声强对豚鼠下丘给声响应神经元间隔探测的影响

Effects of stimulus intensity on gap detection in the onset unit of the inferior colliculus in guinea pigs

目的探讨声音信号强度对豚鼠下丘给声响应神经元间隔探测的影响。方法采用单细胞记录的方法,刺激信号由100 ms和50 ms白噪声相加组成,声音强度10～80 dB SPL,中间间隔时间为0、1、2、4、8、16、48、96 ms,分别统计阈响应组和阈上10,20,30 dB时,给声响应神经元的间隔阈值,并观察间隔阈值与放电率和潜伏期的关系。结果本实验共记录96个神经元,其中,给声响应神经元有35个,在阈响应强度时,给声响应神经元间隔阈值明显增大,四组强度的间隔阈值均值分别为(22.91±4.36)ms,(9.00±2.69)ms,(4.00±0.49)ms和(11.33±3.11)ms(P<0.01),但阈上各组间的差异无统计学意义(P>0.05)。在间隔时间为48 ms时,给声响应神经元间隔后放电恢复率的均值分别为0.44±0.15,0.83±0.12,0.88±0.07和0.61±0.10(P<0.01)。而首次放电潜伏期分别为(12.86±0.72)ms,(11.65±0.64)ms,(11.03±0.65)ms和(10.68±0.55)ms(P>0.05)。结论声音信号强度对豚鼠下丘给声响应神经元的间隔探测有一定影响。

Objective To explore the effects of stimulus intensity on gap detection responses of onset neurons in inferior colliculus （IC） of guinea pigs. Methods Gap stimuli were noise bursts, with levels from 10 to 80 dB SPL. A series of silent gaps including 0, 1, 2, 4, 8, 16, 48 and 96 ms gap duration were embedded between the initial lOOms white noise burst （NB1） and the final 50ms burst （NB2） in the stimuli. The minimal gap threshold （MGT）, first spike latency （FSL） and NB2 recovery rate were also analyzed according to four intensity groups： minimum threshold （MT）, MT＋ 10 dB SPL （MT＋ 10）, MT＋ 20 dB SPL （MT＋ 20）, and MT＋ 30dB SPL（MT＋ 30）. Results Thirty-five onset units were collected from 96 recorded neurons. The average MGT was （22.91 ±4.36）ms, （9.00±2.69）ms, （4.00±0.49）ms and （11.33±3.11）ms in the groups of MT, MT＋ 10, MT ＋ 20 and MT ＋ 30, respectively （ P 〈 0.01 ）. However, this effect was not significant among the group of supra-threshold. The NB2 recover）, rate in 48ms gap duration was 0.44 ± 0.15, 0.83 ± 0.12, 0.88 ± 0.07 and 0.61 ± 0.10, respectively. The FSL in Oms gap duration was （12.86±0.72）ms, （11.65±0.64）ms, （11.03±0.65）ms and （10.68± 0.55）ms respectively in the four groups. Conclusion The level of white noise gap stimuli has some effects on the gap response in the onset unit of inferior colliculus in guinea pigs.