Imaging Neuronal Activity using Electrical Impedance Tomography

描述(由申请人提供)： EIT是一种新的医学成像方法。受试者的电学特性的断层图像是由一个DVD播放器大小的电子盒和放置在头部、胸部或腹部周围的蛋形电极产生的。微小的、不敏感的电信号被施加到电极上，复杂的数学方法用PC实时将这些信号转换成图像。它是便携的，便宜，安全，快速。与EEG源建模不同，图像是独一无二的；重建几乎与光学断层扫描相同。在过去的二十年里，申请人率先使用EIT进行脑功能成像。大多数工作都是为了成像阻抗的更大变化，这些变化与中风或癫痫发作等几秒钟内血流和细胞肿胀的变化有关。EIT还具有独特的潜力来成像在神经元去极化过程中离子通道打开时在大脑中发生的微小阻抗变化。有强有力的理由相信这是可能的：生物物理模型表明这种活动使大脑局部的阻力改变1%；该模型已在螃蟹神经记录中得到验证，这种变化可在充满盐水的水箱中成像，而对体积传导场的详细建模表明信号大到足以在头皮上可靠地检测到。到目前为止，用脑磁图记录电压或磁场的人体研究显示出了微小的变化，但还没有得到优化。这项应用的目的是通过记录植入电极的动物在诱发正常活动期间的这些快速阻抗变化来验证该方法的生理学基础。该方法将被改进，然后评估已经为癫痫手术植入留置电极的人类的成像准确性。如果成功，这将为未来在人类身上进行非侵入性记录的最终目标奠定基础。如果成功，这将产生一种革命性的非侵入性新方法，通过一种廉价的便携式成像设备，在毫秒内对快速电活动进行成像，这是大脑活动的真正基础。这将使我们能够更深入地了解大脑是如何工作的，因为它将使对大脑通路中快速电活动的数学分析成为可能。这将导致对精神分裂症、抑郁症和癫痫等疾病的理解和治疗方面的根本性改进。

DESCRIPTION (provided by applicant): EIT is a new medical imaging method. Tomographic images of the electrical properties of a subject are produced with a box of electronics about the size of a DVD player, and EGG type electrodes placed around the head, chest or abdomen. Small, insensible, electrical signals are applied to the electrodes and sophisticated mathematical methods translate these into images with a PC in real time. It is portable, inexpensive, safe, and rapid. Unlike EEG source modelling, the images are unique; reconstruction is almost identical to that of optical tomography. Over the past two decades, the applicant has pioneered the use of EIT for imaging brain function. Most work has been into EIT to image the larger changes in impedance which occur related to changes in blood flow and cell swelling over seconds, as in stroke or epileptic seizures. EIT also has the unique potential to image the small impedance changes which occur in the brain as ion channels open during neuronal depolarization. There are strong grounds for believing that this is possible : Biophysical modelling indicates such activity changes resistance by 1% locally in the brain; the model has been validated in crab nerve recording, such changes are imageable in saline filled tanks, and detailed modelling of volume conducted fields indicates signals just large enough for reliable detection on the scalp. So far, human studies recording voltage or magnetic fields with Magnetoencephalography have shown marginal changes but have not been optimised. The purpose of this application is to validate the physiological basis of this method by recording these fast impedance changes in animals with implanted electrodes, during evoked normal activity. The method will be refined and then assessed for imaging accuracy in humans with indwelling electrodes already implanted for epilepsy surgery. If successful, this will set the foundation for the ultimate goal of future recordings non-invasively in humans. If successful, this would produce a revolutionary new non-invasive method for imaging the fast electrical activity over milliseconds which is the true basis of brain activity, with an inexpensive portable imaging device. It would enable a much deeper understanding of how the brain works, as it would enable mathematical analysis of the fast electrical activity in pathways in the brain. This would lead to radical improvements in understanding and treatment of disorders like schizophrenia, depression and epilepsy.