Inattention and hyperactivity-impulsivity: psychobiological and evolutionary underpinnings of ADHD

Attention-deficit/hyperactivity disorder is a prevalent and disabling disorder that is characterized by inattention and/or hyperactivity-impulsivity, impairment in executive functions, structural and functional abnormalities in frontal-striatal circuitry, associations with particular catecholamine gene variants, and responsiveness to dopaminergic and noradrenergic agents. There is a growing integration of findings from basic and clinical studies, of data from different methods (eg, genetics and imaging), and of empirical data with hypotheses drawn from evolutionary thinking. Here we briefly summarize work on the cognitive-affective neuroscience of attention-deficit/hyperactivity disorder.     

Mind and muscle: the cognitive-affective neuroscience of exercise

There is growing basic-science interest in the mechanisms underpinning the positive effects of exercise on brain function and cognitive-affective performance. There is also increasing clinical evidence that exercise may prevent and treat various neuropsychiatric disorders. At the same time, there is growing awareness that athletic performance is mediated in crucial ways by central nervous system mechanisms. The relevant mechanisms in all these cases requires further exploration, but likely includes neurotrophic, neuroendocrine, and neurotransmitter systems, which in turn are crucial mediators of psychopathology and resilience. The hypothesis that Homo sapiens evolved as a specialist endurance runner provides an intriguing context against which to research the proximal mechanisms relevant to a cognitive-affective neuroscience of exercise.     

5-HT2A: its role in frontally mediated executive function and related psychopathology

Serotonin (5-HT)2A receptors are widely distributed, with high levels in the frontal cortex, where postsynaptic activation may increase activity in pyramidal glutamatergic neurons and mediate various executive functions. More specifically, reciprocal cortical-raphe pathways may allow the ventral prefrontal cortex to inhibit stress-induced neural activity in the brainstem when stressors are perceived as controllable. However, early adversity and negative attitudes may be associated with higher frontal 5-HT2A receptor levels and greater risk for stress-induced psychopathology, and certain 5-HT2A gene variants have been associated with increased risk for impulsive behavior. Conversely, many antidepressants result in decreased levels of 5-HT2A receptor levels, and blockade of 5-HT2A receptors has proven useful in the treatment of a number of psychiatric disorders.     

Acute exposure to a 50 Hz magnetic field impairs consolidation of spatial memory in rats

This study was planned to evaluate the effect of an exposure to magnetic fields on consolidation and retrieval of hippocampus dependent spatial memory using a water maze. In Experiments 1 and 2, rats were trained in a hidden version (spatial) of water maze task with two blocks of four trials. The retention of spatial memory was evaluated 48 h later. Exposure to a 50 Hz 8 mT, but not 2 mT magnetic fields for 20 min immediately after training impaired retention performance. The same time exposure shortly before retention testing had no effect. In Experiment 3, rats were trained in a cued version of water maze with two blocks of four trials. Exposure to magnetic field at 8 mT for 20 min immediately after training did not impair retention performance. These findings indicate that acute exposure to a 50 Hz magnetic field at 8 mT for short time can impair consolidation of spatial memory.     

2岁幼儿的社会朝向反应——本质及功能

本研究以66对17至32个月的幼儿和母亲为研究对象,研究了在实验室情境中,幼儿在不同实验情境下对母亲的社会朝向反应,并探讨了幼儿社会朝向行为的功能以及母亲的行为对幼儿社会朝向反应的影响。结果显示,（1）大多数幼儿在实验中都表现出了至少一次的社会朝向反应,社会朝向反应的发生是酱遍的;（2）在不同情境中,幼儿的社会朝向反应不同,在积极的情境中,社会朝向反应有分享情绪经历的功能;在抗拒诱惑的任务中,社会朝向行为与获得支持有关;（3）母亲对情境的非信息性反应对幼儿的社会朝向行为有影响,社会朝向是幼儿对社会情境的适应性行为,对这种非语言的情感交流行为的研究可以帮助我们探究幼儿情绪社会化的过程。     

Inference in regression models of heavily skewed alcohol use data: a comparison of ordinary least squares, generalized linear models, and bootstrap resampling.

Analysis of alcohol use data and other low base rate risk behaviors using ordinary least squares regression models can be problematic. This article presents 2 alternative statistical approaches, generalized linear models and bootstrapping, that may be more appropriate for such data. First, the basic theory behind the approaches is presented. Then, using a data set of alcohol use behaviors and consequences, results based on these approaches are contrasted with the results from ordinary least squares regression. The less traditional approaches consistently demonstrated better fit with model assumptions, as demonstrated by graphical analysis of residuals, and identified more significant variables potentially resulting in theoretically different interpretations of the models of alcohol use. In conclusion, these models show significant promise for furthering the understanding of alcohol-related behaviors.     

Nonparametric item response theory axioms and properties under nonlinearity and their exemplification with knowledge space theory

This paper investigates the dichotomous Mokken nonparametric item response theory (IRT) axioms and properties under incomparabilities among latent trait values and items. Generalized equivalents of the unidimensional nonparametric IRT axioms and properties are formulated for nonlinear (quasi-ordered) person and indicator spaces. It is shown that monotone likelihood ratio (MLR) for the total score variable and nonlinear latent trait implies stochastic ordering (SO) of the total score variable, but may fail to imply SO of the nonlinear latent trait. The reason for this and conditions under which the implication holds are specified, based on a new, simpler proof of the fact that in the unidimensional case MLR implies SO. The approach is applied in knowledge space theory (KST), a combinatorial test theory. This leads to a (tentative) Mokken-type nonparametric axiomatization in the currently parametric theory of knowledge spaces. The nonparametric axiomatization is compared with the assumptions of the parametric basic local independence model which is fundamental in KST. It is concluded that this paper may provide a first step toward a basis for a possible fusion of the two split directions of psychological test theories IRT and KST.     

Less is more: the lure of ambiguity, or why familiarity breeds contempt

The present research shows that although people believe that learning more about others leads to greater liking, more information about others leads, on average, to less liking. Thus, ambiguity--lacking information about another--leads to liking, whereas familiarity--acquiring more information--can breed contempt. This "less is more" effect is due to the cascading nature of dissimilarity: Once evidence of dissimilarity is encountered, subsequent information is more likely to be interpreted as further evidence of dissimilarity, leading to decreased liking. The authors document the negative relationship between knowledge and liking in laboratory studies and with pre- and postdate data from online daters, while showing the mediating role of dissimilarity.     

标量计时模型中的神经机制

标量计时模型中各阶段的神经机制有重叠也有分离。从当今认知神经科学的研究结果看,与内部时钟有关的神经结构有小脑、基底神经节、前额皮质、前运动辅助皮质及顶叶下回皮质等;与记忆阶段有关的神经结构有基底神经节、背外侧前额皮质、右侧额下皮质及外侧前运动皮质等;与决策阶段有关的神经结构有背外侧前额皮质、前扣带回、高级颞叶皮质和基底神经节等。文章还从神经机制角度论证了计时的标量特性,讨论了今后研究值得注意的三个问题,即研究结果的确定性、研究手段的局限性以及该模型的适用性     

Combining experiences over time: the effects of duration,intensity changes and on-line measurements on retrospective pain evaluations

Two experiments were conducted to examine the effects of various factors on retrospective pain evaluation. The factors examined in Experiment 1 were the rate and pattern of change, the intensity (particularly the final intensity), and the duration of the painful experience. Experiment 2 manipulated these factors and, in addition, examined the effect of continuous (on-line) ratings on the overall retrospective evaluation. The two experiments utilized different pain modalities, heat in the first and mechanical pressure in the second. In addition, all subjects in Experiment 1 experienced stimuli with the same physical magnitude, while in Experiment 2 stimuli were individually tailored to make them subjectively equivalent. In both experiments, subjects were presented with a series of painful stimuli and evaluated the intensity of each stimulus immediately upon its termination. The stimuli themselves were composed of multiple intensity levels that differentially changed over time (Intensity-Patterns). Subjects' on-line ratings in Experiment 2 closely mirrored the physical patterns of the intensities. The main conclusion from both experiments is that the retrospective evaluations of painful experiences are influenced primarily by a combination of the final pain intensity and the intensity trend during the latter half of the experience. In addition, results indicated that duration has little impact on retrospective evaluations for stimuli of relatively constant intensity. However, when the stimulus intensity changes over time, duration does play a role. Finally, the task of continuously reporting the stimulus intensity had a moderating impact on the retrospective evaluations. © 1998 John Wiley & Sons, Ltd.