Willott J F, Turner J G
Department of Psychology, Northern Illinois University, DeKalb, IL 60115, USA.
Hear Res. 2000 Sep;147(1-2):275-81. doi: 10.1016/s0378-5955(00)00137-4.
C57BL/6J (C57) and DBA/2J (DBA) mice exhibit progressive high-frequency hearing loss. Extracellular recordings of responses of neurons in the inferior colliculus (IC) evoked by 70-dB SPL tones indicated that normal tonotopic organization was greatly disrupted in both strains: still-audible lower frequencies (4-12 kHz) evoked responses in a large percentage of recording sites in ventral tonotopic regions that normally respond strongly to high frequencies only. To relate the IC responses to an auditory behavior, prepulse inhibition (PPI) was measured using 70-dB tones as prepulses. As high-frequency hearing loss progressed in C57 mice, prepulses of 4-12 kHz elicited stronger PPI, and this was significantly correlated with changes in the percentage of IC recording sites responding to 70-dB tones (the neural pathway for PPI includes the IC). The analysis was extended to DBA mice that had been exposed to an augmented acoustic environment (AAE) - a procedure that improves PPI. In these mice, a higher percentage of IC recording sites responded to 70-dB tones, and this was correlated with improved PPI. The data suggest that responses of IC neurons reflect both hearing loss-induced plasticity and changes induced by exposure to an AAE, and these neural changes are correlated with the magnitude of PPI.
C57BL/6J（C57）和DBA/2J（DBA）小鼠表现出进行性高频听力损失。用70分贝声压级纯音诱发下丘（IC）神经元反应的细胞外记录表明，两种品系的正常音频定位组织都受到了极大破坏：仍可听见的较低频率（4 - 12千赫）在腹侧音频定位区域的大部分记录位点诱发反应，而这些位点通常仅对高频有强烈反应。为了将IC反应与听觉行为联系起来，使用70分贝纯音作为预脉冲来测量前脉冲抑制（PPI）。随着C57小鼠高频听力损失的进展，4 - 12千赫的预脉冲诱发更强的PPI，并且这与IC记录位点对70分贝纯音反应的百分比变化显著相关（PPI的神经通路包括IC）。该分析扩展到暴露于增强声学环境（AAE）的DBA小鼠——这一程序可改善PPI。在这些小鼠中，更高比例的IC记录位点对70分贝纯音有反应，并且这与改善的PPI相关。数据表明，IC神经元的反应既反映了听力损失诱导的可塑性，也反映了暴露于AAE所诱导的变化，并且这些神经变化与PPI的幅度相关。
