Willott J F, Parham K, Hunter K P
Department of Psychology, Northern Illinois University, DeKalb 60115.
Hear Res. 1988 Dec;37(1):15-27. doi: 10.1016/0378-5955(88)90074-3.
Extracellular recordings were obtained from inferior colliculus (IC) neurons in young (2-month) and middle-aged (7-month; 12- to 13-month) C57BL/6J mice in response to contralateral tone and noise stimuli. An age-related progressive loss of spiral ganglion cells, most pronounced near the cochlear base, was observed in the mice, accompanied by severe high frequency hearing loss manifested as elevation of neuronal thresholds, especially in the ventromedial half of the IC. There was a small age-related increase (2% to 11%) in 'sluggish' neurons (auditory, but poorly driven by sound); however, most neurons were well-driven by suprathreshold stimuli. Nine response types were derived from post-stimulus time histograms; they were found in all age groups with little difference in their relative incidence. The percentage of neurons that were spontaneously active increased with age in the central nucleus but not in other subnuclei. Parameters of response areas (range, upper frequency range, best frequency, and rate-best frequency) showed pronounced age differences in the ventromedial half of the IC and minimal differences in the dorsolateral half of the IC. The percentage of neurons with nonmonotonic rate-level functions decreased with age, especially in the IC dorsal cortex.
在年轻（2个月）和中年（7个月；12至13个月）的C57BL/6J小鼠中，对下丘（IC）神经元进行细胞外记录，以响应同侧音调及噪声刺激。在这些小鼠中观察到螺旋神经节细胞出现与年龄相关的渐进性丧失，在耳蜗底部附近最为明显，同时伴有严重的高频听力损失，表现为神经元阈值升高，尤其是在IC的腹内侧半部。“反应迟缓”的神经元（听觉正常，但对声音驱动反应不佳）有与年龄相关的少量增加（2%至11%）；然而，大多数神经元对阈上刺激反应良好。从刺激后时间直方图得出了九种反应类型；在所有年龄组中均能发现这些类型，其相对发生率差异不大。在中央核中，自发活动的神经元百分比随年龄增加，而在其他亚核中则不然。反应区域的参数（范围、高频范围、最佳频率和最佳频率处的放电率）在IC腹内侧半部显示出明显的年龄差异，而在IC背外侧半部差异最小。具有非单调放电率-强度函数的神经元百分比随年龄下降，尤其是在IC背侧皮质。
