论1981年诺贝尔生理学或医学奖金获得者罗杰·斯佩里的大脑功能理论与实验存在的问题

科学发展验证出大脑半球各有优势又相互作用的分工理论是错误的。根本原因是单侧化试验的失误。尽管耳、目是单侧性输入信息,但大脑两半球却同时对其信息发生作用,分离的左右半球并未“分离”。大脑两半球是统一的整体,意识是整个大脑物质运动形态的反映,两半球不能各自独立产生意识,亦非各有优势,当其中一个半球失去作用时,另一个半球将担负起全脑的功能。[第一段]     

胼胝体分步全切病人左右侧命名的不对称

以一位第一次进行胼胝体前部切开,第二次作后部切开的胼胝体全切断患者为被试,在第二次手术前后进行了Ⅰ。左右单侧操作检查,和Ⅱ。两半球之间感觉信息传递两类神经心理学实验。结果提示:后部切断前,左右侧操作没有明显的差异。同时,视觉和触觉的感觉信息的传递基本正常。在后部切断后,命名作业呈右视野和右手优势,图形临摹左手似乎较好,这时视觉和触党的感觉信息的传递发生了障碍。左视野和左手命名高于随机水平,讨论了这一结果与右脑语言的关系。方位比较等多个实验提供了支持两半球协同活动理论的证据。     

视野分离速示条件下歧义词意义判断研究

据已有研究．句子阅读理解的过程是复杂的。阐述其过程的理论之一是,句子阅读理解的过程可能是词的某些意义在整个句子中被整合而无关信息却被抑制的过程。由于此过程是在大脑两半球上进行的,两半球上需保持住语词及有关意义才能做出判断,因此,两半球各自起何作用呢?有人研究得到在图形负荷记忆下,左、右半球的加工效率均有所提高,甚至可能会出现两半球均势现象;两个半球上的语义系统也不一定起同等作用,     

整体/局部加工中的半球功能不对称效应

20世纪末的研究证据显示,对Navon等级刺激的整体/局部加工中半球功能不对称效应发生在早期还是晚期阶段,研究者存在着争论。近期的电生理和功能成像研究资料表明,整体/局部加工的半球不对称效应可能是一个受到多种因素调节的复杂动态系统;早期信息表征的半球功能不对称效应可能主要受知觉因素的影响,而注意控制和反应冲突可能主要调节晚期知觉加工的半球功能不对称     

中-英双语者词汇语义通达的大脑功能偏侧化与合作效应

采用半视野速示术对48名英语专业硕士研究生进行词汇判别的语义启动实验,检查中一英双语者词汇语义通达可能存在的大脑功能偏侧化与合作效应.结果提示:(1)相对熟练的中一英双语者L1(中文)和L2(英文)均可直接通达一个共同的词汇语义概念表征系统,但L1可以通过两半球,而L2可能主要依赖于大脑右半球;(2)跨语言条件出现了半球间语义通达的合作优势效应.     

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。     

对裂脑人手术前后心理活动变化的研究

一、问题提出割裂脑,即切断连合大脑两半球的主要连合部——胼胝体,不仅有助于控制顽固性癫痫,而且为心理学研究人的心理机制,进一步揭示人脑的奥密提供了良好的条件。R.W.Sperry 及M.s.Gazzaniga 近二十年来做了大量研究,他们提出,裂脑人两半球可以各自独立活动,右半球并非左半球的附庸,而是能够理解词义、辨别语言,并具有自我意识和社会意识的重要半球。这方面的研究在我国尚未曾开展。中国医科大学附属第一医院神经外科于1983年下半年先后做了两例裂脑手术,我们对这两例病人在手术前后做了神经心理学的检查和实验,以研究其心理活动的变化状况。     

情绪的大脑半球功能的单侧化

原文作者通过对数百篇有关研究文献的分析、综合与概括,对脑功能不对称性问题的又一新的研究领域——情绪的脑功能不对称性问题的研究进展,进行了全面的介绍和评述。文章描述了情绪单侧化的三个可能的方面:右脑半球在情绪的识别上占有优势;对情绪的表达和有关行为的控制主要发生在右脑半球;右脑半球专门处理消极性情绪,而左脑半球专门处理积极性情绪。这三个方面的证据来自分别以有脑损伤的,有情感障碍的或完全正常的人为研究对象的方法各异的许多研究,其结论是以不同来源的多条证明线索为依据的。根据已有的资料,作者提出了一个以在右脑半球(偏重于消极情绪)和左脑半球(偏重于积极情绪)之间的相互抑制为基础的情绪控制模式。     

语言功能偏侧化及其与利手、功能连接的关系

对大脑语言功能偏侧化的探索起始于早期对脑损伤病人的研究。现代脑影像学研究发现, 语言功能偏侧化涉及额叶、颞叶、扣带回、梭状回和辅助运动区等脑区。语言偏侧化与利手和静息态功能连接之间的关系表现为：右利手的语言优势位于左半球, 而左利手的则分布在左半球、右半球或两个半球; 语言功能偏侧化与利手系数、静息态半球内功能连接之间具有正相关关系, 与半球间功能连接呈负相关, 并且语言功能偏侧化与静息态功能连接之间的关系在左右利手个体之间存在差异。总之, 大脑语言功能偏侧化、利手和静息态功能连接三者之间存在相互影响, 基于脑连接和遗传机制的研究将有望揭示出其底层的神经生理机制。     

对汉字认知与大脑两半球关系研究的一些回顾

汉字可以说是世界上现存唯一的表意文字,其历史之悠久和使用人口之众多也是绝无仅有的,关于汉字的特点有关文献已有相当详细的介绍,我们这里不加多述。毋庸置疑,言语是大脑的机能,而有关言语和大脑两半球关系的研究主要是对使用拼音文字的欧美人进行的,因而神经语言学上许多著名的论断也是基于这一前提的。对欧美人进行的研究结论较为一致:大脑左半球是言语优势半球,左半球具有文字处理能力;而右半球则在空间、图形知觉上占优。对于汉字认知的脑机制,争论颇为激烈,有的认为中国人对汉     

The Role of the Corpus Callosum in Interhemispheric Transfer of Information: Excitation or Inhibition?

The corpus callosum is the major neural pathway that connects homologous cortical areas of the two cerebral hemispheres. The nature of how that interhemispheric connection is manifested is the topic of this review; specifically, does the corpus callosum serve to communicate an inhibitory or excitatory influence on the contralateral hemisphere? Several studies take the position that the corpus callosum provides the pathway through which a hemisphere or cortical area can inhibit the other hemisphere or homologous cortical area in order to facilitate optimal functional capacity. Other studies suggest that the corpus callosum integrates information across cerebral hemispheres and thus serves an excitatory function in interhemispheric communication. This review examines these two contrasting theories of interhemispheric communication. Studies of callosotomies, callosal agenesis, language disorders, theories of lateralization and hemispheric asymmetry, and comparative research are critically considered. The available research, no matter how limited, primarily supports the notion that the corpus callosum serves a predominantly excitatory function. There is evidence, however, to support both theories and the possibility remains that the corpus callosum can serve both an inhibitory and excitatory influence on the contralateral hemisphere.     

Effects of callosal lesions in a model of letter perception

During cognitive tasks, the cerebral hemispheres cooperate, compete, and in general, interact via the corpus callosum. Although behavioral studies in normal and split-brain subjects have revealed a great deal about the transcallosal exchange of information, a fundamental question remains unanswered and controversial: Are transcallosal interhemispheric influences primarily excitatory or inhibitory? In this context, we examined the effects of simulating sectioning of the corpus callosum in a computational model of visual letter recognition. Differences were found, following simulated callosal sectioning, in the performance of each individual hemisphere, in the mean activation levels of hemispheres, and in the specific patterns of activity, depending on the nature of the callosal influences. Together with other recent computational modeling results, the findings are most consistent with the hypothesis that transcallosal influences are predominantly excitatory, and they suggest measures that could be examined in future experimental studies to help resolve this issue.     

Contribution of Callosal Connections to the Interhemispheric Integration of Visuomotor and Cognitive Processes

In recent years, cognitive neuroscience has been concerned with the role of the corpus callosum and interhemispheric communication for lower-level processes and higher-order cognitive functions. There is empirical evidence that not only callosal disconnection but also subtle degradation of the corpus callosum can influence the transfer of information and integration between the hemispheres. The reviewed studies on patients with callosal degradation with and without disconnection indicate a dissociation of callosal functions: while anterior callosal regions were associated with interhemispheric inhibition in situations of semantic (Stroop) and visuospatial (hierarchical letters) competition, posterior callosal areas were associated with interhemispheric facilitation from redundant information at visuomotor and cognitive levels. Together, the reviewed research on selective cognitive functions provides evidence that the corpus callosum contributes to the integration of perception and action within a subcortico-cortical network promoting a unified experience of the way we perceive the visual world and prepare our actions.     

Cerebral hemispheres and selective attention

The present paper is intended to discuss critically the integration model of the functional interhemispheric relation that has become dominant in neuropsychology with the development, in the last two decades, of split-brain studies.While the split-brain research has undoubtedly produced new experimental methodologies, the current theorizing in this area has been contrastingly conservative. The present paper examines some of its basic assumptions, in particular that the corpus callosum is an association pathway devoted to interhemispheric transmission of information, and that the disconnected cerebral hemispheres function in a parallel way. It is shown that these assumptions have only low consistency both with split-brain behavior and with the normal organization of the fore-brain connectivity.In the early seventies, theoretical novelty has emerged from another research field with Kinsbourne's interpretation of laterality effects in normal man. His concept of asymmetrical hemispheric arousal is shown to be supported, with some reservations, by evidence in this field. But this dynamical concept has a more general value and there are signs that current ideas about the functional relation between the cerebral hemispheres are presently deeply transformed.     

Two brains, one clock

A recent study has shown that information about the duration of brief time intervals acquired by one side of the brain is readily available to the other cerebral hemisphere in a patient in which the corpus callosum and the other forebrain commissures have been sectioned. This strongly suggests that the internal clock that measures time duration is subcortical, and that its output can be easily projected to both hemispheres via subcortical commissures.     

Bernstein's Theory of Movement Behavior: Historical Development and Contemporary Relevance

The traditional concept of cerebral dominance relies for support on the facts of handedness and the association of propositional speech with the leading hemisphere. This is regarded as evidence for specialization but not that the hemispheres are involved in an unchanging dominance relationship. The fact that the corpus callosum forms a bridge between the hemispheres means that they are not isolated units and that one may work through the other to control the functions of the limbs. Control however may be switched as the tasks demand the respective specializations of each hemisphere.     

Benefits of interhemispheric collaboration can be eliminated by mixing stimulus formats that involve different cortical access routes

Previous studies indicate that the benefits of dividing an information processing load across both cerebral hemispheres outweigh the costs of interhemispheric transfer as tasks become more difficult or cognitively complex. This is demonstrated as better performance when two stimuli to be compared are presented one to each visual field and hemisphere than when both stimuli are presented to the same single hemisphere (an across-hemisphere advantage). Two experiments indicate that this finding does not generalize to complex tasks that require matching numeric quantities represented by two very different visual formats whose processing involves somewhat different cortical areas: digits and dice-like dot patterns. In fact, mixing these stimulus formats consistently produces a within-hemisphere advantage. We propose that, when two simultaneously presented stimuli are presented in sufficiently different visual formats, identification of the two stimuli may take place in parallel, via different cortical access routes and with little or no interference, even when they are presented to the same cerebral hemisphere.     

Plasticity of the callosal system

A series of experiments examined the potential plasticity of the callosal system in both epileptic patients and in kittens submitted to corpus callosotomy at various ages. The patients were tested for unilateral discrimination and interhemispheric transfer of tactile information. The youngest patient was also required to perform additional inter- and intrahemispheric comparisons of visual and tactile stimuli. The animals were tested for interhemispheric transfer of visual discriminations. The results suggest that in both animals and humans there exists a critical period before which callosal section does not disrupt interhemispheric communication. The results also indicate that the compensatory mechanisms used to achieve interhemispheric transfer in the absence of the corpus callosum may vary according to the sensory modality involved. The possible physiological and/or functional mechanisms responsible for callosal plasticity are discussed.     

Simulating consciousness in a bilateral neural network: "nuclear" and "fringe" awareness

A technique for the bilateral activation of neural nets that leads to a functional asymmetry of two simulated "cerebral hemispheres" is described. The simulation is designed to perform object recognition, while exhibiting characteristics typical of human consciousness-specifically, the unitary nature of conscious attention, together with a dual awareness corresponding to the "nucleus" and "fringe" described by William James (1890). Sensory neural nets self-organize on the basis of five sensory features. The system is then taught arbitrary symbolic labels for a small number of similar stimuli. Finally, the trained network is exposed to nonverbal stimuli for object recognition, leading to Gaussian activation of the "sensory" maps-with a peak at the location most closely related to the features of the external stimulus. "Verbal" maps are activated most strongly at the labeled location that lies closest to the peak on homologous sensory maps. On the verbal maps activation is characterized by both excitatory and inhibitory Gaussians (a Mexican hat), the parameters of which are determined by the relative locations of the verbal labels. Mutual homotopic inhibition across the "corpus callosum" then produces functional cerebral asymmetries, i.e., complementary activation of homologous "association" and "frontal" maps within a common focus of attention-a nucleus in the left hemisphere and a fringe in the right hemisphere. An object is recognized as corresponding to a known label when the total activation of both hemispheres (nucleus plus fringe) is strongest for that label. The functional dualities of the cerebral hemispheres are discussed in light of the nucleus/fringe asymmetry.     

Can semantic information be transferred between hemispheres in the split-brain?

Data from experiments with split-brain patients, who have had their left and right hemispheres disconnected, suggests a remarkable specialization of function within each hemisphere. At the same time, these patients conduct their daily lives with great proficiency. This ability suggests that some information integral to coordinated function between the hemispheres is available in the absence of the corpus callosum. Is information about the semantics of words one type of information that is shared? An experiment by suggests that it may be. Lambert reported that living/nonliving word categorization was delayed when disconnected hemispheres processed words belonging to the same category. Although other interpretations are plausible, Lambert described this effect as having a semantic source. We attempted to replicate the original effect with two additional split-brain patients, J.W. and V.P., and to extend the original design to clarify the source of the putative semantic effect. Our results indicate that any semantic interaction between the split hemispheres is not reliable. As such our study adds to the growing literature indicating that subcortical transfer of semantic information is more illusory than real.