Arcuate fasciculus and speech in congenital bilateral perisylvian syndrome

Standard magnetic resonance imaging can diagnose congenital bilateral perisylvian polymicrogyria, but is limited in explaining the heterogeneous clinical spectrum of the related congenital bilateral perisylvian syndrome, characterized by pseudobulbar dysfunction, developmental delay, and epilepsy. We analyzed arcuate fasciculi using diffusion tensor imaging, a major language tract in the perisylvian region interconnecting the Broca and Wernicke areas, and at high risk of becoming developmentally affected in this condition. Six patients with congenital bilateral perisylvian syndrome underwent diffusion tensor imaging and were evaluated. The arcuate fasciculus was manually isolated, using tractography. The tract was identified in three patients who had developed speech, and whose values for various diffusion parameters were similar to those in age-matched controls (patients/controls means: fractional anisotropy, 0.50/0.52; apparent diffusion coefficient, 0.0022/0.0022 mm(2)/second; P = ns for both). However, in three patients with severe impairment and no speech development, the arcuate fasciculus could not be identified by fiber-tracking. In this small series, the absence of arcuate fasciculi on diffusion tensor imaging correlated with a more severe phenotype, which cannot be appreciated via structural magnetic resonance imaging alone.     

多模态影像联合电生理监测在脑功能区胶质瘤手术中的应用研究

目的研究多模态影像联合电生理监测技术在脑功能区胶质瘤手术中的保护脑功能的应用价值。方法回顾性分析5例语言区和55例运动区胶质瘤患者的临床资料。术前行功能磁共振定位功能区,弥散张量成像显示重要传导束,融合多模态影像构建功能神经导航,术中采用皮层体感诱发电位定位中央沟,并运用皮层-皮层下电刺激技术监测语言区、运动区和皮层下重要神经传导束,在保护功能前提下尽可能切除病灶。术后评价肿瘤切除程度和神经功能。结果 5例语言区胶质瘤和30例病变毗邻运动皮层胶质瘤患者术前功能磁共振成功定位功能区,通过弥散张量成像3例语言区胶质瘤和42例运动区胶质瘤患者分别重建出弓状束和锥体束。术中电刺激语言区和运动区检出率分比为100%和92.7%;92.7%的运动区肿瘤患者可通过皮层体感诱发电位技术定位中央沟。术中神经导航对手术具有指导作用。肿瘤影像全切率86.7%,术后功能保留率91.7%。结论运用多模态影像技术有助于术前定位脑功能区,功能神经导航有助于术前规划、术中引导病灶切除,但需注意影像漂移。术中电生理监测技术是定位和保护脑功能结构的主要手段。     

Abnormal language pathway in children with Angelman syndrome

Angelman syndrome is a genetic disorder characterized by pervasive developmental disability with failure to develop speech. We examined the basis for severe language delay in patients with Angelman syndrome by diffusion tensor imaging. Magnetic resonance imaging/diffusion tensor imaging was performed in 7 children with genetically confirmed Angelman syndrome (age 70 ± 26 months, 5 boys) and 4 age-matched control children to investigate the microstructural integrity of arcuate fasciculus and other major association tracts. Six of 7 children with Angelman syndrome had unidentifiable left arcuate fasciculus, while all control children had identifiable arcuate fasciculus. The right arcuate fasciculus was absent in 6 of 7 children with Angelman syndrome and 1 of 4 control children. Diffusion tensor imaging color mapping suggested aberrant morphology of the arcuate fasciculus region. Other association tracts, including uncinate fasciculus, inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, and corticospinal tract, were identifiable but manifested decreased fractional anisotropy in children with Angelman syndrome. Increased apparent diffusion coefficient was seen in all tracts except uncinate fasciculus when compared to control children. Patients with Angelman syndrome have global impairment of white matter integrity in association tracts, particularly the arcuate fasciculus, which reveals severe morphologic changes. This finding could be the result of a potential problem with axon guidance during brain development, possibly due to loss of UBE3A gene expression.     

Reorganization of the right arcuate fasciculus following left arcuate fasciculus resection in children with intractable epilepsy

The authors evaluated postsurgical reorganization of the arcuate fasciculus longitudinally using diffusion tensor imaging in 10 children with intractable epilepsy, whose resections included the left arcuate fasciculus. Evaluation of fractional anisotropy before and after surgery (mean follow-up: 7.5 months) showed a significant increase (P = .002) in the right arcuate fasciculus during follow-up. There was marked enlargement of the right arcuate fasciculus postsurgically in 8 patients. The change in right arcuate fasciculus fractional anisotropy values showed a positive correlation with interval between resection and postsurgical magnetic resonance imaging (MRI) (P = .044). Comparison of 10 age-matched controls to patients pre- and postsurgery showed significantly reduced presurgery fractional anisotropy in the left (P = .018) and right (P = .036) arcuate fasciculus and no difference in postsurgery fractional anisotropy in the right arcuate fasciculus (P = .399) in patients. These findings suggest a compensatory reorganization in the right arcuate fasciculus in children with intractable epilepsy following left arcuate fasciculus resection.     

Perisylvian language networks of the human brain

Early anatomically based models of language consisted of an arcuate tract connecting Broca's speech and Wernicke's comprehension centers; a lesion of the tract resulted in conduction aphasia. However, the heterogeneous clinical presentations of conduction aphasia suggest a greater complexity of perisylvian anatomical connections than allowed for in the classical anatomical model. This article re-explores perisylvian language connectivity using in vivo diffusion tensor magnetic resonance imaging tractography. Diffusion tensor magnetic resonance imaging data from 11 right-handed healthy male subjects were averaged, and the arcuate fasciculus of the left hemisphere reconstructed from this data using an interactive dissection technique. Beyond the classical arcuate pathway connecting Broca's and Wernicke's areas directly, we show a previously undescribed, indirect pathway passing through inferior parietal cortex. The indirect pathway runs parallel and lateral to the classical arcuate fasciculus and is composed of an anterior segment connecting Broca's territory with the inferior parietal lobe and a posterior segment connecting the inferior parietal lobe to Wernicke's territory. This model of two parallel pathways helps explain the diverse clinical presentations of conduction aphasia. The anatomical findings are also relevant to the evolution of language, provide a framework for Lichtheim's symptom-based neurological model of aphasia, and constrain, anatomically, contemporary connectionist accounts of language.     

MR diffusion tensor imaging documented arcuate fasciculus lesion in a patient with normal repetition performance

Background: The pathophysiology of the syndrome of conduction aphasia has been thought to involve a disconnection between posterior and anterior language areas. The arcuate fasciculus has been one of the principal candidates for an anatomical link between Wernicke's and Broca's area, but direct evidence for its involvement in conduction aphasia has been difficult to obtain. Aims: The purpose of this study was to examine white matter tract integrity, using the novel magnetic resonance imaging technique of diffusion tensor imaging, in a patient with transcortical aphasia. Methods & Procedures: A case study of a 55-year-old, right-handed man with aphasia following a left hemisphere stroke is reported. The patient's language performance was assessed with the Boston Diagnostic Aphasia Examination twice: at 10 days and at 2 years after his stroke. An MR diffusion tensor imaging study was obtained approximately 2 years after his stroke using the 1.5 T Phillips Gyroscan NT system. White matter fibre tracts maps were reconstructed using the “FACT” algorithm. Outcomes and Results: Ten days after his stroke, the patient had a non-fluent aphasia with marked impairment of both auditory comprehension and spontaneous speech. However, repetition was relatively intact. By 2 years, when the MR diffusion tensor imaging study was performed, repetition was completely normal and the patient had only subtle deficits in areas of naming and auditory comprehension. The MR diffusion tensor imaging study revealed a lesion of the dominant hemisphere arcuate fasciculus. Conclusions: This study documents normal repetition performance in a patient who on subsequent MR diffusion tensor imaging was found to have a lesion involving the dominant hemisphere arcuate fasciculus lesion. This case adds to previously published cases of normal repetition performance despite a documented lesion of the arcuate fasciculus, and thus further challenges the traditional model of conduction aphasia invoking a critical role of this white matter tract. Our case also suggests that MR diffusion tensor imaging may be a potentially useful technique to evaluate regional involvement of specific white matter tract projections in patients with aphasia.     

术中磁共振联合显微镜下导航在难治性癫癎脑深部小病变切除术中的应用

目的探讨术中MRI联合显微镜下导航在难治性癫癎病人脑深部小病灶切除中的价值。方法回顾性分析10例脑深部小病灶难治性癫癎病人的临床资料,所有病人行弥散张量纤维束重建,并在术中MRI及显微镜导航下切除病灶,记录骨瓣的大小、手术时间、病灶移位距离、术中MRI扫描次数、术后癫癎发作情况及功能缺失情况。结果本组病人开颅骨窗（44.60±9.19）cm2,手术时间（3.99±0.81）h,病变移位距离（10.50±2.92）mm。病灶移位距离与骨瓣大小、手术时间无明显关系（P〉0.05）。所有病人术中MRI共扫描19次,病灶全部切除。5例病人术后出现肢体偏瘫及视野缺失,术后1年症状改善。术后1年随访癫癎控制疗效：EngelⅠ级5例,Ⅱ级2例,Ⅲ级2例,Ⅳ级1例。结论在伴有癫癎的脑深部小病灶切除术中,应用术中MRI可以及时纠正病灶移位,减少术后神经功能缺失,疗效肯定。     

Language lateralization in temporal lobe epilepsy using functional MRI and probabilistic tractography

Purpose: Language functional magnetic resonance imaging (fMRI) is used to noninvasively assess hemispheric language specialization as part of the presurgical work-up in temporal lobe epilepsy (TLE). White matter asymmetries on diffusion tensor imaging (DTI) may be related to language specialization as shown in controls and TLE. To refine our understanding of the effect of epilepsy on the structure–function relationships, we focused on the arcuate fasciculus (ArcF) and the inferior occipitofrontal fasciculus (IOF) and tested the relationship between DTI- and fMRI-based lateralization indices in TLE.
Methods: fMRI with three language tasks and DTI were obtained in 20 patients (12 right and 8 left TLE). The ArcF, a major language-related tract, and the IOF were segmented bilaterally using probabilistic tractography to obtain fractional anisotropy (FA) lateralization indices. These were correlated with fMRI-based lateralization indices computed in the inferior frontal gyrus (Pearson's correlation coefficient).
Results: fMRI indices were left-lateralized in 16 patients and bilateral or right-lateralized in four. In the ArcF, FA was higher on the left than on the right side, reaching significance in right but not in left TLE. We found a positive correlation between ArcF anisotropy and fMRI-based lateralization indices in right TLE (p < 0.009), but not in left TLE patients. No correlation was observed for the IOF.
Conclusions: Right TLE patients with more left-lateralized functional activations also showed a leftward-lateralized arcuate fasciculus. The decoupling between the functional and structural indices of the ArcF underlines the complexity of the language network in left TLE patients.     

Aberrations in the arcuate fasciculus are associated with auditory verbal hallucinations in psychotic and in non‐psychotic individuals

The pathophysiology of auditory verbal hallucinations (AVH) is still unclear. Cognitive as well as electrophysiological studies indicate that a defect in sensory feedback (corollary discharge) may contribute to the experience of AVH. This could result from disruption of the arcuate fasciculus, the major tract connecting frontal and temporo‐parietal language areas. Previous diffusion tensor imaging studies indeed demonstrated abnormalities of this tract in schizophrenia patients with AVH. It is, however, difficult to disentangle specific associations with AVH in this patient group as many other factors, such as other positive and negative symptoms, medication or halted education could likewise have affected tract integrity. We therefore investigated AVH in relative isolation and studied a group of non‐psychotic individuals with AVH as well as patients with AVH and non‐hallucinating matched controls. We compared tract integrity of the arcuate fasiculus and of three other control tracts, between 35 non‐psychotic individuals with AVH, 35 schizophrenia patients with AVH, and 36 controls using diffusion tensor imaging and magnetization transfer imaging. Both groups with AVH showed an increase in magnetization transfer ratio (MTR) in the arcuate fasciculus, but not in the other control tracts. In addition, a general decrease in fractional anisotropy (FA) for almost all bundles was observed in the patient group, but not in the non‐psychotic individuals with AVH. As increased MTR in the arcuate fasciculus was present in both hallucinating groups, a specific association with AVH seems plausible. Decreases in FA, on the other hand, seem to be related to other disease processes of schizophrenia. Hum Brain Mapp, 2013. © 2011 Wiley Periodicals, Inc.     

Diffusion tensor analysis of temporal and extra-temporal lobe tracts in temporal lobe epilepsy

OBJECTIVE: To determine whether the major temporal lobe white matter tracts in patients with temporal lobe epilepsy manifest abnormal water diffusion properties. METHODS: Diffusion tensor MRI measurements were obtained from tractography for uncinate, arcuate, inferior longitudinal fasciculi and corticospinal tract in 13 children with left temporal lobe epilepsy and normal conventional MRI, and the data were compared to measurements in 12 age-matched normal volunteers. The relationship between tensor parameters and duration of epilepsy was also determined. RESULTS: All four tracts in the affected left hemisphere showed lower mean anisotropy, planar and linear indices, but higher spherical index in patients versus controls. Diffusion changes in the left uncinate and arcuate fasciculus correlated significantly with duration of epilepsy. Arcuate fasciculus showed a reversal of the normal left-right asymmetry. Various diffusion abnormalities were also seen in the four tracts studied in the right hemisphere. CONCLUSION: Our findings indicate abnormal water diffusion in temporal lobe and extra-temporal lobe tracts with robust changes in the direction perpendicular to the axons. Diffusion abnormalities associated with duration of epilepsy suggest progressive changes in ipsilateral uncinate and arcuate fasciculus due to chronic seizure activity. Finally, our results in arcuate fasciculus are consistent with language reorganization to the contralateral right hemisphere.     

3.0T 术中磁共振实时影像功能导航联合术中神经电生理监测技术在岛叶胶质瘤手术中的应用

目的评价3.0 T术中磁共振成像(intraoperative magnetic resonance imaging,iMRI)联合弥散张量成像(diffusion tensor imaging,DTI)锥体束示踪导航及术中神经电生理监测(intraoperative neurophysiologicalmonitoring,IONM)技术在各种累及岛叶的胶质瘤切除手术中的应用价值。方法 2010年9月至2011年6月以3.0 T iMRI数字一体化神经外科手术中心为平台,在iMRI功能导航结合IONM下对18例累及岛叶的胶质瘤实施切除手术。其中对10例主侧半球肿瘤采用唤醒麻醉下术中直接皮质电刺激进行语言区定位。对所有18例岛叶胶质瘤,术中均采用DTI导航结合术中连续经皮质刺激运动诱发电位和皮质下电刺激进行锥体束定位。结果通过iMRI实时扫描,18例患者中有13例发现肿瘤残留,其中6例在iMRI实时影像导航下获得了进一步切除,使肿瘤的影像学全切除率从5/18提高至9/18。经Fisher检验,iMRI前、后的肿瘤切除率(包括全切除及次全切除)具有统计学意义(P=0.046)。9例因DTI导航或IONM提示切缘临近功能皮质或深部锥体束,而未强求全切除。10例主侧半球肿瘤患者中,术后近期(1周内)出现一过性语言功能障碍5例,随访至术后1个月,语言功能均恢复到术前水平或以上;18例患者中3例术后近期出现肢体运动功能障碍,随访至术后1个月,其中2例完全恢复。总体术后1个月的神经功能障碍仅1例。无iMRI及IONM相关的并发症发生。结论应用3.0 T iMRI术中实时影像导航联合DTI锥体束示踪成像技术及IONM技术有助于最大程度地安全切除岛叶胶质瘤。     

Plasticity of language pathways in patients with low-grade glioma A diffusion tensor imaging study

Knowledge of the plasticity of language pathways in patients with low-grade glioma is important for neurosurgeons to achieve maximum resection while preserving neurological function. The current study sought to investigate changes in the ventral language pathways in patients with low-grade glioma located in regions likely to affect the dorsal language pathways. The results revealed no significant difference in fractional anisotropy values in the arcuate fasciculus between groups or between hemispheres. However, fractional anisotropy and lateralization index values in the left inferior longitudinal fasciculus and lateralization index values in the left inferior fronto-occpital fasciculus were higher in patients than in healthy subjects. These results indicate plasticity of language pathways in patients with low-grade glioma. The ventral language pathways may perform more functions in patients than in healthy subjects. As such, it is important to protect the ventral language pathways intraoperatively.     

Resection of glioma in an fMRI-defined “split” Broca’s area

Gross total resection of gliomas can be limited by the involvement of tumor in eloquent areas. Moreover, lesions can impart cortical reorganization and make the precise determination of hemispheric dominance and localization of language function even more difficult. Preoperative mapping with functional magnetic resonance imaging (fMRI), intraoperative imaging modalities, and intraoperative direct cortical stimulation enable surgeons to map the functional topography of the brain in relation to the tumor and perform a safe maximal resection. In this report, we present a patient with left frontal glioma of complex morphology, wherein the tumor was enveloped by Broca’s area on fMRI. Intraoperative mapping and intraoperative magnetic resonance imaging (iMRI) allowed gross total resection of the tumor with preservation of language function and illustrate the utility of multiple contemporary modalities in the surgical management of low-grade gliomas located in eloquent cortices.     

Verifying the hypothesis of disconnection syndrome in patients with conduction aphasia using diffusion tensor imaging

BACKGROUND: It is thought in disconnection theory that connection of anterior and posterior language function areas, i.e. the lesion of arcuate fasciculus causes conduction aphasia. OBJECTIVE: To verify the theory of disconnection elicited by repetition disorder in patients with conduction aphasia by comparing the characteristics of diffusion tensor imaging between healthy persons and patients with conduction aphasia. DESIGN: Case-control observation. SETTING: Department of Neurology, Hongqi Hospital Affiliated to Mudanjiang Medical College. PARTICIPANTS: Five male patients with cerebral infarction-involved arcuate fasciculus conduction aphasia, averaged （43±2）years, who hospitalized in the Department of Neurology, Hongqi Hospital Affiliated to Mudanjiang Medical College from February 2004 to February 2005 were involved in this experiment. The involved patients were all confirmed as cerebral infarction by skull CT and MRI, and met the diagnosis criteria revised in 1995 4th Cerebrovascular Conference. They were examined by the method of Aphasia Battery of Chinese (ABC) edited by Surong Gao. The results were poorer than auditory comprehension disproportionately, and consistented with the mode of conduction aphasia. Another 5 male healthy persons, averaged （43±1）years, who were physicians receiving further training in the Department of Neurology, Beijing Tiantan Hospital were also involved in this experiment. Informed consents of detected items were obtained from all the subjects. METHODS: All the subjects were performed handedness assessment with assessment criteria of handedness formulated by Department of Neurology, First Hospital Affiliated to Beijing Medical University. Arcuate fasciculus of involved patients and health controls were analyzed with diffusion tensor imaging (DTI) and divided into 3 parts (anterior, middle and posterior segments) for determining FA value (mean value was obtained after three times of measurements), and a comparison of FA value was made between two sides. MAIN OUTCOME MEASURES: Analysis results of arcuate fasciculus DTI of healthy controls and patients with conduction aphasia. RESULTS: Five patients with conduction aphasia and 5 healthy controls participated in the final analysis. ①All the subjects were right-handedness. ② The left FA value of anterior, middle and posterior segments of arcuate fasciculus was larger than the right one in most normal volunteers, i.e. arcuate fasciculus with normal function on the left side was more than that on the right side. Because the amount of healthy controls was small, so positive conclusion has not been obtained, and only above-mentioned tendency was demonstrated. Healthy controls had good bilateral arcuate fasciculus; Three patients with conduction aphasia presented left FA value of anterior segment of arcuate fasciculus smaller than the right one, and two patients presented the left FA value larger than the right one. Four patients presented the left FA value of middle segment of arcuate fasciculus smaller than the right one, and one patient presented the left FA value larger than the right one, i.e. middle segment of arcuate fasciculus of 5 patients with conduction aphasia was all involved in at different degrees. Four patients with conduction aphasia presented the left FA value of posterior segment of arcuate fasciculus smaller than the right one, and one patient presented the left FA value larger than the right one, i.e. posterior segment of arcuate fasciculus of 5 patients was all injured at different degrees. CONCLUSION: Arcuate fasciculus of patients with conduction aphasia all is involved in at different degrees, which verifies the theory of disconnection of repetition disorder in patients with conduction aphasia.     

Aphasia induced by gliomas growing in the ventrolateral frontal region: assessment with diffusion MR tractography, functional MR imaging and neuropsychology

IntroductionLesions in the ventrolateral region of the dominant frontal lobe have been historically associated with aphasia. Recent imaging results suggest that frontal language regions extend beyond classically defined Broca’s area to include the ventral precentral gyrus (VPCG) and the arcuate fasciculus (AF). Frontal gliomas offer a unique opportunity to identify structures that are essential for speech production. The aim of this prospective study was to investigate the correlation between language deficits and lesion location in patients with gliomas.MethodsNineteen patients with glioma and 10 healthy subjects were evaluated with diffusion tensor imaging magnetic resonance (MR) tractography, functional MR (verb generation task) and the Aachener Aphasie Test. Patients were divided into two groups according to lesion location with respect to the ventral precentral sulcus: (i) anterior (n = 8) with glioma growing in the inferior frontal gyrus (IFG) and underlying white matter; (ii) posterior (n = 11) with glioma growing in the VPCG and underlying white matter. Virtual dissection of the AF, frontal intralobar tract, uncinate fasciculus (UF) and inferior frontal occipital fasciculus (IFOF) was performed with a deterministic approach.ResultsSeven posterior patients showed aphasia classified as conduction (4), Broca (1), transcortical motor (1) and an isolated deficit of semantic fluency; one anterior patient had transcortical mixed aphasia. All posterior patients had invasion of the VPCG, however only patients with aphasia had also lesion extension to the AF as demonstrated by tractography dissections. All patients with language deficits had high grade glioma. Groups did not differ regarding tumour volume. A functional pars opercularis was identified with functional MR imaging (fMRI) in 17 patients.ConclusionsGliomas growing in the left VPCG are much more likely to cause speech deficits than gliomas infiltrating the IFG, including Broca’s area. Lesion extension to the AF connecting frontal to parietal and temporal regions is an important mechanism for the appearance of aphasia.     

A sensitive diffusion tensor imaging quantification method to detect language laterality in children: correlation with the Wada test

Using diffusion tensor imaging tractography and color-coded anisotropy map quantification, we investigated asymmetry of the arcuate fasciculus to determine language laterality in children and compared it with the Wada test. Arcuate fasciculus volume and fractional anisotropy were measured after tractography. We also quantified the fiber orientation distribution in the arcuate fasciculus region, ie, the fraction of arcuate fasciculus fibers oriented in the anteroposterior and mediolateral directions. A Laterality Index was calculated for each of the measured parameters. Volumetric analysis of the arcuate fasciculus showed asymmetry favoring the language dominant hemisphere (P = .02), while fractional anisotropy showed no significant asymmetry (P = .07). The mean anteroposterior and mediolateral components on the language dominant side were significantly higher than on the nondominant side (P = .003 and .002, respectively). The Laterality Index values were concordant with the Wada test results except for 1 case. Fractional anisotropy also falsely lateralized language in 1 case.     

传导性失语双向分布学说的验证

目的通过分析扩散张量成像及传导性失语患者言语障碍的特点,验证传导性失语发病机制的双向分布学说。方法对5例传导性失语患者和5例健康自愿者进行北京医科大学附属第一医院神经内科制定的利手评定标准判断进行利手评定,对传导性失语患者进行口语流利型评定,应用扩散张量成像分析所有入选者的Broca区和Wer- nicke区的情况。结果1例患者为非流利型口语,其他4例为流利型口语;入选者均为右利手,传导性失语患者的Broca区和Wernicke区与正常对照组相比均有不同程度的受损,如痛变靠近Broca区则引起非流利型口语,如病变靠近Wernicke区,则为流利型口语,患者听理解障碍严重。结论传导性失语患者的Broca区和Wernicke区均可受累,损伤的部位不同,传导性失语言语障碍的特点也不同。     

Structural and functional asymmetry of the language network emerge in early childhood

Structural and functional neuroimaging studies show language and reading processes are left-lateralized, and associated with a dispersed group of left brain regions. However, it is unclear when and how asymmetry of these regions emerges. We characterized the development of structural and functional asymmetry of the language network in 386 datasets from 117 healthy children (58 male) across early childhood (2–7.5 years). Structural asymmetry was investigated using diffusion tensor imaging (DTI) and manual delineation of the arcuate fasciculus. Functional connectivity asymmetry was calculated from seed regions in the inferior frontal gyrus (IFG) and middle temporal gyrus (MTG). We show that macrostructural asymmetry of the arcuate fasciculus is present by age 2 years, while leftward asymmetry of microstructure and functional connectivity with the IFG increases across the age range. This emerging microstructural and functional asymmetry likely underlie the development of language and reading skills during this time.     

Microstructural alterations of the arcuate fasciculus in schizophrenia patients with frequent auditory verbal hallucinations

Auditory verbal hallucinations (AVH) is a common and stressful symptom of schizophrenia. Disrupted connectivity between frontal and temporo-parietal language areas, giving rise to the misattribution of inner speech, is speculated to underlie this phenomenon. Disrupted connectivity should be reflected in the microstructure of the arcuate fasciculi (AF); the main connection between frontal and temporo-parietal language areas. In this study we compared microstructural properties of the AF and three other fiber tracts (cortical spinal tract, cingulum and uncinate fasciculus), between 44 schizophrenia patients with chronic severe hallucinations and 42 control subjects using diffusion tensor imaging (DTI) and magnetic transfer imaging (MTI). The DTI scans were used to compute fractional anisotropy (FA) and to reconstruct the fiber bundles of interest, while the MTI scans were used to compute magnetic transfer ratio (MTR) values. The patient group showed a general decrease in FA for all bundles. In the arcuate fasciculus this decreased FA was coupled to a significant increase in MTR values. A correlation was found between mean MTR values in both arcuate fasciculi and the severity of positive symptoms. The combination of decreased FA and increased MTR values observed in the arcuate fasciculi in patients suggests increased free water concentrations, probably caused by degraded integrity of the axons or the supportive glia cells. This suggests that disintegrated fiber integrity in the connection between frontal and temporo-parietal language areas in the schizophrenia patients is associated with their liability for auditory verbal hallucinations.     

脑白质疏松症患者弥散张量成像及与认知功能的相关性

Abstract Background and aims　Diffusion tensor imaging(DTI) 技术能够检测脑白质微结构的变化, Correlation with vascular risk factors and cognitive dysfunction seems to be feasible using this technique. We aimed to应用DTI检查leukoaraiosis (LA)病灶的fraction anisotropy (FA)值 and average diffusion coefficient(Dcavg)与LA严重程度的关系,探讨常规MRI检查正常的脑白质微结构在DTI 中的变化及与认知功能的相关性。方法　对60例LA 患者和30名健康老年人行DTI 检查,测量LA病灶和正常白质区域的DCavg、FA值。采用简明精神状态量表(MMSE)进行评价认知功能。结果 LA程度越严重,DCavg值越高,呈正相关;FA 值越低,呈负相关。神经心理学测试(简易智能精神状态量表,MMSE) 与LA患者的正常脑白质区域的DCavg、FA值明显相关,尤其是前角白质、半卵圆中心的正常脑白质。结论　DTI 检查LA ,其DCavg、FA值显示出特征性的改变,DTI能够发现常规MRI检查正常的脑白质微结构改变,且这种改变与认知功能相关。