Loizides Charalambos, Achilleos Achilleas, Iannetti Gian Domenico, Mitsis Georgios D
Annu Int Conf IEEE Eng Med Biol Soc. 2014;2014:4543-6. doi: 10.1109/EMBC.2014.6944634.
The recording of brain event-related potentials (ERPs) is a widely used technique to investigate the neural basis of sensory perception and cognitive processing in humans. A commonly used assumption, when dealing with potentially overlapping ERPs elicited by successive stimuli with interstimulus interval (ISI) smaller than the latency of the ERPs, is that their interaction is linear. These overlaps are usually dealt by using averaged waveforms, mostly to enhance the signal-to-noise ratio (SNR) and performing algebraic waveform subtractions. In this paper, we examine the hypothesis of linear interactions by providing a statistical framework that examines the presence of nonlinear additive effects between overlapping ERPs elicited by successive stimuli with short ISIs. The statistical analysis is designed for single trial rather than averaged waveforms. The results suggest that there are no nonlinear additive effects due to the time overlap per se but that, for the range of ISIs examined, the second ERP is modulated by the presence of the first stimulus irrespective of whether there is time overlap or not. In other words, two ERPs that overlap in time can still be written as an addition of two ERPs, with the second ERP being different to the first. The modulation effect on the second ERP by the first stimulus varies for different ISIs.
记录大脑事件相关电位（ERP）是一种广泛应用的技术，用于研究人类感觉知觉和认知加工的神经基础。当处理由刺激间隔（ISI）小于ERP潜伏期的连续刺激引发的潜在重叠ERP时，一个常用的假设是它们的相互作用是线性的。这些重叠通常通过使用平均波形来处理，主要是为了提高信噪比（SNR）并进行代数波形减法。在本文中，我们通过提供一个统计框架来检验线性相互作用的假设，该框架检验由短ISI的连续刺激引发的重叠ERP之间非线性加性效应的存在。统计分析是针对单次试验而非平均波形设计的。结果表明，时间重叠本身不会产生非线性加性效应，但在所研究的ISI范围内，第二个ERP会受到第一个刺激的存在的调制，无论是否存在时间重叠。换句话说，时间上重叠的两个ERP仍然可以写成两个ERP的相加，第二个ERP与第一个不同。第一个刺激对第二个ERP的调制效应因不同的ISI而异。
