前脉冲抑制在自闭症研究中的进展和展望

The progress and prospect of prepulse inhibition in autism

惊反射的前脉冲抑制(prepulse inhibition,PPI)是指当引发惊反射的强刺激之前出现了一个弱刺激(即前脉冲刺激)时,该弱刺激对惊反射有显著的抑制作用。PPI是一种大脑适应复杂环境的感觉运动门控过程,通过减弱惊反射使得由前脉冲刺激所引发的中枢加工活动得到保护。自闭症患者不仅存在感觉运动门控机制的缺失,还伴随注意加工的损害。但是对自闭症患者是否存在PPI的缺失还存在争议,这与患者的年龄、性别、疾病严重程度以及实验参数有关。前人的研究仅涉及对自闭症患者低水平门控机制的探讨,未探究自闭症患者高级认知加工过程是否存在缺损。本综述重点探讨注意和情绪等高级认知活动对PPI的调节作用,通过引入恐惧条件化和知觉空间分离去掩蔽范式,考察自闭症高级认知过程与门控机制之间的交互作用。

Prepulse inhibition（PPI） is suppression of the startle reflex when an intense startling stimulus is preceded by a weaker sensory stimulus（the prepulse）. It is an operational measurement of sensorimotor gating mechanism to help human adapt to complex environment. This weak prepulse protect central cognitive processing by damping the effect of intense stimuli. Autistics cannot select out behaviorally important information from a lot of irrelevant resources and reflect abnormal gating mechanism and attentional abnormalities. Previous studies have not made agreement on whether autistic patients demonstrated deficits in PPI, because the results depend on age, sex, severity of the disease as well as the experimental parameters used. Moreover, these studies have not covered whether autistics have suffered deficits in higher-order processing. In this review, the ＂top-down＂ modulation of selective attention and subjective emotion are introduced into the PPI experiment. We also introduce fear conditioning and perceived spatial separation paradigm to further explore the interaction between autistic cognitive process and gating mechanism.