Center of Dental Medicine, University of Zurich, Zurich, Switzerland Balgrist University Hospital, Zurich, Switzerland
Center of Dental Medicine, University of Zurich, Zurich, Switzerland Department of Psychiatry (UPK), University of Basel, Switzerland.
J Dent Res. 2015 May;94(5):690-6. doi: 10.1177/0022034515572022. Epub 2015 Feb 17.
Local anesthesia has made dental treatment more comfortable since 1884, but little is known about associated brain mechanisms. Functional magnetic resonance imaging is a modern neuroimaging tool widely used for investigating human brain activity related to sensory perceptions, including pain. Most brain regions that respond to experimental noxious stimuli have recently been found to react not only to nociception alone, but also to visual, auditory, and other stimuli. Thus, presumed functional attributions have come under scrutiny regarding selective pain processing in the brain. Evidently, innovative approaches are warranted to identify cerebral regions that are nociceptive specific. In this study, we aimed at circumventing known methodological confounders by applying a novel paradigm in 14 volunteers: rather than varying the intensity and thus the salience of painful stimuli, we applied repetitive noxious dental stimuli at constant intensity to the left mandibular canine. During the functional magnetic resonance imaging paradigm, we suppressed the nociceptive barrage by a mental nerve block. Brain activity before and after injection of 4% articaine was compared intraindividually on a group level. Dental pain extinction was observed to correspond to activity reduction in a discrete region of the left posterior insular cortex. These results confirm previous reports demonstrating that direct electrical stimulation of this brain region-but not of others-evokes bodily pain sensations. Hence, our investigation adds further evidence to the notion that the posterior insula plays a unique role in nociceptive processing.
自 1884 年局部麻醉应用于牙科治疗以来，该治疗方法使牙科治疗变得更加舒适，但人们对其相关的大脑机制知之甚少。功能磁共振成像（fMRI）是一种广泛应用于研究与感觉感知（包括疼痛）相关的人类大脑活动的现代神经影像学工具。最近发现，大多数对实验性有害刺激作出反应的大脑区域不仅对伤害感受有反应，而且对视觉、听觉和其他刺激也有反应。因此，大脑中对疼痛的选择性处理的功能归因受到了严格的审查。显然，需要创新的方法来识别大脑中特定的疼痛感受区域。在这项研究中，我们旨在通过在 14 名志愿者中应用一种新的范式来避免已知的方法学混淆：我们不是通过改变疼痛刺激的强度和因此改变其显著性来应用重复性有害的牙科刺激，而是以恒定的强度应用于左侧下颌犬齿。在功能磁共振成像范式中，我们通过精神神经阻滞来抑制疼痛的冲击。在注射 4%阿替卡因前后，我们在个体内和组水平上比较了大脑活动。观察到在注射后，口腔疼痛的消失与左后岛叶皮质离散区域的活动减少相对应。这些结果证实了先前的报告，表明对该脑区的直接电刺激——而不是对其他脑区的电刺激——会引起身体疼痛感觉。因此，我们的研究进一步证明了后岛叶在疼痛处理中具有独特作用的观点。
