不同时程的前掩蔽声对小鼠下丘神经元声反应的掩蔽效应

自由声场条件下,以强度为神经元最佳频率阈上5dB,时程分别为40、60、80和100ms的纯音作为前掩蔽声,观察和记录了不同时程掩蔽声对小鼠(MusmusculusKm)下丘神经元发放和声强处理的影响.结果发现:随掩蔽声时程的增加,神经元发放抑制率逐渐增大(P<0.0001,n=41),反应潜伏期延长(P<0.01,n=41);其中受掩蔽声抑制的41个神经元中,绝大部分的(90.2%,37/41)反应动力学范围随掩蔽声时程的增加而逐渐变窄(P<0.0001),另有4个神经元的反应动力学范围则出现增加(9.8%,4/41).推测前掩蔽声的时程效应与掩蔽声激活的抑制性输入强度以及持续时间相关.

Masking effect of forward masker sound with different durations on acoustical responses of mouse inferior collicular neurons to probe sound

To study the effects of forward masker sound with different durations on neuronal firing and rate-intensity function (RIF) of mouse inferior colliculus (IC) neurons, a tone relative to 5 dB above minimum threshold (re MT+5 dB) at the best frequency of recorded neurons was used as forward masker sound under free field stimulation conditions. The masker durations were 40, 60, 80, 100 ms. The results showed that as masker duration increasing, inhibition in neuronal firing was enhanced (P<0.000 1, n=41) and the latency of neurons was lengthened (P<0.01, n=41). In addition, among 41 inhibited IC neurons, the dynamic range (DR) of the most majority (90.2%, 37/41) narrowed with masker sound duration increasing (P<0.000 1), whereas the DR of others (9.8%, 4/41) became wider. These data suggest that the masking effects of forward masker sound with different durations might be correlated with the amplitude and duration of inhibitory input to IC neurons elicited by masker sound.