Neuropsychological And Cognitive Studies In Epilepsy

癫痫不受控制的患者可能会出现与癫痫发作相关的语言和记忆障碍。此外，在考虑手术时，映射这些功能至关重要。我们正在努力使用成像方法来取代更具侵入性的方法来检测癫痫对语言和记忆的影响，并进行术前定位。研究方法：我们使用正电子发射断层扫描（PET）和功能磁共振成像（fMRI）映射颞叶癫痫患者的语言和记忆，以进行功能皮层的无创性评估，并研究癫痫对儿童和成人癫痫患者认知解剖的影响。我们在正常志愿者和癫痫发作不受控制的患者中的研究表明，影像学评估与更具侵入性的程序（如电刺激标测和颈动脉内阿米妥钠试验）相比效果良好。我们还评估了癫痫发作对功能性认知解剖学发展的影响。近期发现： 10名正常儿童在1.5T Signa MRI扫描仪上进行了额叶BOLD回波平面成像，包括语言流畅性范式，隐蔽词生成，字母。研究采用互相关算法进行分析。感兴趣的区域分析用于确定范围和幅度，以及大脑激活的偏侧性。儿童和成人激活相似的区域，主要是在左下额叶皮层（布罗卡？s区）和左额中回（背外侧前额叶皮层）。儿童平均比成人多60%的激活，具有更大程度的AR激活趋势。在IFG和MFG中，儿童的偏侧化程度低于成人，但不显着。结论：在语言流畅性测试中，儿童往往比成人更广泛地激活皮层，但流畅性的激活模式似乎是在童年中期建立的。这样的测试可以应用于儿科患者群体以确定语言优势。在儿童中发现的更大的激活可能反映了作为语言能力基础的神经网络的持续组织的发育可塑性。 功能磁共振成像语言任务很容易识别额叶语言区;时间激活不太一致。没有研究将临床视觉判断与定量感兴趣区域（ROI）分析进行比较。我们使用临床和ROI解释的阅读范例确定了部分癫痫患者的颞叶语言区。30例颞叶癫痫患者，年龄8 ~ 56岁，进行了1.5T fMRI检查。与视觉对照相比，患者默默地说出了一个由句子描述的物体。利用来自t图的ROI分析来分析数据。由三名阅片人在三个t阈值下对t图进行视觉评分。21例患者进行了颈动脉内异戊巴比妥试验（IAT）。功能磁共振阅读任务提供了证据的语言偏侧化的30例患者的ROI分析。25例为左侧优势型，2例为右侧优势型，1例为双侧优势型，2例为非诊断型; IAT和fMRI在大多数患者中一致，3例部分一致，无明显不一致。评价者间一致性范围为0.77至0.82，视觉和ROI阅读与IAT之间的一致性为0.71至0.77。在较低的阈值下查看数据增加了对12名患者进行视觉分析和8名患者进行ROI分析的解释。结论：功能磁共振阅读范式可以识别额叶和颞叶区域的语言优势。临床目视判读与定量ROI分析相当。 视觉词知觉参与言语代码的程度（即，语音再编码）仍然是理解阅读机制的关键问题。在这项研究中，我们使用功能磁共振成像（fMRI）技术结合行为反应措施，以检查神经反应集中与偶然的语音和语义处理的书面文字。三组受试者在语音（押韵判断）或语义（类别判断）为重点的任务或两个任务相同的视觉刺激组简单的按钮按下的反应。在语音任务中，受试者在不同的扫描运行中被分开的单词和假词。基线任务要求对从实验条件的刺激中创建的乱序字母串进行特征搜索。结果表明，当任务要求对词义进行主动加工时，与语义和语音过程相关的皮层区域被强烈激活。然而，当受试者积极处理同一组书面单词的语音时，通常参与语义处理的大脑区域变得沉默。此外，受试者在完成押韵和语义任务时，在前额、颞叶和其他大脑区域表现出多样而显著的双侧激活。总的来说，大脑活动的模式提供了神经基础的证据，支持了这样一种理论：在正常的文字阅读中，语音编码是自动的，有助于书面文字的语义处理，而快速理解词义需要投入注意力。这些结果也提出了关于在同一神经成像会话中包括多个认知任务的问题。 当前研究： 我们正在开发新的模式，特别是使用与事件有关的战略，适合不同年龄组和发展水平（重点是较年轻的年龄组，特别是7岁以下的儿童）。这些研究将主要使用3 T磁体。我们还将设计使用3 T动脉自旋标记的fMRI激活研究，以检查脑血流和BOLD信号反应的发育差异。我们还计划研究颞叶切除术对语言和工作记忆功能解剖的影响。

Patients with uncontrolled epilepsy may have impairment of language and memory associated with their seizures. In addition, it is critical to map these functions when surgery is being considered. We are using imaging methods in an effort to replace more invasive approaches to detecting the effects of epilepsy on language and memory, and for preoperative mapping. Methods: We use positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) to map language and memory in patients with temporal lobe epilepsy to perform non-invasive evaluation of functional cortex, and study the effect of epilepsy on cognitive anatomy in children and adults with seizures. Our studies in both normal volunteers and patients with uncontrolled seizures have shown that imaging evaluation compares well with more invasive procdures such as electrostimulation mapping and the intracarotid sodium amytal test. We also evaluate the effect of seizures on the development of functional cognitive anatomy. Recent findings: 10 normal children were studied on a 1.5 T Signa MRI scanner using BOLD echo planar imaging of the frontal lobes with a verbal fluency paradigm, covert word generation, letters. Studies were analyzed with a cross correlation algorithm. A region of interest analysis was used to determine extent and magnitude, and laterality of brain activation. Children and adults activated similar regions, predominantly in left inferior frontal cortex (Broca?s area) and left middle frontal gyrus (dorsolateral prefrontal cortex). Children had, on average, 60% more activation than adults, with a trend for greater degree of activation AR. The degree of laterality appeared less in children than for adults in IFG and MFG but this was not significant. CONCLUSIONS: In a test of verbal fluency children tended to activate cortex more widely than adults but activation patterns for fluency appear to be established by middle childhood. Such tests may be applied to pediatric patient populations for determining language dominance. The greater activation found in children may reflect developmental plasticity for the ongoing organization of neural networks which underlie language capacity. fMRI language tasks readily identify frontal language areas; temporal activation has been less consistent. No studies have compared clinical visual judgment to quantitative region of interest (ROI) analysis. We identified temporal language areas in patients with partial epilepsy using a reading paradigm with clinical and ROI interpretation. Thirty patients with temporal lobe epilepsy, aged 8 to 56 years, had 1.5-T fMRI. Patients silently named an object described by a sentence compared to a visual control. Data were analyzed with ROI analysis from t-maps. t-Maps were visually rated by three readers at three t thresholds. Twenty-one patients had intracarotid amobarbital test (IAT). The fMRI reading task provided evidence of language lateralization in 27 of 30 patients with ROI analysis. Twenty-five were left dominant, two right, one bilateral, and two were nondiagnostic; IAT and fMRI agreed in most patients, three had partial agreement, none overtly disagreed. Interrater agreement ranged between 0.77 to 0.82 agreement between visual and ROI reading with IAT was 0.71 to 0.77. Viewing data at lower thresholds added interpretation to 12 patients on visual analysis and 8 with ROI analysis. Conclusions: An fMRI reading paradigm can identify language dominance in frontal and temporal areas. Clinical visual interpretation is comparable to quantitative ROI analysis. The extent to which visual word perception engages speech codes (i.e., phonological recoding) remains a crucial question in understanding mechanisms of reading. In this study, we used functional magnetic resonance imaging (fMRI) techniques combined with behavioral response measures to examine neural responses to focused versus incidental phonological and semantic processing of written words. Three groups of subjects made simple button-pressing responses in either phonologically (rhyming-judgment) or semantically (category-judgment) focused tasks or both tasks with identical sets of visual stimuli. In the phonological tasks, subjects were given both words and pseudowords separated in different scan runs. The baseline task required feature search of scrambled letter strings created from the stimuli for the experimental conditions. The results showed that cortical regions associated with both semantic and phonological processes were strongly activated when the task required active processing of word meaning. However, when subjects were actively processing the speech sounds of the same set of written words, brain areas typically engaged in semantic processing became silent. In addition, subjects performed both the rhyming- and semantic tasks showed diverse and significant bilateral activation in the prefrontal, temporal, and other brain regions. Taken together, the pattern of brain activity provides evidence of a neural basis supporting the theory that in normal word reading, phonological recoding is automatic and facilitates semantic processing of written words, while rapid comprehension of word meaning requires devoted attention. These results also raise questions about including multiple cognitive tasks in the same neuroimaging sessions. Current Studies: we are developing new paradigms, particularly using event-related strategies, appropriate for various age groups and developmental levels (with an emphasis on younger age groups, particularly children younger than 7 years old). These studies will primarily use the 3T magnet. We will also design fMRI activation studies using arterial spin tagging at 3T that will examine developmental differences in cerebral blood flow and BOLD signal response. We also plan to study the effects of temporal lobectomy on the functional anatomy of language and working memory.