Spatial and temporal effects of interleaved masking in cochlear implants.
Spatial and temporal effects of interleaved masking in cochlear implants.
复制标题
人工耳蜗植入物中交错掩蔽的空间和时间效应。
DOI：
10.1007/s10162-009-0168-9
复制
发表时间：
2009
期刊：
影响因子：
--
通讯作者：
vandenHonert,Chris
中科院分区：
文献类型：
--
作者：
Kwon,BomJun;vandenHonert,Chris
现代人工耳蜗利用不同电极上脉冲的交错呈现来避免多个电流场之间的物理干扰，但神经相互作用仍然存在。在本研究中，四名 Nucleus24 用户使用带状电极阵列在交错掩蔽范例中检查了掩蔽，其中探针刺激与掩蔽刺激交错。通过将掩蔽器固定在电极阵列的中间并改变探头的位置并测试各种刺激速率（125、500、2,000 和 6,410 Hz），解决了掩蔽的空间和时间方面的问题。此外，通过分六个步骤改变掩蔽剂水平来评估掩蔽生长 (GOM)。结果表明，无论刺激率如何，掩蔽模式通常比声学听力中的掩蔽模式要宽得多。即使在最高掩蔽水平下，掩蔽量也以大约 0.5 dB/mm 的速率从峰值下降。速率高于 500 Hz 的 GOM 模式与之前的掩蔽研究中观察到的模式不同，其特征是在低掩蔽剂水平下明显浅生长或整体浅生长。怀疑掩蔽器的促进作用（降低阈值），除了 125 Hz 条件外，因为纤维被掩蔽器在膜电位的局部扰动下被激发，但没有放电，并且随后当掩蔽器和探针之间的时间间隙足够短时，很容易被较低水平的探针放电。这些结果表明，在以高但临床相关的刺激速率进行脉冲交错刺激时，应考虑神经元的不应特性和神经求和。总体而言，目前的掩蔽研究可能为当前利用高速交错刺激的人工耳蜗植入系统中的心理物理学和言语理解模型提供基础。
Modern cochlear implants utilize interleaved presentation of pulses on different electrodes to avoid physical interference among multiple current fields, yet neural interaction still exists. In the present study, masking was examined with four Nucleus24 users with the banded electrode array in an interleaved masking paradigm, where a probe stimulus was interleaved with a masker stimulus. Spatial and temporal aspects of masking were addressed by fixing the masker at the middle of the electrode array and changing the location of the probe and by testing various stimulation rates: 125, 500, 2,000, and 6,410 Hz. In addition, growth of masking (GOM) was assessed by changing the masker level in six steps. Results indicated that masking patterns were generally much wider, regardless of stimulation rate, than those in acoustic hearing. The amount of masking decreased from the peak at the rate of approximately 0.5 dB/mm even at the highest masker level. The pattern of GOM with the rates higher than 500 Hz was different from that observed in previous masking studies, characterized by markedly shallow growth at low masker levels or overall shallow growth. A facilitating effect of the masker (lowering the threshold) was suspected, except for the 125-Hz condition, due to the fibers that were subliminally excited, but not discharged, by the masker with local perturbations of membrane potentials, and were subsequently discharged easily by a lower level probe when the temporal gap between masker and probe was sufficiently short. These results suggest that both refractory characteristics of neurons and neural summation be considered in interleaved stimulation of pulses at high, but clinically relevant, stimulation rates. Overall, the present masking study might provide a basis for models in psychophysics and speech understanding in current cochlear implant systems utilizing high-rate interleaved stimulation.