Kleinschmidt A, Obrig H, Requardt M, Merboldt K D, Dirnagl U, Villringer A, Frahm J
Max Planck Institut for Biophysical Chemistry, Göttingen, Germany.
J Cereb Blood Flow Metab. 1996 Sep;16(5):817-26. doi: 10.1097/00004647-199609000-00006.
Changes in cerebral blood oxygenation due to functional activation of the primary sensorimotor cortex during a unilateral finger opposition task were simultaneously mapped by deoxyhemoglobin-sensitive magnetic resonance imaging (MRI) and monitored by near-infrared spectroscopy (NIRS). Activation foci along the contralateral central sulcus displayed task-associated increases in MRI signal intensity, indicating a concomitant decrease of the focal concentration of deoxyhemoglobin. This interpretation was confirmed by simultaneous reductions in deoxyhemoglobin measured optically. Since observation of the latter effect required exact spatial matching of the MRI-detected activation foci and position of the fiber optic bundles ("optodes") used for transmitting and receiving light, it may be concluded that optical recordings of changes in deoxyhemoglobin during functional challenge probe only a restricted brain tissue region. While deoxyhemoglobin responses seen by NIRS were smaller for ipsi- than for contralateral finger movements, task-related increases in oxyhemoglobin were rather similar between both conditions and, thus, seem to be less specific. Furthermore, no consistent changes were obtained for total hemoglobin during task performance, possibly due to the short timing of the repetitive protocol. In general, results underline, in humans, the hitherto assumed signal physiology for functional brain mapping by oxygenation-sensitive MRI and allow assessment of both constraints and practicability of functional studies by NIRS.
在单侧手指对指任务期间，通过脱氧血红蛋白敏感磁共振成像（MRI）同步绘制初级感觉运动皮层功能激活引起的脑血氧变化，并通过近红外光谱（NIRS）进行监测。沿对侧中央沟的激活灶显示MRI信号强度出现与任务相关的增加，表明脱氧血红蛋白的局部浓度随之降低。通过光学测量的脱氧血红蛋白同时减少证实了这一解释。由于观察到后一种效应需要MRI检测到的激活灶与用于发射和接收光的光纤束（“光极”）位置进行精确的空间匹配，因此可以得出结论，在功能挑战期间对脱氧血红蛋白变化进行光学记录仅探测了有限的脑组织区域。虽然NIRS观察到的同侧手指运动的脱氧血红蛋白反应比对侧手指运动的小，但两种情况下与任务相关的氧合血红蛋白增加相当相似，因此似乎特异性较低。此外，在任务执行期间总血红蛋白没有获得一致的变化，这可能是由于重复方案的时间较短。总体而言，研究结果强调了在人类中，迄今为止通过氧合敏感MRI进行功能性脑图谱绘制所假定的信号生理学，并允许评估NIRS功能研究的局限性和实用性。
