Gesture paves the way for language development

In development, children often use gesture to communicate before they use words. The question is whether these gestures merely precede language development or are fundamentally tied to it. We examined 10 children making the transition from single words to two-word combinations and found that gesture had a tight relation to the children's lexical and syntactic development. First, a great many of the lexical items that each child produced initially in gesture later moved to that child's verbal lexicon. Second, children who were first to produce gesture-plus-word combinations conveying two elements in a proposition (point at bird and say "nap") were also first to produce two-word combinations ("bird nap"). Changes in gesture thus not only predate but also predict changes in language, suggesting that early gesture may be paving the way for future developments in language.     

Gesture in the developing brain

Speakers convey meaning not only through words, but also through gestures. Although children are exposed to co-speech gestures from birth, we do not know how the developing brain comes to connect meaning conveyed in gesture with speech. We used functional magnetic resonance imaging (fMRI) to address this question and scanned 8- to 11-year-old children and adults listening to stories accompanied by hand movements, either meaningful co-speech gestures or meaningless self-adaptors. When listening to stories accompanied by both types of hand movement, both children and adults recruited inferior frontal, inferior parietal, and posterior temporal brain regions known to be involved in processing language not accompanied by hand movements. There were, however, age-related differences in activity in posterior superior temporal sulcus (STSp), inferior frontal gyrus, pars triangularis (IFGTr), and posterior middle temporal gyrus (MTGp) regions previously implicated in processing gesture. Both children and adults showed sensitivity to the meaning of hand movements in IFGTr and MTGp, but in different ways. Finally, we found that hand movement meaning modulates interactions between STSp and other posterior temporal and inferior parietal regions for adults, but not for children. These results shed light on the developing neural substrate for understanding meaning contributed by co-speech gesture.     

Gesture is at the cutting edge of early language development

Children who produce one word at a time often use gesture to supplement their speech, turning a single word into an utterance that conveys a sentence-like meaning ('eat'+point at cookie). Interestingly, the age at which children first produce supplementary gesture-speech combinations of this sort reliably predicts the age at which they first produce two-word utterances. Gesture thus serves as a signal that a child will soon be ready to begin producing multi-word sentences. The question is what happens next. Gesture could continue to expand a child's communicative repertoire over development, combining with words to convey increasingly complex ideas. Alternatively, after serving as an opening wedge into language, gesture could cease its role as a forerunner of linguistic change. We addressed this question in a sample of 40 typically developing children, each observed at 14, 18, and 22 months. The number of supplementary gesture-speech combinations the children produced increased significantly from 14 to 22 months. More importantly, the types of supplementary combinations the children produced changed over time and presaged changes in their speech. Children produced three distinct constructions across the two modalities several months before these same constructions appeared entirely within speech. Gesture thus continues to be at the cutting edge of early language development, providing stepping-stones to increasingly complex linguistic constructions.     

Event-related brain potentials and human language

The human capacity to produce and comprehend language is one of the most distinctive characteristics of our species. However, understanding the cognitive and neural underpinnings of human language has proved difficult, in part because these processes are rapid, complex and (for the most part) inaccessible to conscious reflection. Methodologies are needed that provide continuous measurement during language processing and that do not rely on a conscious response. One such method involves the recording of event-related brain potentials (ERPs) elicited during language comprehension or production. ERPs are continuous, multidimensional records of the electrical activity that occurs in the brain during the process of interest. We review recent work demonstrating that ERPs are quite sensitive to (at least some of) the psychological and neural events underlying human language. Indeed, researchers have used ERPs to investigate the separability of syntactic and semantic processes, the on-line analysis of sentence constituent structure and the lexical processing capacities of language-disordered populations.     

第二语言学习与脑可塑性

脑可塑性指人脑会因为环境刺激、认知需求和行为经验而产生功能或结构改变。近10年来的单双语者对比和语言训练研究结果表明, 不论儿童、青年或老年人, 第二语言学习和使用都能改变其脑运行模式并带来相应结构变化, 包括灰质(GM)体积和白质(WM)密度增加, 且长期持续的双语经验还能形成认知优势, 帮助抵制由老化导致的负面认知影响。基于脑可塑性概念及其研究证据, 从双语经验与语言训练两方面, 对比分析了长期和短期第二语言学习引起脑功能或结构变化及其内在机制, 并对未来相关研究进行了展望。     

Genes, language development, and language disorders

Genetic factors are important contributors to language and learning disorders, and discovery of the underlying genes can help delineate the basic neurological pathways that are involved. This information, in turn, can help define disorders and their perceptual and processing deficits. Initial molecular genetic studies of dyslexia, for example, appear to converge on defects in neuronal and axonal migration. Further study of individuals with abnormalities of these genes may lead to the recognition of characteristic cognitive deficits attributable to the neurological dysfunction. Such abnormalities may affect other disorders as well, and studies of co-morbidity of dyslexia with attention deficit disorder and speech sound disorder are helping to define the scope of these genes and show the etiological and cognitive commonalities between these conditions. The genetic contributions to specific language impairment (SLI) are not as well defined at this time, but similar molecular approaches are being applied to identify genes that influence SLI and comorbid disorders. While there is co-morbidity of SLI with dyslexia, it appears that most of the common genetic effects may be with the language characteristics of autism spectrum disorders rather than with dyslexia and related disorders. Identification of these genes and their neurological and cognitive effects should lay out a functional network of interacting genes and pathways that subserve language development. Understanding these processes can form the basis for refined procedures for diagnosis and treatment.     

Bilateral brain processes for comprehending natural language

Comprehension of natural language--stories, conversations, text--is very simple for those doing the comprehending and very complex for cognitive neuroscientists. It also presents a paradox: the advantage of the left hemisphere (LH) for most language tasks is one of the best-established facts about the brain; yet, when it comes to comprehending complex, natural language, the right hemisphere (RH) might play an important role. Accumulated evidence from neuropsychology, neuroimaging, and neuroanatomy suggests at least three roughly separable (but highly interactive) components of semantic processing. Each process in turn has bilateral components, with the RH component performing coarser computations for the same general process. Examining asymmetrical brain and cognitive functions provides a unique opportunity for understanding the neural basis of complex cognition.     

Dissociating language and word meaning in the bilingual brain

How do bilingual (or multilingual) persons keep different languages apart and switch between them as needs arise? Crinion et al. have used an ingenious method to dissociate brain regions sensitive to word meaning from those sensitive to the combination of meaning and language. This work should stimulate further research examining the role of subcortical areas in language processing and in context-appropriate language production.     

First and second language in the brain: Neuronal correlates of language processing and spelling strategies

This study explores oscillatory brain activity by means of event-related synchronization and desynchronization (%ERS/ERD) of EEG activity during the use of phonological and orthographic-morphological spelling strategies in L2 (English) and L1 (German) in native German speaking children. EEG was recorded while 33 children worked on a task requiring either phonological or orthographic-morphological spelling strategies. L2 processing elicited more theta %ERS than L1 processing (particularly at bilateral frontal and right posterior parietal sites) which might suggest a stronger involvement of semantic encoding and retrieval of the less familiar L2. The highest level of theta %ERS was revealed for the orthographic-morphological strategy in L2 which might indicate a more intense way of lexical retrieval compared to the phonological strategy in L2 and the orthographic-morphological strategy in L1. Analyses moreover revealed that phonological processing (both in L1 and L2) was associated with comparatively strong left-hemispheric %ERD in the upper alpha frequency band.     

Gesture and early bilingual development

The relationship between speech and gestural proficiency was investigated longitudinally (from 2 years to 3 years 6 months, at 6-month intervals) in 5 French-English bilingual boys with varying proficiency in their 2 languages. Because of their different levels of proficiency in the 2 languages at the same age, these children's data were used to examine the relative contribution of language and cognitive development to gestural development. In terms of rate of gesture production, rate of gesture production with speech, and meaning of gesture and speech, the children used gestures much like adults from 2 years on. In contrast, the use of iconic and beat gestures showed differential development in the children's 2 languages as a function of mean length of utterance. These data suggest that the development of these kinds of gestures may be more closely linked to language development than other kinds (such as points). Reasons why this might be so are discussed.     

Profiles of right hemisphere language and speech following brain bisection

A variety of language tasks were administered to two patients who had undergone staged callosal section in an effort to control otherwise intractable epilepsy. Right hemisphere lexical capacity varied and preliminary results suggest that the case displaying greater semantic power also possessed some syntactic competence. This same case (V.P.) was also capable of expressive language from the right hemisphere. This rare capacity allowed for fresh observations on the dynamic interactions of conscious control that occur in this kind of patient.     

Gesture, speech, and computational stages: a reply to McNeill

McNeill (1985) claimed that speech and its accompanying gestures "share a common computational stage" that is located early in the speech production process. This position depends on two crucial arguments that we believe are unsound: first, that gestures "are synchronized with linguistic units in speech" and, second, that gestures "have semantic and pragmatic functions that parallel those of speech." Careful analysis of the relevant data indicated that although the processes underlying gestural production are globally autonomous, they are linked to speech production at more than just one computational stage. An account is offered that explicates these links.     

Gesture production and text structure

In the present pilot study, we examined the relationship between gesture and verbal production. Subjects were asked to read a story and then to narrate what they remembered. We analyzed verbal production according to Kintsch's procedure and obtained a list of hierarchically organized propositions that represented the meaning of subject's narration. Propositions were subdivided into High- and Low-level propositions. Further, we analyzed gesture production by identifying hand or arm movement that accompanied subject's narration. Each gesture was associated with the word simultaneously produced, and then with the proposition to which the word belonged. Analysis showed subjects were more likely to produce gestures in association with High- rather than with Low-level propositions. High-level propositions may elicit the production of gestures which, in turn, mark the importance of verbal meaning conveyed simultaneously.     

Frequency effects in language acquisition, language use, and diachronic change

Recent work in psychology and linguistics has shown that frequency of occurrence is an important determinant of language acquisition, language use, and diachronic change. This paper surveys the effects of frequency on the use and development of language and considers the psychological mechanisms that underlie the various frequency effects. The paper shows that frequency has an impact on the emergence of linguistic structure and that some well-known cross-linguistic tendencies arise from frequency effects.