An fMRI investigation of a novel analogue to the Trail-Making Test

The Trail-Making Test (TMT) is a widely used neuropsychological measure that assesses visuomotor abilities and cognitive flexibility. For the TMT-A condition participants are required to locate and connect numbers (i.e. 1-2-3…) while in the TMT-B condition participants perform the set-shifting task of locating and connecting numbers and letters (i.e. 1-A-2-B…). The TMT-B condition has shown impairments in many clinical populations, particularly schizophrenia patients, but the neurobiological underpinning of the task can be difficult to discern given pragmatic obstacles in adapting the task for neuroimaging. In a behavioural testing experiment we demonstrated a close correspondence between performance on the standard TMT and a novel, computer programmed adaptation of the TMT (pcTMT). The pcTMT was designed for functional magnetic resonance imaging (fMRI) administration and neuroimaging data for this task were obtained in. A whole brain analysis revealed significantly greater activation during the pcTMT-B relative to the pcTMT-A in right inferior/middle frontal cortices, right precentral gyrus, left angular gyrus/left middle temporal gyrus. These results identify the regions that most likely underlie cognitive flexibility during the TMT and are candidate regions underlying the impairment of groups with poor set-shifting abilities.     

On the automaticity of emotion processing in words and faces: event-related brain potentials evidence from a superficial task

The degree to which emotional aspects of stimuli are processed automatically is controversial. Here, we assessed the automatic elicitation of emotion-related brain potentials (ERPs) to positive, negative, and neutral words and facial expressions in an easy and superficial face-word discrimination task, for which the emotional valence was irrelevant. Both emotional words and facial expressions impacted ERPs already between 50 and 100 ms after stimulus onset, possibly reflecting rapid relevance detection. Following this initial processing stage only emotionality in faces but not in words was associated with an early posterior negativity (EPN). Therefore, when emotion is irrelevant in a task which requires superficial stimulus analysis, automatically enhanced sensory encoding of emotional content appears to occur only for evolutionary prepared emotional stimuli, as reflected in larger EPN amplitudes to faces, but not to symbolic word stimuli.     

Operation-specific encoding in single-digit arithmetic

Solving simple arithmetic problems involves three stages: encoding the problem, retrieving or calculating the answer, and reporting the answer. This study compared the event-related potentials elicited by single-digit addition and multiplication problems to examine the relationship between encoding and retrieval/calculation stages. Results showed that the operation effect appeared as early as the encoding of the first operand and continued to the retrieval/calculation stage: compared to addition, multiplication elicited larger negative potentials in the left anterior electrodes and larger positive potentials in the right posterior electrodes. The consistency of this operation effect across the first two stages of arithmetic processing suggests that encoding of arithmetic problems can be modulated by the nature of representation of the to-be-retrieved arithmetic facts, and thus these two stages are additive rather than interactive.     

Opposing amygdala and ventral striatum connectivity during emotion identification

Lesion and electrophysiological studies in animals provide evidence of opposing functions for subcortical nuclei such as the amygdala and ventral striatum, but the implications of these findings for emotion identification in humans remain poorly described. Here we report a high-resolution fMRI study in a sample of 39 healthy subjects who performed a well-characterized emotion identification task. As expected, the amygdala responded to THREAT (angry or fearful) faces more than NON-THREAT (sad or happy) faces. A functional connectivity analysis of the time series from an anatomically defined amygdala seed revealed a strong anticorrelation between the amygdala and the ventral striatum/ventral pallidum, consistent with an opposing role for these regions in during emotion identification. A second functional connectivity analysis (psychophysiological interaction) investigating relative connectivity on THREAT vs. NON-THREAT trials demonstrated that the amygdala had increased connectivity with the orbitofrontal cortex during THREAT trials, whereas the ventral striatum demonstrated increased connectivity with the posterior hippocampus on NON-THREAT trials. These results indicate that activity in the amygdala and ventral striatum may be inversely related, and that both regions may provide opposing affective bias signals during emotion identification.     

Unsupervised Classification During Time-Series Model Building

Researchers who collect multivariate time-series data across individuals must decide whether to model the dynamic processes at the individual level or at the group level. A recent innovation, group iterative multiple model estimation (GIMME), offers one solution to this dichotomy by identifying group-level time-series models in a data-driven manner while also reliably recovering individual-level patterns of dynamic effects. GIMME is unique in that it does not assume homogeneity in processes across individuals in terms of the patterns or weights of temporal effects. However, it can be difficult to make inferences from the nuances in varied individual-level patterns. The present article introduces an algorithm that arrives at subgroups of individuals that have similar dynamic models. Importantly, the researcher does not need to decide the number of subgroups. The final models contain reliable group-, subgroup-, and individual-level patterns that enable generalizable inferences, subgroups of individuals with shared model features, and individual-level patterns and estimates. We show that integrating community detection into the GIMME algorithm improves upon current standards in two important ways: (1) providing reliable classification and (2) increasing the reliability in the recovery of individual-level effects. We demonstrate this method on functional MRI from a sample of former American football players.     

心理预期与认知方式对负面情绪的交互调节

近年来, 研究发现对负性事件发生之前预先的心理准备, 即心理预期, 能有效降低负性事件发生后的情绪影响, 但预期过程本身却导致情绪相关神经环路的激活与主观焦虑体验。因此, 采用适应性认知调节方式克服预期过程本身的负面情绪效应, 以充分发挥事先预期的情绪调控优势, 成为情绪调节领域亟待解决的问题。另一方面, 过度负性预期--对潜在负性事件不仅作负面心理预期同时以情绪化的认知方式应对该事件, 是焦虑障碍的核心特征。因此, 对焦虑症患者进行适应性认知方式的训练以消除其情绪化应对方式, 最终减弱该人群对未知事件的过度负面预期, 可能是焦虑障碍干预的重要途径。因此, 有必要综合行为学, 多导外周生理记录与神经成像手段以揭示认知方式与心理预期对负面情绪的交互调节效应; 旨在探求发挥心理预期情绪调节优势, 减弱其情绪代价的方法; 并为焦虑症的临床治疗提供新的思路。     

内倾特质个体的自我参照加工程度效应

采用事件相关电位技术和三类刺激的经典oddball范式,以内隐的方式探讨内倾特质个体的自我参照加工程度效应及其神经机制。实验发现,在P2的波幅上,在电极前部、前中部和中部位置高自我相关的刺激比其它刺激诱发了更大的P2波幅。在P2的潜伏期上,在电极前部、中部、和中后部位置高自我相关的刺激比其它刺激诱发了更短的潜伏期。在N2的波幅上,高自我相关名字比其它刺激在左脑所诱发了更大的P2的波幅;对比内倾型被试,中间型被试的高自我相关名字比其它刺激诱发了更大的N2的波幅。在N2的潜伏期上,高自我相关的刺激在全脑都比其它刺激诱发了更短的N2潜伏期,且中后部电极位置的潜伏期最短;两类人格被试的高自我相关名字比其它刺激诱发了更短的N2潜伏期,但中间型人格被试的潜伏期最短。在P3平均波幅上,高自我相关的刺激在全脑都比其它刺激诱发了更大的P3波幅,其中中部脑区效应最大。研究结果表明内倾特质个体的自我参照加工具有程度效应,但对比中间型个体,内倾特质个体的自我参照加工的程度效应更弱。     

Alertness in young healthy subjects: An fMRI study of brain region interactivity enhanced by a warning signal

An effective connectivity study was carried out on 16 young, healthy subjects performing an alertness task. The objective of this study was to develop and to evaluate a putative network model of alertness by adapting structural equation modeling to fMRI data. This study was designed to evaluate the directed interactivity of an attentional network during intrinsic and phasic alerting tasks. On the basis of theoretical hypotheses, clinical observations, behavioral data and neuroimaging studies, it was hypothesized that neural circuits in the right hemisphere including the dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex, inferior parietal cortex and the thalamus were involved. The results of this study support the existence of a common network of activated areas with significant path coefficient differences between intrinsic and phasic alertness. Functional interactivity was significantly reinforced during the phasic alertness task and appeared to preferentially involve activity in the DLPFC region, whereas the path coefficients of the model were well-balanced during intrinsic alertness. This study highlights the predominant role of the DLPFC region in maintenance of a state of alertness and in temporal preparation during an alertness task.     

My face or yours? Event-related potential correlates of self-face processing

The neural basis of self-recognition is mainly studied using brain-imaging techniques which reveal much about the localization of self-processing in the brain. There are comparatively few studies using EEG which allow us to study the time course of self-recognition. In this study, participants monitored a sequence of images, including 20 distinct images of their own face, a friend’s face and a stranger’s face articulating different speech sounds, while EEG was recorded from 64 scalp electrodes. Differences in the ERP waveforms were observed very early on, with increased N170 and VPP amplitude to self relative to both friend and stranger measured over posterior and fronto-central sites, respectively. This ‘self effect’ was also marked at ∼250 ms where P2/N2 amplitude was significantly reduced for self-faces. By comparison, differences between friend and stranger faces did not emerge until 250 ms and beyond, where a more conventional ‘familiarity effect’ was observed. The data also point to a ‘less lateralized’ representation of self over posterior sites. These findings are consistent with both behavioral and fMRI studies which suggest that self-face processing is ‘special’ and are discussed with reference to EEG studies of face processing.