Johnson Luke A, Della Santina Charles C, Wang Xiaoqin
Departments of Biomedical Engineering and.
Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland 21025.
J Neurosci. 2016 Dec 7;36(49):12468-12484. doi: 10.1523/JNEUROSCI.1699-16.2016.
Despite the success of cochlear implants (CIs) in human populations, most users perform poorly in noisy environments and music and tonal language perception. How CI devices engage the brain at the single neuron level has remained largely unknown, in particular in the primate brain. By comparing neuronal responses with acoustic and CI stimulation in marmoset monkeys unilaterally implanted with a CI electrode array, we discovered that CI stimulation was surprisingly ineffective at activating many neurons in auditory cortex, particularly in the hemisphere ipsilateral to the CI. Further analyses revealed that the CI-nonresponsive neurons were narrowly tuned to frequency and sound level when probed with acoustic stimuli; such neurons likely play a role in perceptual behaviors requiring fine frequency and level discrimination, tasks that CI users find especially challenging. These findings suggest potential deficits in central auditory processing of CI stimulation and provide important insights into factors responsible for poor CI user performance in a wide range of perceptual tasks.
The cochlear implant (CI) is the most successful neural prosthetic device to date and has restored hearing in hundreds of thousands of deaf individuals worldwide. However, despite its huge successes, CI users still face many perceptual limitations, and the brain mechanisms involved in hearing through CI devices remain poorly understood. By directly comparing single-neuron responses to acoustic and CI stimulation in auditory cortex of awake marmoset monkeys, we discovered that neurons unresponsive to CI stimulation were sharply tuned to frequency and sound level. Our results point out a major deficit in central auditory processing of CI stimulation and provide important insights into mechanisms underlying the poor CI user performance in a wide range of perceptual tasks.
尽管人工耳蜗（CI）在人类群体中取得了成功，但大多数使用者在嘈杂环境以及音乐和声调语言感知方面表现不佳。人工耳蜗设备如何在单个神经元水平上与大脑相互作用在很大程度上仍然未知，尤其是在灵长类动物大脑中。通过比较单侧植入CI电极阵列的狨猴在声学刺激和CI刺激下的神经元反应，我们发现CI刺激在激活听觉皮层中的许多神经元方面出奇地无效，特别是在CI同侧的半球。进一步分析表明，对CI无反应的神经元在用声学刺激探测时对频率和声音水平的调谐很窄；这类神经元可能在需要精细频率和水平辨别的感知行为中起作用，而人工耳蜗使用者在这些任务中尤其具有挑战性。这些发现表明CI刺激在中枢听觉处理方面可能存在缺陷，并为导致人工耳蜗使用者在广泛感知任务中表现不佳的因素提供了重要见解。
人工耳蜗（CI）是迄今为止最成功的神经假体设备，已为全球数十万聋人恢复了听力。然而，尽管取得了巨大成功，人工耳蜗使用者仍然面临许多感知限制，并且通过人工耳蜗设备进行听力的大脑机制仍知之甚少。通过直接比较清醒狨猴听觉皮层中对声学刺激和CI刺激的单神经元反应，我们发现对CI刺激无反应的神经元对频率和声音水平有敏锐的调谐。我们的结果指出了CI刺激在中枢听觉处理方面的一个主要缺陷，并为人工耳蜗使用者在广泛感知任务中表现不佳的潜在机制提供了重要见解。
