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.

前掩蔽声时程所致的探测声频率感受野的变化

本实验在自由声场条件下,以阈上5 dB强度,神经元最佳频率(best frequency,BF)纯音作为掩蔽声,其时程分别为40、60、80和100 ms,观察掩蔽声对探测声频率感受野的影响,结果发现给不同时程的掩蔽声后,全部神经元的频率感受野都明显减小,P<0.001.用单因素方差分析(one-way ANOVA)结果表明:掩蔽声对神经元频率感受野的抑制率随掩蔽声时程(masker duration,MD)的增加而变大,通过对高低频感受野抑制分析结果表明:掩蔽声对神经元高频感受野的抑制率明显高于低频部分,P<0.05.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.

Effect of Weak Noise on the Frequency Tuning of Mouse Inferior Collicular Neurons

In order to study the effect of weak noise on the sound signal extraction of mouse (Mus musculus Km) inferior collicular (IC) neurons from environments,we examined the changes in frequency tuning curves (FTCs) of 32 neurons induced by a weak noise relative to 5 dB below minimum threshold of tone (reMT-5 dB) under free field stimulation conditions.The results were as follows:① There were three types of variations in FTCs,sharpened (34.4%),broadened (18.8%),and unaffected (46.9%),nevertheless,only the alteration of sharpened FTCs was statistically different.② Sharpness of frequency tuning induced by a reMT-5 dB noise was very strong.Q 10 and Q 30 of FTCs were increased by (34.42±17.04)% (P=0.026,n=11) and (46.34±22.88)% (P=0.009,n=7).③ The changes of inverse-slopes (ISs,kHz/dB) between high (IS high) and low (IS low) limbs of FTCs were dissymmetry.The IS high of FTCs decreased markedly (P=0.046,n=7),however,there was little change (P=0.947,n=7) in IS low.Our data revealed for the first time that the weak noise could sharpen frequency tuning and increase the sensitivity on the high frequency of sound signal in IC neurons of mouse.

Effect of electroacupuncture pretreatment on the protein expression of c-fos in fastigial nucleus and lateral hypothalamus area in rats with acute myocardial ischemia-reperfusion injury

Objective:To observe the effect of electroacupuncture(EA)pretreatment on the protein expression of c-fos in fastigial nucleus(FN)and lateral hypothalamus area(LHA)in rats with acute myocardial ischemia-reperfusion injury(MIRI),and to explore the role and mechanism of FN and LHA in EA at the Heart Meridian fighting against acute MIRI reaction.Methods:Seventy Sprague-Dawley rats were randomly divided into a sham operation group,a model group,an EA-Heart Meridian group and an EA-Lung Meridian group,with 14 rats in each group;an LHA lesion plus EA-Heart Meridian group(LHA+EA-Heart Meridian group)and a FN lesion plus EA-Heart Meridian group(FN+EA-Heart Meridian group),with 7 rats in each group.Except the sham operation group,the left anterior descending branch of coronary artery was ligated to establish acute MIRI rat models in the other 5 groups.In the three groups with EA-Heart Meridian treatment,Shenmen(HT 7)and Tongli(HT 5)were selected;Taiyuan(LU 9)and Lieque(LU 7)were selected in the EA-Lung Meridian group.All the EA groups received EA stimulation prior to modeling,with 1 mA in current intensity and 2 Hz in frequency,20 min each time,once a day for a total of 7 d.The sham operation group and the model group did not receive EA stimulation.The electrocardiogram was observed in the rats to analyze the ST-segment deviation and cardiac arrhythmia score.The expression of c-fos protein in FN and LHA was detected by immunohistochemistry method.Results:Compared with the sham operation group,the ST-segment deviation,cardiac arrhythmia score and the expression of c-fos protein in the FN and LHA increased significantly in the model group(all P<0.05).Compared with the model group,the ST-segment deviation,cardiac arrhythmia score and the expression of c-fos protein in FN and LHA decreased significantly in the EA-Heart Meridian group(all P<0.05).Compared with the EA-Heart Meridian group,the ST-segment deviation and cardiac arrhythmia score increased significantly in the EA-Lung Meridian group,LHA+EA-Heart Meridian group and FN+EA-Heart Meridian group(all P<0.05);the expression of c-fos in FN increased significantly in the EA-Lung Meridian group and LHA+EA-Heart Meridian group(both P<0.05);the expression of c-fos in LHA increased significantly in the EA-Lung Meridian group and FN+EA-Heart Meridian group(both P<0.05).Conclusion:FN and LHA are involved in the mechanism of EA at Heart Meridian to improve the acute MIRI reactions,and the cerebellum may participate in the improvement of cardiac function by EA through the cerebellum-hypothalamus projection.