Neural correlates of altered sensorimotor gating in boys with Tourette Syndrome: A combined EMG/fMRI study

<i>Objectives</i>: It has been hypothesised that altered sensorimotor gating might be a core problem in Tourette Syndrome (TS). However, the underlying neurophysiological mechanisms are elusive. <i>Methods</i>: We applied functional magnetic resonance imaging (fMRI) to investigate the neural correlates of altered sensorimotor gating by means of prepulse inhibition (PPI) in 22 boys with TS and 22 healthy boys using tactile PPI. The electromyography of the startle response was recorded simultaneously to the acquisition of the fMRI images. <i>Results</i>: As expected, PPI of the startle response was reduced in boys with TS compared to the healthy boys. We found decreased PPI-related blood oxygen level-dependent (BOLD) activity in boys with TS in the middle frontal gyrus, postcentral gyrus, superior parietal cortex, cingulate gyrus and caudate body. In boys with TS PPI of the startle response was positively correlated to PPI-related BOLD activity in the superior parietal cortex. <i>Conclusions</i>: Our findings indicate that deficient sensorimotor gating in boys with TS is associated with reduced recruitment of brain regions responsible for the higher-order integration of somatosensory stimuli. Due to our strict sample selection we were able to reduce confounding by neural adaptation processes, long-term medication, gender or comorbidities.### 研究目的 有假说提出，感觉运动门控（sensorimotor gating）异常可能是抽动秽语综合征（Tourette Syndrome，TS）的核心病理特征，但背后的神经生理学机制仍未明确。 ### 研究方法 本研究采用功能磁共振成像（functional magnetic resonance imaging，fMRI），通过前脉冲抑制（prepulse inhibition，PPI）范式结合触觉前脉冲抑制（tactile PPI）手段，纳入22名TS男性患儿与22名健康男性对照儿童，探究其感觉运动门控异常的神经关联。实验同步采集功能磁共振成像数据与惊反射（startle response）的肌电图（electromyography，EMG）信号。 ### 研究结果 如预期所示，与健康对照儿童相比，TS男性患儿的惊反射前脉冲抑制效应显著减弱。研究发现，TS患儿的额中回（middle frontal gyrus）、中央后回（postcentral gyrus）、顶上叶皮层（superior parietal cortex）、扣带回（cingulate gyrus）及尾状核体部（caudate body）中，与PPI相关的血氧水平依赖（blood oxygen level-dependent，BOLD）信号活动显著降低。此外，在TS患儿群体中，惊反射的PPI效应与顶上叶皮层内的PPI相关BOLD活动呈正相关。 ### 研究结论 本研究结果表明，TS男性患儿的感觉运动门控缺陷，与负责躯体感觉刺激（somatosensory stimuli）高阶整合的脑区激活募集不足密切相关。由于本研究采用了严格的样本筛选标准，得以有效控制神经适应（neural adaptation）过程、长期用药、性别及共病（comorbidities）等混杂因素的干扰。