Development of the SQUID-CT for Functional Brain Mapping Based on a Helmet-Shaped Whole Head Magnetoencephalography System

在本研究中，我们设计了一种新的脑磁图（MEG）系统作为先进的临床诊断工具，如下：首先，设计了视觉和味觉刺激器，使其不产生磁噪声。其次，仔细选择刺激和测量参数，以最大限度地减少患者诱发磁场的总测量时间。第三，分析比较正常受试者与颅内结构性病变患者的多模态诱发反应。结果总结如下。对于躯体感觉刺激，不仅确定了上肢和下肢的主要神经刺激，而且还确定了单指刺激和阴茎背神经刺激的相应初级感觉皮层。初级感觉皮层的功能定位与脑回解剖有很好的对应关系。对于听觉刺激，诱发场的中后期成分都显示出不同类型的半球间不对称。在颞叶肿瘤病例中发现主峰延迟。使用全视野刺激和双偶极子模型定位两个半球的初级视觉皮质。同侧偏盲和双侧偏盲患者分别呈现相应的磁场模式。对正常人的味觉诱发磁场进行测量。对缺血性病变的慢波异常进行了观察。这些结果预示着MEG作为临床诊断工具的进一步应用以及非侵入性人脑功能研究的新工具。加快临床脑磁图系统的开发和超导物理的其他应用。

In this study, we have designed a new magnetoencephalography (MEG) system as an advanced clinical diagnostic tool, as follows : First, visual and gustatory stimurators were designed so as not to produce magnetic noise. Second, stimulation and measurement parameters were carefully selected in order to minimize total measurement time of evoked magnetic fields for patients. Third, multimodal evoked responses were analyzed and compared between normal subjects and patients with intracranial structural lesions.Results are summarized as follows. For somatosensory stimuli, corresponding primary sensory cortices were indentified for not only major nerve stimuli in upper and lower extremities but also for single digit stimuli and for dorsal penile nerve stimuli. There found fine correspondence between functional localization and gyral anatomy in primary sensory cortex. For auditory stimuli, various types of interhemispheric asymmetries were revealed for both middle and late components of the evoked fields. Delayd latency of the major peaks were found in cases of temporal lobe tumors. Primary visual cortices on both hemispheres were localized using full visual-field stimuli and a two-dipole model. Patients with homonymous hemianopsia and bitemporal hemianopsia presented corresponding magnetic field patterns respectively. Gustatory evoked magnetic fields were measured in normal subjects. Abnormal slow wave of magnetic fields were also investigated in cases with ischemic lesion.These results promise further utility of MEG as clinical diagnostic tools as well as new rsearch tools of non-invasive human brain function. Development of clinical MEG system and other applications of superconducting physics will be accelerated.