantial role in language processing. However, despite numerous studies demonstrating that contextual information facilitates both syntactic and lexical–semantic processing, there exists no direct evidence pertaining to the neural correlates of the prediction process itself. Using magnetoencephalography (MEG), this study found that brain activity was modulated by whether or not a specific noun could be predicted, given a picture prime. Specifically, before the noun was presented, predictive contexts triggered enhanced activation in left mid-temporal cortex (implicated in lexical access), ventro-medial prefrontal cortex (previously associated with top-down processing), and visual cortex (hypothesized to index the preactivation of predicted form features), successively. This finding suggests that predictive language processing recruits a top-down network where predicted words are activated at different levels of representation, from more ‘abstract’ lexical–semantic representations in temporal cortex, all the way down to visual word form features. The same brain regions that exhibited enhanced activation for predictive contexts before the onset of the noun showed effects of congruence during the target word. To our knowledge, this study is one of the first to directly investigate the anticipatory stage of predictive language processing.     

社会决策中的公平准则及其神经机制

社会决策中的公平准则一直受到广泛的关注,经济学家和心理学家们分别从动机和认知的角度对这个课题进行了深入探索.在这些工作中,最为突出的是“均等”,“互惠”和“情绪”三个模型的提出.均等和互惠模型试图从动机角度理解个体的公平行为,而情绪模型则更强调个体在公平决策中的认知和情绪的加工过程.近年来脑成像的研究也为这些模型提供了相应的支持,其中与公平准则最密切的脑区是脑岛和背外侧前额叶:前者一般被认为是反映了个体面对不公平待遇时的负性情绪体验;而后者主要负责决策过程中的抑制控制.但这些脑区具体的功能还存在很多争议,反映了不同理论模型对特定脑区功能的不同理解.未来研究应注意三个模型之间的相互补充,以及加强多模态的脑指标的运用,并注重相关脑区的整体性,此外,公平决策行为中的个体差异,以及社会情境对其的影响也应受到重视.     

价值观的神经机制:另一种研究视角

神经机制分析是价值观研究的一种新视角.内稳态机制和情绪反应的固有模式可能体现出价值观的神经生物原型.社会认知神经科学试图从子价值观、价值取向、价值观结构等方面寻找价值观的神经实体证据,也对价值评价、价值决策等相关过程进行了神经活动分析.初步发现了个体价值观与部分脑区活动的相关关系,涉及前额叶-顶叶-颞叶神经网络带的众多大脑结构.未来研究可沿循静态的价值观结构和动态的价值观加工过程两条线路,整合和完善现有分散的神经生理研究,将有助于更系统地理解价值观的神经机制.     

Prediction of treatment outcomes and longitudinal analysis in children with autism undergoing intensive behavioral intervention

Outcome prediction is an important component of treatment planning and prognosis. However, reliable predictors of intensive behavioral intervention (IBI) have not been clearly established. IBI is an evidence-based approach to the systematic teaching of academic, social, verbal, and daily living skills to individuals with autism spectrum disorder. Incorporating longitudinal analysis to IBI outcome studies may help to identify outcome predictors of clinical value. Twenty-four children with autism underwent on average two years of IBI and completed language, daily living skills, cognitive, and motor assessments (Early Learning Accomplishment Profile and the Learning Accomplishment Profile-Diagnostic, 3rd edition) every six months. We used multilevel analysis to identify potential longitudinal predictors including gender, age, intervention intensity, intervention duration, total intervention time, and pre-intervention functioning. Results indicated that total intervention time, pre-intervention functioning, and age caused the greatest increase in goodness-of-fit of the longitudinal multilevel models. Longitudinal analysis is a promising analytical strategy to identify reliable predictors of the clinical outcome of IBI.     

视觉特征捆绑：基于时间同步还是基于相同空间位置？

通过操纵客体呈现的空间位置和时间顺序,来考察视觉特征捆绑是基于相同空间位置线索还是基于时间邻近线索。在两个实验中,给被试在固定的注视点位置（固定呈现条件）或在注视点上/下位置（变换呈现条件）快速地系列呈现刺激,记录靶子前后各两个时间位置（-2、-1、+1、+2）的错觉性结合（IC）率。结果发现,在固定呈现条件下,IC更多地出现在-1和+1的时间位置上;而在变换呈现条件下,错觉性结合更多地出现在-2和+2时间位置上。为了进一步排除特定实验范式的影响,在实验3中,我们采用特征分离范式,使被分离的刺激特征同时呈现在相同（相同位置同步）或不同（不同位置同步）的空间位置上。结果表明,这两种条件下的IC率无显著差异,这说明错觉性结合不受时间同步模式的影响。综上所述,来自三个实验的结果表明,时间范围内的特征捆绑机制是按空间位置,而不是按时间邻近,线索进行的：若特征的空间位置相同,时间邻近的特征才被捆绑起来;若空间位置不同,即使时间邻近的特征也不能被捆绑到一起。