San-Martin Rodrigo, Zimiani Maria Inês, Noya Claudemiro, Ávila Milton Augusto Vendramini, Shuhama Rosana, Del-Ben Cristina Marta, Menezes Paulo Rossi, Fraga Francisco José, Salum Cristiane
Center for Mathematics, Computation and Cognition, Universidade Federal do ABC, São Bernardo do Campo, Brazil.
Engineering, Modeling and Applied Social Sciences Center, Universidade Federal do ABC, Santo André, Brazil.
Front Neurosci. 2018 Sep 26;12:654. doi: 10.3389/fnins.2018.00654. eCollection 2018.
Prepulse inhibition (PPI) test has been widely used to evaluate sensorimotor gating. In humans, deficits in this mechanism are measured through the orbicularis muscle response using electromyography (EMG). Although this mechanism can be modulated by several brain structures and is impaired in some pathologies as schizophrenia and bipolar disorder, neural PPI evaluation is rarely performed in humans. Since eye blinks are a consequence of PPI stimulation, they strongly contaminate the electroencephalogram (EEG) signal. This paper describes a method to reduce muscular artifacts and enable neural PPI assessment through EEG in parallel to muscular PPI evaluation using EMG. Both types of signal were simultaneously recorded in 22 healthy subjects. PPI was evaluated by the acoustical startle response with EMG and by the P2-N1 event-related potential (ERP) using EEG in Fz, Cz, and Pz electrodes. In order to remove EEG artifacts, Independent Component Analysis (ICA) was performed using two methods. Firstly, visual inspection discarded components containing artifact characteristics as ocular and tonic muscle artifacts. The second method used visual inspection as gold standard to validate parameters in an automated component selection using the SASICA algorithm. As an outcome, EEG artifacts were effectively removed and equivalent neural PPI evaluation performance was obtained using both methods, with subjects exhibiting consistent neural as well as muscular PPI. This novel method improves PPI test, enabling neural gating mechanisms assessment within the latency of 100-200 ms, which is not evaluated by other sensory gating tests as P50 and mismatch negativity.
预脉冲抑制（PPI）测试已被广泛用于评估感觉运动门控。在人类中，这种机制的缺陷是通过使用肌电图（EMG）测量眼轮匝肌反应来评估的。尽管这种机制可由多个脑结构调节，且在某些病理状态如精神分裂症和双相情感障碍中受损，但在人类中很少进行神经PPI评估。由于眨眼是PPI刺激的结果，它们会严重干扰脑电图（EEG）信号。本文描述了一种方法，可减少肌肉伪迹，并能通过EEG并行评估神经PPI，同时使用EMG评估肌肉PPI。在22名健康受试者中同时记录了两种类型的信号。通过EMG的听觉惊吓反应和使用Fz、Cz和Pz电极处的EEG的P2 - N1事件相关电位（ERP）来评估PPI。为了去除EEG伪迹，使用两种方法进行独立成分分析（ICA）。首先，通过目视检查丢弃包含眼部和紧张性肌肉伪迹等伪迹特征的成分。第二种方法使用目视检查作为金标准，在使用SASICA算法的自动成分选择中验证参数。结果表明，EEG伪迹被有效去除，两种方法均获得了等效的神经PPI评估性能，受试者表现出一致的神经和肌肉PPI。这种新方法改进了PPI测试，能够在100 - 200毫秒的潜伏期内评估神经门控机制，而其他感觉门控测试如P50和失配负波则不评估这一潜伏期。
