Smith J M, James M F, Bockhorst K H, Smith M I, Bradley D P, Papadakis N G, Carpenter T A, Parsons A A, Leslie R A, Hall L D, Huang C L
Physiological Laboratory, University of Cambridge, UK.
J Anat. 2001 May;198(Pt 5):537-54. doi: 10.1046/j.1469-7580.2001.19850537.x.
Cortical spreading depression (CSD) and peri-infarct depolarisation (PID) are related phenomena that have been associated with the human clinical syndromes of migraine (CSD), head injury and stroke (PID). Nevertheless the existence of CSD in man remains controversial, despite the detection of this phenomenon in the brains of most, if not all, other animal species investigated. This failure to unambiguously detect CSD clinically may be at least partly due to the anatomically complex, gyrencephalic structure of the human brain. This study was designed to establish conditions for the study of CSD in the brain of a gyrencephalic species using the noninvasive technique of magnetic resonance imaging (MRI). The 3-dimensional (3D) gyrencephalic anatomy of the cat brain was examined to determine the imaging conditions necessary to detect CSD events. Orthogonal transverse, sagittal and horizontal T1-weighted image slices showed that the marginal and suprasylvian gyri were the most appropriate cortical structures to study CSD. This was in view of (1) their simple geometry: (2) their lengthy extent of grey matter orientated rostrocaudally in the cortex: (3) their separation by a sulcus across which CSD spread could be studied and (4) the discontinuity in the grey matter in these regions between the right and left hemispheres dorsal to the corpus callosum. The structure suggested by the T1-weighted images was corroborated by systematic diffusion tensor imaging to map the fractional anisotropy and diffusion trace. Thus a single horizontal image plane could visualise the neighbouring suprasylvian and marginal gyri of both cerebral hemispheres, whereas its complex shape and position ruled out the ectosylvian gyrus for CSD studies. With the horizontal imaging plane, CSD events were reproducibly detected by animating successive diffusion-weighted MR images following local KCl stimulation of the cortical surface. In single image frames, CSD detection and characterisation required image subtraction or statistical mapping methods that, nevertheless, yielded concordant results. In repeat experiments, CSD events were qualitatively similar in appearance whether elicited by sustained or transient KCl applications. Our experimental approach thus successfully describes cat brain anatomy in vivo, and elucidates the necessary conditions for the application of MRI methods to detect CSD propagation.
皮质扩散性抑制（CSD）和梗死灶周围去极化（PID）是相关现象，与偏头痛（CSD）、头部损伤和中风（PID）的人类临床综合征有关。然而，尽管在大多数（如果不是所有）其他被研究的动物物种的大脑中都检测到了这种现象，但CSD在人类中的存在仍存在争议。临床上未能明确检测到CSD可能至少部分归因于人类大脑解剖结构复杂的脑回状结构。本研究旨在利用磁共振成像（MRI）的非侵入性技术，建立在脑回状物种大脑中研究CSD的条件。对猫脑的三维（3D）脑回状解剖结构进行了检查，以确定检测CSD事件所需的成像条件。正交的横向、矢状和水平T1加权图像切片显示，缘回和上薛氏回是研究CSD最合适的皮质结构。这是鉴于：（1）它们简单的几何形状；（2）它们在皮质中沿前后方向有较长的灰质范围；（3）它们被一条沟隔开，通过这条沟可以研究CSD的传播；（4）胼胝体背侧左右半球这些区域灰质的不连续性。T1加权图像显示的结构通过系统的扩散张量成像得到证实，以绘制分数各向异性和扩散轨迹。因此，单个水平图像平面可以可视化两个大脑半球相邻的上薛氏回和缘回，而其复杂的形状和位置排除了将外薛氏回用于CSD研究。使用水平成像平面，在局部KCl刺激皮质表面后，通过对连续的扩散加权MR图像进行动画处理，可重复检测到CSD事件。在单图像帧中，CSD的检测和特征描述需要图像减法或统计映射方法，不过，这些方法得出了一致的结果。在重复实验中，无论是持续还是短暂应用KCl引发的CSD事件，其外观在定性上都是相似的。因此，我们的实验方法成功地描述了猫脑的体内解剖结构，并阐明了应用MRI方法检测CSD传播的必要条件。
