Schröger E
Institute of Psychology, University of Munich, Germany.
Neuroreport. 1994 Mar 21;5(7):825-8.
The influence of stimulus intensity on the automatic detection of frequency change was studied. Ten human subjects were presented with a high-probability standard tone (700 Hz) and a low-probability deviant tone (750 Hz). In a between-block design, the intensity of the auditory stimuli was varied over a 40 dB range. The frequency deviant elicited the mismatch negativity (MMN), an event-related brain potential component indicative of automatic change detection in the auditory cortex. The MMN for a frequency change was even elicited in low-intensity blocks and it did not significantly vary with intensity. These results suggest that the frequency MMN is sensitive to the informational content of a change not to the total amount of stimulus energy. Furthermore, the data imply that an efficient encoding of frequency information, which underlies the change detection mechanism, takes place even with weak sensory stimulation.
研究了刺激强度对频率变化自动检测的影响。向10名人类受试者呈现高概率标准音调（700赫兹）和低概率偏差音调（750赫兹）。在组间设计中，听觉刺激的强度在40分贝范围内变化。频率偏差引发了失配负波（MMN），这是一种与事件相关的脑电成分，表明听觉皮层中存在自动变化检测。即使在低强度组中也能引发频率变化的MMN，并且它不会随强度显著变化。这些结果表明，频率MMN对变化的信息内容敏感，而非对刺激能量的总量敏感。此外，数据表明，即使在微弱的感觉刺激下，作为变化检测机制基础的频率信息的有效编码也会发生。
