The Development of Specialized Brain Systems in Reading and Oral-Language

Functional magnetic resonance imaging (fMRI) was used to examine differences between children (9–12 years) and adults (21–31 years) in the distribution of brain activation during word processing. Orthographic, phonologic, semantic and syntactic tasks were used in both the auditory and visual modalities. Our two principal results were consistent with the hypothesis that development is characterized by increasing specialization. Our first analysis compared activation in children versus adults separately for each modality. Adults showed more activation than children in the unimodal visual areas of middle temporal gyrus and fusiform gyrus for processing written word forms and in the unimodal auditory areas of superior temporal gyrus for processing spoken word forms. Children showed more activation than adults for written word forms in posterior heteromodal regions (Wernicke's area), presumably for the integration of orthographic and phonologic word forms. Our second analysis compared activation in the visual versus auditory modality separately for children and adults. Children showed primarily overlap of activation in brain regions for the visual and auditory tasks. Adults showed selective activation in the unimodal auditory areas of superior temporal gyrus when processing spoken word forms and selective activation in the unimodal visual areas of middle temporal gyrus and fusiform gyrus when processing written word forms.     

The development of specialized brain systems in reading and oral-language.

Functional magnetic resonance imaging (fMRI) was used to examine differences between children (9-12 years) and adults (21-31 years) in the distribution of brain activation during word processing. Orthographic, phonologic, semantic and syntactic tasks were used in both the auditory and visual modalities. Our two principal results were consistent with the hypothesis that development is characterized by increasing specialization. Our first analysis compared activation in children versus adults separately for each modality. Adults showed more activation than children in the unimodal visual areas of middle temporal gyrus and fusiform gyrus for processing written word forms and in the unimodal auditory areas of superior temporal gyrus for processing spoken word forms. Children showed more activation than adults for written word forms in posterior heteromodal regions (Wernicke's area), presumably for the integration of orthographic and phonologic word forms. Our second analysis compared activation in the visual versus auditory modality separately for children and adults. Children showed primarily overlap of activation in brain regions for the visual and auditory tasks. Adults showed selective activation in the unimodal auditory areas of superior temporal gyrus when processing spoken word forms and selective activation in the unimodal visual areas of middle temporal gyrus and fusiform gyrus when processing written word forms.     

Homotopic language reorganization in the right hemisphere after early left hemisphere injury

Speech production is inextricably linked to speech perception, yet they are usually investigated in isolation. In this study, we employed a verbal-repetition task to identify the neural substrates of speech processing with two ends active simultaneously using functional MRI. Subjects verbally repeated auditory stimuli containing an ambiguous vowel sound that could be perceived as either a word or a pseudoword depending on the interpretation of the vowel. We found verbal repetition commonly activated the audition-articulation interface bilaterally at Sylvian fissures and superior temporal sulci. Contrasting word-versus-pseudoword trials revealed neural activities unique to word repetition in the left posterior middle temporal areas and activities unique to pseudoword repetition in the left inferior frontal gyrus. These findings imply that the tasks are carried out using different speech codes: an articulation-based code of pseudowords and an acoustic-phonetic code of words. It also supports the dual-stream model and imitative learning of vocabulary.     

Dissociation and association of the embodied representation of tool-use verbs and hand verbs: An fMRI study

Embodied semantic theories suppose that representation of word meaning and actual sensory-motor processing are implemented in overlapping systems. According to this view, association and dissociation of different word meaning should correspond to dissociation and association of the described sensory-motor processing. Previous studies demonstrate that although tool-use actions and hand actions have overlapping neural substrates, tool-use actions show greater activations in frontal–parietal–temporal regions that are responsible for motor control and tool knowledge processing. In the present study, we examined the association and the dissociation of the semantic representation of tool-use verbs and hand action verbs. Chinese verbs describing tool-use or hand actions without tools were included, and a passive reading task was employed. All verb conditions showed common activations in areas of left middle frontal gyrus, left inferior frontal gyrus (BA 44/45) and left inferior parietal lobule relative to rest, and all conditions showed significant effects in premotor areas within the mask of hand motion effects. Contrasts between tool-use verbs and hand verbs demonstrated that tool verbs elicited stronger activity in left superior parietal lobule, left middle frontal gyrus and left posterior middle temporal gyrus. Additionally, psychophysiological interaction analyses demonstrated that tool verbs indicated greater connectivity among these regions. These results suggest that the brain regions involved in tool-use action processing also play more important roles in tool-use verb processing and that similar systems may be responsible for word meaning representation and actual sensory-motor processing.     

Large,colorful, or noisy? Attribute- and modality-specific activations during retrieval of perceptual attribute knowledge

Position emission tomography was used to investigate whether retrieval of perceptual knowledge from long-term memory activates unique cortical regions associated with the modality and/or attribute type retrieved. Knowledge about the typical color, size, and sound of common objects and animals was probed, in response to written words naming the objects. Relative to a nonsemantic control task, all the attribute judgments activated similar left temporal and frontal regions. Visual (color, size) knowledge selectively activated the right posterior inferior temporal (PIT) cortex, whereas sound judgments elicited selective activation in the left posterior superior temporal gyrus and the adjacent parietal cortex. All of the attribute judgments activated a left PIT region, but color retrieval generated more activation in this area. Size judgments activated the right medial parietal cortex. These results indicate that the retrieval of perceptual semantic information activates not only a general semantic network, but also cortical areas specialized for the modality and attribute type of the knowledge retrieved.     

Modulation of brain activity during phonological familiarization

We measured brain activity in 12 adults for the repetition of auditorily presented words and nonwords, before and after repeated exposure to their phonological form. The nonword phoneme combinations were either of high (HF) or low (LF) phonotactic frequency. After familiarization, we observed, for both word and nonword conditions, decreased activation in the left posterior superior temporal gyrus, in the bilateral temporal pole and middle temporal gyri. At the same time, interaction analysis showed that the magnitude of decrease of activity in bilateral posterior temporal lobe was significantly smaller for LF nonwords, relative to words and HF nonwords. Decrease of activity in this area also correlated with the size of behavioral familiarization effects for LF nonwords. The results show that the posterior superior temporal gyrus plays a fundamental role during phonological learning. Its relationship to sublexical and lexical phonological processing as well as to phonological short-term memory is discussed.     

The anatomy of auditory word processing: individual variability

This study used functional magnetic resonance imaging (fMRI) to investigate the neural substrate underlying the processing of single words, comparing activation patterns across subjects and within individuals. In a word repetition task, subjects repeated single words aloud with instructions not to move their jaws. In a control condition involving reverse speech, subjects heard a digitally reversed speech token and said aloud the word "crime." The averaged fMRI results showed activation in the left posterior temporal and inferior frontal regions and in the supplementary motor area, similar to previous PET studies. However, the individual subject data revealed variability in the location of the temporal and frontal activation. Although these results support previous imaging studies, demonstrating an averaged localization of auditory word processing in the posterior superior temporal gyrus (STG), they are more consistent with traditional neuropsychological data, which suggest both a typical posterior STG localization and substantial individual variability. By using careful head restraint and movement analysis and correction methods, the present study further demonstrates the feasibility of using overt articulation in fMRI experiments.     

没听到？“听”到！——来自听觉表象神经机制研究的证据

近年来听觉表象开始得到关注,相关研究包括言语声音、音乐声音、环境声音的听觉表象三类。本文梳理了认知神经科学领域对上述三种听觉表象所激活的脑区研究,比较了听觉表象和听觉对应脑区的异同,并展望了听觉表象未来的研究方向。     

Cortical integration of audio–visual speech and non-speech stimuli

Using fMRI we investigated the neural basis of audio–visual processing of speech and non-speech stimuli using physically similar auditory stimuli (speech and sinusoidal tones) and visual stimuli (animated circles and ellipses). Relative to uni-modal stimuli, the different multi-modal stimuli showed increased activation in largely non-overlapping areas. Ellipse-Speech, which most resembles naturalistic audio–visual speech, showed higher activation in the right inferior frontal gyrus, fusiform gyri, left posterior superior temporal sulcus, and lateral occipital cortex. Circle-Tone, an arbitrary audio–visual pairing with no speech association, activated middle temporal gyri and lateral occipital cortex. Circle-Speech showed activation in lateral occipital cortex, and Ellipse-Tone did not show increased activation relative to uni-modal stimuli. Further analysis revealed that middle temporal regions, although identified as multi-modal only in the Circle-Tone condition, were more strongly active to Ellipse-Speech or Circle-Speech, but regions that were identified as multi-modal for Ellipse-Speech were always strongest for Ellipse-Speech. Our results suggest that combinations of auditory and visual stimuli may together be processed by different cortical networks, depending on the extent to which multi-modal speech or non-speech percepts are evoked.     

Simulating single word processing in the classic aphasia syndromes based on the Wernicke-Lichtheim-Geschwind theory

The Wernicke-Lichtheim-Geschwind (WLG) theory of the neurobiological basis of language is of great historical importance, and it continues to exert a substantial influence on most contemporary theories of language in spite of its widely recognized limitations. Here, we suggest that neurobiologically grounded computational models based on the WLG theory can provide a deeper understanding of which of its features are plausible and where the theory fails. As a first step in this direction, we created a model of the interconnected left and right neocortical areas that are most relevant to the WLG theory, and used it to study visual-confrontation naming, auditory repetition, and auditory comprehension performance. No specific functionality is assigned a priori to model cortical regions, other than that implicitly present due to their locations in the cortical network and a higher learning rate in left hemisphere regions. Following learning, the model successfully simulates confrontation naming and word repetition, and acquires a unique internal representation in parietal regions for each named object. Simulated lesions to the language-dominant cortical regions produce patterns of single word processing impairment reminiscent of those postulated historically in the classic aphasia syndromes. These results indicate that WLG theory, instantiated as a simple interconnected network of model neocortical regions familiar to any neuropsychologist/neurologist, captures several fundamental "low-level" aspects of neurobiological word processing and their impairment in aphasia.     

Multichannel fNIRS assessment of overt and covert confrontation naming

Confrontation naming tasks assess cognitive processes involved in the main stage of word production. However, in fMRI, the occurrence of movement artifacts necessitates the use of covert paradigms, which has limited clinical applications. Thus, we explored the feasibility of adopting multichannel functional near-infrared spectroscopy (fNIRS) to assess language function during covert and overt naming tasks. Thirty right-handed, healthy adult volunteers underwent both naming tasks and cortical hemodynamics measurement using fNIRS. The overt naming task recruited the classical left-hemisphere language areas (left inferior frontal, superior and middle temporal, precentral, and postcentral gyri) exemplified by an increase in the oxy-Hb signal. Activations were bilateral in the middle and superior temporal gyri. However, the covert naming task recruited activation only in the left-middle temporal gyrus. The activation patterns reflected a major part of the functional network for overt word production, suggesting the clinical importance of fNIRS in the diagnosis of aphasic patients.     

汉语双字词在心理词典中的表征方式:来自fNIRS的证据

以汉语双字构成的真词与假词为实验材料,22名大学生为被试,采用功能性近红外脑成像技术(f NIRS)和事件相关设计,考察被试在完成词汇判断任务时的大脑激活模式,探索汉语双字词在心理词典中的表征方式。结果发现:(1)在完成真假词判断任务时,被试大脑左侧额叶和左侧颞叶均被激活;(2)与判断假词相比,被试在判断真词时显著地激活左额上回和左额中回。这一结果说明汉语双字词在心理词典中是混合表征的。     

视觉词形加工：从脑区到神经通路

视觉词形加工是阅读机制中的重要环节。基于获得性阅读障碍的早期阅读“神经病学模型”对视觉词形加工的神经通路进行了描述。近年来,随着脑功能成像技术的发展和左梭状回中部视觉词形区的发现,研究者们对原有视觉词形加工的神经通路加以补充和修订,并提出了新的模型。该文对视觉词形加工障碍患者的神经心理学研究和正常人视觉词形加工的脑功能成像研究进行了总结,并讨论了研究的局限性,对今后该领域的发展方向进行展望     

The brain adapts to orthography with experience: evidence from English and Chinese

Using functional magnetic resonance imaging (fMRI), we examined the process of language specialization in the brain by comparing developmental changes in two contrastive orthographies: Chinese and English. In a visual word rhyming judgment task, we found a significant interaction between age and language in left inferior parietal lobule and left superior temporal gyrus, which was due to greater developmental increases in English than in Chinese. Moreover, we found that higher skill only in English children was correlated with greater activation in left inferior parietal lobule. These findings suggest that the regions associated with phonological processing are essential in English reading development. We also found greater developmental increases in English than in Chinese in left inferior temporal gyrus, suggesting refinement of this region for fine‐grained word form recognition. In contrast, greater developmental increases in Chinese than in English were found in right middle occipital gyrus, suggesting the importance of holistic visual‐orthographic analysis in Chinese reading acquisition. Our results suggest that the brain adapts to the special features of the orthography by engaging relevant brain regions to a greater degree over development.     

Neural correlates of music recognition in Down syndrome

The brain mechanisms that subserve music recognition remain unclear despite increasing interest in this process. Here we report the results of a magnetoencephalography experiment to determine the temporal dynamics and spatial distribution of brain regions activated during listening to a familiar and unfamiliar instrumental melody in control adults and adults with Down syndrome (DS). In the control group, listening to the familiar melody relative to the unfamiliar melody, revealed early and significant activations in the left primary auditory cortex, followed by activity in the limbic and sensory-motor regions and finally, activation in the motor related areas. In the DS group, listening to the familiar melody relative to the unfamiliar melody revealed increased significant activations in only three regions. Activity began in the left primary auditory cortex and the superior temporal gyrus and was followed by enhanced activity in the right precentral gyrus. These data suggest that familiar music is associated with auditory–motor coupling but does not activate brain areas involved in emotional processing in DS. These findings reveal new insights on the neural basis of music perception in DS as well as the temporal course of neural activity in control adults.     

Aging affects both perceptual and lexical/semantic components of word stem priming: An event-related fMRI study

In this event-related fMRI study, brain activity patterns were compared in extensive groups of young (N=25) and older (N=38) adults, while they were performing a word stem completion priming task. Based on behavioral findings, we tested the hypothesis that aging affects only the lexical/semantic, but not the perceptual component of word stem priming. To this end, we distinguished between priming-related activity reductions in posterior regions involved in visual processing, and regions associated with lexical/semantic retrieval processes, i.e., left lateral temporal and left prefrontal regions. Both groups revealed significant priming-related response time reductions. However, in accordance with earlier findings, a larger priming effect was found in the group of young participants. In line with previous imaging studies, the groups showed common priming-related activity reductions in the anterior cingulate, and the left inferior prefrontal cortex extending into the anterior portion of the left superior temporal gyrus, and at lower thresholds also in the right occipital lobe. However, when directly comparing the groups, greater priming-related reductions were found for the young group in the left anterior superior temporal gyrus and the right posterior occipital lobe. These findings suggest that, converse to current psychological views, aging affects both perceptual and lexical/semantic components of repetition priming.     

How reading acquisition changes children’s spoken language network

To examine the influence of age and reading proficiency on the development of the spoken language network, we tested 6- and 9-years-old children listening to native and foreign sentences in a slow event-related fMRI paradigm. We observed a stable organization of the peri-sylvian areas during this time period with a left dominance in the superior temporal sulcus and inferior frontal region. A year of reading instruction was nevertheless sufficient to increase activation in regions involved in phonological representations (posterior superior temporal region) and sentence integration (temporal pole and pars orbitalis). A top-down activation of the left inferior temporal cortex surrounding the visual word form area, was also observed but only in 9 year-olds (3 years of reading practice) listening to their native language. These results emphasize how a successful cultural practice, reading, slots in the biological constraints of the innate spoken language network.     

TIME COURSE OF ACTIVATING BRAIN AREAS IN GENERATING VERBAL ASSOCIATIONS

Abstract— Generating a use far a visual word in comparison with reading the word aloud activates frontal attention areas first (170 MS), a left lateral frontal area next (250 ms), and then a left temporoparietal (Wernicke's) area (650 ms). A brief period of practice reduces these activations. If subjects are asked to respond to a word from the same practiced list by giving a novel use, the original activations reappear and are joined by activity similar in location and time to Wernicke's activation but in the right hemisphere. These findings demonstrate the time course of activations of neuroanatomical areas in word processing and indicate a role for the right hemisphere when semantic processing is more difficult, such as in generating a less frequent association in the presence of a highly practiced one.     

Neural correlates of morphological decomposition in a morphologically rich language: an fMRI study

By employing visual lexical decision and functional MRI, we studied the neural correlates of morphological decomposition in a highly inflected language (Finnish) where most inflected noun forms elicit a consistent processing cost during word recognition. This behavioral effect could reflect suffix stripping at the visual word form level and/or subsequent meaning integration at the semantic-syntactic level. The first alternative predicts increased activation for inflected vs. monomorphemic words in the left occipitotemporal cortex while the second alternative predicts left inferior frontal gyrus and/or left posterior temporal activation increases. The results show significant activation effects in the latter areas. This provides support for the second alternative, i.e., that the morphological processing cost stems from the semantic-syntactic level.