Chen G-D, Sheppard A, Salvi R
Center for Hearing and Deafness, SUNY at Buffalo, Buffalo, NY 14214, USA.
Center for Hearing and Deafness, SUNY at Buffalo, Buffalo, NY 14214, USA.
Neuroscience. 2016 Feb 19;315:228-45. doi: 10.1016/j.neuroscience.2015.12.005. Epub 2015 Dec 14.
The effects of intense noise exposure on the classical auditory pathway have been extensively investigated; however, little is known about the effects of noise-induced hearing loss on non-classical auditory areas in the brain such as the lateral amygdala (LA) and striatum (Str). To address this issue, we compared the noise-induced changes in spontaneous and tone-evoked responses from multiunit clusters (MUC) in the LA and Str with those seen in auditory cortex (AC) in rats. High-frequency octave band noise (10-20 kHz) and narrow band noise (16-20 kHz) induced permanent threshold shifts at high-frequencies within and above the noise band but not at low frequencies. While the noise trauma significantly elevated spontaneous discharge rate (SR) in the AC, SRs in the LA and Str were only slightly increased across all frequencies. The high-frequency noise trauma affected tone-evoked firing rates in frequency and time-dependent manner and the changes appeared to be related to the severity of noise trauma. In the LA, tone-evoked firing rates were reduced at the high-frequencies (trauma area) whereas firing rates were enhanced at the low-frequencies or at the edge-frequency dependent on severity of hearing loss at the high frequencies. The firing rate temporal profile changed from a broad plateau to one sharp, delayed peak. In the AC, tone-evoked firing rates were depressed at high frequencies and enhanced at the low frequencies while the firing rate temporal profiles became substantially broader. In contrast, firing rates in the Str were generally decreased and firing rate temporal profiles become more phasic and less prolonged. The altered firing rate and pattern at low frequencies induced by high-frequency hearing loss could have perceptual consequences. The tone-evoked hyperactivity in low-frequency MUC could manifest as hyperacusis whereas the discharge pattern changes could affect temporal resolution and integration.
高强度噪声暴露对经典听觉通路的影响已得到广泛研究；然而，关于噪声性听力损失对大脑中非经典听觉区域（如外侧杏仁核（LA）和纹状体（Str））的影响却知之甚少。为解决这一问题，我们比较了噪声引起的大鼠LA和Str中多单位簇（MUC）的自发反应和纯音诱发反应的变化与听觉皮层（AC）中的变化。高频倍频程噪声（10 - 20 kHz）和窄带噪声（16 - 20 kHz）在噪声频段内及以上的高频区域诱发了永久性阈值偏移，但在低频区域未诱发。虽然噪声损伤显著提高了AC中的自发放电率（SR），但LA和Str中的SR在所有频率上仅略有增加。高频噪声损伤以频率和时间依赖性方式影响纯音诱发的放电率，且这些变化似乎与噪声损伤的严重程度有关。在LA中，高频（损伤区域）的纯音诱发放电率降低，而低频或边缘频率的放电率则根据高频听力损失的严重程度而增强。放电率时间分布从宽平台变为一个尖锐的延迟峰值。在AC中，高频的纯音诱发放电率降低，低频则增强，同时放电率时间分布变得明显更宽。相比之下，Str中的放电率总体上降低，放电率时间分布变得更具相位性且持续时间更短。高频听力损失在低频诱发的放电率和模式改变可能会产生感知后果。低频MUC中纯音诱发的活动亢进可能表现为听觉过敏，而放电模式的变化可能会影响时间分辨率和整合。
