The amygdalostriatal and corticostriatal effective connectivity in anticipation and evaluation of facial attractiveness

Decision-making consists of several stages of information processing, including an anticipation stage and an outcome evaluation stage. Previous studies showed that the ventral striatum (VS) is pivotal to both stages, bridging motivation and action, and it works in concert with the ventral medial prefrontal cortex (vmPFC) and the amygdala. However, evidence concerning how the VS works together with the vmPFC and the amygdala came mainly from neuropathology and animal studies; little is known about the dynamics of this network in the functioning human brain. Here we used fMRI combined with dynamic causal modeling (DCM) to investigate the information flow along amygdalostriatal and corticostriatal pathways in a facial attractiveness guessing task. Specifically, we asked participants to guess whether a blurred photo of female face was attractive and to wait for a few seconds (“anticipation stage”) until an unblurred photo of feedback face, which was either attractive or unattractive, was presented (“outcome evaluation stage”). At the anticipation stage, the bilateral amygdala and VS showed higher activation for the “attractive” than for the “unattractive” guess. At the outcome evaluation stage, the vmPFC and the bilateral VS were more activated by feedback faces whose attractiveness was congruent with the initial guess than by incongruent faces; however, this effect was only significant for attractive faces, not for unattractive ones. DCM showed that at the anticipation stage, the choice-related information entered the amygdalostriatal pathway through the amygdala and was projected to the VS. At the evaluation stage, the outcome-related information entered the corticostriatal pathway through the vmPFC. Bidirectional connectivities existed between the vmPFC and VS, with the VS-to-vmPFC connectivity weakened by unattractive faces. These findings advanced our understanding of the reward circuitry by demonstrating the pattern of information flow along the amygdalostriatal and corticostriatal pathways at different stages of decision-making.     

Exposure to violence reduces empathetic responses to other’s pain

Past researches showed that empathy for pain not only triggers a resonance mechanism between other and self, but also is modulated by contextual factors. Using functional magnetic resonance imaging, the present study demonstrated that short-term media violence exposure reduced both pain ratings and also the activation of anterior insula and anterior mid-cingulate cortex to other’s pain. Thus, violence exposure modulated empathic responses to other’s pain based on a physiological desensitization.     

Competitive Processes in Cross‐Situational Word Learning

Cross‐situational word learning, like any statistical learning problem, involves tracking the regularities in the environment. However, the information that learners pick up from these regularities is dependent on their learning mechanism. This article investigates the role of one type of mechanism in statistical word learning: competition. Competitive mechanisms would allow learners to find the signal in noisy input and would help to explain the speed with which learners succeed in statistical learning tasks. Because cross‐situational word learning provides information at multiple scales—both within and across trials/situations—learners could implement competition at either or both of these scales. A series of four experiments demonstrate that cross‐situational learning involves competition at both levels of scale, and that these mechanisms interact to support rapid learning. The impact of both of these mechanisms is considered from the perspective of a process‐level understanding of cross‐situational learning.     

真实火灾和模拟火灾情境下小鼠的逃生决策比较*

探讨并比较真实火灾和模拟火灾情境下小鼠是否采用直觉性逃生决策。研究包括一个预备训练和两个主实验。预备训练的目的：首先训练小鼠获得有关迷宫路线及出口的经验,然后再经过遗忘处理使它们遗忘相关经验。两个主实验均采用3(情境：真实火灾,模拟火灾,普通情境)×2(记忆：遗忘前和遗忘后)混合实验设计,因变量均为逃生决策。实验组被试为72只经过训练的小鼠,控制组为24只未经过训练的小鼠。通过考察小鼠在不同情境和不同记忆条件下的逃生时间和对逃生出口的选择探测并比较真实火灾和模拟火灾情境下小鼠的逃生决策差异。主要结果：(1)实验组在真实火灾情境下的逃生时间无论遗忘前后都明显比模拟火灾情境下短;(2)实验组在真实火灾和模拟火灾情境下的逃生时间都明显比控制组短;(3)当熟悉和陌生出口均开启同时熟悉出口处有烟雾条件下,真实火灾组在遗忘前后均倾向于选择熟悉出口逃生,其他两组则倾向于选择陌生出口离开。结论：真实火灾和模拟火灾情境下小鼠的逃生决策存在明显差异：真实火灾情境下受过训练的小鼠倾向于直觉性逃生决策;模拟火灾情境下受过训练的小鼠不倾向于直觉性逃生决策。     

Interactions between interfacial dislocations and γ/γ′ interface during high temperature – low stress creep in nickel-based single crystal superalloy

ABSTRACT

The interaction between interfacial dislocations and γ/γ′ interface is critical to the high temperature creep properties of single crystal superalloys. However, only a few studies have paid attention to the detailed structure such as local interfacial morphologies and the elemental distribution around interfacial dislocations. In this paper, the interfacial protrusions and related dislocations in a single crystal superalloy after creep at high temperature – low stress have been investigated in detail. It is found that the morphology and size of the interfacial protrusions remain almost the same during the early and middle stages of high temperature creep, which indicates a local equilibrium at the interfacial protrusions. Steps at different height are formed at the γ/γ′ interface at the initial stage of high temperature creep since dislocations could move along the γ/γ′ interface, which indicates that dislocation motion at different creep stage may affect the morphology of γ/γ′ interface.     

Long-term natural ageing of a dissociated dislocation in a Cu-13.43 at.% Al alloy

The nature of impurity-dislocation interactions is one of the key questions governing the strength and plasticity of solid-solution materials. To investigate the influence of impurities on the mechanical properties of intermetallic NiAl, the electronic structure and energy of NiAl with a <100>{010} edge dislocation and transition-metal impurities was calculated using the real-space tight-binding linear muffin-tin orbital method. The localized electronic states, appearing in the core of the dislocation, are found to lead to strong impurity-dislocation interactions via two mechanisms: firstly, chemical locking, due to strong hybridization between impurity electronic states and dislocation localized states; secondly, electrostatic locking, due to long-range charge oscillations caused by the electron localization in the dislocation core. The results obtained explain qualitatively why the solid-solution hardening effect in NiAl correlates with the electronic structure of impurities rather than with size misfit, as expected according to traditional views.     

Real temperature of nanoparticles in electron microscope beams

Abstract

This Letter presents a solution of the problem of the real temperature of nanoparticles under conditions of electron microscope beam irradiation. It is shown that the average temperature of the nanoparticles (NPs) may increase to several hundred degrees depending on contact conditions with the substrate, the intensity of the beam and the size of the NPs. The temperature increases with NP size a according to the dependence: T α a² for sufficiently small particles.     

The kinetics of infralow-frequency viscoelastic internal friction induced by irreversible structural relaxation of a metallic glass

This letter presents the results of internal-friction measurements of Co 70 Fe 5 Si 15 B10 metallic glass at temperatures 400K h T h 700K and frequencies 0.01 Hz h f h 0.05Hz. It is shown that Maxwellian viscoelastic damping is predominant in this case. The nature of this damping is determined by irreversible structural relaxation. The kinetic relaxation law is derived.     

Locating dysprosium dopant atoms in the Bi2Sr2CaCu2Oy unit cell: Direct-space chemical crystallography

The position of Dy in the unit cell of Bi2Sr2CaCu2Oy has been determined by a real-space method. This is compared with the reciprocal-space atom location by channelling-enhanced microanalysis (ALCHEMI) method.     

Dependence of normal contact stress on the surface morphology of solid surfaces

Contact problems between two solids are essential to interpret the loading-unloading behaviour in indentation tests. Using linear elastic theory, a general relationship between the normal stress and the surface deformation for elastic contact of two solids was derived, in which the normal stress is a function of the mean curvature of the undeformed surface.