Department of Radiology and Radiological Science, Vanderbilt University Medical Center, Nashville, TN, USA Institute of Imaging Science, Vanderbilt University, Nashville, TN, USA Department of Psychology, Vanderbilt University, Nashville, TN, USA Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA.
Pain. 2011 Mar;152(3):522-532. doi: 10.1016/j.pain.2010.10.048. Epub 2010 Dec 21.
This study mapped the fine-scale functional representation of tactile and noxious heat stimuli in cortical areas around the central sulcus of anesthetized squirrel monkeys by using high-resolution blood oxygen level-dependent (BOLD) fMRI at 9.4T. Noxious heat (47.5°C) stimulation of digits evoked multiple spatially distinct and focal BOLD activations. Consistent activations were observed in areas 3a, 3b, 1, and 2, whereas less frequent activation was present in M1. Compared with tactile activations, thermal nociceptive activations covered more area and formed multiple foci within each functional area. In general, noxious heat activations in area 3b did not colocalize with tactile responses. The spatial relationships of heat and tactile activations in areas 3a and 1/2 varied across animals. Subsequent electrophysiological mapping confirmed that the evoked heat and tactile BOLD signals were somatotopically appropriate. The magnitude and temporal profiles of the BOLD signals to noxious heat stimuli differed across cortical areas. Comparatively late-peaking but stronger signals were observed in areas 3b and 2, whereas earlier-peaking but weaker signals were observed in areas 3a, 1, and M1. In sum, this study not only confirmed the involvement of somatosensory areas of 3a, 3b, and 1, but also identified the engagements of area 2 and M1 in the processing of heat nociceptive inputs. Differential BOLD response profiles of the individual cortical areas along the central sulcus suggest that these areas play different roles in the encoding of nociceptive inputs. Thermal nociceptive and tactile inputs may be processed by different clusters of neurons in different areas. To critically bridge animal and human pain studies, human fMRI was related to primate fMRI and electrophysiology of nociceptive processing, examining the functional role of the primary somatosensory cortex in heat nociception and demonstrating that subregion areas 3a, 3b, 1, 2, and M1 are responsive to noxious heat stimuli.
本研究使用高分辨率血氧水平依赖（BOLD）fMRI 在 9.4T 下，对麻醉松鼠猴中央沟周围的皮质区域进行了触觉和有害热刺激的精细功能描绘。数字的有害热（47.5°C）刺激引发了多个空间上不同且聚焦的 BOLD 激活。在 3a、3b、1 和 2 区观察到一致的激活，而 M1 区的激活则较少。与触觉激活相比，热伤害性感受激活覆盖的区域更大，并在每个功能区域内形成多个焦点。一般来说，3b 区的有害热激活与触觉反应不重叠。3a 和 1/2 区热和触觉激活的空间关系在动物之间有所不同。随后的电生理映射证实了诱发的热和触觉 BOLD 信号与躯体感觉有关。有害热刺激的 BOLD 信号的幅度和时间特征在不同的皮质区域有所不同。相对而言，在 3b 和 2 区观察到峰值较晚但信号较强，而在 3a、1 和 M1 区观察到峰值较早但信号较弱。总之，本研究不仅证实了 3a、3b 和 1 等躯体感觉区域的参与，还确定了 2 区和 M1 区在处理热伤害性传入中的参与。中央沟沿线单个皮质区域的 BOLD 反应谱差异表明，这些区域在伤害性传入的编码中发挥不同的作用。热伤害性和触觉输入可能由不同区域的不同神经元簇处理。为了批判性地弥合动物和人类疼痛研究之间的差距，我们将人类 fMRI 与灵长类动物 fMRI 和伤害性处理的电生理学相关联，研究了初级躯体感觉皮层在热伤害感受中的功能作用，并证明了亚区 3a、3b、1、2 和 M1 对有害热刺激有反应。
