Neuropsychological And Cognitive Studies In Epilepsy

失控癫痫患者可能有与其癫痫发作相关的语言和记忆障碍。此外，当考虑手术时，绘制这些功能图是至关重要的。我们正在使用成像方法，努力取代更具侵入性的方法，以检测癫痫对语言和记忆的影响，并用于术前标测。方法：应用正电子发射断层扫描(PET)和功能磁共振成像(FMRI)对颞叶癫痫患者的语言和记忆功能进行无创性评估，研究癫痫对儿童和成人癫痫患者认知解剖学的影响。我们在正常志愿者和失控癫痫患者中的研究表明，成像评估与更具侵入性的检查，如电刺激标测和颈动脉内淀粉样钠试验相比，具有很好的可比性。我们还评估了癫痫发作对功能认知解剖学发展的影响。最新调查结果： 10名正常儿童在1.5T Signa磁共振扫描仪上对额叶进行了大胆的回声平面成像，并进行了语言流利性、隐蔽单词生成、字母等方面的研究。研究采用互相关算法进行分析。兴趣区分析被用来确定大脑激活的程度和程度，以及大脑的偏侧性。儿童和成人激活相似的区域，主要在左下额叶皮质(Broca？S区)和左侧额中回(背外侧前额叶皮质)。平均而言，儿童的激活程度比成年人高60%，而且AR的激活程度更高。在IFG和MFG中，儿童的偏侧程度比成人要小，但这并不显着。结论：在语言流畅性测试中，儿童往往比成年人更广泛地激活皮质，但流利性的激活模式似乎在童年中期就建立起来了。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正在进行的神经网络组织的发育可塑性，而神经网络是语言能力的基础。 FMRI语言任务很容易识别额叶语言区域；时间激活则不太一致。还没有研究将临床视觉判断与感兴趣区(ROI)定量分析进行比较。我们使用临床和感兴趣区解读的阅读范式确定了部分癫痫患者的颞叶语言区域。30例颞叶癫痫患者，年龄8~56岁，均行1.5T fMRI检查。与视觉控制相比，患者会默默地说出用句子描述的物体的名字。对数据进行t-map的ROI分析。T-Maps被三位读者以三个t阈值进行视觉评分。21例行颈动脉异巴比妥钠试验(IAT)。FMRI阅读任务为30名ROI分析患者中的27名提供了语言偏侧化的证据。左侧占优势25例，右侧2例，双侧1例，非诊断性2例；IAT和功能磁共振成像在大多数患者中一致，3例部分一致，没有明显不一致。评价者之间的一致性在0.77到0.82之间，视觉和ROI读数与IAT之间的一致性在0.71到0.77之间。以较低的阈值查看数据为12名患者的视觉分析和8名ROI分析的患者增加了解释。结论：fMRI阅读范式可以识别额叶和颞叶区域的语言优势。临床目测解释可与定量ROI分析相媲美。 视觉单词知觉在多大程度上参与语音编码(即语音重新编码)仍然是理解阅读机制的一个关键问题。在这项研究中，我们使用功能磁共振成像(FMRI)技术结合行为反应测量来检查神经对书写单词的集中和附带语音和语义加工的反应。三组受试者在语音(押韵判断)或语义(类别判断)聚焦任务或两种任务都有相同的视觉刺激时做出简单的按键反应。在语音任务中，受试者被分成不同扫描顺序的词和假词。基线任务要求对实验条件下从刺激中产生的扰乱字母串进行特征搜索。结果表明，当任务需要对词义进行主动加工时，与语义和语音加工相关的大脑皮层区域被强烈激活。然而，当受试者积极地处理同一组书面单词的语音时，大脑中通常负责语义处理的区域变得沉默。此外，完成押韵和语义任务的受试者在前额叶、颞叶和其他脑区表现出不同且显著的双侧激活。综上所述，大脑活动模式提供了神经基础的证据，支持这一理论，即在正常的单词阅读中，语音重新编码是自动的，有助于书面单词的语义处理，而快速理解单词含义需要专心关注。这些结果还提出了将多项认知任务包括在同一神经成像会话中的问题。 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，适合不同的年龄组和发展水平(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3T磁铁。我们还将设计在3T时使用动脉自旋标记的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的功能解剖的影响。

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.