High-sensitivity optical-atomic MEG

 描述（由申请人提供）：在神经病学、临床神经科学和认知神经科学中，人们对使用MEG（脑磁图）以毫秒时间分辨率绘制大脑活动非常感兴趣。大脑中的电流源活动产生磁场，该磁场由保持在接近绝对零度的温度下的超导量子干涉装置（SQUID）线圈检测。SQUID线圈在MEG的频率范围内（< 100 Hz）具有不理想的灵敏度。低温操作需要将SQUID线圈放置在头皮上方2-3 cm的距离处，从而降低了空间分辨率。SQUID MEG线圈的构造和维护成本昂贵，这导致部署的MEG系统由于在相当远的距离处对磁场的有限采样而具有差的空间分辨率 在头皮上。由于这些限制，MEG用于脑活动定位（称为磁源成像）的巨大潜力尚未实现，并且MEG相对于脑电图（EEG）用于脑功能定位的优势仍有待研究人员或临床医生广泛利用。在这个项目中，我们提出了一种新的方法来测量磁场在头皮在室温下使用原子光学技术来测量磁场，克服了目前MEG技术的所有限制。我们将使用一种独特的光纤Sagnac干涉仪，该干涉仪最初是为物理应用而开发的，作为在室温下工作并可以贴着头皮放置的磁力计和梯度计的检测方案。由此产生的Sagnac MEG技术具有更高的灵敏度（在0.01飞秒特斯拉的量子噪声限制），更好的空间分辨率，并大大低于SQUID MEG的成本。三轴梯度仪，记录所有3个梯度的大脑的磁场将被构建和测试与幻影头和实验中的人类受试者。一种新的时空编码和解码方案将开发同时记录从多个Sagnac梯度计。将进行模拟、体模实验和人体实验，以指导未来全头Sagnac MEG系统的设计。

 DESCRIPTION (provided by applicant): In Neurology, Clinical Neuroscience, and Cognitive Neuroscience there is considerable interest in mapping brain activity with millisecond temporal resolution using MEG (Magnetoencephalography). Current source activity in the brain generates magnetic fields that are detected by Superconducting Quantum Interference Device (SQUID) coils maintained at near absolute-zero temperature. SQUID coils have non-ideal sensitivity in the frequency range of MEG (< 100 Hz). Cryogenic operation requires placing the SQUID coils at a distance of 2-3 cm above the scalp, reducing spatial resolution. SQUID MEG coils are expensive to construct and maintain, which has led to the deployment of MEG systems with poor spatial resolution due to the limited sampling of the magnetic field at a significant distance above the scalp. The tremendous potential of MEG for localization of brain activity (known as Magnetic Source Imaging), has not been realized due to these limitations and the advantages of MEG over electroencephalography (EEG) for localization of brain function remains to be widely exploited by researchers or clinicians. In this project, we propose a new method to measure the magnetic fields at the scalp at room temperature using an atomic-optical technique to measure magnetic fields that overcomes all of the limitations of current MEG technology. We will use a unique fiber- optic Sagnac interferometer, which was originally developed for physics applications, as the detection scheme for magnetometers and gradiometers that operate at room temperature and can be placed against the scalp. The resulting Sagnac MEG technology has higher sensitivity (at the quantum noise limit of 0.01 femtoTesla), better spatial resolution, and dramatically lower cost than SQUID MEG. Tri-axis gradiometers that record all 3 gradients of the brain's magnetic field will be constructed and tested with phantom heads and experiments in human subjects. A novel spatial-temporal encoding and decoding scheme will be developed for simultaneous recording from multiple Sagnac gradiometers. Simulations, phantom experiments, and human experiments will be carried out to inform the design of future whole-head Sagnac MEG systems.