BRAIN IMAGING AND PAIN: ANALYSIS OF PLACEBO ANALGESIA

描述（由申请人提供）：本项目旨在研究安慰剂镇痛的神经机制。将采用一种创新的安慰剂方案，评估安慰剂对内脏和皮肤疼痛刺激的反应。功能性磁共振成像（fMRI）将使参与安慰剂镇痛的临床人群，经历内脏疼痛作为其临床综合征的一部分，脑机制的表征。这个项目将利用以前的工作与肠易激综合征（IBS）的病人，其中差异的大脑激活被证明内脏和皮肤疼痛刺激。在同一人群中，已证明安慰剂对特定预期反应集的有效性和可靠性。拟议项目将联合收割机这些方案，以获得IBS受试者在自然病程、安慰剂和活性药物（直肠利多卡因）条件下的脑图像。预计结果将表明安慰剂反应将选择性地激活特定的大脑区域。与安慰剂条件相比，在以下脑区域中，自然病史条件下的神经活动（通过rCBF测量）将更大：-外侧和/或内侧丘脑、体感区1和2、岛叶皮质、前扣带皮质（ACC）、后扣带皮质（PCC）和前额皮质。此外，主要通过在较低神经系统水平（脊髓）处的伤害感受信号的衰减来起作用的安慰剂机制将通过降低的丘脑、躯体感觉、ACC和PCC激活来证明。先前的研究表明，对疼痛缓解的期望和愿望将显着预测安慰剂的疼痛减轻。预期这些测量也将与上述大脑激活模式相关联。通过比较安慰剂条件与直肠利多卡因条件，将区分脑和中枢神经系统相关机制与外周（受体部位）相关机制。

DESCRIPTION (provided by applicant): This project is designed to investigate the neural mechanisms of placebo analgesia. An innovative placebo protocol that assesses the placebo response to both visceral and cutaneous pain stimulation will be employed. Functional Magnetic Resonance Imaging (fMRI) will enable the characterization of brain mechanisms involved in placebo analgesia in a clinical population which experiences visceral pain as part of their clinical syndrome. This project will capitalize on previous work with Irritable Bowel Syndrome (IBS) patients where differential brain activation was demonstrated to visceral and cutaneous pain stimuli. In this same population a powerful and reliable placebo response to specific expectancy response sets has been demonstrated. The proposed project will combine these protocols to obtain brain images of IBS subject during natural history, placebo, and active agent (rectal lidocaine) conditions. It is anticipated that results will show that the placebo response will selectively activate specific brain regions. Neural activity (as measured by rCBF) will be greater in natural history conditions as compared to placebo conditions in the following brain regions: - lateral and/or medial thalamus, somatosensory areas 1 and 2, insular cortex, anterior cingulate cortex (ACC), posterior cingulate cortex (PCC), and prefrontal cortex. Furthermore, placebo mechanisms that operate primarily through attenuation of nociceptive signals at lower nervous system levels (spinal cord) will be evidenced by decreased thalamic, somatosensory, ACC, and PCC activation. Previous research indicates that expectancy and desire for pain relief will significantly predict the pain reduction from placebo. It is anticipated that these measures will also be associated with the above described brain activation patterns. By comparing the placebo conditions to the rectal lidocaine condition, brain and central nervous system related mechanisms versus peripheral (receptor site) related mechanisms will be differentiated.