Ear Institute, University College London, London WC1X 8EE, United Kingdom
Ear Institute, University College London, London WC1X 8EE, United Kingdom.
J Neurosci. 2022 Jun 1;42(22):4580-4593. doi: 10.1523/JNEUROSCI.0291-22.2022. Epub 2022 May 2.
The location of sounds can be described in multiple coordinate systems that are defined relative to ourselves, or the world around us. Evidence from neural recordings in animals point toward the existence of both head-centered and world-centered representations of sound location in the brain; however, it is unclear whether such neural representations have perceptual correlates in the sound localization abilities of nonhuman listeners. Here, we establish novel behavioral tests to determine the coordinate systems in which ferrets can localize sounds. We found that ferrets could learn to discriminate between sound locations that were fixed in either world-centered or head-centered space, across wide variations in sound location in the alternative coordinate system. Using probe sounds to assess broader generalization of spatial hearing, we demonstrated that in both head and world-centered tasks, animals used continuous maps of auditory space to guide behavior. Single trial responses of individual animals were sufficiently informative that we could then model sound localization using speaker position in specific coordinate systems and accurately predict ferrets' actions in held-out data. Our results demonstrate that ferrets, an animal model in which neurons are known to be tuned to sound location in egocentric and allocentric reference frames, can also localize sounds in multiple head and world-centered spaces. Humans can describe the location of sounds either relative to themselves, or in the world, independent of their momentary position. These different spaces are also represented in the activity of neurons in animals, but it is not clear whether nonhuman listeners also perceive both head and world-centered sound location. Here, we designed behavioral tasks in which ferrets discriminated between sounds using their position in the world, or relative to the head. Subjects learnt to solve both problems and generalized sound location in each space when presented with infrequent probe sounds. These findings reveal a perceptual correlate of neural sensitivity previously observed in the ferret brain and establish that, like humans, ferrets can access an auditory map of their local environment.
声音的位置可以用多种相对于我们自身或周围世界的坐标系来描述。来自动物神经记录的证据表明，大脑中存在以头为中心和以世界为中心的声音位置表示；然而，尚不清楚这种神经表示是否与非人类听众的声音定位能力存在知觉相关。在这里，我们建立了新的行为测试来确定雪貂可以在其中定位声音的坐标系。我们发现，雪貂可以学习区分在世界中心或头中心空间中固定的声音位置，同时在替代坐标系中声音位置有很大的变化。使用探测声音来评估空间听觉的更广泛概括，我们证明，在头和世界中心任务中，动物使用听觉空间的连续图谱来指导行为。单个动物的反应足够有信息，我们可以使用特定坐标系中的扬声器位置来建模声音定位，并在保留数据中准确预测雪貂的行为。我们的结果表明，雪貂是一种已知神经元在自我和非自我参照框架中对声音位置进行调谐的动物模型，也可以在多个头和世界中心空间中定位声音。人类可以描述声音的位置，要么相对于自己，要么相对于世界，而不考虑他们的当前位置。这些不同的空间也在动物神经元的活动中得到了表示，但尚不清楚非人类听众是否也能感知到头和世界中心的声音位置。在这里，我们设计了行为任务，其中雪貂使用它们在世界上或相对于头部的位置来区分声音。当出现不频繁的探测声音时，受试者学会解决这两个问题，并在每个空间中对声音位置进行概括。这些发现揭示了先前在雪貂大脑中观察到的神经敏感性的知觉相关，并表明，像人类一样，雪貂可以访问其局部环境的听觉图谱。
