自尊的认知神经机制

自尊是个体对自己总体的情感性评价。自尊有助于促进个体的心理健康,帮助个体应对威胁,具有重要的适应价值。近年来随着社会认知神经科学的兴起,关于自尊的认知神经机制的研究日益增多,主要涉及三个方面:1)自尊与大脑的结构(如海马体积、前扣带回等区域的灰质体积)和功能(静息态下的默认网络活动以及脑区之间的功能联结性)存在一定的关联;2)自尊调节大脑对威胁的反应,与高自尊个体相比,低自尊个体面对威胁时产生更强的防御性反应,自尊通过影响个体面对威胁时的大脑活动帮助个体更好地应对威胁;3)自我评价过程涉及大脑前额叶、眶额叶、扣带回等多个脑区,自尊调节个体在自我评价过程中的大脑活动。总之,自尊作为个体重要的人格特质,与大脑的结构、功能以及活动状态等都具有一定的关系;这些发现在一定程度上揭示了自尊的神经机制,加深了对自尊及其功能的理解。     

Improving executive function using transcranial infrared laser stimulation

Transcranial infrared laser stimulation is a new non‐invasive form of low‐level light therapy that may have a wide range of neuropsychological applications. It entails using low‐power and high‐energy‐density infrared light from lasers to increase metabolic energy. Preclinical work showed that this intervention can increase cortical metabolic energy, thereby improving frontal cortex‐based memory function in rats. Barrett and Gonzalez‐Lima (2013, Neuroscience, 230, 13) discovered that transcranial laser stimulation can enhance sustained attention and short‐term memory in humans. We extend this line of work to executive function. Specifically, we ask whether transcranial laser stimulation enhances performance in the Wisconsin Card Sorting Task that is considered the gold standard of executive function and is compromised in normal ageing and a number of neuropsychological disorders. We used a laser of a specific wavelength (1,064 nm) that photostimulates cytochrome oxidase – the enzyme catalysing oxygen consumption for metabolic energy production. Increased cytochrome oxidase activity is considered the primary mechanism of action of this intervention. Participants who received laser treatment made fewer errors and showed improved set‐shifting ability relative to placebo controls. These results suggest that transcranial laser stimulation improves executive function and may have exciting potential for treating or preventing deficits resulting from neuropsychological disorders or normal ageing.     

慢性应激性抑郁发生中大鼠眶额叶多巴胺D1受体对谷氨酸及其NMDA受体的调节

本文旨在探讨慢性应激性抑郁发生过程中眶额叶多巴胺D1受体对谷氨酸(glutamic acid, Glu)及其N-甲基-D-天冬氨酸(N-methyl-D-aspartic acid, NMDA)受体的NR2B亚基的影响。实验通过建立慢性不可预见性温和应激(chronic unpredictable mild stress, CUMS)抑郁模型, 结合眶额叶微量注射多巴胺D1受体激动剂SKF38393和多巴胺D1受体拮抗剂SCH23390, 运用糖水偏爱测试、悬尾实验和敞箱实验等方法检测动物的行为表现, 采用高效液相色谱法(high-performance liquid chromatography, HPLC)和蛋白质免疫印迹法(Western blot, WB)来检测眶额叶内谷氨酸、多巴胺含量及NR2B和多巴胺D1受体的表达。结果显示, 与对照组相比, CUMS组大鼠表现出明显的抑郁样行为变化, 且眶额叶多巴胺含量降低, 其D1型受体表达降低, 谷氨酸含量升高, 其NMDA受体的NR2B亚基也明显上调; 注射SKF38393后可明显改善应激引起的抑郁样行为, 且眶额叶谷氨酸含量显著下降, NMDA受体的NR2B亚基表达也有所降低; 正常大鼠注射多巴胺D1受体拮抗剂SCH23390, 大鼠表现出和CUMS模型组相似的抑郁样行为, 且眶额叶谷氨酸含量升高, 其NMDA受体的NR2B亚基也明显上调。以上结果表明, 慢性不可预见性应激可能使眶额叶多巴胺释放减少, 从而使谷氨酸过量释放, NMDA受体过度激活, 导致抑郁发生。多巴胺抗抑郁作用是通过D1型受体抑制谷氨酸及其NMDA受体NR2B亚基表达来实现。     

Cognitive deficits in relation to personality type and hypothalamic-pituitary-adrenal (HPA) axis dysfunction in women with stress-related exhaustion

Exhaustion caused by long-term work-related stress may cause cognitive dysfunction. We explored factors that may link chronic stress and cognitive impairment. Personality, psychiatric screening, and behavior were assessed by self-reporting measures in 20 female patients (mean age 39.3 years; range 26-53) with a preliminary diagnosis of stress-related exhaustion and in 16 healthy matched controls. Cognitive performance was investigated with a detailed neuropsychological test battery. Cortisol axis function was assessed by urinary and saliva collections of cortisol, dexamethasone suppression, Synacthen response, and corticotropin-releasing hormone (CRH) tests. Proinflammatory cytokines were measured. Hippocampal volumes were estimated by magnetic resonance imaging. Multivariate and univariate statistical methods were used to explore putative differences between groups and factors linked to cognitive impairment. Cognitive function clearly differed between groups, with decreased attention and visuospatial memory in the patient group, suggesting frontal cortex/medial temporal cortex-network dysfunction. Increased harm avoidance and persistence was present among patients, with lowered self-directedness linked to lower quality of life, increased anxious and depressive tendencies, and experiences of psychosocial stress. Attention was decreased with concomitantly impaired visuospatial memory. The pituitary (adrenocorticotropic hormone, ACTH) response to CRH was decreased in patients, with an increased cortisol/ACTH response to CRH. However, cortisol production rates, diurnal or dexamethasone-suppressed saliva cortisol levels, and the cortisol response to Synacthen were unaltered. Hippocampal volumes did not differ between groups. These findings suggest that cognitive dysfunction in stress-related exhaustion is linked to distinct personality traits, low quality of life, and a decreased ACTH response to CRH.     

Neural correlates of metonymy resolution

Metonymies are exemplary models for complex semantic association processes at the sentence level. We investigated processing of metonymies using event-related functional magnetic resonance imaging (fMRI).During an 1.5 Tesla fMRI scan, 14 healthy subjects (12 female) read 124 short German sentences with either literal (like “Africa is arid”), metonymic (“Africa is hungry”), or nonsense (“Africa is woollen”) content. Sentences were constructed so that they obey certain grammatical, semantic, and plausibility conditions and were matched for word frequency, semantic association, length and syntactic structure. We concentrated on metonymies that were not yet fossilised; we also examined a wide variety of metonymic readings.Reading metonymies relative to literal sentences revealed signal changes in a predominantly left-lateralised fronto-temporal network with maxima in the left and right inferior frontal as well as left middle temporal gyri. Left inferior frontal activation may reflect both inference processes and access to world knowledge during metonymy resolution.     

Magnitude and chronometry of neural mechanisms of emotion regulation in subtypes of aggressive children

Emotion regulation is a key social skill and children who fail to master it are at risk for clinical disorders. Specific styles of emotion regulation have been associated with particular patterns of prefrontal activation. We investigated whether anxious aggressive children would reveal a different pattern of cortical activation than non-anxious aggressive children and normally-developing children. We examined the magnitude and timing of source activation underlying the N2—an ERP associated with inhibitory control—during a go/nogo task with a negative emotion induction component (loss of earned points). We estimated cortical activation for two regions of interest—a ventral prefrontal and a dorsomedial prefrontal region—for three 100-ms windows over the range of the N2 (200–500 ms). Anxious aggressive children showed high ventral prefrontal activation in the early window; non-anxious aggressive children showed high ventral prefrontal activation in the late window, but only for the duration of the emotion induction; and normally-developing children showed low ventral prefrontal activation throughout. There were no group differences in dorsomedial prefrontal activation. These results suggest that anxious aggressive children recruit ventral prefrontal activation quickly and indiscriminately, possibly giving rise to their rigid, threat-oriented approach to conflict. The late ventral prefrontal activation seen for non-anxious aggressive children may underlie a more delayed, situation-specific, but ineffective response to frustration.     

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.