Eipert Lena, Klump Georg M
Cluster of Excellence Hearing4all, Division Animal Physiology and Behavior, Department of Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, D-26111, Oldenburg, Germany.
Cluster of Excellence Hearing4all, Division Animal Physiology and Behavior, Department of Neuroscience, School of Medicine and Health Sciences, University of Oldenburg, D-26111, Oldenburg, Germany.
Hear Res. 2020 Jul;392:107959. doi: 10.1016/j.heares.2020.107959. Epub 2020 Apr 8.
Informational masking emerges with processing of complex sounds in the central auditory system and can be affected by uncertainty emerging from trial-to-trial variation of stimulus features. Uncertainty can be non-informative but confusing and thus mask otherwise salient stimulus changes resulting in increased discrimination thresholds. With increasing age, the ability for processing of such complex sound scenes degrades. Here, 6 young and 4 old gerbils were tested behaviorally in a vowel discrimination task. Animals were trained to discriminate between sequentially presented target and reference vowels of the vowel pair/I/-/i/. Reference and target vowels were generated shifting the three formants of the reference vowel in steps towards the formants of the target vowels. Non-informative but distracting uncertainty was introduced by random changes in location, level, fundamental frequency or all three features combined. Young gerbils tested with uncertainty for the target or target and reference vowels showed similar informational masking effects for both conditions. Young and old gerbils were tested with uncertainty for the target vowels only. Old gerbils showed no threshold increase discriminating vowels without uncertainty in comparison with young gerbils. Introducing uncertainty, vowel discrimination thresholds increased for young and old gerbils and vowel discrimination thresholds increased most when presenting all three uncertainty features combined. Old gerbils were more susceptible to non-informative uncertainty and their thresholds increased more than thresholds of young gerbils. Gerbils' vowel discrimination thresholds are compared to human performance in the same task (Eipert et al., 2019).
信息掩蔽在中枢听觉系统对复杂声音的处理过程中出现，并且可能受到刺激特征逐次试验变化所产生的不确定性的影响。不确定性可能是非信息性但令人困惑的，从而掩盖原本显著的刺激变化，导致辨别阈值增加。随着年龄的增长，处理此类复杂声音场景的能力会下降。在此，对6只年轻沙鼠和4只老年沙鼠进行了一项元音辨别任务的行为测试。训练动物辨别依次呈现的元音对/I/-/i/中的目标元音和参考元音。通过逐步将参考元音的三个共振峰朝着目标元音的共振峰移动来生成参考元音和目标元音。通过位置、强度、基频的随机变化或这三个特征的组合引入非信息性但分散注意力的不确定性。对目标元音或目标元音和参考元音存在不确定性的情况下进行测试的年轻沙鼠，在两种情况下都表现出类似的信息掩蔽效应。仅对目标元音存在不确定性的情况下对年轻和老年沙鼠进行测试。与年轻沙鼠相比，老年沙鼠在没有不确定性的情况下辨别元音时阈值没有增加。引入不确定性后，年轻和老年沙鼠的元音辨别阈值都增加了，并且在同时呈现所有三个不确定性特征时，元音辨别阈值增加最多。老年沙鼠更容易受到非信息性不确定性的影响，并且它们的阈值增加幅度比年轻沙鼠的阈值增加幅度更大。将沙鼠的元音辨别阈值与同一任务中的人类表现进行了比较（Eipert等人，2019年）。
