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，当考虑将手术作为一种可能的治疗方法时，能够描绘这些功能是非常重要的。在这项研究中，我们试图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，以及术前标测。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神经成像进行无创性评估，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。最新发现：我们使用功能磁共振成像和正电子发射计算机断层扫描来研究成人和儿童的语言子系统。我们使用O15PET来识别对语音编码(即语音系统)计算至关重要的大脑皮层区域。大脑损伤可能会选择性地损害阅读伪词(即可发音的非单词)的能力，使阅读熟悉单词的能力基本保持不变。我们发现，单词和假词的押韵都是神经活动的强烈左侧化中枢，这表明联合神经网络用于语音加工。然而，假词押韵在左侧前额叶后皮质和左侧枕颞下交界处招募了更多的皮质组织，并激活了左侧缘上回，这在单词押韵中并不明显。不同语言子系统参与的大脑活动表现出相对的区域性差异。我们的结果表明，传统语音区域之外的区域对语音编码、阅读和理解的计算可能是至关重要的。虽然语义分类不需要计算语音编码，但它自动激活了语音系统。语音系统似乎对单词阅读和文本阅读都至关重要。多项任务对功能成像的影响还没有被研究过。这种跨任务干扰将使功能映射难以解释。我们发现，在同一实验会话中包含多个参与复杂认知过程(例如，语义与语音)的认知任务可能会导致大脑激活，这与所研究的认知过程不同。为了激活颞叶皮质，我们使用了一项基于先前PET研究的语义回忆任务，适用于阅读，以及一项新的寓言阅读任务。这两种范式都被证明是颞叶皮质以及前部语言区域(可能与工作记忆或语义回忆有关)的强大激活器，尽管阅读的侧向性更强。尤其重要的是，任务可靠地激活了受试者内部和跨受试者的左侧时间语言区。有趣的是，与早先的一些报道不同，我们的fMRI和PET研究中没有一项研究表明，在言语流畅性、听觉反应性命名、阅读或押韵任务中，性别对激活的侧化有显著影响。目前的研究：我们正在使用几个新的任务来研究患者，特别是语言处理区域癫痫灶儿童的功能重组。

Patients with uncontrolled epilepsy may have impairment of language and memory associated with their seizures. In addition, it is very important to be able to map these functions when surgery is being considered as a possible treatment. In this study, we are using imaging methods to try 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 neuroimaging 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: We used fMRI and PET to study language subsystems in adults and children. we used O15 PET to identify cortical regions crucial for the computation of speech codes (i.e., the phonological system). Brain lesions may selectively impair the ability to read pseudowords (i.e., pronounceable non-words), leaving the ability to read familiar words largely intact. We found strong left lateralized epicenters of neural activity in rhyming both for words and pseudowords, suggesting conjoint neural networks for phonological processing. However, pseudoword rhyming recruited significantly more cortical tissue in the left posterior prefrontal cortex and the left inferior occipital-temporal junction, and activated the left supramarginal gyrus, which was not apparent in word rhyming. Brain activation shows relative regional variation with engagement of different language subsystems. Our results suggest that regions beyond traditional speech areas may be crucial for the computation of speech codes, reading, and comprehension in general. Although semantic categorization did not require computation of speech codes, it automatically activated the phonological system. The phonological system appears to be crucial for word reading, as well as text reading. Effects of multiple tasks in functional imaging have not been examined. Such cross-task interference would render functional mapping difficult to interpret. We found that including multiple cognitive tasks that engage in complex cognitive processes (e.g., semantics vs. phonology) in the same experimental session may induce brain activation uncharacteristic for cognitive processes under investigation. In order to activate temporal cortex, we used a semantic recall task based on our prior PET studies, adapted for reading, as well as a new fable reading task. Both paradigms proved robust activators of temporal cortex, as well as anterior language regions (possibly related to working memory or semantic recall), though reading was more strongly lateralized. It was particularly important that the tasks reliably activated left temporal language regions within as well as across subjects. Interestingly, none of our studies with either fMRI or PET, in contrast to some earlier reports, have shown significant gender effects on lateralization of activation for verbal fluency, auditory responsive naming, reading or rhyming tasks. Current studies: We are using several new tasks to investigate functional reorganization in patients, particularly children with epileptic foci in language processing regions.