利手与语言功能偏侧化的遗传模型

利手与语言功能偏侧化现象不仅具有跨文化一致性和发生、发展上的关联性, 还具有明显的生态学优势, 从遗传角度探讨它们的成因是必要的。早期遗传模型认为, 存在一对等位基因分别决定左、右利手。当代单基因模型则将语言功能偏侧化也纳入进来, 认为等位基因不仅可以决定具有方向性的偏侧化, 而且可以使偏侧化有一定几率向左或向右。在这个框架下形成了方向-随机等位基因模型、X-连锁隐性基因模型和右侧位移理论, 它们对等位基因的位置和功能有不同表述, 对利手的划分标准、性别差异以及遗传和环境的关系也有不同阐释。今后需加强对语言偏侧化的数据验证, 进一步阐明语言感知、理解与利手的关系, 并注重基因怎样决定表型、基因多效性和多基因合作等问题的研究。     

一本具有特色的脑功能开发研究的学术著作--读沈德立教授主编的《脑功能开发的理论与实践》

20世纪90年代,国际科学界开展了广泛的脑科学研究,曾被命名为“脑的10年”,许多发达国家对于大脑的研究倾注了很大的力量,对大脑的认识也得到了进一步深化。二十一世纪随着科学技术快速发展,脑科学与行为科学的研究是整个科学研究中最具挑战性的内容。尤其是脑高级功能的研究,更是其中的热点。由天津师范大学沈德立教授主编的《脑功能开发的理论与实践》(教育科学出版社,2001年6月)一书的出版,使我们欣喜地看到,我国科研工作者正在为缩小我国与发达国家间的脑科学开发研究方面的差距而不断努力着。该书共包括十章,内容分别是：绪论、人脑的基本知识、大脑左右半球功能概述、评价大脑左右半球功能的心理学方法、利手与大脑左右半球功能的发展研究、大脑左右半球功能的性别差异、大脑功能开发基础、大脑左右半球功能开发方法、脑功能开发的若干实验研究和中小学教师谈脑功能开发。     

人格特质及脑功能连接对社交网络的影响

采用网络分析的方法, 本研究从个体受欢迎程度和个体间亲密程度两方面探究了人格特质对社交网络的影响, 并在此基础上进一步探究了个体间大脑静息态功能连接相似性和社交网络的关系。结果发现：(1)高尽责性的个体在需要“值得信任”特质的社交网络中更受欢迎, 高宜人性的个体在需要“共享时光”的社交网络中更受欢迎; (2)在需要“相同兴趣”特质的社交网络中, 个体间人格相似性和社会距离呈显著负相关关系; (3)同样在需要“相同兴趣”特质的社交网络中, 个体间部分功能连接相似性与社会距离呈显著负相关关系, 这些功能连接主要集中在额顶控制网络以及背侧注意网络; 同时, 部分节点功能连接相似性与社会距离呈显著正相关关系, 这些功能连接主要集中在默认网络。研究结果揭示了人格特质对不同社交网络结构的影响, 以及个体间人格特质相似性和静息态脑网络相似性与社会距离的关系。本研究对理解社交网络的结构, 形成规律以及其中的信息传播规律有着重要启示意义。     

刺激呈现时间对汉字语义加工脑偏侧化的影响

以往关于汉字字词识别脑功能偏侧化的研究发现了左半球优势、右半球优势或者大脑两半球均势三种不同的结果。该研究采用一侧化Stroop范式(刺激分别只呈现于左视野、中央视野或右视野中),通过系统地改变刺激呈现时间以期探讨刺激呈现时间是可以解释这些不一致结果的可能因素之一。结果显示:对于右利手被试,在刺激呈现时间为60 ms时右半球出现了较强的Stroop效应,在刺激呈现200 ms时左右半球的Stroop效应没有表现出差异,在刺激呈现时间较长时左半球表现出较强的Stroop效应。该结果提示,随着刺激呈现时间的延长,语义优势发生了从右半球到左半球的转换。     

高功能孤独症者非字面语义理解缺陷：隐喻视角的ERP研究

研究采用事件相关电位技术从隐喻语义理解角度考察了高功能孤独症成人非字面语义理解中的行为特点及脑半球参与模式。行为结果显示：高功能孤独症成人对新异隐喻句的反应时最长,两类隐喻句的反应时均长于普通成人,但错误率上两组被试间无差异。脑电结果显示：高功能孤独症组对新异隐喻句的N400波幅最大,未出现半球偏侧化现象,传统隐喻句在左半球的N400波幅大于右半球,两类隐喻句的N400波幅均大于正常被试。结论：高功能孤独症成人具备隐喻理解能力,并对新异隐喻的理解做出更多努力,但右脑功能异常仍旧存在,左右半球在总体功能或神经联通性上仍旧弱于常人。     

精神分裂症与躁狂抑郁症的利手研究(不同利手分类法的比较)

“利手”是反映脑功能优势化体制的一个重要外部标志,利手研究也是探索精神病患者大脑两半球运动优势变异的重要手段。迄今,利手研究资料提示分裂症与优势半球机能障碍,情感性精神病与     

等级图形加工半球偏侧化的发展

以往的研究显示,大脑对等级视觉信息的加工有半球偏侧化的现象,左半球有加工局部特征的优势,右半球有加工整体的优势。本研究采用2年级、4年级、6年级和成人4个年龄组的被试,对等级复合图形中的靶子做选择判断,通过单侧呈现来考察整体-局部加工的大脑功能偏侧化发展。结果发现反应时发展呈现从局部优先到整体优先的过程,半球偏侧化发展呈现从无偏侧化到左侧呈现较右侧呈现更强的整体优先。发展的转折点可能在4～6年级(约9岁～12岁)之间。     

失眠患者静息态脑网络的改变：网络内与网络间的功能连接异常

失眠已成为现代人群中的一种高发健康问题。静息态功能磁共振以其数据采集便利性和无创性, 成为失眠研究的主要成像手段之一。基于近年来静息态功能磁共振的发现, 失眠患者存在前额叶、颞叶、前扣带回、脑岛等认知-情绪神经环路的异常。大尺度脑网络是涵盖多个脑区、功能相对单一的大脑结构。失眠患者存在默认网络、突显网络、认知控制网络和负性情绪网络内部活动与连接异常, 而且呈现出以默认网络为核心, 包含认知控制网络、突显网络、负性情绪网络的网络间连接异常模式。此外, 结合症状、治疗和大尺度脑网络的视角, 可为失眠的“精准治疗”提供神经理论依据。未来研究可结合大数据和多模态分析技术, 验证静息态功能磁共振已有发现。而失眠的纵向追踪和队列研究会有利于进一步阐释失眠的神经机制。     

整体运动知觉老化伴随颞中回静息态功能改变

以个体整体运动一致性阈值为指标, 探讨老年人整体运动敏感性(GMS)下降和静息态下兴趣脑区功能活动的关系。发现与阈值负相关且老年人低于青年人的指标主要有：MT/V5区的ReHo和ALFF值, 各网络拓扑属性; 与阈值正相关且老年人显著高于青年人的有：MT/V5区与前运动皮层之间的、各兴趣脑区之间的功能连接。结果用“去分化”等观点进行了解释, 提示老年人GMS的下降可能不仅与安静状态下MT/V5区的功能改变有关, 还可能与全脑更广泛区域的功能改变有关。     

抑郁症的脑功能异常:来自静息态功能磁共振成像的证据

静息态功能磁共振成像是指在静息状态下测量的BOLD信号,即受试者安静地躺在扫描仪中,不给受试者任何特定的任务,受试者也不用做任何反应,此时受试者的大脑活动处于自发状态。通过使用该技术可以为抑郁症发作的临床现象提供神经影像学依据,以期为将来抑郁症的治疗提供生物标记。因此,本文综述了大量抑郁症患者在静息态脑功能方面的差异研究,发现了单、双相抑郁症,首、复发抑郁症,早发性、晚发性抑郁症,难治、非难治性抑郁症等不同类型的抑郁症在包括局部一致性(Re Ho)和低频振幅(ALFF)在内的功能分化以及包括功能连接密度(FCD)、功能同伦(VMHC)、复杂网络(Complex Network)和ROI功能连接在内的功能整合两大指标的改变。     

Atypicalities in Cortical Structure, Handedness, and Functional Lateralization for Language in Autism Spectrum Disorders

Language is typically a highly lateralized function, with atypically reduced or reversed lateralization linked to language impairments. Given the diagnostic and prognostic role of impaired language for autism spectrum disorders (ASDs), this paper reviews the growing body of literature that examines patterns of lateralization in individuals with ASDs. Including research from structural and functional imaging paradigms, and behavioral evidence from investigations of handedness, the review confirms that atypical lateralization is common in people with ASDs. The evidence indicates reduced structural asymmetry in fronto-temporal language regions, attenuated functional activation in response to language and pre-linguistic stimuli, and more ambiguous (mixed) hand preferences, in individuals with ASDs. Critically, the evidence emphasizes an intimate relationship between atypical lateralization and language impairment, with more atypical asymmetries linked to more substantive language impairment. Such evidence highlights opportunities for the identification of structural and functional biomarkers of ASDs, affording the potential for earlier diagnosis and intervention implementation.     

The influence of vestibular system and fetal presentation on handedness,cognitive and motor development: A comparison between cephalic and breech presentation

Genetics are undoubtedly implicated in the ontogenesis of laterality. Nonetheless, environmental factors, such as the intrauterine environment, may also play a role in the development of functional and behavioral lateralization. The aim of this study was to test the Left-Otolithic Dominance Theory (LODT; Previc, 1991) by investigating a hypothetical developmental pattern where it is assumed that a breech presentation, which is putatively associated with a dysfunctional and weakly lateralized vestibular system, can lead to weak handedness and atypical development associated with language and motor difficulties. We used the ALSPAC cohort of children from 7 to 10 years of age to conduct our investigation. Our results failed to show an association between the vestibular system and fetal presentation, nor any influence of the latter on hand preference, hand performance, or language and motor development. Bayesian statistical analyses supported these findings. Contrary to our LODT-derived hypotheses, this study offers evidence that fetal presentation does not influence the vestibular system's lateralization and seems to be a poor indicator for handedness. Nonetheless, we found that another non-genetic factor, prematurity, could lead to atypical development of handedness.     

Atypical speech lateralization in adults with developmental coordination disorder demonstrated using functional transcranial Doppler ultrasound

Research using clinical populations to explore the relationship between hemispheric speech lateralization and handedness has focused on individuals with speech and language disorders, such as dyslexia or specific language impairment (SLI). Such work reveals atypical patterns of cerebral lateralization and handedness in these groups compared to controls. There are few studies that examine this relationship in people with motor coordination impairments but without speech or reading deficits, which is a surprising omission given the prevalence of theories suggesting a common neural network underlying both functions. We use an emerging imaging technique in cognitive neuroscience; functional transcranial Doppler (fTCD) ultrasound, to assess whether individuals with developmental coordination disorder (DCD) display reduced left‐hemisphere lateralization for speech production compared to control participants. Twelve adult control participants and 12 adults with DCD, but no other developmental/cognitive impairments, performed a word‐generation task whilst undergoing fTCD imaging to establish a hemispheric lateralization index for speech production. All participants also completed an electronic peg‐moving task to determine hand skill. As predicted, the DCD group showed a significantly reduced left lateralization pattern for the speech production task compared to controls. Performance on the motor skill task showed a clear preference for the dominant hand across both groups; however, the DCD group mean movement times were significantly higher for the non‐dominant hand. This is the first study of its kind to assess hand skill and speech lateralization in DCD. The results reveal a reduced leftwards asymmetry for speech and a slower motor performance. This fits alongside previous work showing atypical cerebral lateralization in DCD for other cognitive processes (e.g., executive function and short‐term memory) and thus speaks to debates on theories of the links between motor control and language production.     

A combined fMRI and DTI examination of functional language lateralization and arcuate fasciculus structure: Effects of degree versus direction of hand preference

The present study examined the relationship between hand preference degree and direction, functional language lateralization in Broca’s and Wernicke’s areas, and structural measures of the arcuate fasciculus. Results revealed an effect of degree of hand preference on arcuate fasciculus structure, such that consistently-handed individuals, regardless of the direction of hand preference, demonstrated the most asymmetric arcuate fasciculus, with larger left versus right arcuate, as measured by DTI. Functional language lateralization in Wernicke’s area, measured via fMRI, was related to arcuate fasciculus volume in consistent-left-handers only, and only in people who were not right hemisphere lateralized for language; given the small sample size for this finding, future investigation is warranted. Results suggest handedness degree may be an important variable to investigate in the context of neuroanatomical asymmetries.     

Schizotypal personality traits and atypical lateralization in motor and language functions

Atypical cerebral lateralization in motor and language functions in regard to schizotypal personality traits in healthy populations, as well as among schizophrenic patients, has attracted attention because these traits may represent a risk factor for schizophrenia. Although the relationship between handedness and schizotypal personality has been widely examined, few studies have adopted an experimental approach. This study consisted of three experiments focusing on motor and language functional lateralization in regard to schizotypal personality in the absence of mental illness: line-drawing, finger tapping, and a semantic go/no-go task. The results suggested that positive schizotypal personality might be related to functional non-lateralization in regard to at least some functions (e.g., spatial motor control and semantic processing in the present study). Subjects with high schizotypal personality traits performed equally with their right and left-hands in the line-drawing task and they reacted equally with their right and left-hands in a semantic go/no-go task involving semantic auditory stimuli presented in both ears. However, those low in schizotypal personality traits showed typical lateralization in response to these tasks. We discuss the implications of these findings for schizotypal atypical lateralization.     

Altered lateralization of dorsal language tracts in 6‐week‐old infants at risk for autism

Altered structural connectivity has been identified as a possible biomarker of autism spectrum disorder (ASD) risk in the developing brain. Core features of ASD include impaired social communication and early language delay. Thus, examining white matter tracts associated with language may lend further insight into early signs of ASD risk and the mechanisms that underlie language impairments associated with the disorder. Evidence of altered structural connectivity has previously been detected in 6‐month‐old infants at high familial risk for developing ASD. However, as language processing begins in utero, differences in structural connectivity between language regions may be present in the early infant brain shortly after birth. Here we investigated key white matter pathways of the dorsal language network in 6‐week‐old infants at high (HR) and low (LR) risk for ASD to identify atypicalities in structural connectivity that may predict altered developmental trajectories prior to overt language delays and the onset of ASD symptomatology. Compared to HR infants, LR infants showed higher fractional anisotropy (FA) in the left superior longitudinal fasciculus (SLF); in contrast, in the right SLF, HR infants showed higher FA than LR infants. Additionally, HR infants showed more rightward lateralization of the SLF. Across both groups, measures of FA and lateralization of these pathways at 6 weeks of age were related to later language development at 18 months of age as well as ASD symptomatology at 36 months of age. These findings indicate that early differences in the structure of language pathways may provide an early predictor of future language development and ASD risk.     

Theoretical Speculations on the Evolutionary Origins of Hemispheric Specialization

ABSTRACT— Hemispheric specialization has long been considered a uniquely human trait associated with the evolution of language and handedness. Recent studies in a host of vertebrate species have reported evidence of population-level behavioral and brain asymmetries, challenging the claims for the uniqueness of hemispheric specialization to the human species. Here we summarize the findings in nonhuman species and discuss the adaptive significance and potential costs of lateralization of function.     

Subject variable effects in correlations between auditory and visual language processing asymmetries

The cross-modal correlations between auditory and visual language lateralization were examined as a function of the subject variables of handedness, sex, familial sinistrality, and handwriting posture. In this study, left-handers showed a significantly greater correlation between visual and auditory language processing asymmetries than right-handers, contradicting previous reports.     

Time sharing and dichotic listening asymmetry in normal and learning-disabled children

Time-sharing and dichotic listening techniques were used to examine cerebral lateralization for language function in 48 normal and 48 learning-disabled children. All subjects were matched according to age, sex, and handedness. An analysis of results indicated that both nornal and learning-disabled children demonstrated left hemisphere lateralization of language function on the time-sharing and dichotic listening tasks. However, no developmental trends were evident for either group. Differences observed in the performance of the normal and learning-disabled children may relate to how each group utilizes “verbal strategies” and processes simultaneous information in the left hemisphere. The results strongly question the notion that attributes learning disabilities to incomplete or delayed language lateralization and lend support to the notion that cerebral lateralization is not a developmental phenomena.