Temporal properties of chronic cochlear electrical stimulation determine temporal resolution of neurons in cat inferior colliculus.
Temporal properties of chronic cochlear electrical stimulation determine temporal resolution of neurons in cat inferior colliculus.
复制标题
慢性耳蜗电刺激的时间特性决定了猫下丘神经元的时间分辨率。
DOI：
10.1152/jn.1999.82.6.2883
复制
发表时间：
1999
影响因子：
2.5
通讯作者：
Rebscher,SJ
中科院分区：
文献类型：
--
作者：
Vollmer,M;Snyder,RL;Leake,PA;Beitel,RE;Moore,CM;Rebscher,SJ
随着人工耳蜗植入在重度听力障碍成人康复中越来越成功，儿科植入受试者的数量也在增加。我们建立了一种先天性耳聋的动物模型，并研究了电刺激频率对发育中的聋猫听觉系统中枢神经元时间分辨力的影响。记录了两组猫对侧下丘（IC）单个神经元对脑内电脉冲串（电荷平衡、恒流双相脉冲）的最大跟随频率（Fmax）和反应时间。将结果与未受刺激、急性聋和植入的成年猫的数据进行比较，这些猫先前听力正常（对照）。在IC的外核（ICX;记录的所有记录的16%）和中央核（ICC;记录的所有记录的181%）的神经元的时间响应特性之间观察到特征性差异：1）在所有三个实验组中，ICX中的神经元比ICC中的神经元具有显著更低的Fmax和更长的响应潜伏期。2）慢性电刺激在癫痫猫中仅改变ICC中的神经元的时间分辨率，而不改变ICX中的神经元。这种效应的大小取决于慢性刺激的频率。具体地，低频信号（30 pps，80 pps）维持ICC神经元的时间分辨率，而高频刺激显著提高ICC神经元的时间分辨率（即，更高的Fmax和更短的反应潜伏期）。此外，Fmax和lavelian电刺激与ICC的tonotopic梯度不相关，并且在慢性电刺激后的时间分辨率的变化均匀地发生在整个ICC。在所有三个实验组中，增加Fmax与较短的反应潜伏期相关。结果表明，长期施加的电信号的时间特性严重影响耳蜗组织的ICC神经元的时间处理。我们认为，这种可塑性的变化，在中央听觉神经元的时间处理可能有助于受试者间的变异性和逐步改善言语识别性能的聋儿使用人工耳蜗植入的临床研究中观察到的。
As cochlear implants have become increasingly successful in the rehabilitation of adults with profound hearing impairment, the number of pediatric implant subjects has increased. We have developed an animal model of congenital deafness and investigated the effect of electrical stimulus frequency on the temporal resolution of central neurons in the developing auditory system of deaf cats. Maximum following frequencies (Fmax) and response latencies of isolated single neurons to intracochlear electrical pulse trains (charge balanced, constant current biphasic pulses) were recorded in the contralateral inferior colliculus (IC) of two groups of neonatally deafened, barbiturate-anesthetized cats: animals chronically stimulated with low-frequency signals (≤80 Hz) and animals receiving chronic high-frequency stimulation (≥300 pps). The results were compared with data from unstimulated, acutely deafened and implanted adult cats with previously normal hearing (controls). Characteristic differences were seen between the temporal response properties of neurons in the external nucleus (ICX; ∼16% of the recordings) and neurons in the central nucleus (ICC; ∼81% of all recordings) of the IC:1) in all three experimental groups, neurons in the ICX had significantly lower Fmax and longer response latencies than those in the ICC.2) Chronic electrical stimulation in neonatally deafened cats altered the temporal resolution of neurons exclusively in the ICC but not in the ICX. The magnitude of this effect was dependent on the frequency of the chronic stimulation. Specifically, low-frequency signals (30 pps, 80 pps) maintained the temporal resolution of ICC neurons, whereas higher-frequency stimuli significantly improved temporal resolution of ICC neurons (i.e., higher Fmax and shorter response latencies) compared with neurons in control cats. Furthermore, Fmax and latencies to electrical stimuli were not correlated with the tonotopic gradient of the ICC, and changes in temporal resolution following chronic electrical stimulation occurred uniformly throughout the entire ICC. In all three experimental groups, increasing Fmax was correlated with shorter response latencies. The results indicate that the temporal features of the chronically applied electrical signals critically influence temporal processing of neurons in the cochleotopically organized ICC. We suggest that such plastic changes in temporal processing of central auditory neurons may contribute to the intersubject variability and gradual improvements in speech recognition performance observed in clinical studies of deaf children using cochlear implants.