Department of Psychiatry, VU University Medical Center, Amsterdam, the Netherlands.
CNS Spectr. 2013 Feb;18(1):34-42. doi: 10.1017/S1092852912000703. Epub 2012 Dec 3.
The need for symmetry and ordering objects related to a "just right"-feeling is a common symptom in Tourette's syndrome (TS) and resembles symmetry behavior in obsessive-compulsive disorder, but its pathophysiology is unknown. We used a symptom provocation paradigm to investigate the neural correlates of symmetry behavior in TS and hypothesized the involvement of frontal-striatal and limbic brain areas.
Pictures of asymmetrically and symmetrically arranged objects were presented in randomized blocks (4 blocks of each condition) to 14 patients with TS and 10 matched healthy controls (HC). A H2 15O positron emission tomography scan was acquired during each stimulus block, resulting in 8 scans per subject. After each scan, state anxiety and symmetry behavior (the urge to rearrange objects) were measured using a visual analogue scale.
During the asymmetry condition, TS patients showed increased regional cerebral blood flow (rCBF) in the anterior cingulate cortex, supplementary motor area, and inferior frontal cortex, whereas HC showed increased rCBF in the visual cortex, primary motor cortex, and dorsal prefrontal cortex. Symmetry ratings during provocation correlated positively with orbitofrontal activation in the TS group and sensorimotor activation in the HC group, and negatively with dorsal prefrontal activity in HC.
Results suggest that both motor and limbic circuits are involved in symmetry behavior in TS. Motor activity may relate to an urge to move or perform tics, and limbic activation may indicate that asymmetry stimuli are salient for TS patients. In contrast, symmetry provocation in HC resulted in activation of brain regions implicated in sensorimotor function and cognitive control.
与“恰到好处”感觉相关的对象的对称和有序排列的需求是妥瑞氏症（TS）的常见症状，类似于强迫症中的对称行为，但其病理生理学尚不清楚。我们使用症状诱发范式来研究 TS 中对称行为的神经相关性，并假设涉及额纹状体和边缘脑区。
以随机块（每种条件 4 个块）向 14 名 TS 患者和 10 名匹配的健康对照者（HC）呈现不对称和对称排列的物体的图片。在每个刺激块期间采集 H2 15O 正电子发射断层扫描（PET），每个受试者获得 8 次扫描。每次扫描后，使用视觉模拟量表测量状态焦虑和对称行为（重新排列物体的冲动）。
在不对称条件下，TS 患者在前扣带皮层、辅助运动区和下额前皮质中显示出区域脑血流（rCBF）增加，而 HC 则在视觉皮层、初级运动皮层和背侧前额叶皮质中显示出 rCBF 增加。在诱发时的对称评分与 TS 组的眶额激活呈正相关，与 HC 组的感觉运动激活呈正相关，与 HC 的背侧前额叶活动呈负相关。
结果表明，运动和边缘回路都参与了 TS 中的对称行为。运动活动可能与移动或执行抽搐的冲动有关，而边缘激活可能表明不对称刺激对 TS 患者很明显。相比之下，HC 中的对称诱发导致与感觉运动功能和认知控制相关的脑区激活。
