Davis K D, Kwan C L, Crawley A P, Mikulis D J
Department of Surgery, (Division of Neurosurgery), University of Toronto, Ontario, Canada.
J Neurophysiol. 1998 Sep;80(3):1533-46. doi: 10.1152/jn.1998.80.3.1533.
Positron emission tomography studies have provided evidence for the involvement of the thalamus and cortex in pain and temperature perception. However, the involvement of these structures in pain and temperature perception of individual subjects has not been studied in detail with high spatial resolution imaging. As a first step toward this goal, we have used functional magnetic resonance imaging (fMRI) to locate discrete regions of the thalamus, insula, and second somatosensory cortex (S2) modulated during innocuous and noxious thermal stimulation. Results were compared with those obtained during tactile stimulation of the palm. High resolution functional images were acquired on a 1.5 T echospeed GE MR system with an in-plane resolution of 1.7 mm. A modified peltier-type thermal stimulator was used to deliver innocuous cool and warm and noxious cold and hot stimuli for 40-60 s to the thenar eminence of normal male and female volunteers. Experimental paradigms consisted of four repetitions of interleaved control and task stimuli. A pixel by pixel statistical analysis of images obtained during each task versus control (e.g., noxious heat vs. warm, warm vs. neutral temperature, etc.) was used to determine task-related activations. Painful thermal stimuli activated discrete regions within the lateral and medial thalamus, and insula, predominantly in the anterior insula in most subjects, and the contralateral S2 in 50% of subjects. The innocuous thermal stimuli did not activate the S2 in any of the subjects but activated the thalamus and posterior insula in 50% of subjects. By comparison, innocuous tactile stimulation consistently activated S2 bilaterally and the contralateral lateral thalamus. These data also demonstrate that noxious thermal and innocuous tactile-related activations overlap in S2. The data also suggest that innocuous and noxious-related activations may overlap within the thalamus but may be located in different regions of the insula. Therefore, we provide support for a role of the anterior insula, S2, and thalamus in the perception of pain; whereas the posterior insula appears to be involved in tactile and innocuous temperature perception. These data demonstrate the feasibility of using fMRI for studies of pain, temperature, and mechanical stimuli in individual subjects, even in small regions such as thalamic nuclei. However, the intersubject variability should be considered in future single subject imaging studies and studies that rely on averaged group responses.
正电子发射断层扫描研究为丘脑和皮层参与疼痛及温度感知提供了证据。然而，这些结构在个体受试者的疼痛和温度感知中的参与情况尚未通过高空间分辨率成像进行详细研究。作为朝着这一目标迈出的第一步，我们使用功能磁共振成像（fMRI）来定位在无害和有害热刺激期间被调制的丘脑、岛叶和第二躯体感觉皮层（S2）的离散区域。将结果与在手掌触觉刺激期间获得的结果进行比较。在一台1.5T的Echospeed GE MR系统上采集高分辨率功能图像，平面分辨率为1.7毫米。使用一种改良的珀尔帖式热刺激器向正常男性和女性志愿者的鱼际隆起部位施加40 - 60秒的无害冷、热以及有害冷、热刺激。实验范式由四次交错的对照和任务刺激重复组成。对每个任务与对照期间获得的图像进行逐像素统计分析（例如，有害热与热、热与中性温度等），以确定与任务相关的激活情况。疼痛性热刺激激活了外侧和内侧丘脑以及岛叶内的离散区域，在大多数受试者中主要在前岛叶，在50%的受试者中激活了对侧S2。无害热刺激在任何受试者中均未激活S2，但在50%的受试者中激活了丘脑和后岛叶。相比之下，无害触觉刺激始终双侧激活S2以及对侧外侧丘脑。这些数据还表明，有害热刺激和无害触觉相关的激活在S2中重叠。数据还表明，无害和有害相关的激活可能在丘脑中重叠，但可能位于岛叶的不同区域。因此，我们为前岛叶、S2和丘脑在疼痛感知中的作用提供了支持；而后岛叶似乎参与触觉和无害温度感知。这些数据证明了使用fMRI研究个体受试者的疼痛、温度和机械刺激的可行性，即使是在诸如丘脑核等小区域。然而，在未来的单受试者成像研究以及依赖平均组反应的研究中应考虑受试者间的变异性。
