Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, 02114, USA.
Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, MA, USA.
J Assoc Res Otolaryngol. 2022 Jun;23(3):391-412. doi: 10.1007/s10162-022-00840-8. Epub 2022 Apr 5.
The auditory brainstem implant (ABI) is an auditory neuroprosthesis that provides hearing to deaf patients by electrically stimulating the cochlear nucleus (CN) of the brainstem. Whether such stimulation activates one or the other of the CN's two major subdivisions is not known. Here, we demonstrate clear response differences from the stimulation of the dorsal (D) vs. ventral (V) subdivisions of the CN in a mouse model of the ABI with a surface-stimulating electrode array. For the DCN, low levels of stimulation evoked multiunit responses in the inferior colliculus (IC) that were unimodally distributed with early latencies (avg. peak latency of 3.3 ms). However, high levels of stimulation evoked a bimodal distribution with the addition of a late latency response peak (avg. peak latency of 7.1 ms). For the VCN, in contrast, electrical stimulation elicited multiunit responses that were usually unimodal and had a latency similar to the DCN's late response. Local field potentials (LFP) from the IC showed components that correlated with early and late multiunit responses. Surgical cuts to sever the output of the DCN, the dorsal acoustic stria (DAS), gave insight into the origin of these early and late responses. Cuts eliminated early responses but had little-to-no effect on late responses. The early responses thus originate from cells that project through the DAS, such as DCN's pyramidal and giant cells. Late responses likely arise from the spread of stimulation from a DCN-placed electrode array to the VCN and could originate in bushy and/or stellate cells. In human ABI users, the spread of stimulation in the CN may result in abnormal response patterns that could hinder performance.
听觉脑干植入物 (ABI) 是一种听觉神经假体，通过电刺激脑干的耳蜗核 (CN) 为聋人提供听力。目前尚不清楚这种刺激是激活 CN 的两个主要分支中的一个还是两个。在这里，我们在 ABI 的小鼠模型中使用表面刺激电极阵列证明了来自 CN 的背侧 (D) 与腹侧 (V) 分支的刺激存在明显的反应差异。对于 DCN，低水平的刺激在丘脑中引发多单位反应 (IC)，潜伏期较早 (平均峰值潜伏期为 3.3ms)。然而，高水平的刺激会引起双峰分布，增加一个潜伏期较长的反应峰 (平均峰值潜伏期为 7.1ms)。相比之下，对于 VCN，电刺激引发的多单位反应通常是单峰的，潜伏期与 DCN 的晚反应相似。来自 IC 的局部场电位 (LFP) 显示出与早期和晚期多单位反应相关的成分。切断切断 DCN 输出的手术切口，即背侧听纹 (DAS)，深入了解了这些早期和晚期反应的起源。切口消除了早期反应，但对晚期反应几乎没有影响。因此，早期反应源自通过 DAS 投射的细胞，如 DCN 的锥体和巨大细胞。晚期反应可能源自从 DCN 放置的电极阵列向 VCN 传播的刺激，并且可能起源于布什和/或星状细胞。在人类 ABI 用户中，CN 中的刺激传播可能会导致异常的反应模式，从而阻碍性能。
