Gosain A K, Birn R M, Hyde J S
Department of Plastic and Reconstructive Surgery, Medical College of Wisconsin, Milwaukee 53226, USA.
Plast Reconstr Surg. 2001 Oct;108(5):1136-44. doi: 10.1097/00006534-200110000-00005.
Functional magnetic resonance imaging (fMRI) can serve to localize activity in the cerebral cortex. The present study was performed to develop a quantitative means of describing the cortical location activated during voluntary smiling in multiple subjects and to determine whether this location is specific to smiling when compared with other motor tasks. Five human subjects were instructed to smile or to tap the fingers of both hands. Both tasks were performed in a blocked-trial paradigm that consisted of alternating 15-second blocks of a repetitive motor task and 15 seconds of rest. Smiling was also performed as an event-related paradigm in which the subject smiled briefly once every 15 seconds for 20 repetitions that were combined to produce an average response to a single smile. A series of 300 images was acquired using an echo-planar imaging sequence (24-cm field of view; 5-mm slice thickness; repetition time/echo time, 1000/27.2 msec). Each subject's three-dimensional brain images were transformed to Talairach coordinates by stretching or compressing the brain images to fit the standard brain as defined in the Talairach atlas. This allowed data from five subjects to be combined for a numeric description. Functional activation maps acquired by use of the event-related paradigm contained significantly fewer motion artifacts than maps acquired with the blocked-trial paradigm, allowing better visualization of functionally active areas. Three-dimensional Talairach coordinates to describe the locations of peak cortical activity after smiling and finger tapping were established. These coordinates were consistent among subjects. During smiling, statistically significant activation was seen in the motor cortex, primarily along the precentral sulcus; this was inferior and anterior to the region that was associated with finger tapping. This study demonstrates that motion artifacts associated with traditional blocked-trial fMRI protocols can be overcome by employing an event-related paradigm to obtain an average response from a single smile. With the implementation of new imaging paradigms with fMRI, an area of the cerebral cortex has been identified that is specifically activated during voluntary smiling, and remains consistent among subjects. Quantification of fMRI data represents a powerful tool by which to study the cortical response to motor activity and to monitor possible alteration in this activity after injury or surgery. When combined with biofeedback therapy, this technique may help to improve the outcome of facial reanimation procedures in the future.
功能磁共振成像（fMRI）可用于定位大脑皮层的活动。本研究旨在开发一种定量方法，以描述多个受试者在自愿微笑时大脑皮层激活的位置，并确定与其他运动任务相比，该位置是否特定于微笑。五名受试者被要求微笑或轻敲双手手指。两项任务均采用组块设计范式进行，即由重复运动任务的15秒组块和15秒休息时间交替组成。微笑也作为事件相关范式进行，受试者每15秒短暂微笑一次，共20次，将这些微笑组合起来以产生对单个微笑的平均反应。使用回波平面成像序列（视野24厘米；切片厚度5毫米；重复时间/回波时间，1000/27.2毫秒）采集了一系列300张图像。通过拉伸或压缩大脑图像，使其符合Talairach图谱中定义的标准大脑，将每个受试者的三维脑图像转换为Talairach坐标。这使得来自五名受试者的数据能够合并进行数值描述。与组块设计范式获得的图谱相比，使用事件相关范式获得的功能激活图谱中的运动伪影明显更少，从而能够更好地可视化功能活跃区域。建立了用于描述微笑和轻敲手指后皮层活动峰值位置的三维Talairach坐标。这些坐标在受试者之间是一致的。在微笑过程中，在运动皮层中观察到具有统计学意义的激活，主要沿着中央前沟；该区域位于与轻敲手指相关区域的下方和前方。本研究表明，通过采用事件相关范式从单个微笑中获得平均反应，可以克服与传统组块设计fMRI协议相关的运动伪影。随着fMRI新成像范式的实施，已确定大脑皮层的一个区域在自愿微笑时会被特异性激活，并且在受试者之间保持一致。fMRI数据的量化是研究皮层对运动活动的反应以及监测损伤或手术后该活动可能变化的有力工具。当与生物反馈疗法相结合时，该技术可能有助于改善未来面部恢复手术的效果。
