心算的加工机制：来自认知神经科学的研究

心算加工分编码（表征）、运算（或提取）和反应三个阶段,这三个阶段相互影响。不同输入形式的数字表征在顶叶的不同区域完成。算术知识提取主要与左脑顶内沟有关,但当心算变得更复杂时而需要具体运算时,左脑额叶下部出现明显激活。所有与心算有关的脑区涉及大脑前额皮层和颞顶枕联合皮层的综合作用,并总体表现为左脑优势,但估算、珠心算以及某些具有特殊心算能力的人的心算还依赖视空间表征,这与右脑额顶区和楔前叶的活动有关     

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。     

心算加工的认知神经科学研究

近几年(1999-2005)有关心算加工的脑活动机制研究发现,类似九九乘法表这样的算术知识提取(如3×5)主要与左脑顶内沟有关,但当心算变得更复杂时(如26×38),左脑额叶下部出现明显激活,这表明心算与语言和工作记忆关系密切。另一方面,也存在不依赖于语言的即表现为视觉表象活动的心算,右脑的一些脑区在其中起了作用。简言之,所有与心算有关的脑区涉及到大脑前额皮层和颞顶枕联合皮层的综合作用,并总体表现为左脑优势,但具有特殊心算能力的人其心算还与右脑前额叶和颞叶内侧脑区的活动有关。     

计算的脑科学研究及其对数学教育的启示

脑科学研究发现,简单心算主要涉及算术事实的提取,依赖于左半球的语言中枢,而复杂心算激活了左侧顶—额叶网络和双侧颞下回,与视觉空间表征和视觉表象加工有关;精算主要激活左额叶下部区域,而估算激活了两半球更大的区域。在计算过程中所激活的脑区受年龄发展与个体差异以及训练的影响。研究对有效地促进儿童计算能力的发展提供了重要启示。     

语言经验对大脑激活的影响：来自第二语言初学者的证据

研究采用功能磁共振成像技术考察语言经验在塑造大脑激活模式中的作用。12名只有很少英语学习经验因而熟练程度很低的小学儿童参与了实验。结果发现,在视觉呈现的押韵判断任务中,英文任务和中文任务共同激活了左侧额下回负责语音加工的脑区。更重要的是,虽然英文任务更难,也更多地激活了双侧的顶叶区域,但是它在额叶诱发的激活强度显著低于中文。这个结果进一步说明第二语言的语音皮层表征是随着学习经验的增加而逐渐发展起来的。     

心算加工年老化及其机制研究

以172名20－79岁成人为被试对心算加工的年老化过程及其机制进行了研究。任务为连续减法心算,依难度分为5种：1000－1、1000－3、1000－7、1000－13及1000－17。结果表明,年龄与心算难度存在明显的交互作用,且随着年龄增加,不同难度心算效率均以幂函数形式降低。结构方程建模分析发现心算加工年老化过程存在两个中介作用因子,即速度因子和非速度因子,且速度因子对非速度因子存在明显的正效应。     

任务难度与老化对大脑激活的影响——以线索记忆编码为例

以汉语名词双字词对为材料,采用了两种性质、三种难度水平的线索回忆任务对12名老年被试和15名年轻被试的项目记忆编码过程进行fMRI扫描,考察在编码阶段大脑激活受任务难度变化和老化的影响。行为研究结果发现:年龄的主效应、难度的主效应以及难度与年龄交互作用均显著,即,随着任务难度的增加,老年人的成绩更加明显地低于年轻人。神经成像研究结果发现:(1)当词对的相关性降低时,大脑激活的增强主要表现为面积的增加,而当词对的频率降低时,主要表现在激活强度的增加上。(2)任务难度和大脑激活面积、强度之间均不存在对应的递增变化关系。(3)仅当词对的相关性降低时,老年人比年轻人调用了更多的额叶脑区。     

记忆汉字和英语单词的差异脑区研究

通过英文词和汉字的记忆实验,探讨储存和提取不同阶段汉字与英文的脑加工差异。采用经典的"学习-再认"实验范式,8名大学生进行英文与汉字记忆和再认测验,fMRI采集数据,AFNI软件进行预处理、多元回归及ANOVA组分析统计语言差异。结果显示:汉字记忆减英文记忆激活右扣带回;英文记忆减汉字记忆激活右颞上回(BA38)、左扣带回(BA31)、左小脑扁桃体。汉字再认减英文再认的差异脑区为小脑扁桃体、左颞上回。英文再认减汉字再认在0.05水平上没有脑区差异。汉字记忆激活左侧梭状回、右舌回、左顶上小叶、左额下回;英文记忆激活右舌回、左内侧前额叶、左中央前回、左额中回。汉字再认激活左枕下回、左顶下小叶、右额下回、左额中回、右豆状核、左小脑扁桃体、左颞上回、右内侧前额叶。英文再认激活右舌回、左额上回、左顶下小叶、额下回、左中央前回、右顶上小叶、豆状核、右侧尾状核、左中央后回、左侧丘脑。本研究发现:(1)记忆的差异性统计激活颞叶,表明颞叶是记忆存储脑区;(2)学习和记忆阶段有额叶、顶叶激活,表明这些脑区参与文字加工;(3)英文再认比汉字再认激活更多脑区,花费更多的脑资源。     

音乐知觉的神经基础：脑成像研究的元分析

本研究根据音乐加工的层级结构, 对现有的脑成像研究进行了元分析, 探讨了音乐知觉的神经基础。具体而言, 对特异于音乐知觉加工的两个层级, 音程分析和结构分析的神经基础进行了分析, 并在此基础上对比了参与两个层级加工的脑区。结果发现, 音程分析主要的激活分布在双侧颞上回和右侧额下回, 在中央前回、角回和脑岛等脑区也有分布。音程分析在颞上回激活最多, 可能表明颞上回为音程分析的核心区域。结构分析激活分布较广, 主要激活颞上回、颞横回和前额叶区域, 此外, 还激活了下顶叶、缘上回和舌回等顶枕区域。结构分析在前额叶激活最多, 可能表明前额叶为结构分析的核心区域。最后, 对比两层级激活的脑区发现, 二者仅在后侧颞上回存在着重合, 而在绝大部分脑区则表现出分离, 这暗示了音程分析和结构分析通过颞上回进行交流, 并负责音乐不同层面的加工。     

认知重评和表达抑制情绪调节策略的脑网络分析：来自EEG和ERP的证据

本文旨在对认知重评和表达抑制两种常用情绪调节策略的自发脑网络特征及认知神经活动进行深入探讨。研究采集36名在校大学生的静息态和任务态脑电数据, 经过源定位和图论分析发现节点效率与两种情绪调节显著相关的脑区, 以及脑区之间的功能连接。研究结果表明, 在使用认知重评进行情绪调节时会激活前额叶皮质、前扣带回、顶叶、海马旁回和枕叶等多个脑区, 在使用表达抑制进行情绪调节时会激活前额叶皮质、顶叶、海马旁回、枕叶、颞叶和脑岛等多个脑区。因此, 这些脑区的节点效率或功能连接强度可能成为评估个体使用认知重评和表达抑制调节情绪效果的指标。     

An fMRI study of sex differences in regional activation to a verbal and a spatial task

Sex differences in cognitive performance have been documented, women performing better on some phonological tasks and men on spatial tasks. An earlier fMRI study suggested sex differences in distributed brain activation during phonological processing, with bilateral activation seen in women while men showed primarily left-lateralized activation. This blood oxygen level-dependent fMRI study examined sex differences (14 men, 13 women) in activation for a spatial task (judgment of line orientation) compared to a verbal-reasoning task (analogies) that does not typically show sex differences. Task difficulty was manipulated. Hypothesized ROI-based analysis documented the expected left-lateralized changes for the verbal task in the inferior parietal and planum temporal regions in both men and women, but only men showed right-lateralized increase for the spatial task in these regions. Image-based analysis revealed a distributed network of cortical regions activated by the tasks, which consisted of the lateral frontal, medial frontal, mid-temporal, occipitoparietal, and occipital regions. The activation was more left lateralized for the verbal and more right for the spatial tasks, but men also showed some left activation for the spatial task, which was not seen in women. Increased task difficulty produced more distributed activation for the verbal and more circumscribed activation for the spatial task. The results suggest that failure to activate the appropriate hemisphere in regions directly involved in task performance may explain certain sex differences in performance. They also extend, for a spatial task, the principle that bilateral activation in a distributed cognitive system underlies sex differences in performance.     

Manipulation of frontal brain asymmetry by cognitive tasks

The purpose of the present study was to evaluate whether verbal fluency tasks may specifically induce relatively greater left than right hemispheric activation in the dorsolateral prefrontal cortex. The effectiveness of the manipulation was evaluated by EEG, which was recorded during performance of the verbal fluency task and during two control conditions, i.e., a baseline condition without cognitive demands, and a mental arithmetic task, respectively. The results demonstrate that the desired effect can only be achieved in individuals with good performance on the verbal fluency task. Good and poor performers do not only differ in lateral asymmetry, but also in the most affected region within the prefrontal cortex. Whereas good performers show relatively increased activation in the cortical region and hemisphere putatively most specialized for this kind of task (i.e., the left dorsolateral frontal cortex), poor performers show a marked shift of frontopolar asymmetry to the right.     

Generating an image from an ambiguous visual input: an electroencephalographic (EEG) investigation

Fourteen right-handed males were shown slides of common objects (e.g., wristwatch), familiar situations (e.g., two people shaking hands), and inkblots from a popular projective test (Holtzman, 1986) and then asked to name the object, assess the situation, or describe the most salient image emerging from the inkblot. Alpha power suppression was monitored over the left and right frontal, temporal, parietal, and occipital lobes to determine the brain circuitry responsible for the processing of each type of stimulus. When processing common objects and familiar situations there was bilateral activation of the parietal and occipital lobes; when processing inkblots, bilateral activation of the parietal and occipital lobes was again obtained, but complemented by selective activation of the right frontal lobe. The later suggests that anterior regions of the right cerebral hemisphere contribute to the generation of dynamic images like those evoked by visually ambiguous inkblots.     

The functional anatomy of inspection time: a pilot fMRI study

Seven healthy subjects underwent functional magnetic resonance imaging (fMRI) of the brain while performing an inspection time task. Employing a block-type design, the task had three difficulty levels: a control condition, an easy (200 ms stimulus duration), and a more difficult (40 ms) discrimination. Based on group results, there were widespread significant areas of difference in brain activation and deactivation when pairwise comparisons were conducted among the three task conditions. When the difficult condition was compared with the easy condition, there was relative activation in areas of the following brain regions: cingulate gyrus and some frontal and parietal lobe areas. Areas within the following regions showed relative deactivation (greater blood oxygenation level-dependent, BOLD, signal in the easy condition): frontal, temporal, and parietal lobe. There were overlaps between these areas and those found to be active while performing higher cognitive tasks in other functional brain imaging studies. These pilot data encourage future studies of the functional anatomy of inspection time and its relevance to psychometric intelligence.     

Cognitive control of a simple mental image in patients with obsessive--compulsive disorder

The nature of obsessions has led researchers to try to determine if the main problem in obsessive-compulsive disorder (OCD) is impaired inhibitory control. Previous studies report that the effort to suppress is one of the factors that increase the frequency of obsessive thoughts. Based on these results and those of the present study that suggest inferior parietal lobe (IPL) abnormality in OCD and findings of a recent study that reported the importance of the right posterior parietal cortex in cognitive control of a simple mental image, the present cognitive control paradigm study aimed to determine whether there is a difference in brain dynamics between OCD patients and non-obsessive controls while performing tasks that necessitate cognitive control of a simple mental image, and whether the right posterior parietal region is one of the regions in which a difference in activity between the OCD patients and controls would be observed. Functional brain imaging was performed while the participants attempted to suppress, imagine, or manipulate a mental image. The general linear model showed that there was a main effect of group and main effect of task. Accordingly, in all contrasts (suppression minus free-imagination, erasing minus free-imagination, and imagination minus free-imagination), the right IPL, right posterior cingulate cortex, and right superior frontal gyrus activity were lower in the OCD patients than in the healthy controls. These results and the observed correlations between activity levels, and symptom and subjective performance scores are discussed. In conclusion, the results of the present study and those of previous studies suggest that the main problem in OCD might be difficulty activating the right frontoparietal networks during tasks that require cognitive control, which might result in the intrusiveness of obsessive thoughts.     

Serial reaction time performance following right parietal lobe damage

The serial reaction time task (SRT) is used to assess implicit sequence learning. Neuroimaging studies implicate parietal involvement; however, the necessity of this area is unclear. We tested six unilateral right parietal patients and compared their performance to matched controls. Both groups showed similar levels of learning and explicit awareness. Two patients with the largest lesions extending into either frontal or cerebellar regions showed no learning. These data suggest that implicit sequence learning can occur despite damage to the right parietal lobe.     

Children's left parietal brain activation during mental rotation is reliable as well as specific

Some recent evidence suggests that mental rotation of characters in children aged 7 or 8 years might be lateralized to the left parietal hemisphere. An alternative statement exists, however, the finding might be completely unspecific for mental rotation but either be simply a function of task difficulty or a consequence of the use of characters as stimuli. To test these alternatives, ERPs of 24 second graders were measured twice: (a) during mental rotation with characters as stimuli and orientations of 30°, 90°, or 150° and (b) during memory scanning with characters as stimuli and set sizes of 1, 2, or 3 letters. In both cases, an amplitude modulation was found. The effect of mental rotation as a function of character orientation turned out to be lateralized to the left parietal hemisphere. The effect of memory scanning as a function of set size, however, turned out to be completely non-lateralized. Thus, children's left hemisphere activation during mental rotation is reliable as well as specific.     

Neural dichotomy of word concreteness: a view from functional neuroimaging

Our perception about the representation and processing of concrete and abstract concepts is based on the fact that concrete words are highly imagined and remembered faster than abstract words. In order to explain the processing differences between abstract and concrete concepts, various theories have been proposed, yet there is no unanimous consensus about its neural implication. The present study investigated the processing of concrete and abstract words during an orthography judgment task (implicit semantic processing) using functional magnetic resonance imaging to validate the involvement of the neural regions. Relative to non-words, both abstract and concrete words show activation in the regions of bilateral hemisphere previously associated with semantic processing. The common areas (conjunction analyses) observed for abstract and concrete words are bilateral inferior frontal gyrus (BA 44/45), left superior parietal (BA 7), left fusiform gyrus and bilateral middle occipital. The additional areas for abstract words were noticed in bilateral superior temporal and bilateral middle temporal region, whereas no distinct region was noticed for concrete words. This suggests that words with abstract concepts recruit additional language regions in the brain.