Abstract

Signals containing attended frequencies are facilitated while those with unexpected frequencies are suppressed by an auditory filtering process. The neurocognitive mechanism underlying the auditory attentional filter is, however, poorly understood. The olivocochlear bundle (OCB), a brainstem neural circuit that is part of the efferent system, has been suggested to be partly responsible for the filtering via its noise-dependent antimasking effect. The current study examined the role of the OCB in attentional filtering, particularly the validity of the antimasking hypothesis, by comparing attentional filters measured in quiet and in the presence of background noise in a group of normal-hearing listeners. Filters obtained in both conditions were comparable, suggesting that the presence of background noise is not crucial for attentional filter generation. In addition, comparison of frequency-specific changes of the cue-evoked enhancement component of filters in quiet and noise also did not reveal any major contribution of background noise to the cue effect. These findings argue against the involvement of an antimasking effect in the attentional process. Instead of the antimasking effect mediated via medial olivocochlear fibers, results from current and earlier studies can be explained by frequency-specific modulation of afferent spontaneous activity by lateral olivocochlear fibers. It is proposed that the activity of these lateral fibers could be driven by top-down cortical control via a noise-independent mechanism.

Significance

The neural basis for auditory attentional filter remains a fundamental but poorly understood area in auditory neuroscience. The efferent olivocochlear pathway that projects from the brainstem back to the cochlea has been suggested to mediate the attentional effect via its noise-dependent antimasking effect. The current study demonstrates that the filter generation is mostly independent of the background noise, and therefore is unlikely to be mediated by the olivocochlear brainstem reflex. It is proposed that the entire cortico-olivocochlear system might instead be used to alter the hearing sensitivity during focus attention via frequency-specific modulation of afferent spontaneous activity.

中文翻译：

---

听觉注意力过滤器在没有掩盖噪声的情况下

摘要

通过听觉滤波过程可以抑制包含出席频率的信号，而抑制具有非预期频率的信号。然而，对听觉注意力过滤器的神经认知机制了解甚少。有人提出，耳蜗束（OCB）是脑干神经回路，是传出系统的一部分，其通过依赖噪声的抗掩盖作用部分负责过滤。当前的研究通过比较一组正常听力的听众在安静和有背景噪音的情况下测得的注意过滤器，从而检查了OCB在注意过滤中的作用，尤其是抗掩盖假设的有效性。在两种情况下获得的过滤器都是可比的，这表明背景噪声的存在对于注意滤波器的生成不是至关重要的。此外，比较安静和噪声条件下滤波器的提示诱发增强分量的特定频率变化，也没有发现背景噪声对提示效果的任何重大贡献。这些发现反对在注意力过程中涉及掩盖效应。代替通过内侧少筋纤维介导的抗掩蔽作用，当前和较早研究的结果可以通过外侧少筋纤维对自发活动的频率特异性调节来解释。提出可以通过独立于噪声的机制由自上而下的皮质控制来驱动这些侧纤维的活动。在安静和噪声条件下比较滤波器的提示诱发增强分量的特定频率变化，也没有发现背景噪声对提示效果有任何重大贡献。这些发现反对在注意力过程中涉及掩盖效应。代替通过内侧小耳蜗纤维介导的抗掩盖作用，当前和较早研究的结果可以通过外侧小耳蜗纤维对传入自发活动的频率特异性调制来解释。提出可以通过独立于噪声的机制由自上而下的皮质控制来驱动这些侧纤维的活动。在安静和噪声条件下比较滤波器的提示诱发增强分量的特定于频率的变化，也没有发现背景噪声对提示效果有任何重大贡献。这些发现反对在注意力过程中涉及掩盖效应。代替通过内侧小耳蜗纤维介导的抗掩盖作用，当前和较早研究的结果可以通过外侧小耳蜗纤维对传入自发活动的频率特异性调制来解释。提出可以通过独立于噪声的机制由自上而下的皮质控制来驱动这些侧纤维的活动。这些发现反对在注意力过程中涉及掩盖效应。代替通过内侧小耳蜗纤维介导的抗掩盖作用，当前和较早研究的结果可以通过外侧小耳蜗纤维对传入自发活动的频率特异性调制来解释。提出可以通过独立于噪声的机制由自上而下的皮质控制来驱动这些侧纤维的活动。这些发现反对在注意力过程中涉及掩盖效应。代替通过内侧小耳蜗纤维介导的抗掩盖作用，当前和较早研究的结果可以通过外侧小耳蜗纤维对传入自发活动的频率特异性调制来解释。提出可以通过独立于噪声的机制由自上而下的皮质控制来驱动这些侧纤维的活动。

意义

听觉注意力过滤器的神经基础仍然是听觉神经科学的一个基本领域，但人们对此知之甚少。已建议从脑干向耳蜗传出的传出少脂途径通过其噪声依赖性抗掩蔽作用来介导注意作用。当前的研究表明，过滤器的产生主要与背景噪声无关，因此不太可能由乳突性脑干反射介导。有人提出，整个皮质-脂小脑系统可通过传入自发活动的频率特定调制来代替注意力集中过程中的听力敏感性。