Функциональная асимметрия мозга: что изменилось в наших
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Функциональная асимметрия мозга: что изменилось в наших знаниях за 30 лет? Татьяна Черниговская Санкт-Петербургский государственный университет Ю.Лотман, Б.Успенский. Миф—имя—культура • Мир есть материя. Мир есть конь. • Одна из этих фраз принадлежит тексту заведомо мифологическому (“Упанишады”), между тем как другая может служить примером текста противоположного типа. При внешнем формальном сходстве данных конструкций между ними имеется принципиальная разница: • а) одинаковая связка (есть) обозначает здесь совершенно различные в логическом смысле операции: в первом случае речь идет об определенном соотнесении (которое может приниматься, например, как соотнесение частного с общим, включение во множество и т. п.), во втором — непосредственно об отождествлении; • б) предикат также различен. С позиции современного сознания слова материя и конь в приведенных конструкциях принадлежат различным уровням логического описания: первое тяготеет к уровню метаязыка, а второе — к уровню языка-объекта. В первом случае существенно принципиальное отсутствие изоморфизма между описываемым миром и системой описания; во втором случае, напротив, — принципиальное признание такого изоморфизма. Второй тип описания мы будем называть “мифологическим”, первый — “немифологическим” (или “дескриптивным”). Юрий Михайлович Лотман Параллель между двуполушарной структурой человеческого мозга и культурой, биполярность как минимальная структура семиотической организации...на всех уровнях мыслящего механизма Л. С. Выготский • Перерастание диалога «между разными людьми» в диалог «внутри одного мозга». М. М. Бахтин • Событие жизни текста, т. е. его подлинная сущность, всегда развивается на рубеже двух сознаний ... Диалогические рубежи пересекают все поле живого человеческого мышления Вяч. Вс. Иванов • Процессы обмена информацией внутри мозга и внутри общества... - разные стороны единого процесса. В. С. Библер • Процесс внутреннего диалогизма– столкновение радикально различных логик мышления Мераб Мамардашвили • Пока нет языка, ничего о мире сказать нельзя, а когда он есть – то это необратимо: многие вещи определяются нами в возможностях именно этого, а не другого языка. Иначе говоря, сначала, когда нет языка, мы ничего не можем сказать, а когда язык есть, сказать можем не всё. Мераб Мамардашвили Значит, мы как бы подвешены в языке...Эта подвешенность, чётко удерживаемая и сознаваемая граница выразимого и невыразимого и есть ноуменальная часть человеческого мышления... Точность и красота мышления Канта и Декарта состоит в том, что они чётко выдерживали такое понимание Густав Шпет • Слова – не свивальники мысли, а её плоть. Мысль рождается в слове и вместе с ним. Даже и этого мало – мысль зачинается в слове Вопросы: • Есть ли основания говорить о генетической основе языковой способности человека? • Имеет ли латерализация мозговых функций решающее значение для формирования языка человека и когниции высокого ранга? T. Deacon : Язык – поразит, оккупировавший мозг! •Bickerton: «у нас не было большего и лучшего мозга, который дал нам язык; мы приобрели язык, и он позволил нам увеличить и улучшить наш мозг» [Бикертон 2012: 35]. •Эпигенез…. (Шмальгаузен,Deacon) • По независимым оценкам разных групп исследователей, что показал анализ митохондриальной ДНК, временем появления Homo sapiens как биологического вида следует считать период около 185 тысяч лет назад. Около 60–70 тысяч лет назад, ещё до выхода из Африки эта популяция разделилась по крайней мере на три подгруппы, давшие начало африканской, монголоидной и европеоидной рассам [Cavalli-Sforza, 2000; Rosser et al., 2000]. Cопоставимые результаты дают и исследования Ухромосомы, хотя и указывают на более поздние сроки — 140–175 тысяч лет назад [Thomson et al., 2000]. • T. Crow argues that language and psychosis have a common evolutionary origin. Language originated in a critical change (the `speciation event'--the genetic change on the sex X and Y chromosomes that defined the species) to determine the plateau of brain development that led to a progressive delay in maturation and an increase in communicative capacity. It occurred in East Africa between 100 and 250 thousand years ago and allowed the two hemispheres to develop with a degree of independence and subserve the generativity of language. • Krause et al. (Current Biology, 2007, 17: 19081912 ) claim that two Neanderthals from the El Sidrón site in Spain had the same FOXP2 mutations as modern humans do, which led these researches to conclude that "these two amino acid substitutions [...] associated with the emergence of fully modern language ability... were probably inherited both by Neanderthals and modern Sapiens from their last common ancestor (300,000 to 400,000 years B.P.)" Выделен ген, который претерпел наиболее значительные изменения на пути к современному человеку. Это HAR1, в котором содержалось 118 (!) различий между человеком и шимпанзе. Для сравнения, между шимпанзе и птицами расхождений всего 2. Асимметрия чего? Когнитивная? Вегетативная? Моторная? Left brain subserves specific features of human language ‘Digital’ and hierarchical structure (phonemes - morphemes - words -phrases - discourse) Productivity governed by the linguistic rules Differences in the superficial order of constituents Left brain subserves specific features of human language The use of null elements (e.g. ‘it’, ‘there’) The use of sub-categorical argument structure for verbs Mechanisms for expansion of utterances Embedding The Left hemisphere introduces an object into generalized classes of phenomena and provides for logical operations and categorical perception The Right Brain is responsible for Global/Gestalt recognition. Revealing the relevant components of a situation (or a scene). Relatively high speed of decision making Classification of colours and odours Orientation in space and time Evaluation of gestures, face expressions and verbal prosody Genetic associations.... • Fisher, S.E., Vargha-Khadem, F., Watkins. K.E., Monaco, A.P., and Pembey, M.E. Localisation of a Gene Implicated in a Severe Speech and Language Disorder, Nature Genet., 1998, vol. 18, pp. 168-170. • Crow, T.J. Schizophrenia as the Price that Homo sapience Pays for Language: A Resolution of the Central Paradox in the Origin of the Species, Brain Res. Rev., 2000, vol. 31, pp. 118-129 • Andrew, S. Communicating a New Gene Vital for Speech and Language, Clin. Genet., 2000, vol. 61, pp. 97-100. FoxP2 regulates excitatory synapse density through SRPX2 Previous studies have suggested that FoxP2 may regulate neurite growth dendritic morphology, and synaptic physiology of basal ganglia neurons • FoxP2 представляет собой транскрипционный фактор, контролирующий работу многих генов и экспрессирующийся в разных органах тела человека. Одним из генов, находящихся под контролем FoxP2, является ген CNTNAP2, нарушения в работе участков которого связывают с аутизмом. Некоторые варианты этого гена у детей с аутизмом влияют на возраст, в котором произносится первое слово. Кроме того он не специфичен только для человека, а функционируют и в других организмах, включая дрозофил и крыс. • Итак: Экспрессия гена FoxP2 у человека связывается с процессом последовательного обучения, который определяется как способность людей вычленять и обрабатывать дискретные компоненты в организованных временных последовательностях. определяется как сложно Это ключевое деятельности человека. умение в языковой • Развитие эволюционной генетики позволило сделать целый ряд очень важных открытий, в том числе обнаружить ген FoxP2, идентичный функционирующему в современном человеке, у неандертальцев и денисовцах, что стало одним из косвенных доказательств того, что синтаксис мог быть уже у нашего общего с неандертальцами предка. • But the form in chimpanzees is slightly different. The gene provides instructions for a protein of the same name that varies by just two amino acids - proteins' building blocks from the chimpanzees' version. • . But among those 116 genes ‘tied’ to the human FOXP2 gene there is at least one "that is involved in the development of brain regions that are part of a critical circuit we know is important for higher cognition“ (Geschwind). • Нарушение в FOXB1 приводит к дизгенезу медиальных маммилярных тел в области среднего мозга (их роль в процессах памяти такая же, как у гиппокампа, и они обеспечивают рабочую память). Мыши с нарушением этого гена обнаруживают дизгенез маммилярных тел и нарушение памяти (Анохинская "корсаковская мышь" ). У таких мышей нормальная долговременная память и нарушенная оперативная память. • Т.е. FOXB1 обеспечивает оперативную память и работу гиппокампа в когнитивных задачах, что вполне может влиять на обеспечение таких сложных функций у человека как языковые процессы. • SCIENCE:22 NOVEMBER 2013 Vol. 342 G. M. Sia, R. L. Clem, R. L. Huganir. The Human Language–Associated Gene SRPX2 Regulates Synapse Formation and Vocalization in Mice • Expression of this protein is known to be repressed by the transcription factor FOXP2, which has been implicated in human language acquisition. SCIENCE:22 NOVEMBER 2013 Vol. 342 • Philip Lieberman. Synapses, Language, and Being Human. • We do not yet know the full range of genetic events that yielded the human brain, but a mutation at a site near the FOXP2 amino acid mutations that are unique to humans appears to be responsible for a “selective sweep” that occurred about 200,000 years ago in Africa. Such sweeps on genes occur when they enhance the survival of progeny. A process in which FOXP2 targets the SRPX2 gene to control the release of a protein that promotes the development of synapses would clearly play a role in that aspect of the evolution of the human brain. • Synapse formation in the developing brain depends on the coordinated activity of synaptogenic proteins, some of which have been implicated in a number of neurodevelopmental disorders. The sushi repeat– containing protein X-linked 2 (SRPX2) gene encodes a protein that promotes synaptogenesis in the cerebral cortex. In humans, SRPX2 is an epilepsy- and languageassociated gene that is a target of the foxhead box protein P2 (FoxP2) transcription factor. FoxP2 modulates synapse formation through regulating SRPX2 levels and that SRPX2 reduction impairs development of ultrasonic vocalization in mice. The results suggest FoxP2 modulates the development of neural circuits through regulating synaptogenesis and that SRPX2 is a synaptogenic factor that plays a role in the pathogenesis of language disorders. Stephen J. Gottsa, Hang Joon Job, Gregory L. Wallacea, Ziad S. Saadb, Robert W. Coxb, and Alex Martina. Two distinct forms of functional lateralization in the human brain. // PNAS July 25, 2013 The hemispheric lateralization of certain faculties in the human brain has long been held to be beneficial for functioning. However, quantitative relationships between the degree of lateralization in particular brain regions and the level of functioning have yet to be established. Here we demonstrate that two distinct forms of functional lateralization are present in the left vs. the right cerebral hemisphere, with the left hemisphere showing a preference to interact more exclusively with itself, particularly for cortical regions involved in language and fine motor coordination. In contrast, righthemisphere cortical regions involved in visuospatial and attentional processing interact in a more integrative fashion with both hemispheres. The degree of lateralization present in these distinct systems selectively predicted behavioral measures of verbal and visuospatial ability, providing direct evidence that lateralization is associated with enhanced cognitive ability. Neuropsychological and neuroimaging studies have revealed a strong bias toward left hemisphere representation of language and fine motor control of the hands, with a well-documented association between handedness and language lateralization that is most pronounced in right-handed males . In contrast, visuospatial attentional abilities are represented more strongly in the right hemisphere, with right-sided brain damage being more likely to produce hemi-spatial attentional neglect . Although the mechanisms underlying functional lateralization are unknown, theoretical proposals have appealed to the computational benefits of functional specialization, with distinct functions and a division of labor between the hemispheres that improves overall cognitive ability and performance. A basic distinction that derives from the separate literatures on language, motor, and visuospatial lateralization is that the hemispheres differ qualitatively in their within- and between-hemisphere interactions. Left hemisphere representations of language and fine motor control have been proposed to be more “focal,” permitting rapid cortical interactions with shorter conduction delays, whereas right-lateralized visuospatial attention mechanisms requirea greater degree of interhemispheric integration due to the bilateral representation of visual space. Nevertheless, the proposed preferences of each hemisphere for unilateral vs. bilateral interaction and how such preferences relate quantitatively to particular cognitive abilities have yet to be examined. !!! The data on cerebral lateralization are broadly consistent with computational theories of functional specialization that hold that information processing is more effective and efficient when larger functions can be decomposed into smaller independent processes, reducingfunctional interference. Hemispheric lateralization can be thought of as a special case of functional specialization, but other cases, such as the division of labor in the visual system between space and form or category selectivity in occipitotemporal brain regions , may ultimately be found to follow similar considerations. • Poeppel D (2003) The analysis of speech in different temporal integration windows: Cerebral lateralization as ‘asymmetric sampling in time’. Speech Commun 41(1):245–255. • Hickok G, Poeppel D (2007) The cortical organization of speech processing. Nat Rev. Neurosci 8(5):393–402 • Rosch RE, Bishop DV, Badcock NA (2012) Lateralised visual attention is unrelated to language lateralisation, and not influenced by task difficulty - a functional transcranial Doppler study. Neuropsychologia 50(5):810–815. • Fox MD, et al. (2005) The human brain is intrinsically organized into dynamic, anticorrelated functional networks. Proc Natl Acad Sci USA 102(27):9673–9678. • Chernigovskaya, Slussar, Medvedev, Kireev (2012-2013): • The generation of regular and irregular past tense verbs has long been a testing ground for different models of inflection in the mental lexicon. According to the dualsystem view, regular forms are generated by a rule and irregular forms are retrieved from memory. The singlesystem view postulates a single integrated system for all forms. Behavioral studies examined a variety of languages, but neuroimaging studies still rely almost exclusively on English and German data. We used Russian, a language with a much more complex verb class system. To avoid problems identified in earlier studies, we randomly mixed different tasks (inflecting nonce and real verbs and nouns of different types) and compiled large sets of stimuli matched for frequency and phonological complexity. Unlike most previously obtained results, our findings are more readily compatible with the single-system approach. Observed activation patterns are best explained by the difference in processing load between experimental tasks. A) brain areas involved in irregular verb production (IV>RV); B) brain areas involved in nonce irregular verb production (INV>RNV); C) brain areas responding to the increase in processing difficulty (RV<IV<RNV<INV). fMRI data are projected onto a reference anatomical image. BA, approximate Brodmann’s area; L/R, left/right hemisphere; IFG, inferior frontal gyrus; IPL, inferior parietal lobule; SFG, superior frontal gyrus; SMA, supplementary motor area. The cortex is a network – no modules or blocks So, the cortical representation of language is a network The cortical representation of knowledge in general is a network The representation of memory is a network Language uses the same cortical structures and processes as other cognitive skills Except for phonetics, which has specialization We know a lot about neurons as units We are starting to know how they work together, we can even see it. Functional blocks, no modules, some localization and spread activity Prosody: Chernigovskaya, Strelnikov et al. • Syntactic processing of spoken speech often involves evaluation of prosodic clues. In the present PET and ERP study, subjects listened to phrases in which different prosodic segmentation dramatically changed the meaning of the phrase. In the contrast of segmented vs. nonsegmented phrases, PET data revealed activation in the right dorsolateral prefrontal cortex and in the right cerebellum. These brain structures, therefore, might be part of the syntactic analysis network involved in prosodic segmentation and pitch processing. ERP results revealed frontal negativity that was sensitive to the position of the segmenting pause, possibly reflecting prosody-based semantic prediction. The present results are discussed in the context of their relation to brain networks of emotions, prosody, and syntax perception. • The neuroanatomical basis of syntactic parsing is believed to include the left perisylvian associative cortex, with possible contribution of the homologous contralateral cortex, as suggested by brain lesion studies (Grodzinsky, 1990; 1995; Berndt et al., 1996; Caplan et al., 1996). Broca’s area seems to be the most frequently mentioned candidate for the key brain structure of syntactic analysis (Swinney et al., 1995; 1996). The activation level of Broca’s area correlated with syntactic complexity in some PET studies for both visual (Just et al., 1996; Stromswold et al., 1996) and auditory (Caplan et al., 1998; 1999) sentence presentation. • Areas adjacent to Broca’s were shown to subserve syntactic errors detection (Indefrey et al., 2001; Friederici et al., 2003). In numerous studies, the processing of syntactic structures was also associated with some ERP components--e.g., P600 and the socalled left anterior negativity (LAN), which has its maximum above Broca’s area (e.g., Neville et al., 1991; Kluender and Kutas, 1993). The nature of these ERP components is being actively discussed (e. g., Friederici, 2002; Ullman, 2004). • However, the regions in the right hemisphere, homologous to Broca’s and Wernicke’s areas, were also implicated during syntactic processing (Just et al., 1996). Humphries et al. (2001) found bilateral activations in the anterior temporal cortex during speech sounds, as opposed to non-speech sounds. In their PET study, Mazoyer et al. (1993) showed that the bilateral anterior temporal cortex was the only structure specifically activated by listening to sentences, whereas Broca’s area was activated also by separate words. Friederici et al. (2000) also showed that syntactic processing of speech bilaterally influenced anterior temporal cortex activation. Thus, syntactic processing seems to be subserved by the crosshemispheric neural networks. • According to Homae et al. (2002), activation in the left inferior frontal gyrus during sentence processing does not depend on sensory modality. Natural language perception and oral speech syntax are based primarily on the auditory modality--in particular, on such prosodic features as changes in pace, tone, and loudness (Shattuck-Hufnagel and Turk, 1996). Further understanding of oral speech processing requires an investigation of its prosodic mediation (Friederici, 2002). Studies of prosodic processing have suggested the involvement of either the right hemisphere or both hemispheres (Baum and Pell, 1999; Meyer et al., 2002; Kotz et al., 2003; Meyer et al., 2004), whereas modality-independent syntactic processing is usually associated with the left hemisphere (e. g., Chernigovskaya and Deglin, 1986; Caplan et al., 1998; Caplan et al., 1999; Indefrey et al., 2001; Röder et al., 2002). • However, an interaction between the structural conditions and prosodic conditions was observed bilaterally in the anterior temporal lobe along the superior temporal gyrus (Humphries et al., 2005). ERP studies have revealed some commonalities in prosody and syntax processing: the same electrophysiological phenomenon accompanied the processing of prosodic boundaries in spoken speech and the processing of commas during silent reading (Steinhauer et al., 1999; Steinhauer, 2003). Generally, though the direct interaction of prosody and syntax is proved, the existing data do not allow judgment on the specific brain mechanisms of the prosody/syntax interface - an intriguing question for further neurolinguistic studies. Activation areas obtained when the segmented phrases were actively analyzed (rCBF increase in the "Segmented" condition vs. the "Non-segmented" condition). The right prefrontal and cerebellar activations are shown as projections to the right and posterior brain surfaces, respectively. Areas of rCBF increase in the "Non-segmented" condition as compared to the "Segmented" condition. The white line on the rendered right hemisphere surface depicts the level of the horizontal slice. L and R indicate the left and right sides • The ERP study involved presentation of four phrases in which the place of the pause and the corresponding comma in writing dramatically changed the meaning: • To chop not, to saw. ( “Рубить нельзя, пилить.”) • To chop, not to saw. (“Рубить, нельзя, пилить.”) • To saw not, to chop. (“Нельзя пилить, рубить.”) • To saw, not to chop. (“Пилить, нельзя рубить.”). • These four phrases were selected from 60 presented in the PET study. • The observed right cerebellar activation might be related to the perception of speech timing. Indeed, the cerebellum is often believed to be a key structure for timing estimation, which is important for many sensory, motor, and cognitive activities (Ackermann et al., 1999; Ivry and Richardson, 2002; Salman, 2002). It is also possible that the right cerebellar activation is related to estimating phonetic and semantic borders of syntagms, or to keeping the phrase structure in the working memory during processing (Marien, 2001). • The right posterior prefrontal cortex and the right medial posterior cerebellar area participate in the brain network of spoken speech syntactic parsing, being involved in the prosody/syntax interface. The acquired ERP data support the idea that prosodybased semantic prediction is important for such processing. Furthermore, comparing our results with other brain mapping studies, we conclude that the right posterior prefrontal cortex might represent the functional overlap of brain networks of emotions, prosody, and syntax perception. Peak values and anatomic locations of the PET activations. Brodmann areas, and stereotactic coordinates. Abbreviations: L = the left hemisphere; R = the right hemisphere; Inf. = inferior; Mid = middle. • Brain region, Brodmann Area • “Segmented” vs. “Non-segmented” • R. Mid. Frontal Gyrus / Inf. Frontal Sulcus, BA 9/46/44 • R. Cerebellum • “Non-segmented” vs. “Segmented” • L. Sylvian Sulcus, BA 42/40/13 • L. Heschl Gyrus BA 41/42 • R. Heschl Gyrus, BA 41 R. L. Moseley, F. Pulvermu¨ller & Yu. Shtyrov. Sensorimotor semantics on the spot:brain activity dissociates between conceptual categories within 150 ms. SCIENTIFIC REPORTSJune,2013 Although semantic processing has traditionally been associated with brain responses maximal at 350–400 ms, recent studies reported that words of different semantic types elicit topographically distinct brain responses substantially earlier, at 100–200 ms. These earlier responses have, however, been achieved using insufficiently precise source localisation techniques, therefore casting doubt on reported differences in brain generators. Reliable neurophysiological word-category dissociations emerged bilaterally at 150 ms, at which point actionrelated words most strongly activated frontocentral motor areas and visual object-words occipitotemporal cortex. These data now show that different cortical areas are activated rapidly by words with different meanings and that aspects of their category-specific semantics is reflected by dissociating neurophysiological sources in As can be seen, brain activation exhibited its absolute maximum between 140–160 ms, Note that activity predominates in occipitotemporal areas, as words were presented visually, and is present in widespread cortical areas at this early latency. AD Friederici. The Brain Basis of Language Processing: From Structure to Function.Physiol Rev 2011 91: 1357–1392 Networks involving the temporal cortex and the inferior frontal cortex with a clear left lateralization were shown to support syntactic processes, whereas less lateralized temporo-frontal networks subserve semantic processes. These networks have been substantiated both by functional as well as by structural connectivity data. Electrophysiological measures indicate that within these networks syntactic processes of local structure building precede the assignment of grammatical and semantic relations in a sentence. Suprasegmental prosodic information overtly available in the acoustic language input is processed predominantly in a temporo-frontal network in the right hemisphere. Studies with patients suffering from lesions in the corpus callosum reveal that the posterior portion of this structure plays a crucial role in the interaction of syntactic and prosodic information during language processing. We suggest that a given area,for example, Broca’s area, receives its particular domainspecific function as part of a particular domain-specific network which, for the language domain, involves the posterior STG and which, for the action domain, involves the parietal cortex. Thus the function of an area should always be considered within a neural network of which it is a part. Thank you !
