Takahashi Hirokazu, Nakao Masayuki, Kaga Kimitaka
Department of Engineering Synthesis, Graduate School of Engineering, the University of Tokyo, Tokyo 113-8656, Japan.
IEEE Trans Biomed Eng. 2005 Jul;52(7):1333-44. doi: 10.1109/TBME.2005.847554.
Auditory brainstem implants (ABI) that electrically stimulate the surface of cochlear nucleus have been clinically used for the rehabilitation of deaf patients with bilateral vestibular schwannomas. The change of pitch perception with an active electrode location is not as clear in ABIs as in cochlear implants, a factor which might play a role in poorer speech performance in ABIs. The objective of present work was to develop an animal ABI model that could provide physiological data for future ABI development and optimization. The experimental system included a penetrating microelectrode array for microstimulation of the cochlear nucleus and a surface microelectrode array for mapping evoked potentials over the auditory cortex. We first obtained tone-evoked cortical activation patterns, which represented a place code of the frequency and intensity of test tones, i.e., the ampli-tonotopic organization, and compared the patterns with those evoked by cochlear nuclear microstimulation. Our experimental results demonstrated that microstimulation of both the dorsal and ventral cochlear nucleus (DCN and VCN) could access the cortical ampli-tonotopic organization as acoustic stimuli did. We also found that the cortical dynamic range was wider for the DCN than VCN stimulation and for the low-frequency than for the high-frequency pathway. The present results have great implications for improved ABI performance.
听觉脑干植入物（ABI）通过电刺激耳蜗核表面，已在临床上用于双侧前庭神经鞘瘤致聋患者的康复治疗。与人工耳蜗相比，ABI中音调感知随有源电极位置的变化并不那么明显，这一因素可能导致ABI患者的言语表现较差。本研究的目的是建立一种动物ABI模型，为未来ABI的开发和优化提供生理数据。实验系统包括一个用于微刺激耳蜗核的穿透式微电极阵列和一个用于绘制听觉皮层诱发电位的表面微电极阵列。我们首先获得了音调诱发的皮层激活模式，该模式代表了测试音调的频率和强度的位置编码，即振幅-音调组织，并将这些模式与耳蜗核微刺激诱发的模式进行了比较。我们的实验结果表明，刺激耳蜗背核和腹核（DCN和VCN）均可像声刺激一样激活皮层振幅-音调组织。我们还发现，DCN刺激比VCN刺激的皮层动态范围更广，低频通路比高频通路的皮层动态范围更广。目前的结果对改善ABI性能具有重要意义。
