Neuronal Substrates of Perceptual Salience in the Auditory System

你站在一个部门的社交活动中，手里拿着一杯塑料酒，懒洋洋地想着你的猫，而这时你耳边响起了许多正在进行的谈话的声音。突然，你听到你的名字在其中一个对话中被提到，之前模糊的嗡嗡声变成了背景噪音和前景对话，现在吸引了你的全部注意力。这是怎么发生的？知觉显著性在听觉脑中是如何表现的？听觉加工如何与行为状态和注意相互作用以区分听与听？我们最近开发了强大的新计算工具来解决这些问题，这使我们能够分析声音发生的环境如何影响声音在听觉大脑中的表现。使用这些新颖的工具，我们发现听觉系统中的上下文敏感机制在单个神经元水平上实现了众所周知的感知现象，这些现象描述了人类如何将复杂的声音解析为突出的事件。因此，这些环境敏感机制可能是听觉系统中感知显著性的神经元基质。我们假设，这些情境敏感机制的变化是主动倾听过程中感知显著性变化的基础——例如，当你突然意识到，在多个正在进行的对话中，一个人的声音正在谈论你。我们将通过记录听觉皮层、丘脑和中脑神经元对复杂声音的反应来验证这一假设，同时动物在两种不同的行为任务中关注听觉或视觉线索。通过比较大脑区域、感觉注意状态和行为任务之间神经元的上下文依赖性，我们旨在确定感知显著性是如何从注意和神经元对声音环境的敏感性之间的相互作用中产生的。最终，这项工作不仅可以揭示听觉系统中感知显著性的神经元基质，还可以为机器听力中未解决的问题提供新的方法，例如如何从多个正在进行的对话中提取单个声音。

You are standing in the midst of a departmental social event with a plastic cup of wine in your hand, idly thinking about your cat, while the sound of multiple ongoing conversations washes over you. Suddenly, you hear your name mentioned in one of those conversations, and what was formerly an indistinct hum of voices separates into background noise and a foreground conversation that now commands your full attention. How does this happen? How is perceptual salience represented in the auditory brain? How does auditory processing interact with behavioural state and attention to differentiate hearing from listening?We have recently developed powerful new computational tools for addressing these questions, which have enabled us to analyse how the context in which a sound occurs affects the representation of that sound in the auditory brain. Using these novel tools, we have found that context-sensitive mechanisms in the auditory system implement, at a single-neuron level, well-known perceptual phenomena that describe how humans parse complex sounds into salient events. Therefore, these context-sensitive mechanisms may be the neuronal substrates of perceptual salience in the auditory system. We hypothesise that changes in these context-sensitive mechanisms underlie changes in perceptual salience during active listening - for example, when you suddenly realize that one individual voice in multiple ongoing conversations is talking about you.We will test this hypothesis by recording the responses of auditory cortical, thalamic and midbrain neurons to complex sounds while animals are attending to auditory or visual cues in two different behavioral tasks. By comparing the context-dependence of neurons between brain areas, sensory attentional states, and behavioural tasks, we aim to determine how perceptual salience arises from interactions between attention and neuronal sensitivity to sound context. Ultimately, this work may not only reveal the neuronal substrates of perceptual salience in the auditory system, but also suggest new approaches to unsolved problems in machine listening -- such as how to extract the sound of an individual voice from multiple ongoing conversations.