Haenschel Corinna, Vernon David J, Dwivedi Prabuddh, Gruzelier John H, Baldeweg Torsten
Department of Psychiatry, Johann Wolfgang Goethe University, 60590 Frankfurt, Germany.
J Neurosci. 2005 Nov 9;25(45):10494-501. doi: 10.1523/JNEUROSCI.1227-05.2005.
The event-related potential (ERP) component mismatch negativity (MMN) is a neural marker of human echoic memory. MMN is elicited by deviant sounds embedded in a stream of frequent standards, reflecting the deviation from an inferred memory trace of the standard stimulus. The strength of this memory trace is thought to be proportional to the number of repetitions of the standard tone, visible as the progressive enhancement of MMN with number of repetitions (MMN memory-trace effect). However, no direct ERP correlates of the formation of echoic memory traces are currently known. This study set out to investigate changes in ERPs to different numbers of repetitions of standards, delivered in a roving-stimulus paradigm in which the frequency of the standard stimulus changed randomly between stimulus trains. Normal healthy volunteers (n = 40) were engaged in two experimental conditions: during passive listening and while actively discriminating changes in tone frequency. As predicted, MMN increased with increasing number of standards. However, this MMN memory-trace effect was caused mainly by enhancement with stimulus repetition of a slow positive wave from 50 to 250 ms poststimulus in the standard ERP, which is termed here "repetition positivity" (RP). This RP was recorded from frontocentral electrodes when participants were passively listening to or actively discriminating changes in tone frequency. RP may represent a human ERP correlate of rapid and stimulus-specific adaptation, a candidate neuronal mechanism underlying sensory memory formation in the auditory cortex.
事件相关电位（ERP）成分失匹配负波（MMN）是人类回声记忆的一种神经标志物。MMN由频繁出现的标准声音流中嵌入的异常声音引发，反映了与标准刺激的推断记忆痕迹的偏差。这种记忆痕迹的强度被认为与标准音调的重复次数成正比，表现为MMN随重复次数的逐渐增强（MMN记忆痕迹效应）。然而，目前尚不清楚回声记忆痕迹形成的直接ERP相关因素。本研究旨在调查在一种游动刺激范式中，标准刺激重复不同次数时ERP的变化，在该范式中标准刺激的频率在刺激序列之间随机变化。正常健康志愿者（n = 40）参与了两种实验条件：被动聆听和主动辨别音调频率的变化。正如预期的那样，MMN随着标准刺激次数的增加而增强。然而，这种MMN记忆痕迹效应主要是由标准ERP中刺激后50至250毫秒的一个缓慢正波的刺激重复增强引起的，在此称为“重复正波”（RP）。当参与者被动聆听或主动辨别音调频率变化时，从额中央电极记录到RP。RP可能代表了人类ERP中与快速且特定于刺激的适应相关的成分，是听觉皮层中感觉记忆形成的潜在神经元机制的一个候选因素。
