静态功能磁共振分析方法在脑胶质瘤术前语言皮质定位中的初步应用

目的 探讨静态功能磁共振(rsfMRI)分析方法在脑胶质瘤术前语言皮质定位中的应用价值.方法 12例主侧半球脑胶质瘤患者行术前rsfMRI,结合语言任务态血氧饱和依赖功能磁共振成像(BOLD fMRI)定位脑语言皮质,采用唤醒开颅结合术中皮质电刺激验证rsfMRI定位语言皮质的敏感性.结果 12例成功行rsfMRI扫描,10例配合完成语言BOLD fMRI扫描.12例唤醒开颅成功,每例各定位1～7个皮质语言阳性位点,共46个.其中22个语言阳性位点在rsfMRI上显示,其显示语言区的敏感度为47.8％(22/46,12例),13个语言阳性位点在语言BOLD fMRI上表现为激活,敏感度为35.1％(13/37,10例).结论 rsfMRI有助于脑胶质瘤术前语言区定位,但其敏感性有待提高.     

Beta EEG band: A measure of functional brain damage and language reorganization in aphasic patients after recovery

Functional reorganization of language was investigated in a group of eleven non-fluent aphasic patients after linguistic recovery and in a group of matched healthy adults. The ElectroEncephaloGram (EEG) was recorded from 38 scalp electrodes and high-beta band (21–28 Hz), an index of cognitive cortical arousal, was computed as normalized percentage across 0–100 Hz spectral range in six electrode clusters during three linguistic tasks: Phonological, Semantic and Orthographic/visuo-perceptual. During the Phonological task, controls showed greater beta activation on left versus right central cluster, whereas aphasic patients exhibited an inverted pattern of lateralization. In addition, patients' left central cluster, located over the core lesion, showed reduced beta activity with respect to controls. A similar inhibited activation was found in aphasics' left posterior cluster located over undamaged areas. At left anterior locations, aphasics, unlike controls, exhibited larger left versus right beta activity during both Phonological and Orthographic/visuo-perceptual tasks. Results point to substantial reorganization of language in recovered non-fluent aphasics at left prefrontal sites located anterior to the damaged Broca's area and inhibited language-related activation in left posterior undamaged, but disconnected, regions.     

Mixed language dominance: insights from a case of unexpected fluent aphasia with semantic jargon resulting from massive left perisylvian lesion

We report a right-handed patient with a massive lesion in left perisylvian language cortex, who unexpectedly presented with fluent aphasia with semantic jargon. Language deficits were assessed with a comprehensive battery of language tests. Comprehension, naming, reading, and writing were severely impaired, and verbal expression was moderately fluent with semantic jargon. Although the patient’s lesion included brain areas typically essential for motor speech coordination, he was neither nonfluent nor apraxic. He exhibited strikingly unexpected aphasia with semantic jargon and prominent comprehension deficits, suggesting that this is a case of mixed dominance: the right hemisphere likely controls motor speech and basic syntactic skills, while the severely damaged left hemisphere controls semantic processing, predictably severely impaired.     

Promoting strategic television viewing in the context of progressive language impairment

Background: Television viewing is one of the most common and readily accessible leisure pursuits in the developed world today. Unfortunately, access to this powerful form of mass communication is frequently diminished in individuals experiencing progressive language impairment, with deficits in both the comprehension and expression of television content reported from the very early stages of the illness. Considering the wide appeal of television viewing in today's culture, it seems reasonable to conclude that improving access to television content should be considered as an ecologically valid goal for intervention in clinical populations with progressive language impairment who have demonstrated difficulties comprehending and speaking about this powerful form of mass communication. This consideration becomes more pressing when we attend to recent research highlighting the potential neuroprotective effect of engagement in cognitively and intellectually stimulating social and leisure pursuits by individuals with dementing illness.

Aims: This pilot therapy programme aimed to explore the effectiveness of aphasia‐friendly television viewing formats for improving discourse comprehension and production in people with progressive language impairment. It was predicted that following intervention, group participants would (1) recall significantly more story information units from the episode, (2) achieve higher transactional success, and (3) demonstrate improved comprehension when viewing aphasia‐friendly television episodes than they did prior to group intervention.

Methods & Procedures: Four participants with progressive language impairment attended eight sessions of group‐based intervention as part of their usual language therapy programme. Each session aimed to instantiate strategic television viewing capabilities in participants through the application of aphasia‐friendly television viewing principles to novel episodes of a popular 30‐minute documentary programme. Repeated measures ANOVA was used to analyse the differences between participants' pre‐therapy viewing patterns and supported post‐therapy measures of episode‐related story information unit production, while paired t‐tests were used for analysis of discourse comprehension measures.

Outcomes & Results: Participants demonstrated significant increases in story information unit reporting and comprehension indicated by performance on concrete and opinion based questions post‐therapy. There was no significant difference in participants' post‐therapy comprehension of inferential questions.

Conclusions: This pilot therapy programme affirms the prediction that aphasia‐friendly television viewing formats are successful in achieving significant improvements in episode related discourse production, communication effectiveness, comprehension of concrete question forms, and opinion generation in individuals with progressive language impairment. It supports the notion that novel, ecologically based intervention techniques can be beneficial in enhancing access to preferred leisure activities in individuals with progressive language impairment.     

Divergence between functional magnetic resonance imaging and clinical indicators of language dominance in preoperative language mapping

Accurate determination of hemispheric language dominance prior to epilepsy surgery is critically important to minimize cognitive morbidity. Functional MRI (fMRI) is a noninvasive method that is highly concordant with other clinical indicators of language laterality, and is now commonly used to confirm language dominance. However, there is also a high frequency of divergence between fMRI findings and other clinical indices that complicate determination of dominance and surgical decision‐making in individual patients. Despite this, divergent cases are rarely published or discussed. This article provides three illustrative examples to demonstrate common scenarios where fMRI may produce conflicting or otherwise difficult‐to‐interpret findings. We will also discuss potential reasons for divergence and propose a flow‐chart to aid clinical decision making in such situations.     

Atypical language impairment in two siblings: relationship with electrical status epilepticus during slow wave sleep

We report the case of a young girl who presented severe learning disabilities in oral and written language related to a continuous spike-waves during slow sleep (CSWS) syndrome. A sleep EEG recording obtained in her younger brother, who presented a clinical pattern suggesting developmental dysphasia, also showed a CSWS syndrome. These two clinical cases underscore the need to look for this syndrome in the siblings of an affected child when learning difficulties appear in a child who previously had normal psychomotor development.     

A systematic review of molecular imaging (PET and SPECT) in autism spectrum disorder: Current state and future research opportunities

Non-invasive positron emission tomography (PET) and single-photon emission computed tomography (SPECT) are techniques used to quantify molecular interactions, biological processes and protein concentration and distribution. In the central nervous system, these molecular imaging techniques can provide critical insights into neurotransmitter receptors and their occupancy by neurotransmitters or drugs. In recent years, there has been an increase in the number of studies that have investigated neurotransmitters in autism spectrum disorder (ASD), while earlier studies mostly focused on cerebral blood flow and glucose metabolism. The underlying and contributing mechanisms of ASD are largely undetermined and ASD diagnosis relies on the behavioral phenotype. Discovery of biochemical endophenotypes would represent a milestone in autism research that could potentially lead to ASD subtype stratification and the development of novel therapeutic drugs. This review characterizes the prior use of molecular imaging by PET and SPECT in ASD, addresses methodological challenges and highlights areas of future opportunity for contributions from molecular imaging to understand ASD pathophysiology.     

颞叶癫痫语言皮层的功能性MR定位研究

目的： 采用功能性ＭＲ对颞叶癫痫患者语言皮层定位, 为研究颞叶癫痫患者语言功能及手术治疗顽固性颞叶癫痫提供新的定位手段; 方法： 对８ 例顽固性颞叶癫痫患者进行颞叶语言皮层的功能性ＭＲ扫描, 作为选择术式的参考依据; 结果： ８ 例患者均发现颞叶皮层出现信号改变, 其中６ 例位于左侧颞叶; ２ 例发现有右侧颞叶活动, ３ 例患者接受阿米妥实验, 与功能ＭＲ结果一致; 术后患者未出现语言功能障碍。结论： 采用功能性ＭＲ可为颞叶癫痫患者语言皮层活动提供可靠的术前判断。     

Remediation of language processing in aphasia: Improving activation and maintenance of linguistic representations in (verbal) short-term memory

Background: Verbal short-term memory (STM) impairments are invariably present in aphasia. Word processing involves a minimal form of verbal STM, i.e., the time course over which semantic and phonological representations are activated and maintained until they are comprehended, produced, or repeated. Thus it is reasonable that impairments of word processing and verbal STM may co-occur. The co-occurrence of language and STM impairments in aphasia has motivated an active area of research that has revealed much about the relationship of these two systems and the effect of their impairment on language function and verbal learning (Freedman & Martin, 2001 Freedman, M. L. and R. Martin, R. C. 2001. Dissociable components of short-term memory and their relation to long-term learning. Cognitive Neuropsychology, 18: 193–226. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar]; Martin & Saffran, 1999 Martin, N. and Saffran, E.M. 1999. Effects of word processing and short-term memory deficits on verbal learning: Evidence from aphasia. International Journal of Psychology, 34(5/6): 330–346. [Web of Science ®] , [Google Scholar]; Trojano & Grossi, 1995 Trojano, L. and Grossi, D. 1995. Phonological and lexical coding in verbal short-term-memory and learning. Brain and Language, 51(2): 336–354.  [Google Scholar]). In keeping with this view a number of researchers have developed treatment protocols to improve verbal STM in order to improve language function (e.g., Koenig-Bruhin & Studer-Eichenberger, 2007 Koenig-Bruhin, M. and Studer-Eichenberger, F. 2007. Therapy of verbal short-term memory disorders in fluent aphasia: A single case study. Aphasiology, 21(5): 448–458. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar]). This account of aphasia predicts that treatment of a fundamental ability, such as STM, which supports language function, should lead to improvements that generalise to content and tasks beyond those implemented in treatment.

Aims: We investigated the efficacy of a treatment for language impairment that targets two language support processes: verbal short-term memory (STM) and executive processing, in the context of a language task (repetition). We hypothesised that treatment of these abilities would improve repetition abilities and performance on other language tasks that require STM.

Method: A single-participant, multiple-baseline, multiple-probe design across behaviours was used with a participant with conduction aphasia. The treatment involved repetition of words and nonwords under three “interval” conditions, which varied the time between hearing and repeating the stimulus. Measures of treatment effects included acquisition, maintenance, and follow-up data, effect sizes, and pre- and post-treatment performance on a test battery that varies the STM and executive function demands of language tasks.

Outcomes & Results: Improvement of repetition was mostly specific to treated stimuli. Post-treatment measures of language ability indicated improvements in single and multiple word processing tasks, verbal working memory tasks, and verbal span.

Conclusions: Treatment of STM and executive processes in the context of a word repetition task resulted in improvements in other non-treated language tasks. The approach used in this study can be incorporated into other language-processing tasks typically used in treatment of language disorders (e.g., sentence processing).     

Suicidal brains: A review of functional and structural brain studies in association with suicidal behaviour

Evidence of an association between a vulnerability to suicidal behaviour and neurobiological abnormalities is accumulating. Post-mortem studies have demonstrated structural and biochemical changes in the brains of suicide victims. More recently, imaging techniques have become available to study changes in the brain in vivo. This systematic review of comparative imaging studies of suicidal brains shows that changes in the structure and functions of the brain in association with suicidal behaviour are mainly found in the orbitofrontal and dorsolateral parts of the prefrontal cortex. Correlational studies suggest that these changes relate to neuropsychological disturbances in decision-making, problem solving and fluency, respectively. As a consequence, the findings from these studies suggest that suicidal behaviour is associated with (1) a particular sensitivity to social disapproval (2) choosing options with high immediate reward and (3) a reduced ability to generate positive future events. Further study is needed to elaborate these findings and to investigate to what extent changes in the structure and function of suicidal brains are amenable to psychological and/or biological interventions.     

Learning to recognize speakers of a non-native language: implications for the functional organization of human auditory cortex

Brain imaging studies of voice perception often contrast activation from vocal and verbal tasks to identify regions uniquely involved in processing voice. However, such a strategy precludes detection of the functional relationship between speech and voice perception. In a pair of experiments involving identifying voices from native and foreign language speech we show that, even after repeated exposure to the same foreign language speakers, accurate talker identification is in a large part dependent on linguistic proficiency. These results suggest that a strong integration between the brain regions implicated in voice perception and speech perception accounts for the accurate identification of talkers.     

Changes in maps of language function and the integrity of the arcuate fasciculus after therapy for chronic aphasia

A patient with chronic aphasia secondary to unilateral stroke in the left hemisphere underwent language testing, diffusion tensor imaging (DTI), and functional imaging using magnetoencephalography (MEG) at four time points: 3 weeks prior to, immediately prior to, immediately after, and 3 months after Constraint Induced Language Therapy (CILT). Performance on language tests involving visual naming and repetition of spoken sentences improved between the immediately prior to and immediately after CILT testing sessions, but not between the pre-CILT sessions. MEG activation in putative pre-morbid language areas of the left hemisphere and homotopic areas of the right hemisphere increased immediately after therapy, as did integrity within the arcuate fasciculus bilaterally. These changes were not evident between the two pre-CILT sessions. While some of these functional, neurophysiological and structural changes had regressed 3 months after therapy, all remained at or above baseline levels. Results provide evidence for an association between improvement in functional status and the increased integrity within a white matter tract known to be involved in language function and its contralateral homologue, as well as increased neurophysiological activity in areas that have the potential to subserve language function bilaterally.     

The arcuate fasciculus and the disconnection theme in language and aphasia: history and current state

Few themes have been more central to neurological models of aphasia than the disconnection paradigm and the role of the arcuate fasciculus. Introduced by luminaries of 19th Century neurology and resurrected by the charismatic work of Norman Geschwind, the disconnection theme has triggered spectacular advances of modern understanding of language and aphasia. But the disconnection paradigm had alternate fortunes, ranging from irrational exuberance to benign neglect, and its followers have not always shared the same view on its functional consequences and anatomical correlates. Our goal in this paper is, first, to survey the 19th Century roots of the connectionist approach to aphasia and, second, to describe emerging imaging technologies based on diffusion tensor imaging (DTI) that promise to consolidate and expand the disconnection approach to language and its disorders.     

Cerebral reorganization as a function of linguistic recovery in children: An fMRI study

Characterizing and mapping the relationship between neuronal reorganization and functional recovery are essential to the understanding of cerebral plasticity and the dynamic processes which occur following brain damage. The neuronal mechanisms underlying linguistic recovery following left hemisphere (LH) lesions are still unknown. Using functional magnetic resonance imaging (fMRI), we investigated whether the extent of brain lateralization of linguistic functioning in specific regions of interest (ROIs) is correlated with the level of linguistic performance following recovery from acquired childhood aphasia. The study focused on a rare group of children in whom lesions occurred after normal language acquisition, but prior to complete maturation of the brain. During fMRI scanning, rhyming, comprehension and verb generation activation tasks were monitored. The imaging data were evaluated with reference to linguistic performance measured behaviorally during imaging, as well as outside the scanner. Compared with normal controls, we found greater right hemisphere (RH) lateralization in patients. However, correlations with linguistic performance showed that increased proficiency in linguistic tasks was associated with greater lateralization to the LH. These results were replicated in a longitudinal case study of a patient scanned twice, 3 years apart. Additional improvement in linguistic performance of the patient was accompanied by increasing lateralization to the LH in the anterior language region. This, however, was the result of a decreased involvement of the RH. These findings suggest that recovery is a dynamic, ongoing process, which may last for years after onset. The role of each hemisphere in the recovery process may continuously change within the chronic stage.     

Activation of Broca's area during the production of spoken and signed language: a combined cytoarchitectonic mapping and PET analysis

Broca’s area in the inferior frontal gyrus consists of two cytoarchitectonically defined regions—Brodmann areas (BA) 44 and 45. Combining probabilistic maps of these two areas with functional neuroimaging data obtained using PET, it is shown that BA45, not BA44, is activated by both speech and signing during the production of language narratives in bilingual subjects fluent from early childhood in both American Sign Language (ASL) and English when the generation of complex movements and sounds is taken into account. It is BA44, not BA45, that is activated by the generation of complex articulatory movements of oral/laryngeal or limb musculature. The same patterns of activation are found for oral language production in a group of English speaking monolingual subjects. These findings implicate BA45 as the part of Broca’s area that is fundamental to the modality-independent aspects of language generation.     

Threshold-independent functional MRI determination of language dominance: A validation study against clinical gold standards

Functional MRI (fMRI) is often used for presurgical language lateralization. In the most common approach, a laterality index (LI) is calculated on the basis of suprathreshold voxels. However, strong dependencies between LI and threshold can diminish the effectiveness of this technique; in this study we investigated an original methodology that is independent of threshold. We compared this threshold-independent method against the common threshold-dependent method in 14 patients with epilepsy who underwent Wada testing. In addition, clinical results from electrocortical language mapping and postoperative language findings were used to assess the validity of the fMRI lateralization method. The threshold-dependent methodology yielded ambiguous or incongruent lateralization outcomes in 4 of 14 patients in the inferior frontal gyrus (IFG) and in 6 of 14 patients in the supramarginal gyrus (SMG). Conversely, the threshold-independent method yielded unambiguous lateralization in all the patients tested, and demonstrated lateralization outcomes incongruent with clinical standards in 2 of 14 patients in IFG and in 1 of 14 patients in SMG. This validation study demonstrates that the threshold-dependent LI calculation is prone to significant within-patient variability that could render results unreliable; the threshold-independent method can generate distinct LIs that are more concordant with gold standard clinical findings.     

Cerebellar Changes in Partial Seizures: Clinical Correlations of Quantitative SPECT and MRI Analysis

Summary: Purpose: To determine the frequency and patterns of periictal cerebellar hyperperfusion, whether it is associated with increased cerebellar atrophy, and whether cerebellar hyperperfusion and cerebellar atrophy are associated with predisposing clinical factors or with the outcome of epilepsy surgery.
Methods: Periictal and interictal SPECT scans and volumetric brain magnetic resonance imaging (MRI) were quantitatively analyzed in 54 consecutive patients with medically refractory partial epilepsy. Their histories were reviewed and their postsurgical outcomes assessed.
Results: Significant periictal cerebellar hyperperfusion was found in 26 (48.1%) patients, of whom 18 had CCH, two had homolateral cerebellar hyperperfusion (HCH), and six had symmetrical bilateral hyperperfusion (BCH). No relation found between the site of the SPECT seizure localization and the presence or type of cerebellar hyperperfusion. CCH was more common when the injected seizure involved unilateral clonic motor activity (p < 0.05). A smaller MRI relative cerebellar volume (cerebellar volume/cerebral volume) was correlated with a greater seizure frequency (R_s= -0.30; p < 0.05) but not with the duration of epilepsy. There was no difference in the cerebellar volumes between the different patterns of cerebellar perfusion (p > 0.05). However, patients without a focal structural MRI lesion had significantly smaller cerebellar volumes (p < 0.05). In patients who underwent epilepsy surgery (n = 31), there was a trend for those without excellent outcomes to have smaller relative cerebellar volumes than did those with excellent outcome (10.6 vs. 11.8%; p = 0.08).
Conclusions: Periictal changes in cerebellar perfusion, particularly CCH, are common in patients with intractable partial epilepsy. However, periictal hyperperfusion does not appear to be a major contributor to the development of cerebellar atrophy.     

Neural correlates of language comprehension in autism spectrum disorders: when language conflicts with world knowledge

In individuals with ASD, difficulties with language comprehension are most evident when higher-level semantic-pragmatic language processing is required, for instance when context has to be used to interpret the meaning of an utterance. Until now, it is unclear at what level of processing and for what type of context these difficulties in language comprehension occur. Therefore, in the current fMRI study, we investigated the neural correlates of the integration of contextual information during auditory language comprehension in 24 adults with ASD and 24 matched control participants. Different levels of context processing were manipulated by using spoken sentences that were correct or contained either a semantic or world knowledge anomaly. Our findings demonstrated significant differences between the groups in inferior frontal cortex that were only present for sentences with a world knowledge anomaly. Relative to the ASD group, the control group showed significantly increased activation in left inferior frontal gyrus (LIFG) for sentences with a world knowledge anomaly compared to correct sentences. This effect possibly indicates reduced integrative capacities of the ASD group. Furthermore, world knowledge anomalies elicited significantly stronger activation in right inferior frontal gyrus (RIFG) in the control group compared to the ASD group. This additional RIFG activation probably reflects revision of the situation model after new, conflicting information. The lack of recruitment of RIFG is possibly related to difficulties with exception handling in the ASD group.