Pekkonen E, Rinne T, Reinikainen K, Kujala T, Alho K, Näätänen R
General Psychology Division, University of Helsinki, Finland.
Exp Aging Res. 1996 Apr-Jun;22(2):171-84. doi: 10.1080/03610739608254005.
Deviant tones randomly embedded in a sequence of standard tones elicit an event-related potential (ERP) called the mismatch negativity (MMN), which reflects automatic stimulus-change detection in the human auditory system. When the tones are attended, deviant tones elicit also an N2b component that partly overlaps the MMN. Sequences of standard and deviant (probability 0.15) tones were presented to 13 healthy younger and 13 older subjects. Deviant stimuli were, in separate blocks, either occasional shorter duration or higher frequency tones. The interstimulus interval (ISI) was, in separate blocks, either 0.5 s or 1.5 s, and in the frequency-change condition also 4.5 s. Aging affected neither frequency nor duration of MMN with the 0.5 s ISI. This finding indicates that automatic stimulus discrimination per se is not impaired with normal aging. However, with a 4.5-s ISI the MMN/N2b-complex attenuated significantly more in the older than younger subjects. This suggests that the stimulus trace decays faster or that involuntary attention switching is less sensitive with aging.
随机嵌入标准音调序列中的异常音调会引发一种称为失配负波（MMN）的事件相关电位（ERP），它反映了人类听觉系统中对刺激变化的自动检测。当音调被注意时，异常音调还会引发一个部分与MMN重叠的N2b成分。向13名健康的年轻受试者和13名年长受试者呈现标准音调和异常音调（概率为0.15）的序列。在不同的组块中，异常刺激要么是偶尔持续时间较短的音调，要么是频率较高的音调。刺激间隔（ISI）在不同的组块中分别为0.5秒或1.5秒，在频率变化条件下也为4.5秒。在ISI为0.5秒时，衰老对MMN的频率和持续时间均无影响。这一发现表明，正常衰老不会损害自动刺激辨别本身。然而，在ISI为4.5秒时，年长受试者的MMN/N2b复合波比年轻受试者衰减得更显著。这表明刺激痕迹衰减更快，或者随着年龄增长，非自愿注意转换的敏感性降低。
