Interpretation of neurophysiological differences between control and patient groups on the basis of scalp-recorded event-related brain potentials (ERPs), although common and promising, is often complicated in the absence of information on the distinct neural generators contributing to the ERP, particularly information regarding individual differences in the generators. For example, while sensory gating differences frequently observed in patients with schizophrenia in the P50 paired-click gating paradigm are typically interpreted as reflecting group differences in generator source strength, differences in the latency and/or orientation of P50 generators may also account for observed group differences. The present study examined how variability in source strength, amplitude, or orientation affects the P50 component of the scalp-recorded ERP. In Experiment 1, simulations examined the effect of changes in source strength, orientation, or latency in superior temporal gyrus (STG) dipoles on P50 recorded at Cz. In Experiment 2, within- and between-subject variability in left and right M50 STG dipole source strength, latency, and orientation was examined in 19 subjects. Given the frequently reported differences in left and right STG anatomy and function, substantial inter-subject and inter-hemispheric variability in these parameters were expected, with important consequences for how P50 at Cz reflects brain activity from relevant generators. In Experiment 1, simulated P50 responses were computed from hypothetical left- and right-hemisphere STG generators, with latency, amplitude, and orientation of the generators varied systematically. In Experiment 2, electroencephalographic (EEG) and magnetoencephalographic (MEG) data were collected from 19 subjects. Generators were modeled from the MEG data to assess and illustrate the generator variability evaluated parametrically in Experiment 1. In Experiment 1, realistic amounts of variability in generator latency, amplitude, and orientation produced ERPs in which P50 scoring was compromised and interpretation complicated. In Experiment 2, significant within and between subject variability was observed in the left and right hemisphere STG M50 sources. Given the variability in M50 source strength, orientation, and amplitude observed here in nonpatient subjects, future studies should examine whether group differences in P50 gating ratios typically observed for patient vs. control groups are specific to a particular hemisphere, as well as whether the group differences are due to differences in dipole source strength, latency, orientation, or a combination of these parameters. Present analyses focused on P50/M50 merely as an example of the broader need to evaluate scalp phenomena in light of underlying generators. The development and widespread use of EEG/MEG source localization methods will greatly enhance the interpretation and value of EEG/MEG data.

中文翻译：

---

解释异常：P50 和听觉配对刺激范式的 EEG 和 MEG 研究

根据头皮记录的事件相关脑电位 (ERP) 来解释对照组和患者组之间的神经生理学差异，虽然常见且有希望，但由于缺乏有关促成 ERP 的不同神经发生器的信息，特别是信息，通常很复杂关于发电机的个体差异。例如，虽然在 P50 配对点击门控范式中精神分裂症患者中经常观察到的感觉门控差异通常被解释为反映发生器源强度的组差异，但 P50 发生器的延迟和/或方向的差异也可能解释观察到的组差异。本研究检查了源强度、振幅或方向的变异性如何影响头皮记录的 ERP 的 P50 分量。在实验 1 中，模拟检查了上颞回 (STG) 偶极子中源强度、方向或延迟的变化对 Cz 记录的 P50 的影响。在实验 2 中，在 19 名受试者中检查了左右 M50 STG 偶极子源强度、潜伏期和方向的受试者内和受试者间变异性。鉴于左右 STG 解剖结构和功能的频繁报告差异，预计这些参数的受试者间和半球间的差异很大，这对 Cz 处的 P50 如何反映相关发生器的大脑活动产生重要影响。在实验 1 中，模拟的 P50 响应是从假设的左半球和右半球 STG 发生器计算出来的，发生器的延迟、幅度和方向有系统地变化。在实验 2 中，收集了 19 名受试者的脑电图 (EEG) 和脑磁图 (MEG) 数据。根据 MEG 数据对发电机进行建模，以评估和说明在实验 1 中参数化评估的发电机可变性。在实验 1 中，发电机延迟、振幅和方向的实际可变性产生了 ERP，其中 P50 评分受到影响且解释复杂。在实验 2 中，在左右半球 STG M50 源中观察到了受试者内部和之间的显着差异。鉴于此处在非患者受试者中观察到的 M50 源强度、方向和幅度的可变性，未来的研究应检查通常在患者与对照组中观察到的 P50 门控比率的组差异是否特定于特定半球，以及组差异是否是由于偶极源强度、延迟、方向或这些参数的组合的差异造成的。目前的分析侧重于 P50/M50，仅作为根据潜在发生器评估头皮现象的更广泛需求的一个例子。EEG/MEG 源定位方法的发展和广泛应用将大大提高 EEG/MEG 数据的解释和价值。