Hybrid TMS/MRI system for regionally tailored causal mapping of human cortical circuits and connectivity

项目摘要。 我们提出了一种新的线圈阵列，它将以前所未有的灵活性实现下一代因果脑图， 分辨率和精确度。所提出的ARES2混合阵列在大脑皮层产生用于经颅磁感应的电磁场。 磁刺激(TMS)以及用于空间和扩散编码应用的B场，包括高分辨率 TIN、高b值弥散磁共振成像和功能磁共振成像。多通道TMS允许探测不同的皮质目标 顺序地或同时地，提供一种灵活的工具来调节同时成像的大脑活动 用核磁共振。由于线圈元件靠近磁头，线圈元件将在扩散中起到很大的促进作用 皮质中的MRI编码超出了当前MRI梯度技术所能实现的范围，使 靶向神经调节后对标测神经元和树突大小及其分布的敏感性 为刺激后大脑皮质的BOLD-fMRI提供亚毫米空间分辨率。 在Aim1中，我们将测试所提出的头部阵列的3通道原型ARES2(用于接收、编码的阵列， 垫片和刺激)通过利用我们在MR兼容经颅磁体方面的最新发展 刺激(TMS)线圈。线圈将由大电流驱动，最大产量为1000 mT/m。渐变和高 回转率。并行设计包括48个编码线圈，允许B0-垫片能力，而28个射频线圈- 与编码线圈交错的Quency线圈提供并行成像。定制驱动放大器和开关 电子学将允许在“刺激”和“成像”模式之间切换。全面的电子控制 系统将允许在所有通道上与扫描仪的脉冲序列同步地播放任意波形。 在AIM2中，我们将把系统向上扩展到完整的48通道阵列。我们构建了一个新的兼容TMS的28路射频接收器 与TMS探头固定器设备机械集成的阵列。TMS探头支架将允许径向 调整TMS探头，使其可以靠在磁头表面。 在Aim3中，我们将在活体内应用该系统来执行亚毫米级的下一代因果脑图 决议。我们将展示ARES2的S提供细胞体(SOMA)和区域特异性测量的能力 运动(M1)和躯体感觉皮质(S1)的轴突大小和密度。这些扩散磁共振实验将 利用gSlider体积扩散编码提高信噪比并达到亚毫米分辨率。对于TMS- FMRI，我们将使用9ch TMS和48ch MRI梯度系统以交错的方式进行连续刺激 M1和S1的fMRI记录。

Project Summary. We propose a new coil array that will enable next-generation causal brain mapping with unprecedented flexibility, resolution and precision. The proposed ARES2 hybrid array generates E-fields in the cortex for transcranial mag- netic stimulation (TMS) as well as B-fields for spatial and diffusion encoding applications including high-resolu- tion, high b-value diffusion MRI and fMRI. Multi-channel TMS allows different cortical targets to be probed either sequentially or simultaneously, providing a flexible tool for modulating brain activity that is imaged concurrently with MRI. By virtue of their close proximity to the head, the coil elements will provide a large boost in diffusion MRI encoding in the cortex beyond what is possible with current MRI gradient technology, enabling improved sensitivity to mapping neuronal and dendritic sizes and their distribution following targeted neuromodulation and providing sub-millimeter spatial resolution for BOLD-fMRI in the cortex following stimulation. In Aim1, we will test a 3-channel prototype of the proposed head array, ARES2 (Array for Reception, Encoding, Shimming, and Stimulation) by leveraging our recent developments in MR-compatible transcranial magnetic stimulation (TMS) coils. The coils will be driven by large currents to yield 1000 mT/m max. gradients and high slew rates. The parallel design comprising 48 encoding coils permit B0-shimming capability, while 28 radiofre- quency coils interlaced with the encoding coils provide parallel imaging. Custom drive amplifiers and switching electronics will allow alternation between “stimulation” and “imaging” modes. A comprehensive electronic control system will allow arbitrary waveforms to be played out on all channels in sync with the scanner’s pulse sequence. In Aim2, we will scale the system up to the full 48-ch array. We build a new TMS-compatible 28-ch RF receive array that is mechanically integrated with a TMS probe holder device. The TMS probe holder will allow radial adjustment of the TMS probe to allow it to be placed against the head surface. In Aim3, we will apply the system in vivo to perform next-generation causal brain mapping at submillimeter resolution. We will demonstrate ARES2’s ability to provide regionally specific measures of cell body (soma) and neurite size and density in the motor (M1) and somatosensory cortex (S1). These diffusion MRI experiments will make use of gSlider volumetric diffusion encoding to boost SNR and reach submillimeter resolution. For TMS- fMRI, we will use the 9ch TMS and 48ch MRI gradient system in an interleaved manner for successive stimulation and fMRI recording in M1 and S1.