Hot and Cool Aspects of Cognitive Control in Children with ADHD: Decision-Making and Inhibition

This study investigated hot and cool aspects of cognitive control in children with Attention Deficit Hyperactivity Disorder (ADHD). The study aimed to: (1) replicate the postulated response inhibition deficit of children with ADHD; (2) explore whether children with ADHD choose disadvantageously in a decision-making task and to explore the mechanisms underlying the expected response pattern; and (3) study whether performance on a combination of hot and cool executive control measures has predictive value for an ADHD diagnosis. The sample consisted of 20 children with ADHD and 22 normal developing children (NC, 8 to 12 years) matched on age, FSIQ, and gender. Two paradigms have been applied: (1) the stop signal paradigm, and (2) the adapted children's version of the IOWA Gambling task. There were no group differences for both paradigms. Both groups chose in a reward-oriented manner and seemed to develop the ability to take future consequences into account in making decisions. Moreover, feedback resulted in direct behavioral changes. Children with ADHD did not have a specific response inhibition deficit or a decision-making deficit.     

Taking control of reflexive social attention

Attention is shifted reflexively to where other people are looking. It has been argued by a number of investigators that this social attention effect reflects the obligatory bottom-up activation of domain-specific modules within the inferior temporal (IT) cortex that are specialized for processing face and gaze information. However, it is also the case that top-down factors may modulate the activation of IT cells. Here we examined behaviorally whether reflexive social orienting is purely automatic or sensitive to top-down modulation. Participants were shown an ambiguous stimulus that could be perceived either as representing EYES or a CAR. In we demonstrated between groups that an automatic shift of attention, equivalent to that triggered by a schematic FACE, occurred only when the stimulus was referred to as possessing EYES. In all participants received the EYES and CAR conditions. When the stimulus was first referred to as a CAR and then as EYES, an attentional shift was only present for the EYES condition. However, when the stimulus was first referred to as possessing EYES, and then later as a CAR, attentional shifts were observed for both conditions. These data indicate that the emergence of a reflexive social attention effect is influenced by top-down mechanisms but in an asymmetrical manner. Top-down processes appear to be effective for triggering IT involvement, that is, for perceiving a stimulus as a face, which produces the social attention effect. But top-down mechanisms are ineffective once IT involvement has been triggered. That is, once a stimulus has been seen as having eyes, it continues to be seen that way, and accordingly, the social attention effect persists.     

Neuronal substrates of relapse to cocaine-seeking behavior: role of prefrontal cortex

The return to drug seeking, even after prolonged periods of abstinence, is a defining feature of cocaine addiction. The neural circuitry underlying relapse has been identified in neuropharmacological studies of experimental animals, typically rats, and supported in brain imaging studies of human addicts. Although the nucleus accumbens (NAcc), which has long been implicated in goal-directed behavior, plays a critical role in this circuit, the prefrontal cortex (PFC) appears to process the events that directly trigger relapse: exposure to acute stress, cues previously associated with the drug, and the drug itself. In this paper, we review animal models of relapse and what they have revealed about the mechanisms underlying the involvement of the NAcc and PFC in cocaine-seeking behavior. We also present electrophysiological data from PFC illustrating how the hedonic, motor, motivational, and reinforcing effects of cocaine can be analyzed at the neuronal level. Our preliminary findings suggest a role for PFC in processing information related to cocaine seeking but not the hedonic effects of the drug. Further use of this recording technology can help dissect the functions of PFC and other components of the neural circuitry underlying relapse.     

Repetitive transcranial magnetic stimulation may induce language switching in bilingual patients

The dorsolateral prefrontal cortex (DLPFC) may participate in the process of language switching in multilingual individuals. We present two cases of bilingual patients who experienced unexpected language switching after receiving high-frequency, repetitive transcranial magnetic stimulation (rTMS) to the left DLPFC as a treatment for major depression. These preliminary findings support the role of the DLPFC in language switching in polyglots and highlight the potential value of rTMS for non-invasively investigating language function in humans. Further investigation is warranted.     

A few thoughts about the mind,the brain,and a child with early deprivation

Infant brain research is having an increasing impact on child psychotherapy and our understanding of the neurobiological effects of trauma and neglect. This paper outlines the 'experience-dependent' nature of brain development in infancy and the concept of critical periods in such development. The effects of deprivation on child development are illustrated and case material from a child who was institutionalized during his second year is used as a basis for posing questions about the nature of the mind and the brain. In spite of his deprivation, he was able to communicate imaginatively. Schore's proposal for the use of early interventions is put forward to counter discouragement that can be engendered by work with severely deprived children.     

Attentional control in the aging brain: insights from an fMRI study of the stroop task

Several recent studies of aging and cognition have attributed decreases in the efficiency of working memory processes to possible declines in attentional control, the mechanism(s) by which the brain attempts to limit its processing to that of task-relevant information. Here we used fMRI measures of neural activity during performance of the color-word Stroop task to compare the neural substrates of attentional control in younger (ages: 21-27 years old) and older participants (ages: 60-75 years old) during conditions of both increased competition (incongruent and congruent neutral) and increased conflict (incongruent and congruent neutral). We found evidence of age-related decreases in the responsiveness of structures thought to support attentional control (e.g., dorsolateral prefrontal and parietal cortices), suggesting possible impairments in the implementation of attentional control in older participants. Consistent with this notion, older participants exhibited more extensive activation of ventral visual processing regions (i.e., temporal cortex) and anterior inferior prefrontal cortices, reflecting a decreased ability to inhibit the processing of task-irrelevant information. Also, the anterior cingulate cortex, a region involved in evaluatory processes at the level of response (e.g., detecting potential for error), showed age-related increases in its sensitivity to the presence of competing color information. These findings are discussed in terms of newly emerging models of attentional control in the human brain.     

Effect of a sex stereotype on cortical activity during a self-paced exercise: A motor-related cortical potential approach

Recent research has shown that inducing a negative stereotype toward women does not always decrease the subsequent motor performance of women, but can increase it, especially during endurance tasks. The mechanisms involved are nonetheless still poorly understood. The main aim of the present study was to investigate the effect of a negative stereotype toward women on men’s and women’s performance during an endurance task, and to analyze the neuropsychological mechanisms involved through motor-related cortical potentials and motivation toward men/women. Thirty-four participants were assigned to a negative stereotype toward women condition and a nullified-stereotype condition and performed 80 self-paced intermittent isometric elbow contractions at a moderate perceived intensity. Results showed that women performed better when assigned to the negative stereotype toward women condition, they were more motivated to outperform men, and their MRCP amplitudes were higher in this same condition over the prefrontal cortex (i.e., FP1 and FP2). Concerning men, they also performed better when the negative stereotype toward women was induced. However, no effect emerged on motivation toward women and MRCP amplitudes. This study showed that inducing a negative stereotype during an endurance task led to a performance increase in women, which is contrary to the stereotype threat theory, strengthening the idea of a task-dependency effect when inducing a negative stereotype. This performance improvement observed in women may be caused by increased motivation to outperform men and a planning of the upcoming movement. Concerning men, more research is needed to clarify the mechanisms involved in such performance improvement.     

腹内侧前额叶在内隐认知重评中的因果作用

情绪调节对维持个体心理健康、适应社会生活十分重要, 然而以往研究主要关注外显情绪调节, 目前我们对内隐情绪调节的认知神经机制的了解还非常有限。为揭示内隐情绪调节的核心脑区, 本研究使用句子整理任务启动内隐认知重评, 并采用经颅直流电刺激(transcranial direct current stimulation, tDCS)激活内侧前额叶特别是腹内侧前额叶(ventromedial prefrontal cortex, vmPFC), 考察该脑区在内隐情绪调节中的因果作用。结果表明, vmPFC被激活的被试组(实验组, n = 40)在内隐认知重评启动条件下比tDCS伪刺激组(对照组, n = 40), 在观看负性图片时报告了更少的负性情绪, 同时负性图片诱发的晚正成分(late positive potential, LPP)波幅更低(LPP是情绪体验强度的客观指标)。同时, 实验组比对照组在观看负性图片时表现出更低的枕区P1波幅(P1为早期视觉注意程度的客观指标)。以上结果说明, 激活以vmPFC为代表的内侧前额叶不但能增强内隐情绪调节的效果, 还能减少被试对负性刺激的早期注意分配。本研究是采用tDCS技术考察启动引起的内隐情绪调节的首次尝试, 研究结果不但表明了以vmPFC为代表的内侧前额叶在内隐认知重评中的关键作用, 还为临床应用研究指出了增强内隐情绪调节能力的神经调控潜在靶点。     

运动区Beta节律的活动特点及功能意义

人类大脑运动皮质的Beta(15~30 Hz)和Mu节律(8~14 Hz)有共同的活动特征,研究指出二者可能是联合的脑电成分。然而越来越多研究表明运动区Beta节律可能独立于Mu节律,且具有特殊的功能意义。线索诱发的Beta节律降低、运动前Beta节律降低和运动后Beta节律回复增强都是Beta与Mu节律不同的活动形式,表明运动区Beta节律有其独特的心理意义。本文主要对运动区Beta节律不同于Mu节律的活动特征及已有的理论解释进行了梳理和分析,并结合儿童研究的数据,从发展的角度对运动后Beta节律的理论假说进行了评述,最后在此基础上为进一步探索运动区Beta节律的功能意义提出了研究的展望。     

风险决策的神经机制:基于啮齿类动物研究

风险决策是在不同选项的结果确定、并且结果出现的概率已知情况下的决策。啮齿类风险决策模型研究发现前额皮层-杏仁核-伏隔核神经环路联系是决定风险决策的选择倾向的关键。前额皮层中的眶额皮层和内侧前额皮层参与风险决策的策略形成和策略转换有关;而皮层下核团中的杏仁核、腹侧纹状体的伏隔核等结构参与策略保持、价值判断,影响决策偏向和行动强度;眶额皮层、伏隔核神经元和多巴胺神经元编码风险决策过程中的概率、风险等因素;此外,多巴胺等单胺类神经递质及受体在风险决策中有复杂的作用。