De Sanctis Pierfilippo, Ritter Walter, Molholm Sophie, Kelly Simon P, Foxe John J
The Cognitive Neurophysiology Laboratory, Nathan S. Kline Institute for Psychiatric Research, Program in Cognitive Neuroscience and Schizophrenia, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA.
Eur J Neurosci. 2008 Mar;27(5):1271-6. doi: 10.1111/j.1460-9568.2008.06080.x.
Segregation of auditory inputs into meaningful acoustic groups is a key element of auditory scene analysis. Previously, we showed that two interwoven sets of tones differing widely along multiple feature dimensions (duration, pitch and location) were pre-attentively separated into different groups, and that tones separated in this manner did not elicit the mismatch negativity component with respect to each other. Grouping was studied with human subjects using a stimulus rate too slow to induce streaming. Here, we varied the separation of tone sequences along a single feature dimension, i.e. frequency. Frequency differences were either 24 Hz (small) or 1054 Hz (large). Two relatively slow stimulus rates were used (2.7 or 1 tone/s) to explicitly investigate grouping outside the so-called 'streaming effect', which requires rates of about 4 tones/s or faster. Two tones were presented in a quasi-random manner with embedded trains of one to four identical tones in a row. Deviants were defined as frequency switches after trains of four identical tones. Mismatch negativity was only elicited for small frequency switches at the slower stimulation rate. The data indicate that pre-attentive grouping of tones occurred when the frequency difference that separated them was large, regardless of stimulation rate. For small frequency differences, inputs were only grouped separately when the stimulation rate was relatively fast.
将听觉输入分离成有意义的声学组是听觉场景分析的关键要素。此前，我们发现，两组相互交织的音调，在多个特征维度（时长、音高和位置）上差异很大，在注意力前阶段就被分离成不同的组，并且以这种方式分离的音调彼此之间不会引发失配负波成分。我们使用一种刺激速率过慢以至于无法诱发听觉流的方法，对人类受试者进行了分组研究。在这里，我们沿着单一特征维度，即频率，改变了音序列的分离程度。频率差异要么是24赫兹（小），要么是1054赫兹（大）。我们使用了两种相对较慢的刺激速率（2.7个或1个音调/秒），以明确研究在所谓的“听觉流效应”之外的分组情况，“听觉流效应”需要大约4个音调/秒或更快的速率。两个音调以准随机的方式呈现，其中嵌入了一到四个连续相同音调的序列。偏差被定义为在四个相同音调序列之后的频率切换。只有在较慢的刺激速率下，小频率切换才会引发失配负波。数据表明，当分离音调的频率差异很大时，无论刺激速率如何，在注意力前阶段都会发生音调分组。对于小频率差异，只有当刺激速率相对较快时，输入才会被分别分组。
