Escera C, Alho K, Winkler I, Näätänen R
University of Barcelona, Department of Psychiatry and Clinical Psychobiology, Barcelona 08035, ES.
J Cogn Neurosci. 1998 Sep;10(5):590-604. doi: 10.1162/089892998562997.
Behavioral and event-related brain potential (ERP) measures were used to elucidate the neural mechanisms of involuntary engagement of attention by novelty and change in the acoustic environment. The behavioral measures consisted of the reaction time (RT) and performance accuracy (hit rate) in a forced-choice visual RT task where subjects were to discriminate between odd and even numbers. Each visual stimulus was preceded by an irrelevant auditory stimulus, which was randomly either a "standard" tone (80%), a slightly higher "deviant" tone (10%), or a natural, "novel" sound (10%). Novel sounds prolonged the RT to successive visual stimuli by 17 msec as compared with the RT to visual stimuli that followed standard tones. Deviant tones, in turn, decreased the hit rate but did not significantly affect the RT. In the ERPs to deviant tones, the mismatch negativity (MMN), peaking at 150 msec, and a second negativity, peaking at 400 msec, could be observed. Novel sounds elicited an enhanced N1, with a probable overlap by the MMN, and a large positive P3a response with two different subcomponents: an early centrally dominant P3a, peaking at 230 msec, and a late P3a, peaking at 315 msec with a right-frontal scalp maximum. The present results suggest the involvement of two different neural mechanisms in triggering involuntary attention to acoustic novelty and change: a transient-detector mechanism activated by novel sounds and reflected in the N1 and a stimulus-change detector mechanism activated by deviant tones and novel sounds and reflected in the MMN. The observed differential distracting effects by slightly deviant tones and widely deviant novel sounds support the notion of two separate mechanisms of involuntary attention.
行为学和事件相关脑电位（ERP）测量方法被用于阐明在听觉环境中，新奇性和变化引发的注意力非自愿参与的神经机制。行为学测量包括在强制选择视觉反应时任务中的反应时（RT）和表现准确性（命中率），在该任务中，受试者要区分奇数和偶数。每个视觉刺激之前都有一个无关的听觉刺激，该听觉刺激随机为“标准”音调（80%）、略高的“偏差”音调（10%）或自然的“新奇”声音（10%）。与跟随标准音调后的视觉刺激的反应时相比，新奇声音使对连续视觉刺激的反应时延长了17毫秒。相反，偏差音调降低了命中率，但对反应时没有显著影响。在对偏差音调的ERP中，可以观察到在150毫秒达到峰值的失匹配负波（MMN）和在400毫秒达到峰值的第二个负波。新奇声音引发了增强的N1，可能与MMN重叠，以及一个大的正向P3a反应，该反应有两个不同的子成分：一个早期中央优势的P3a，在230毫秒达到峰值，和一个晚期P3a，在315毫秒达到峰值，在右额头皮处最大。目前的结果表明，有两种不同的神经机制参与触发对听觉新奇性和变化的非自愿注意：一种由新奇声音激活并反映在N1中的瞬态探测器机制，以及一种由偏差音调和新奇声音激活并反映在MMN中的刺激变化探测器机制。观察到的轻微偏差音调和广泛偏差新奇声音的不同干扰效应支持了非自愿注意的两种独立机制的观点。
