Direct functional imaging of electrical brain stimulation

脑电刺激的直接功能成像

• 批准号: 9024627
• 负责人: ROSALIND J SADLEIR
• 金额: $ 44.16万
• 依托单位: ARIZONA STATE UNIVERSITY-TEMPE CAMPUS
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-03-15 至 2018-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9024627
• 关键词: Abdomen; Activities of Daily Living; Animal Model; Animals; Aplysia; Area; Behavior; Blood flow; Brain; Cells; Chemicals; Complex; Data; Deep Brain Stimulation; Disadvantaged; Electric Conductivity; Electrical Stimulation of the Brain; Elements; Environment; Functional Imaging; Functional Magnetic Resonance Imaging; Ganglia; Health; Human; Image; Imaging Techniques; In Vitro; Intracellular Space; Lead; Life; Light; Location; Magnetic Resonance; Magnetic Resonance Imaging; Magnetism; Maps; Measures; Membrane; Methods; Modeling; Monitor; Motion; Neurons; Noise; Patch-Clamp Techniques; Pathology; Pattern; Phase; Physiologic pulse; Pilot Projects; Plague; Preparation; Protocols documentation; Rattus; Refractory; Research; Resolution; Retinal; Retinal Ganglion Cells; Sequence Analysis; Signal Transduction; Slice; Source; Staging; Structure; Sum; Techniques; Temperature; Testing; Time; Tissues; Work; animal imaging; base; density; electric impedance; experience; gray matter; hemodynamics; imaging modality; in vitro activity; in vivo; insight; magnetic field; multi-electrode arrays; neuroimaging; phase change; programs; relating to nervous system; research study; tomography; white matter

DESCRIPTION (provided by applicant): Direct methods for functional neural imaging are critical to advancements in understanding neural behavior, plasticity, connectivity and pathology. If we can directly image active neurons we will have the ability to examine neural activity more precisely than is presently the case with fMRI. We have developed an MRI-based conductivity imaging technique, Magnetic Resonance Electrical Impedance Tomography (MREIT) that can reconstruct conductivity maps with near-MRI resolution. In MREIT, small external currents are applied to an object. The MR magnetic flux density patterns created by current flow may be converted to conductivity or current density slice images. We developed this technique and have refined it to the stage of producing electrical conductivity images of animal brains in vivo, using relatively low applied currents. The large changes in membrane conductance that occur during activity cause dynamic changes in paths taken by externally applied currents. Changes in spiking activity during external current application will cause differential phase accumulation in MR data that will increase the longer current is applied. Neural activity therefore becomes visible as an increase in apparent conductivities of voxels coincident with active intracellular areas. Because the contrast controlling MREIT signals, conductivity, may only acquire positive values, phase accumulations cannot be cancelled by the presence of opposite polarity or opposingly oriented signals. This may give MREIT an advantage compared with other MRI-based methods for imaging neural currents that are based on perturbations of phase or main magnetic fields caused principally by summed axonal current flows. Thus, MREIT has the potential to detect activity in complex structures including gray matter. In this proposal, we will investigate the ability of functional MREIT (fMREIT) to detect activity-related conductivity changes in neural tissue. We will develop fMREIT techniques to image neural activity in vitro, in a several standard neural preparations, while progressively refining our methods to detect and locate active cells at high signal to noise ratio and using main magnetic field strengths conveniently used in vivo. In isolated preparations, our method has the potential to enable detailed analyses of single cell mechanisms. The method could thus be considered as a non-invasive extension of patch clamping techniques, and could stand alone for this purpose. However, ultimately we wish to image activity in vivo and our final study in this program will include a tentative exploration of fMREIT in a live animal model as a precursor to further research in this area. In summary, this study will establish the basis for functional MREIT (fMREIT) techniques. This method could ultimately be used to visualize effects of more general neural behavior and enable more fundamental analyses of neural behavior in vivo than is available with existing techniques such as fMRI.

描述（由申请人提供）：功能性神经成像的直接方法对于理解神经行为、可塑性、连接性和病理学的进步至关重要。如果我们能够直接对活动神经元进行成像，我们将能够比目前的功能磁共振成像更精确地检查神经活动。我们开发了一种基于 MRI 的电导率成像技术，即磁共振电阻抗断层扫描 (MREIT)，它可以以接近 MRI 的分辨率重建电导率图。在 MREIT 中，小的外部电流被施加到物体上。由电流产生的MR磁通密度图案可以被转换成电导率或电流密度切片图像。我们开发了这项技术，并将其改进到使用相对较低的施加电流生成动物大脑体内电导率图像的阶段。活动期间发生的膜电导的巨大变化导致外部施加电流所采用的路径发生动态变化。施加外部电流期间尖峰活动的变化将导致 MR 数据中的微分相位累积，施加的电流时间越长，该数据就会增加。因此，随着与活跃细胞内区域一致的体素表观电导率的增加，神经活动变得可见。因为控制 MREIT 信号、电导率的对比度只能获取正值，所以相位累积不能通过相反极性或相反方向信号的存在来消除。与其他基于 MRI 的神经电流成像方法相比，这可能使 MREIT 具有优势，这些方法基于主要由总轴突电流引起的相位或主磁场的扰动。因此，MREIT 有潜力检测包括灰质在内的复杂结构的活动。在本提案中，我们将研究功能性 MREIT (fMREIT) 检测神经组织中与活动相关的电导率变化的能力。我们将开发 fMREIT 技术，在几种标准神经制剂中对体外神经活动进行成像，同时逐步完善我们的方法，以高信噪比检测和定位活性细胞，并使用主要 磁场强度可方便地在体内使用。在分离的制剂中，我们的方法有可能对单细胞机制进行详细分析。因此，该方法可以被视为膜片钳技术的非侵入性扩展，并且可以单独用于此目的。然而，最终我们希望对体内活动进行成像，并且我们在该计划中的最终研究将包括在活体动物模型中对 fMREIT 的初步探索，作为该领域进一步研究的先驱。总之，本研究将为功能性 MREIT 奠定基础 （fMREIT）技术。与功能磁共振成像等现有技术相比，这种方法最终可以用于可视化更一般的神经行为的影响，并能够对体内神经行为进行更基础的分析。