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)：功能神经成像的直接方法对于了解神经行为、可塑性、连通性和病理学的进步至关重要。如果我们可以直接成像活跃的神经元，我们将有能力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的电导成像技术--磁共振电阻抗断层成像(MREIT)，它可以以接近MRI的分辨率重建电导率图。在mREIT中，微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为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外加电流在体内产生动物大脑的电导图像的阶段。在活动过程中发生的膜电导的巨大变化会导致外部施加电流的路径发生动态变化。外部电流施加过程中尖峰活动的变化将导致MR数据中的不同相位积累，并且随着电流施加时间的延长而增加。因此，神经活动变得可见，因为体素的表观电导增加与活跃的细胞内区域一致。由于控制对比度的mREIT信号(电导率)可能仅获得正值，因此不能通过相反极性或相反取向的信号的存在来抵消相位累积。与其他基于MRI的方法相比，这可能使mREIT在成像神经电流方面具有优势，这些方法基于主要由轴突电流总和引起的相位或主磁场的扰动。因此，mREIT有可能检测到包括灰质在内的复杂结构中的活动。在这项研究中，我们将研究功能性mREIT(FMREIT)检测神经组织活动相关电导变化的能力。我们将开发fMREIT技术，在几种标准的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，以检测和定位高信噪比的活动细胞，并使用主要 磁场强度在体内使用方便。在分离的制剂中，我们的方法有可能实现对单细胞机制的详细分析。因此，该方法可以被认为是膜片钳技术的非侵入性扩展，并且可以单独用于这一目的。然而，我们最终希望成像体内的活动，我们在这个项目中的最后研究将包括在活体动物模型中进行fMREIT的试探性探索，作为这一领域进一步研究的先导。综上所述，本研究将为mREIT功能化奠定基础 (FMREIT)技术。这种方法最终可以用来可视化更一般的神经行为的影响，并能够比现有的技术，如功能磁共振成像，在体内对神经行为进行更基本的分析。