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目的探讨间隔检测中间隔标记信号的带宽和强度对豚鼠下丘间隔反应阈值的影响。方法经豚鼠下丘埋植金属电极,记录4种带宽间隔标记信号和3个强度下的间隔反应,得出间隔阈值。结果与以往行为实验结果类似,相同声音强度下,豚鼠下丘的间隔反应阈值随着间隔标记信号带宽的增加而下降。例如在85dBSPL时,0.5～8kHz,0.5～16kHz及0.5～32kHz带宽下的间隔反应阈值分别为1.35±0.32ms,1.33±0.33ms及1.17±0.44ms。但是在最高频段(16～32kHz)和线性等带宽低频段(0.5～16kHz),间隔反应阈值未见显著差异,提示高频段的时间分辨可能与低频段相当。相同间隔标记带宽下,声音强度愈低,间隔反应阈值愈大;但仅在最低频段(0.5～8kHz)声音强度效应具有显著性意义。结论豚鼠下丘的间隔反应阈值主要决定于间隔标记信号的总带宽而非频带位置;信号强度也对该阈值有一定影响。
Objective To investigate the effect of the interval and intensity of interval marker signal on the response threshold of inferior colliculus in guinea pigs. Methods The metal electrodes were implanted into the inferior colliculus of guinea pigs, and the interval signals were recorded by four kinds of interval-labeled signals and the intervals of three intensities. The results were similar to the results of previous behavioral experiments. Under the same sound intensity, the threshold of septum reaction in inferior colliculus of guinea pigs decreased with the increase of the bandwidth of septal marker signal. For example, at 85 dB SPL, the interval reaction thresholds at 0.5-8 kHz, 0.5-16 kHz and 0.5-32 kHz bandwidth are 1.35 ± 0.32ms, 1.33 ± 0.33ms and 1.17 ± 0.44ms, respectively. However, there is no significant difference in the interval reaction threshold between the highest band (16 ~ 32kHz) and the linear low band (0.5 ~ 16kHz), suggesting that the temporal resolution of the high band may be comparable to that of the low band. Under the same interval marker bandwidth, the lower the sound intensity is, the greater the threshold of the interval reaction is; however, the sound intensity effect is significant only in the lowest frequency band (0.5-8 kHz). Conclusions The threshold of septum response in inferior colliculus of guinea pig mainly depends on the total bandwidth of interval marker signal rather than the frequency band. The signal intensity also has an impact on the threshold.