Encoding of the amplitude modulation of pulsatile electrical stimulation in the feline cochlear nucleus by neurons in the inferior colliculus; effects of stimulus pulse rate
Encoding of the amplitude modulation of pulsatile electrical stimulation in the feline cochlear nucleus by neurons in the inferior colliculus; effects of stimulus pulse rate
复制标题
DOI：
10.1088/1741-2560/10/5/056010
复制
发表时间：
2013-10-01
影响因子：
4
通讯作者：
Pannu, Satinderpall
中科院分区：
文献类型：
--
作者：
McCreery, Douglas;Han, Martin;Pannu, Satinderpall
目标。没有听觉神经功能的人不能从人工耳蜗中获益，但通过在耳蜗核（CN）表面植入刺激电极的听觉脑干植入物（ABI）可以恢复部分听力。大多数用户受益于他们的ABI，但语音识别往往比人工耳蜗用户差。心理物理学研究表明，较差的调制检测可能导致ABI用户的性能受限。在cat模型中，我们确定了施加在CN内或CN上的电刺激的脉冲速率如何影响下丘中央核（ICC）神经元的振幅调制（AM）的时间和速率编码。的方法。在猫的CN内和CN上长期植入刺激微电极，在ICC中长期植入多位点记录微电极。神经元编码AM脉冲序列的特征为向量强度（VS）、神经元活动与AM的同步性以及神经元动作电位的平均速率（神经元尖峰率（NSR））。主要的结果。对于核内微刺激，当刺激脉冲频率从250增加到500 pps时，AM作为VS的编码增加了3 dB，但仅适用于低最佳声学频率的神经元单元，以及当电刺激调制为低频（10-20 Hz）时。对于CN表面的刺激，在250和500 pps时VS相似，并且当脉冲速率大于250 pps时VS的动态范围减小。当最大刺激幅度在调制深度范围内保持恒定时，调制深度被强烈编码为VS。这种“恒定最大值”协议允许在保持整体动态范围的同时增强调制深度。但是，调制深度的编码强度不如NSR。的意义。这一发现对改进当前和未来abi的声音处理器具有启示意义。abi的性能可能受益于使用比目前大多数abi中使用的脉冲速率更高的脉冲速率，以及通过在保持动态范围的同时增强电刺激调制深度的声音处理策略。
Objectives. Persons without a functional auditory nerve cannot benefit from cochlear implants, but some hearing can be restored by an auditory brainstem implant (ABI) with stimulating electrodes implanted on the surface of the cochlear nucleus (CN). Most users benefit from their ABI, but speech recognition tends to be poorer than for users of cochlear implants. Psychophysical studies suggest that poor modulation detection may contribute to the limited performance of ABI users. In a cat model, we determined how the pulse rate of the electrical stimulus applied within or on the CN affects temporal and rate encoding of amplitude modulation (AM) by neurons in the central nucleus of the inferior colliculus (ICC). Approach. Stimulating microelectrodes were implanted chronically in and on the cats' CN, and multi-site recording microelectrodes were implanted chronically into the ICC. Encoding of AM pulse trains by neurons in the ICC was characterized as vector strength (VS), the synchrony of neural activity with the AM, and as the mean rate of neuronal action potentials (neuronal spike rate (NSR)). Main results. For intranuclear microstimulation, encoding of AM as VS was up to 3 dB greater when stimulus pulse rate was increased from 250 to 500 pps, but only for neuronal units with low best acoustic frequencies, and when the electrical stimulation was modulated at low frequencies (10-20 Hz). For stimulation on the surface of the CN, VS was similar at 250 and 500 pps, and the dynamic range of the VS was reduced for pulse rates greater than 250 pps. Modulation depth was encoded strongly as VS when the maximum stimulus amplitude was held constant across a range of modulation depth. This 'constant maximum' protocol allows enhancement of modulation depth while preserving overall dynamic range. However, modulation depth was not encoded as strongly as NSR. Significance. The findings have implications for improved sound processors for present and future ABIs. The performance of ABIs may benefit from using pulse rates greater than those presently used in most ABIs, and by sound processing strategies that enhance the modulation depth of the electrical stimulus while preserving dynamic range.