Smith Janette L, Johnstone Stuart J, Barry Robert J
School of Psychology, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia; School of Psychology and Brain & Behaviour Research Institute, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia.
School of Psychology and Brain & Behaviour Research Institute, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia.
Clin Neurophysiol. 2008 Mar;119(3):704-714. doi: 10.1016/j.clinph.2007.11.042.
The contribution of movement-related potentials (MRPs) to the Go/NoGo N2 and P3 'inhibitory' effects is controversial. This study examined these components in overt and covert response inhibition tasks.
Twenty adult participants counted or button-pressed in response to frequent (60%) and rare (20%) Go stimuli in a Go/NoGo task with equiprobable rare (20%) NoGo stimuli.
The N2 NoGo effect did not differ between Count and Press responses, but the P3 NoGo effect was amplified during the Press task. Additionally, subtraction of the ERP waveform for Count NoGo from Press NoGo trials revealed a positivity between 200 and 400ms, occurring maximally over the central region, contralateral to the responding hand. This difference wave became significant at 210-260ms, close to the estimated time taken to stop an overt response.
The N2 NoGo effect may reflect a non-motoric stage of inhibition, or recognition of the need for inhibition, while the NoGo P3 may overlap with a positive MRP occurring specifically on trials where overt motor responses must be inhibited.
The study confirms that the N2 and P3 NoGo effects are not solely due to movement-related potentials, and posits the NoGo P3 as a marker of motor inhibition.
与动作相关的电位（MRP）对Go/NoGo N2和P3“抑制性”效应的作用存在争议。本研究在明显和隐蔽的反应抑制任务中考察了这些成分。
20名成年参与者在一个Go/NoGo任务中，对频繁出现（60%）和罕见出现（20%）的Go刺激进行计数或按键反应，其中罕见的NoGo刺激出现概率相等（20%）。
计数和按键反应的N2 NoGo效应没有差异，但在按键任务中P3 NoGo效应增强。此外，从按键NoGo试验中减去计数NoGo的ERP波形，发现在200至400毫秒之间有一个正波，最大程度地出现在与反应手对侧的中央区域。这个差异波在210 - 260毫秒时变得显著，接近停止明显反应所需的估计时间。
N2 NoGo效应可能反映了抑制的非运动阶段，或对抑制需求的识别，而NoGo P3可能与一个在必须抑制明显运动反应的试验中特有的正向MRP重叠。
该研究证实N2和P3 NoGo效应并非完全由与动作相关的电位引起，并将NoGo P3定位为运动抑制的一个标志。
