Schut Christina, Mochizuki Hideki, Grossman Shoshana K, Lin Andrew C, Conklin Christopher J, Mohamed Feroze B, Gieler Uwe, Kupfer Joerg, Yosipovitch Gil
Institute of Medical Psychology, Justus-Liebig-UniversityGiessen, Germany.
Department of Dermatology, Lewis Katz School of Medicine at Temple University, PhiladelphiaPA, United States.
Front Psychol. 2017 Jul 25;8:1267. doi: 10.3389/fpsyg.2017.01267. eCollection 2017.
Several studies show that itch and scratching cannot only be induced by pruritogens like histamine or cowhage, but also by the presentation of certain (audio-) visual stimuli like pictures on crawling insects or videos showing other people scratching. This phenomenon is coined "Contagious itch" (CI). Due to the fact that CI is more profound in patients with the chronic itchy skin disease atopic dermatitis (AD), we believe that it is highly relevant to study brain processing of CI in this group. Knowledge on brain areas involved in CI in AD-patients can provide us with useful hints regarding non-invasive treatments that AD-patients could profit from when they are confronted with itch-inducing situations in daily life. Therefore, this study investigated the brain processing of CI in AD-patients. 11 AD-patients underwent fMRI scans during the presentation of an itch inducing experimental video (EV) and a non-itch inducing control video (CV). Perfusion based brain activity was measured using arterial spin labeling functional MRI. As expected, the EV compared to the CV led to an increase in itch and scratching ( < 0.05). CI led to a significant increase in brain activity in the supplementary motor area, left ventral striatum and right orbitofrontal cortex (threshold: < 0.001; cluster size > 50). Moreover, itch induced by watching the EV was by trend correlated with activity in memory-related regions including the temporal cortex and the (pre-) cuneus as well as the posterior operculum, a brain region involved in itch processing (threshold: < 0.005; cluster size > 50). These findings suggest that the fronto-striatal circuit, which is associated with the desire to scratch, might be a target region for non-invasive treatments in AD patients.
多项研究表明，瘙痒和抓挠不仅可由组胺或刺荨麻等致痒原诱发，还可由某些（视听）刺激引发，如爬行昆虫的图片或他人抓挠的视频。这种现象被称为“传染性瘙痒”（CI）。由于CI在慢性瘙痒性皮肤病特应性皮炎（AD）患者中更为显著，我们认为研究该群体中CI的大脑处理过程具有高度相关性。了解AD患者中与CI相关的脑区，可为我们提供有关非侵入性治疗的有用线索，AD患者在日常生活中遇到诱发瘙痒的情况时可能会从中受益。因此，本研究调查了AD患者中CI的大脑处理过程。11名AD患者在观看诱发瘙痒的实验视频（EV）和非诱发瘙痒的对照视频（CV）时接受了功能磁共振成像（fMRI）扫描。使用动脉自旋标记功能磁共振成像测量基于灌注的脑活动。正如预期的那样，与CV相比，EV导致瘙痒和抓挠增加（<0.05）。CI导致辅助运动区、左腹侧纹状体和右眶额皮质的脑活动显著增加（阈值：<0.001；簇大小>50）。此外，观看EV诱发的瘙痒与包括颞叶皮质、楔叶（前）和后岛盖（参与瘙痒处理的脑区）在内的记忆相关区域的活动呈趋势性相关（阈值：<0.005；簇大小>50）。这些发现表明，与抓挠欲望相关的额纹状体回路可能是AD患者非侵入性治疗的目标区域。
