Langemann U, Klump G M
Institut für Zoologie, Technische Universtät München, Lichtenbergstr. 4, D-85747 Garching, Germany.
Eur J Neurosci. 2001 Mar;13(5):1025-32. doi: 10.1046/j.0953-816x.2001.01464.x.
Vertebrates have evolved mechanisms to exploit amplitude modulations in background noise for improving signal detection. However, the mechanisms underlying this masking release are not yet well understood. Here we present evidence for masking release observed in European starlings (Sturnus vulgaris, Aves) that were trained in a Go/NoGo paradigm to report the detection of a short tone (20 ms) in 100% sinusoidally amplitude-modulated noise maskers (400 ms duration). Maskers centred at the tone frequency were composed of one, three, or five spectrally adjacent noise bands each of auditory filter bandwidth. Envelopes of the masking noise bands were either in-phase (i.e. coherent) or successively phase shifted by 90 degrees (i.e. incoherent). A release from masking of up to 28 dB was observed for detection of signals presented in dips of the envelope of coherent maskers compared with those presented in peaks of coherent maskers and in incoherent maskers. For maskers limited to one auditory filter (i.e. limited to the analysis channel tuned to the test signal) this masking release was about 10 dB less than that observed for maskers allowing a comparison across three or five auditory filters. This indicates that both within-channel cues and across-channel cues are important for signal detection. These behavioural data provide the reference for the study of responses of auditory forebrain neurons in the same species reported in a companion paper [Nieder & Klump (2001) Eur. J. Neurosci., 13, 1033-1044].
脊椎动物已经进化出利用背景噪声中的幅度调制来改善信号检测的机制。然而，这种掩蔽释放背后的机制尚未得到很好的理解。在这里，我们展示了在欧洲椋鸟（Sturnus vulgaris，雀形目）中观察到的掩蔽释放的证据，这些椋鸟在一个Go/NoGo范式中接受训练，以报告在100%正弦幅度调制噪声掩蔽器（持续时间400毫秒）中检测到短音（20毫秒）。以音调频率为中心的掩蔽器由一个、三个或五个每个听觉滤波器带宽的频谱相邻噪声带组成。掩蔽噪声带的包络要么同相（即相干），要么相继相移90度（即非相干）。与出现在相干掩蔽器峰值处和非相干掩蔽器中的信号相比，在相干掩蔽器包络凹陷处呈现的信号检测中观察到高达28分贝的掩蔽释放。对于限于一个听觉滤波器（即限于调谐到测试信号的分析通道）的掩蔽器，这种掩蔽释放比允许跨三个或五个听觉滤波器进行比较的掩蔽器所观察到的要少约10分贝。这表明通道内线索和跨通道线索对于信号检测都很重要。这些行为数据为在一篇配套论文中报道的同一物种听觉前脑神经元反应的研究提供了参考[Nieder & Klump (2001) Eur. J. Neurosci., 13, 1033 - 1044]。
