Intelligence is differentially related to neural effort in the task-positive and the task-negative brain network

Previous studies on individual differences in intelligence and brain activation during cognitive processing focused on brain regions where activation increases with task demands (task-positive network, TPN). Our study additionally considers brain regions where activation decreases with task demands (task-negative network, TNN) and compares effects of intelligence on neural effort in the TPN and the TNN. In a sample of 52 healthy subjects, functional magnetic resonance imaging was used to determine changes in neural effort associated with the processing of a working memory task. The task comprised three conditions of increasing difficulty: (a) maintenance, (b) manipulation, and (c) updating of a four-letter memory set. Neural effort was defined as signal increase in the TPN and signal decrease in the TNN, respectively. In both functional networks, TPN and TNN, neural effort increased with task difficulty. However, intelligence, as assessed with Raven's Matrices, was differentially associated with neural effort in the TPN and TNN. In the TPN, we observed a positive association, while we observed a negative association in the TNN. In terms of neural efficiency (i.e., task performance in relation to neural effort expended on task processing), more intelligent subjects (as compared to less intelligent subjects) displayed lower neural efficiency in the TPN, while they displayed higher neural efficiency in the TNN. The results illustrate the importance of differentiating between TPN and TNN when interpreting correlations between intelligence and fMRI measures of brain activation. Importantly, this implies the risk of misinterpreting whole brain correlations when ignoring the functional differences between TPN and TNN.     

Intrinsic frames of reference in haptic spatial learning

It has been proposed that spatial reference frames with which object locations are specified in memory are intrinsic to a to-be-remembered spatial layout (intrinsic reference theory). Although this theory has been supported by accumulating evidence, it has only been collected from paradigms in which the entire spatial layout was simultaneously visible to observers. The present study was designed to examine the generality of the theory by investigating whether the geometric structure of a spatial layout (bilateral symmetry) influences selection of spatial reference frames when object locations are sequentially learned through haptic exploration. In two experiments, participants learned the spatial layout solely by touch and performed judgments of relative direction among objects using their spatial memories. Results indicated that the geometric structure can provide a spatial cue for establishing reference frames as long as it is accentuated by explicit instructions (Experiment 1) or alignment with an egocentric orientation (Experiment 2). These results are entirely consistent with those from previous studies in which spatial information was encoded through simultaneous viewing of all object locations, suggesting that the intrinsic reference theory is not specific to a type of spatial memory acquired by the particular learning method but instead generalizes to spatial memories learned through a variety of encoding conditions. In particular, the present findings suggest that spatial memories that follow the intrinsic reference theory function equivalently regardless of the modality in which spatial information is encoded.     

年老化对风险决策和模糊决策的影响：来自生理性和病理性老化的证据

随着“全球老龄化”时代的到来, 老年人认知功能的下降引起了研究人员的广泛关注, 其中年老化对决策的影响成为了近年来的一个新关注点。风险决策和模糊决策受生理性老化和病理性老化影响的研究显示, 正常老化个体模糊决策能力受损, 但其风险决策能力受老化影响较小; 而病理性老化个体, 以阿尔兹海默症患者为例, 在两类决策行为上均表现出损伤; 此外, 脑神经机制的研究发现在完成决策任务时正常年老化个体纹状体激活模式与年轻人存在显著差异, 病理性老化个体杏仁核与腹内侧前额叶的功能连接亦存在异常。未来的研究应同时考察并比较两类决策类型, 结合外周和中枢神经证据, 深入探讨老化对决策行为及神经环路造成影响的机制。     

网络游戏成瘾与海洛因成瘾存在相同的神经机制吗?——基于MRI的证据

网游成瘾与海洛因成瘾具有许多相似的临床表现,但其神经机制是否相同还不得而知。综合近5年来的MRI研究发现,两类成瘾存在部分相同区域的脑结构和功能损害,且在成瘾线索诱发下二者的4个成瘾相关环路(认知控制环路、奖赏环路、动机环路和记忆-学习环路)均出现了广泛而增强的脑区激活反应。但海洛因成瘾的脑损害区域偏向更高级的认知控制环路和奖赏环路,损害范围也更广(4个环路的功能连通性均降低),而网游成瘾的脑损害主要发生在相对低级的记忆-学习环路和动机环路,损害范围也较窄(功能连通性降低只发生在认知控制和记忆-学习环路之间)。这些结果说明,两类成瘾行为的神经机制既有相同点,又有差异性。     

发展性计算障碍的最新研究进展

发展性计算障碍是一种影响算术技能获得的特定的学习障碍。截至目前,有关发展性计算障碍的认知与神经机制的理论尚存分歧,有关诊断与鉴别标准也未统一。近年来,对于发展性计算障碍的理论假设有从一般认知因素取向到数学特定因素取向发展的趋势。而随着脑成像技术的不断发展,对于发展性计算障碍神经机制的研究也从针对单个脑区的特异性功能发展到从功能连接网络角度进行研究。并且研究者们开始尝试开发基于数学认知基本理论的干预方法,并采用了利用生物技术手段的新方法。基因-脑-行为的整合研究将有助于全面揭示发展性计算障碍的发生机制,而建立在系统理论基础上经过科学评估的干预手段将可能有效促进障碍者的计算能力。     

Functional magnetic resonance imaging study of Piaget's conservation-of-number task in preschool and school-age children: a neo-Piagetian approach

Jean Piaget’s theory is a central reference point in the study of logico-mathematical development in children. One of the most famous Piagetian tasks is number conservation. Failures and successes in this task reveal two fundamental stages in children’s thinking and judgment, shifting at approximately 7 years of age from visuospatial intuition to number conservation. In the current study, preschool children (nonconservers, 5-6 years of age) and school-age children (conservers, 9-10 years of age) were presented with Piaget’s conservation-of-number task and monitored by functional magnetic resonance imaging (fMRI). The cognitive change allowing children to access conservation was shown to be related to the neural contribution of a bilateral parietofrontal network involved in numerical and executive functions. These fMRI results highlight how the behavioral and cognitive stages Piaget formulated during the 20th century manifest in the brain with age.     

Through the eyes of dieters: Biased size perception of food following tempting food primes

Why do some dieters succeed in controlling their diet while others do not? This research focused on a perceptual process—size perception of food objects—that may moderate the success of dieters in self-control dilemmas. We assessed successful and unsuccessful dieters' size perception of palatable food (Study 1) and diet-food (Study 2) after pre-exposing them to tempting food primes. Dieters perceived palatable food as bigger when primed with tempting food (vs. control prime), regardless of self-regulatory success in dieting (Study 1). Palatable food thus looms larger for both unsuccessful and successful dieters when in a “hot” state. In contrast, the perceived size of diet-food was increased by a tempting food prime only for successful dieters, but decreased for unsuccessful dieters (Study 2). These results are interpreted in terms of differences in the mental accessibility of competing goals (eating enjoyment vs. dieting) in successful vs. unsuccessful dieters. Indeed, when the dieting goal was made accessible for all dieters by a diet prime, even unsuccessful dieters perceived diet-food as bigger (Study 2). This research provides insight into a perceptual process that may be detrimental or beneficial in resolving self-control conflicts in the domain of eating and dieting behavior—and probably other domains of self-control as well.     

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.     

Dichotic listening and left-right confusion

The present study examined the relationship between individual differences in dichotic listening (DL) and the susceptibility to left-right confusion (LRC). Thirty-six men and 59 women completed a consonant-vowel DL test, a behavioral LRC task, and an LRC self-rating questionnaire. Significant negative correlations between overall DL accuracy and LRC rates in men (behavioral task) and self-ratings in women, indicated that the more participants struggled with left-right discrimination, the fewer DL syllables they reported correctly. However, there was no relationship between LRC and the typical right ear advantage. Thus, there is a sex- and task-dependent relationship between LRC and overall DL accuracy, but not between LRC and ear asymmetry. It is concluded that (a) atypical ear asymmetries, as in certain clinical populations, cannot be explained by associated deficits in left-right discrimination, and (b) LRC can negatively affect task performance, even when participants do not have to make explicit "left" versus "right" decisions.     

读写分离的脑神经机制：来自fMRI的证据

使用只读不写的繁体字和会读会写的简体字材料, 以默读为实验任务, 探讨“会读会写”与“只读不写”文字的加工脑区。8名在校大学生在磁共振扫描过程中默读呈现的繁体字或简体字, 采用ANOVA统计全脑激活图。与简体字相比, 繁体字额外激活了右额下回、左小脑。在功能连接性上, 简体字和繁体字相同的激活脑区有左楔前叶-左内侧前额叶, 左楔前叶-左中央前回, 右枕中回-左舌回; 不同的是, 繁体字左楔前叶与右额下回有高相关, 而简体字左楔前叶与右额中回有高相关。左内侧前额叶与中央前回只在繁体字中表现出高相关。繁体字和简体字任务的T检验差异脑区包括左颞中回和右顶下小叶。只读不写的文字具有加工的整体性和轮廓性特征, 它的读音与不规则简体字相似, 具有整字加工特点。繁体字和简体字加工具有相同的功能连接区, 但也存在差异。右脑表现为连接脑区不同, 左脑内侧前额叶与中央前回表现为相关性不同, 说明内侧前额叶-中央前回在繁体字加工中起着重要作用。实验结果还证明顶叶是记忆再认的主要脑区。