数据由部分由美国国立卫生研究院和尼泊尔国立卫生研究院神经科学研究蓝图的16个NIH研究机构和中心资助的人联系项目（WU Minmin Consortium）（主要研究员:David Van Essen和Kamil Ugurbil; 1U54MH091657）提供;和麦克唐纳华盛顿大学系统神经科学中心。图2A和2D经Rhoton集合57许可（http://rhoton.ineurodb.org/?page=21899）复制。

死者在这里被列为人口，虽然死者不是技术上的人类受试者;人类科目由45 CF 46定义为"活人15,16 "。 1.准备样品<ol><li>检查5个福尔马林固定的大脑（10个半球）和2个全人脑。 </li><li>根据Klingler的方法17将样品固定在10％福尔马林溶液中至少2个月。 </li><li>按照克林格方法17将所有标本在-16℃冷冻2周。 </li><li>在自来水下解冻样品。 </li><li> 在尸体头部进行扩展性额颞开颅手术以暴露大脑。 <ol><li>将尸体头置于三针颅骨夹（ Material Table ）中。 </li><li>用手术刀做一个额叶皮肤切口。</li><li>使用手术刀，镊子和剪刀去除皮肤和肌肉。 </li><li>在头骨中形成一个或多个钻孔，直到达到硬脑膜;使用紧凑型减速器的钻头和79,000 rpm的材料表 （ 材料表 ）的14 mm颅骨穿孔附件。 </li><li>切割骨瓣，并使用2 mm x 15.6 mm带槽铣刀的铣刀打开颅骨，钻孔速度为80,000 rpm（ 材料表 ）为2.1 mm针形毛刺附件。 </li></ol></li><li>使用显微镜在6X至40X放大倍率5,18（ 材料表 ）下，用硬度计去除硬脑膜，蛛网膜和皮肤，并用显微镜切片。 </li></ol>纤维解剖技术注意:在手术显微镜下进行6X至40X放大倍数的所有解剖。 <ol><li> 在每个半球上逐步进行纤维解剖从外侧到内侧和内侧到外侧。 <ol><li>使用panfield解剖器（ 材料表 ）分解大脑皮层，并去除所有额叶皮质组织，以暴露短连接纤维束，这些纤维束是相互连接的回路5,13的U型纤维或间叶纤维。 </li><li>通过在显微镜（ 材料表 ）下轻轻修剪，用panfield解剖器和手术微型钩子去除短结缔组织纤维，以达到并暴露长相关纤维，这种纤维连接在同一半球的远处。 </li><li>深入长关联纤维，以使用手术微型钩和panfield解剖器去除表面缔合纤维;在显微镜（ 材料表 ）下取出每个纤维束，以露出投影连合纤维。 </li><li>查看SMA复合体的每个连接根据之前在文献2,8,18,19,20,21中定义的地形解剖结构。 </li></ol></li><li>将解剖期间在10％甲醛溶液（ 材料表 ）中进行解剖时使用的所有标本（全脑和脑）保留。 </li></ol> 3D摄影技术<ol><li>在拍摄标本期间使用黑色平台。 </li><li> 遵循3D摄影技术22 。 <ol><li>将每个样品放在设计的黑色平台上。 </li><li>选择具有样品全幅正视图的场景，并将相机聚焦在样品上任何点上，靠近相机屏幕上的中心点（仪器选项卡）乐）。使用18至55 mm f / 3.5-5.6 SLR镜头或100 mm f / 2.8L微距镜头，并将光圈设置为F29，ISO 100。 </li><li>将照相机稍微向左旋转，直到相机屏幕上最右侧的点与上述对焦点相同。将相机向右滑动，直到屏幕上的中点与样品上的原始对焦点重叠。将相机聚焦在这一点上，再拍摄一次。 </li><li>将照相机的距离和轴线保持恒定值拍摄的样本。 </li></ol></li><li> 通过使用3D图像生成器程序（材料表）创建3D图像。 <ol><li>打开3D软件程序。 </li><li>选择"从文件打开立体声图像"。 </li><li>选择两个图像（左和右），并确保左图像在左侧插槽，右侧图像在右侧插槽中。 </li><li>选择"半色拼图RL / 2"选项，并以jpeg格式生成浮雕。 </li></OL&gt; </li></ol> DTI技术<ol><li>通过从参考网站下载Human Connectome Project扩散数据23获取预处理的扩散数据。 注意:数据下载预处理并由以下过程组成:扩散数据是在正常志愿者中使用修改的3 T MRI设备（仪表）采用自旋回波回波平面成像（EPI）带图像加速24,25,26,27,28。相关序列参数包括:TR = 5,520 ms; TE = 89.5 ms; FOV = 210×180mm;矩阵= 168×144;切片厚度= 1.25mm（体素大小1.25×1.25×1.25mm）;多频段因子= 3;和b值= 1,000s / mm 2 （95个方向），2,000s / mm 2 （96个方向）和3,000s / mm2 （97个方向）。然后使用FreeSurfer 29和FSL 30处理数据 ;该过程包括涡流校正，运动校正，b0强度归一化，磁敏度失真校正和梯度非线性校正28,31,32,33。相应的T1加权MP-RAGE图像也包含在下载包中。人工互联网项目程序手册23中记录了程序 。 </li><li> 使用扩散光谱成像（DSI）Studio 34对扩散数据进行后处理，以使用广义q采样成像（GQI）算法35产生估计的体素扩散取向分布函数（ODF）。 <ol><li>通过sel将下载的数据集加载到软件中ecting"STEP1:开源图像"，并选择data.nii.gz文件。 </li><li>选择"STEP2:重建"按钮。验证脑屏蔽后，进入"步骤2"，选择"GQI"作为重建方法。选择"长度比"为"1.0"的"r ^ 2加权"。将剩余的选择保留为默认值。 </li><li>选择"运行重建"。 </li></ol></li><li> 为感兴趣的地区放置适当的种子以简化光纤跟踪。 <ol><li>在"区域窗口"中，单击"Atlas"按钮，为上级纵向（SLF）放置种子I.选择"Brodmann"并添加"区域6"和"区域7"。在区域窗口中，将"区域6"类型设置为"种子"，将"区域7"类型设置为"包含区域"（ROI）。 <ol><li>在区域窗口中选择"新建区域"，并手动绘制ROI在冠状面上的额上回的最后方面。执行光纤跟踪，如步骤4.4所述。 </li></ol></li><li>通过在区域窗口中使用"新区域"以类似的方式放置种子，在冠状面中画出中前额叶白质后部的"种子"区域。使用"Atlas"（如步骤4.3.1）和Brodmann区域9，10，46，39和19选择ROI。按照步骤4.4中所述执行光纤跟踪。 </li><li>在"区域"窗口中使用"Atlas"（如步骤4.3.1）将"SLF III"种子放置在"种子"区域，并选择"Brodmann地图册"的"40区"，"区域40"中的"Atlas ..." "和"区域44."执行光纤跟踪，如步骤4.4所述。 </li><li>在区域窗口中使用"新区域"放置胼al体纤维的种子，并在包含第三个矢状面的矢状平面上画一个"种子"胼e体。执行光纤跟踪，如步骤4.4所述。 </li><li>在区域窗口中使用"新区域"放置用于扣带纤维的种子，并在冠状视图中在扣带回中间画一个"种子"区域。使用"新区域"绘制两个ROI，一个在较前面的扣带和一个在冠状回的后扣带回。执行光纤跟踪，如步骤4.4所述。 </li><li>在区域窗口中使用"新区域"放置种子，使用"Atlas ..."功能在电晕辐射中使用ROI进行"种子"绘制。选择图集为"JHU-WhiteMatter-labels-1mm"。 <ol><li>选择并添加"Anterior_corona_radiata"，"Posterior_corona_radiata"和"Superior_corona_radiata"。对于所有纤维，通过使用"新区域"的轴向平面中的低于层级的平面的所有纤维绘制避开区域"在区域窗口中执行光纤跟踪，如步骤4.4中所述。 </li></ol></li><li>使用区域窗口中"Atlas ..."功能的"种子"放置皮质脊髓束种子。选择"JHU-WhiteMatter-labels-1mm"，并添加"Corticospinal_tract"区域。执行光纤跟踪，如步骤4.4所述。 </li><li>使用区域窗口中"Atlas ..."功能的"种子"区域为正面坡道（FAT）种植种子，并选择"区域44"和"区域45"中的布罗德曼图谱和"区域6"ROI。 "执行光纤跟踪，如步骤4.4所述。 </li><li>使用"Atlas ..."功能将"F区域"种子放在"Region 6"区域的"种子"中。在"HarvardOxfordSub"图集中的"尾状物"，"壳核"和"苍白球"中插入新区域，并将区域窗口中的类型设置为"结束"。" 注意:FST的纤维跟踪将通过选择第6区种子和每个跟踪会话中仅一个皮质下种子（ 即第6区和尾状，其次是区域6和壳核，最后是区域6和球）进行苍白球）。 <ol><li>对于每个组合，执行步骤4.4中所述的光纤跟踪。 </li></ol></li></ol></li><li> 执行以上每种组合的光纤跟踪。 <ol><li>在"选项"窗口中，将跟踪参数设置为:qa终止指数为0.08，角度阈值为75，步长为0.675，平滑为0.2，最小长度为20 mm，最大长度为200 mm。将种子方向选择为"全部"，将种子位置选为"子体素"，并将种子随机播种为"开"。使用流线型（Euler）跟踪算法进行三线性方向插值。对于上述区域的每个组合，在＆＃中选择"运行跟踪"34;纤维束"窗口。 注意:由于跟踪的随机性质，确定了明确的"假纤维"并选择性地移除，手工绘制的区域作为"新区域"。 </li></ol></li><li> Affine使用DSI-Studio的"Slices - &gt; Insert T1 / T2 Images"功能，将Human Connectome Project数据集中提供的大脑提取的T1加权3D MP-RAGE扫描注册到扩散数据。通过选择"Slices - &gt;添加等值面"来生成大脑的表面渲染。使用"阈值"665。 </li></ol>

作者声称没有竞争的经济利益，也没有资金来源和支持，包括任何设备和药物。

白色通道的重要性和研究技术大脑皮层被认为是与人类生命250万年相关的主要神经结构。基于形态学和细胞规格，大约有200亿个神经元分成了各个部分。这些皮质部分的结构已经在功能上分组，如感觉运动，感觉运动，情感体验和复杂推理。确定灵长类动物中的所有行为都是通过独特的解剖功能连接和通过神经系统的皮层和皮质下区域拓扑分布的区域形成的。虽然大脑皮质已经...

在Brodmann划定的14个正面区域中，位于中心运动皮质前面的前驱和前额叶区长期被认为是一个无声模块，尽管额叶在认知，行为，学习中起着重要作用，和语音处理。除了前SMA和SMA正面（Brodmann Area; BA 6）组成的辅助电机区（SMA）复合体之外，前动脉/前额模块还包括背侧前额叶（BA 46,8，和9），前额叶（BA 10）和腹外侧前额叶（BA 47）皮质，以及脑1,2侧表面的部分眶额叶皮层（BA 11）。 SMA复合体是由其功能及其连接定义的重要解剖区域。该区域的切除和损伤导致称为SMA的显着的临床缺陷综合征。 SMA综合征是包含SMA复合物3的前额神经胶质瘤病例中特别观察到的重要临床病症。 SMA复合体与边缘系统，基底神经节，小脑，丘脑，对侧SMA，上顶叶以及通过纤维束的额叶的部分具有连接。对这些白质连接的损伤的临床效果可能比皮质更严重。这是因为由于高皮质可塑性4，5，6，7，8，9，10，11，12 ，皮质损伤的后果可以随着时间的推移而改善。因此，SMA区域解剖学和白质通路应该是深层次的特别理解胶质瘤手术。 全面了解白质通道的解剖学对于神经外科病变的广谱治疗是重要的。最近对显微手术中获得的解剖结果的三维文献的研究被用于更好地了解脑白质通路13,14的形态解剖学和相互关系。因此，本研究的目的是使用纤维解剖技术对尸体标本和磁共振成像（MRI）动物图谱的组合来检查SMA复合物（SMA前SMA和SMA）的白质连接，并解释所有方法和这两种技术的原理及其详细的文件。 研究规划与策略在进行实验之前，一升对纤维夹层的基本原理进行了检索，进行了解剖前和解剖过程中需要应用于标本的手术，以及已经用剥离和DTI显示的SMA区域之间的所有连接。以前关于前SMA和SMA适合区域的解剖定位和分离以及其连接的地形解剖学的研究进行了综述。

<table><tbody><tr><td>%4 Paraformaldehyde Solution</td><td>AFFYMETRIX, Inc.</td><td>2046C208</td><td>used to fixation</td></tr><tr><td>Freezer</td><td>INSIGNA</td><td>NS-CZ70WH6</td><td>used to freez</td></tr><tr><td>Panfield Dissector</td><td>AESCULAP</td><td>FD305</td><td>used to dissection</td></tr><tr><td>Surgical Micro Scissor</td><td>W. Lorenz</td><td>04-4238</td><td>used to miscrodissection</td></tr><tr><td>Surgical Micro Hook</td><td>V. Mueller</td><td>NL3785-009</td><td>used to miscrodissection</td></tr><tr><td>MICRO VESSEL STRETCHER/DILATOR</td><td>W. Lorenz</td><td>04-4324</td><td>used to miscrodissection</td></tr><tr><td>Emax2 SC 2000 Electric Console</td><td>Anspach Companies</td><td>SC2102</td><td>used to craniatomy</td></tr><tr><td>Drill Set</td><td>Anspach Companies</td><td>NS-CZ70WH6</td><td>used to craniatomy</td></tr><tr><td>20-1000 operating microscope</td><td>Moeller-Wedel,Germany</td><td>FS 4-20</td><td>used to miscrodissection</td></tr><tr><td>Canon EOS 550D 18 MP CMOS APS-C Digital SLR Camera</td><td>Canon Inc.</td><td>DS126271</td><td>used to take photos</td></tr><tr><td>EF 100 mm f/2.8L IS USM Macro Lens</td><td>Canon Inc.</td><td>4657A006</td><td>used to take photos</td></tr><tr><td>MR-14EX II Macro Ring Lite (Flash)</td><td>Canon Inc.</td><td>9389B002</td><td>used to take photos</td></tr><tr><td>Tripod</td><td>Lino Manfrotto</td><td>322RC2</td><td>used to take photos</td></tr><tr><td>MAYFIELD Infinity Skull Clamp</td><td>Integra Inc.</td><td>A0077</td><td>used to fix the head</td></tr><tr><td>Modified Skrya 3T &quot;Connectome&quot; Scanner</td><td>Siemens Company, Inc.</td><td>A911IM-MR-15773-P1-4A00</td><td>used to scan DTI</td></tr><tr><td>XstereO Player</td><td>Yury Golubinsky</td><td>Version 3.6(22)</td><td>used to create anaglyphs</td></tr><tr><td>EF-S 18-55mm f/3.5-5.6 IS II SLR Lens</td><td>Canon Inc.</td><td>2042B002</td><td>used to take photos</td></tr><tr><td>Scalpel</td><td>6B INVENT</td><td>7-104-L</td><td>used to make incision</td></tr><tr><td>Compact Speed Reducer</td><td>Anspach Companies</td><td>CSR60</td><td>used to make burr hole</td></tr><tr><td>14 mm Cranial Perforator</td><td>Anspach Companies</td><td>CPERF-14-11-3F</td><td>used to make burr hole</td></tr><tr><td>2 mm x 15.6 mm Fluted Router</td><td>Anspach Companies</td><td>A-CRN-M</td><td>used to make craniotomy</td></tr><tr><td>2.1 mm Pin-shaped Burrs</td><td>Anspach Companies</td><td>03.000.130S</td><td>used to make craniotomy</td></tr></tbody></table>

fiber connections of the supplementary motor area revisited: methodology of fiber dissection, dti, and three dimensional documentation

本研究的目的是显示使用纤维解剖技术对尸体标本和磁共振（MR）的组合来检查辅助运动区（SMA）复合体（SMA前SMA和SMA）的白质连接的方法）造影。该方案还将描述人脑白质解剖的程序，扩散张量成像和三维文档。人脑和3D文件的纤维解剖在明尼苏达大学，神经外科系显微外科和神经解剖学实验室进行。根据Klingler的方法制备了五个死后人脑标本和两个整体头。在手术显微镜下，从外侧到内侧和外侧逐步解剖脑半球，并在每个阶段捕获3D图像。所有解剖​​结果均受扩散张量支持成像。根据Meynert纤维分类，包括关联纤维（短，优越的纵向筋膜I和前额叶），投影纤维（皮质脊髓，幽闭皮质，关节和前额皮带）和连合纤维（胼al体纤维）的连接的调查分别为也进行了。

SMA复合体位于额上回的后部。 SMA复合体的边界是前中央沟，下侧上髁，下侧有扣带沟18 。 SMA复合体由两部分组成:前SMA前侧和SMA正侧18 。这两个部分18 （ 图1A和B ）之间的白质连接和功能方面存在差异。我们使用纤维解剖和DTI技术研究了这两个部分的皮质和皮质下连接，并将其显示在3D图像中?...

Watch this Scientific Journal Video about Fiber Connections of the Supplementary Motor Area Revisited: Methodology of Fiber Dissection, DTI, and Three Dimensional Documentation at JoVE.com

Fiber Connections of the Supplementary Motor Area Revisited: Methodology of Fiber Dissection, DTI, and Three Dimensional Documentation

本研究的目的是展示纤维解剖技术在人类尸体大脑上的每一步骤，这些解剖的3D文件以及解剖解剖纤维通路的扩散张量成像。

补充电机区的光纤连接重新审视:光纤解剖，DTI和三维文档的方法

The purpose of this study is to show the methodology for the examination of the white matter connections of the supplementary motor area (SMA) complex ...

fiber-connections-supplementary-motor-area-revisited-methodology

Research

JoVE Journal

Neuroscience

11.2K 次观看.  University of Minnesota. 本研究的目的是展示纤维解剖技术在人类尸体大脑上的每一步骤，这些解剖的3D文件以及解剖解剖纤维通路的扩散张量成像。 

视频: Fiber Connections of the Supplementary Motor Area Revisited: Methodology of Fiber Dissection, DTI, and Three Dimensional Documentation

Functional Near Infrared Spectroscopy of the Sensory and Motor Brain Regions with Simultaneous Kinematic and EMG Monitoring During Motor Tasks

There are several advantages that functional near-infrared spectroscopy (fNIRS) presents in the study of the neural control of human movement. It is relatively flexible with respect to participant positioning and allows for some head movements during tasks. Additionally, it is inexpensive, light weight, and portable, with very few contraindications to its use. This presents a unique opportunity to study functional brain activity during motor tasks in individuals who are typically developing, as well as those with movement disorders, such as cerebral palsy. An additional consideration when studying movement disorders, however, is the quality of actual movements performed and the potential for additional, unintended movements. Therefore, concurrent monitoring of both blood flow changes in the brain and actual movements of the body during testing is required for appropriate interpretation of fNIRS results. Here, we show a protocol for the combination of fNIRS with muscle and kinematic monitoring during motor tasks. We explore gait, a unilateral multi-joint movement (cycling), and two unilateral single-joint movements (isolated ankle dorsiflexion, and isolated hand squeezing). The techniques presented can be useful in studying both typical and atypical motor control, and can be modified to investigate a broad range of tasks and scientific questions.

Monitoring brain activity during upright motor tasks is of great value when investigating the neural source of movement disorders. Here, we demonstrate a protocol that combines functional near infrared spectroscopy with continuous monitoring of muscle and kinematic activity during 4 types of motor tasks.

感觉和运动脑区与运动同步和肌电图监测功能近红外光谱在运动任务

There are several advantages that functional near-infrared spectroscopy (fNIRS) presents in the study of the neural control of human movement. It is ...

科研

行为学

Intracortical Inhibition Within the Primary Motor Cortex Can Be Modulated by Changing the Focus of Attention

It is well recognized that an external focus (EF) compared with an internal focus (IF) of attention improves motor learning and performance. Studies have indicated benefits in accuracy, balance, force production, jumping performance, movement speed, oxygen consumption, and fatiguing task. Although behavioral outcomes of using an EF strategy are well explored, the underlying neural mechanisms remain unknown. A recent TMS study compared the activity of the primary motor cortex (M1) between an EF and an IF. More precisely, this study showed that, when adopting an EF, the activity of intracortical inhibitory circuits is enhanced.
On the behavioral level, the present protocol tests the influence of attentional foci on the time to task failure (TTF) when performing submaximal contractions of the first dorsal interosseous (FDI). Additionally, the current paper describes two TMS protocols to assess the influence of attentional conditions on the activity of cortical inhibitory circuits within the M1. Thus, the present article describes how to use single-pulse TMS at intensities below the motor threshold (subTMS) and paired-pulse TMS, inducing short-interval intracortical inhibition (SICI) when applied to the M1. As these methods are assumed to reflect the responsiveness of GABAergic inhibitory neurons, without being affected by spinal reflex circuitries, they are well suited to measuring the activity of intracortical inhibitory circuits within the M1.
The results show that directing attention externally improves motor performance, as participants were able to prolong the time to task failure. Moreover, the results were accompanied by a larger subTMS-induced electromyography suppression and SICI when adopting an EF compared to an IF. As the level of cortical inhibition within the M1 was previously demonstrated to influence motor performance, the enhanced inhibition with an EF might contribute to the better movement efficiency observed in the behavioral task, indicated by a prolonged TTF with an EF.

Using two different transcranial magnetic stimulation (TMS) protocols, this manuscript describes how to measure and compare cortical inhibition within the primary motor cortex when adopting different attentional foci.

通过改变注意力的焦点, 可以调节皮质在初级运动皮层内的抑制

It is well recognized that an external focus (EF) compared with an internal focus (IF) of attention improves motor learning and performance. Studies have ...

Co-analysis of Brain Structure and Function using fMRI and Diffusion-weighted Imaging

The study of complex computational systems is facilitated by network maps, such as circuit diagrams. Such mapping is particularly informative when studying the brain, as the functional role that a brain area fulfills may be largely defined by its connections to other brain areas. In this report, we describe a novel, non-invasive approach for relating brain structure and function using magnetic resonance imaging (MRI). This approach, a combination of structural imaging of long-range fiber connections and functional imaging data, is illustrated in two distinct cognitive domains, visual attention and face perception. Structural imaging is performed with diffusion-weighted imaging (DWI) and fiber tractography, which track the diffusion of water molecules along white-matter fiber tracts in the brain (Figure 1). By visualizing these fiber tracts, we are able to investigate the long-range connective architecture of the brain. The results compare favorably with one of the most widely-used techniques in DWI, diffusion tensor imaging (DTI). DTI is unable to resolve complex configurations of fiber tracts, limiting its utility for constructing detailed, anatomically-informed models of brain function. In contrast, our analyses reproduce known neuroanatomy with precision and accuracy. This advantage is partly due to data acquisition procedures: while many DTI protocols measure diffusion in a small number of directions (e.g., 6 or 12), we employ a diffusion spectrum imaging (DSI)1, 2 protocol which assesses diffusion in 257 directions and at a range of magnetic gradient strengths. Moreover, DSI data allow us to use more sophisticated methods for reconstructing acquired data. In two experiments (visual attention and face perception), tractography reveals that co-active areas of the human brain are anatomically connected, supporting extant hypotheses that they form functional networks. DWI allows us to create a "circuit diagram" and reproduce it on an individual-subject basis, for the purpose of monitoring task-relevant brain activity in networks of interest.

We describe a novel approach for simultaneous analysis of brain function and structure using magnetic resonance imaging (MRI). We assess brain structure with high-resolution diffusion-weighted imaging and white-matter fiber tractography. Unlike standard structural MRI, these techniques allow us to directly relate anatomical connectivity to functional properties of brain networks.

使用功能磁共振成像和弥散加权成像脑结构与功能分析

The study of complex computational systems is facilitated by network maps, such as circuit diagrams. Such mapping is particularly informative when ...

神经科学

Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases

Diffusion tensor imaging (DTI) techniques provide information on the microstructural processes of the cerebral white matter (WM) in vivo. The present applications are designed to investigate differences of WM involvement patterns in different brain diseases, especially neurodegenerative disorders, by use of different DTI analyses in comparison with matched controls. 	
DTI data analysis is performed in a variate fashion, i.e. voxelwise comparison of regional diffusion direction-based metrics such as fractional anisotropy (FA), together with fiber tracking (FT) accompanied by tractwise fractional anisotropy statistics (TFAS) at the group level in order to identify differences in FA along WM structures, aiming at the definition of regional patterns of WM alterations at the group level. Transformation into a stereotaxic standard space is a prerequisite for group studies and requires thorough data processing to preserve directional inter-dependencies. The present applications show optimized technical approaches for this preservation of quantitative and directional information during spatial normalization in data analyses at the group level. On this basis, FT techniques can be applied to group averaged data in order to quantify metrics information as defined by FT. Additionally, application of DTI methods, i.e. differences in FA-maps after stereotaxic alignment, in a longitudinal analysis at an individual subject basis reveal information about the progression of neurological disorders. Further quality improvement of DTI based results can be obtained during preprocessing by application of a controlled elimination of gradient directions with high noise levels.	
In summary, DTI is used to define a distinct WM pathoanatomy of different brain diseases by the combination of whole brain-based and tract-based DTI analysis.

Diffusion tensor imaging (DTI) basically serves as an MRI-based tool to identify in vivo the microstructure of the brain and pathological processes due to neurological disorders within the cerebral white matter. DTI-based analyses allow for application to brain diseases both at the group level and in single subject data.

磁共振扩散张量成像在神经退行性疾病的分析

Diffusion tensor imaging (DTI) techniques provide information on the microstructural processes of the cerebral white matter (WM) in vivo. The present ...

医学

DTI of the Visual Pathway - White Matter Tracts and Cerebral Lesions

DTI is a technique that identifies white matter tracts (WMT) non-invasively in healthy and non-healthy patients using diffusion measurements. Similar to visual pathways (VP), WMT are not visible with classical MRI or intra-operatively with microscope. DTI will help neurosurgeons to prevent destruction of the VP while removing lesions adjacent to this WMT. We have performed DTI on fifty patients before and after surgery between March 2012 to January 2014. To navigate we used a 3DT1-weighted sequence. Additionally, we performed a T2-weighted and DTI-sequences. The parameters used were, FOV: 200 x 200 mm, slice thickness: 2 mm, and acquisition matrix: 96 x 96 yielding nearly isotropic voxels of 2 x 2 x 2 mm. Axial MRI was carried out using a 32 gradient direction and one b0-image. We used Echo-Planar-Imaging (EPI) and ASSET parallel imaging with an acceleration factor of 2 and b-value of 800 s/mm&#178;. The scanning time was less than 9 min.
The DTI-data obtained were processed using a FDA approved surgical navigation system program which uses a straightforward fiber-tracking approach known as fiber assignment by continuous tracking (FACT). This is based on the propagation of lines between regions of interest (ROI) which is defined by a physician. A maximum angle of 50, FA start value of 0.10 and ADC stop value of 0.20 mm&#178;/s were the parameters used for tractography.
There are some limitations to this technique. The limited acquisition time frame enforces trade-offs in the image quality. Another important point not to be neglected is the brain shift during surgery. As for the latter intra-operative MRI might be helpful. Furthermore the risk of false positive or false negative tracts needs to be taken into account which might compromise the final results.

Diffusion tensor imaging (DTI) was performed to try to depict the major parts of the visual pathway. The goal was to use an FDA approved standard commercial workstation which could be used for everyday routine in order to try to reduce postoperative damage of the visual pathway in the patients.

贸工部视觉通路的 - 白质及脑病变

DTI is a technique that identifies white matter tracts (WMT) non-invasively in healthy and non-healthy patients using diffusion measurements. Similar to ...

Targeting Neuronal Fiber Tracts for Deep Brain Stimulation Therapy Using Interactive, Patient-Specific Models

Deep brain stimulation (DBS), which involves insertion of an electrode to deliver stimulation to a localized brain region, is an established therapy for movement disorders and is being applied to a growing number of disorders. Computational modeling has been successfully used to predict the clinical effects of DBS; however, there is a need for novel modeling techniques to keep pace with the growing complexity of DBS devices. These models also need to generate predictions quickly and accurately. The goal of this project is to develop an image processing pipeline to incorporate structural magnetic resonance imaging (MRI) and diffusion weighted imaging (DWI) into an interactive, patient specific model to simulate the effects of DBS. A virtual DBS lead can be placed inside of the patient model, along with active contacts and stimulation settings, where changes in lead position or orientation generate a new finite element mesh and solution of the bioelectric field problem in near real-time, a timespan of approximately 10 seconds. This system also enables the simulation of multiple leads in close proximity to allow for current steering by varying anodes and cathodes on different leads. The techniques presented in this paper reduce the burden of generating and using computational models while providing meaningful feedback about the effects of electrode position, electrode design, and stimulation configurations to researchers or clinicians who may not be modeling experts.

The goal of this project is to develop an interactive, patient-specific modeling pipeline to simulate the effects of deep brain stimulation in near real-time and provide meaningful feedback as to how these devices influence neural activity in the brain.

应用交互式、患者特异性模型对神经纤维束进行深部脑刺激治疗的靶向性

Deep brain stimulation (DBS), which involves insertion of an electrode to deliver stimulation to a localized brain region, is an established therapy for ...

生物工程

Measuring Connectivity in the Primary Visual Pathway in Human Albinism Using Diffusion Tensor Imaging and Tractography

In albinism, the number of ipsilaterally projecting retinal ganglion cells (RGCs) is significantly reduced. The retina and optic chiasm have been proposed as candidate sites for misrouting. Since a correlation between the number of lateral geniculate nucleus (LGN) relay neurons and LGN size has been shown, and based on previously reported reductions in LGN volumes in human albinism, we suggest that fiber projections from LGN to the primary visual cortex (V1) are also reduced. Studying structural differences in the visual system of albinism can improve the understanding of the mechanism of misrouting and subsequent clinical applications. Diffusion data and tractography are useful for mapping the OR (optic radiation). This manuscript describes two algorithms for OR reconstruction in order to compare brain connectivity in albinism and controls.An MRI scanner with a 32-channel head coil was used to acquire structural scans. A T1-weighted 3D-MPRAGE sequence with 1 mm3 isotropic voxel size was used to generate high-resolution images for V1 segmentation. Multiple proton density (PD) weighted images were acquired coronally for right and left LGN localization. Diffusion tensor imaging (DTI) scans were acquired with 64 diffusion directions. Both deterministic and probabilistic tracking methods were run and compared, with LGN as the seed mask and V1 as the target mask. Though DTI provides relatively poor spatial resolution, and accurate delineation of OR may be challenging due to its low fiber density, tractography has been shown to be advantageous both in research and clinically. Tract based spatial statistics (TBSS) revealed areas of significantly reduced white matter integrity within the OR in patients with albinism compared to controls. Pairwise comparisons revealed a significant reduction in LGN to V1 connectivity in albinism compared to controls. Comparing both tracking algorithms revealed common findings, strengthening the reliability of the technique.

This manuscript describes deterministic and probabilistic algorithms for white matter (WM) reconstruction, used to examine differences in optic radiation (OR) connectivity between albinism and controls. Although probabilistic tractography follows the true course of nerve fibers more closely, deterministic tractography was run to compare the reliability and reproducibility of both techniques.

在人类白化病的初级视途径弥散张量成像和测量束成像连通

In albinism, the number of ipsilaterally projecting retinal ganglion cells (RGCs) is significantly reduced. The retina and optic chiasm have been proposed ...

Measuring and Manipulating Functionally Specific Neural Pathways in the Human Motor System with Transcranial Magnetic Stimulation

Understanding interactions between brain areas is important for the study of goal-directed behavior. Functional neuroimaging of brain connectivity has provided important insights into fundamental processes of the brain like cognition, learning, and motor control. However, this approach cannot provide causal evidence for the involvement of brain areas of interest. Transcranial magnetic stimulation (TMS) is a powerful, noninvasive tool for studying the human brain that can overcome this limitation by transiently modifying brain activity. Here, we highlight recent advances using a paired-pulse, dual-site TMS method with two coils that causally probes cortico-cortical interactions in the human motor system during different task contexts. Additionally, we describe a dual-site TMS protocol based on cortical paired associative stimulation (cPAS) that transiently enhances synaptic efficiency in two interconnected brain areas by applying repeated pairs of cortical stimuli with two coils. These methods can provide a better understanding of the mechanisms underlying cognitive-motor function as well as a new perspective on manipulating specific neural pathways in a targeted fashion to modulate brain circuits and improve behavior. This approach may prove to be an effective tool to develop more sophisticated models of brain-behavior relations and improve diagnosis and treatment of many neurological and psychiatric disorders.

This article describes new approaches to measure and strengthen functionally specific neural pathways with transcranial magnetic stimulation. These advanced noninvasive brain stimulation methodologies can provide new opportunities for the understanding of brain-behavior relations and development of new therapies to treat brain disorders.

利用颅内磁刺激测量和操纵人体运动系统中功能特定的神经通路

Understanding interactions between brain areas is important for the study of goal-directed behavior. Functional neuroimaging of brain connectivity has ...

Improving Outcomes in Anteromesial Temporal Lobe Resections - A Demonstration of Resecting the Temporal Piriform Cortex

Anteromesial temporal lobe resection (ATLR) is a useful treatment option for drug-resistant mesial temporal lobe epilepsy (DRmTLE). Growing evidence suggests the piriform cortex plays a crucial role in the generation and propagation of seizures in DRmTLE - and that the resection of the temporal portion of the piriform cortex is associated with significantly improved rates of seizure freedom. 
Here, we present the resection of the temporal portion of the piriform cortex in ATLR, using high-resolution preoperative probabilistic tractography algorithms and fused anatomical masks of the structures of interest into the intraoperative neuronavigation and microscope head-up display (HUD). 
All patients undergoing comprehensive preoperative assessment and investigations for DRmTLE provided informed, written consent to record an intraoperative video of the procedure. Patients were identified by an expert multidisciplinary team of epileptologists, epilepsy neurosurgeons, neuropsychologists, neuropsychiatrists, and electrophysiologists at a large epilepsy surgery center. The preoperative imaging pipeline included the delineation of critical structures. This included the temporal piriform cortex, and high-resolution probabilistic tractography for essential tracts at risk (e.g., optic radiation and inferior fronto-occipital fasciculus). These were co-registered to the preoperative volumetric neuronavigation scan and uploaded to the intra-operative neuronavigation system. 
Presented here is a step-by-step procedure of ATLR, including the resection of the temporal portion of the piriform cortex. The protocol combines Advanced structural and diffusion MR imaging and intraoperative visual aids to integrate anatomical masks of critical grey matter structures and white matter tracts into the surgical workflow in the operating room.

Here, we demonstrate an approach to intraoperative neurosurgical guidance in anteromesial temporal lobe resections, specifically highlighting the use of tractography and anatomical masks to aid safe resection of the temporal portion of the piriform cortex - an area increasingly regarded as a crucial surgical target in drug-resistant mesial temporal lobe epilepsy.

改善前颞叶切除术的预后 - 切除颞梨状皮层的演示

Anteromesial temporal lobe resection (ATLR) is a useful treatment option for drug-resistant mesial temporal lobe epilepsy (DRmTLE). Growing evidence ...

Using Diffusion Tensor Imaging in Traumatic Brain Injury

Source: Laboratories of Jonas T. Kaplan and Sarah I. Gimbel&#8212;University of Southern California
Traditional brain imaging techniques using MRI are very good at visualizing the gross structures of the brain. A structural brain image made with MRI provides high contrast of the borders between gray and white matter, and information about the size and shape of brain structures. However, these images do not detail the underlying structure and integrity of white matter networks in the brain, which consist of axon bundles that interconnect local and distant brain regions.
Diffusion MRI uses pulse sequences that are sensitive to the diffusion of water molecules. By measuring the direction of diffusion, it is possible to make inferences about the structure of white matter networks in the brain. Water molecules within an axon are constrained in their movements by the cell membrane; instead of randomly moving in every direction with equal probability (isotropic movement), they are more likely to move in certain directions, in parallel with the axon (anisotropic movement; Figure 1). Therefore, measures of diffusion anisotropy are thought to reflect properties of the white matter such as fiber density, axon thickness, and degree of myelination. One common measure is fractional anisotropy (FA). FA values range from 0, which represents completely isotropic movement, to 1, reflecting maximum anisotropy.
<img alt="Figure 1" src="/files/ftp_upload/10276/10276fig1.jpg" /> 
Figure 1: Diffusion anisotropy. When the direction of diffusion is unconstrained and random, movement is measured in all directions equally. This is isotropic diffusion (A). When water molecules are contained within the axon of a neuron, diffusion is anisotropic, tending to occur more frequently along the direction of the axon (B). <a href="http://www.jove.com/files/ftp_upload/10276/10276fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
In this experiment we will use diffusion tensor imaging (DTI) to measure white matter integrity in traumatic brain injury (TBI). TBI occurs when an external force injures the brain, such as a blow to the head or a sudden movement like the kind that might occur in a car accident. This type of brain injury from mechanical forces is associated with diffuse axonal injury-damage to white matter throughout the brain. Because it is an injury affecting white matter integrity, standard neuroimaging techniques may not reveal the damage. However, measures of diffusion are especially sensitive to these anatomical changes. Following a study by Kraus et al.1, we compare a group of healthy controls to a group of people with TBI and use diffusion imaging to measure the effect of TBI on cerebral white matter. Furthermore, we will test the relationship between white matter integrity and cognitive function using an attention task.2 This study uses a region of interest (ROI) approach focusing on three white matter tracts: the splenium of the corpus callosum, the anterior corona radiata, and the superior longitudinal fasciculus (Figure 2).
<img alt="Figure 2" src="/files/ftp_upload/10276/10276fig2.jpg" /> 
Figure 2: Regions of interest. The three ROIs, defined from the ICBM DTI-81 atlas, are shown here in horizontal slices through the brain. In green is the splenium of the corpus callosum. The splenium is the most posterior part of the corpus callosum. In blue is the anterior corona radiata. The superior longitudinal fasciculus is shown in red. <a href="http://www.jove.com/files/ftp_upload/10276/10276fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Diffusion Tensor Imaging in Traumatic Brain Injury

弥散张量成像在创伤性脑损伤

Source: Laboratories of Jonas T. Kaplan and Sarah I. Gimbel&#8212;University of Southern California
Traditional brain imaging techniques using MRI are ...