中文摘要：

目的 观察Sprague-Dawley （SD）大鼠出生后发育过程中,初级听皮层神经元所接收到的突触输入的潜伏期和阈值的变化.方法 采用在体细胞外电生理记录的方法,快速定位初级听皮层大致区域,进一步使用在体细胞封接和全细胞电压膜片钳记录的方法,分别在出生后12 ～ 15 d、16 ～18 d、19 ～ 24 d以及成年（＞3个月）SD大鼠上,记录单个神经元水平上的放电反应以及突触水平上的潜伏期和阈值.结果 ①成年大鼠初级听皮层对于特征频率响应的场电位潜伏期（10～20 ms）较幼年大鼠（20～30 ms）短.②处于发育关键期的幼鼠的单个神经元对白噪声脉冲的放电潜伏期出生后12～ 15 d组[（40.15 ±2.67）ms]和出生后16～18 d组[（33.86 ±4.61）ms]明显长于成年组[（22.93±2.94）]ms,t =4.330、1.995,P=0.00及0.04;而出生后19 ～24 d组[（24.80 ±3.63） ms]与成年组相比,差异无统计学意义（P＞0.05）.③幼鼠神经元对于白噪声脉冲兴奋性和抑制性突触输入的潜伏期出生后12 ～ 15 d组[（38.94±1.90） ms,（35.26±2.40） ms]和出生后16～18 d组[（32.68 ±2.52）ms,（30.24±2.18）ms]明显长于成年组[（19.46±1.06）ms,（18.91±0.77） ms],差异具有统计学意义（兴奋性=6.255、4.662,P值均＜0.01;抑制性t=8.918、4.820,P值均＜0.01）,出生后19 ～24 d组[（23.67±2.46） ms,（21.43±1.80） ms]与成年组相比,差异无统计学意义（P值均＞0.01）;兴奋性输入与抑制性输入潜伏期之间的差值在发育过程中逐渐减小,分别为[（3.15±1.02） ms、（2.01±0.73）ms、（1.79±0.85）ms、（0.39±0.48）ms],出生后12～15 d组与成年组相比,差异具有统计学意义（t=1.739,P＜0.01）.④在突触反应阈值方面,幼鼠组[（40.0±1.6）dB,（41.3±1.6）dB,（35.0±2.7）dB]明显高于成年鼠[（30.9±0.6）dB],出生后12 ～15 d、16～ 18 d组与成年组相比,差异具有统计学意义（t =5.284、5.867,P值均＜0.叭）,而出?

英文摘要：

Objective To study the change of synaptic onset latency and threshold in primary auditory cortex （A1） during the development of SD rat.Methods Extracellular recording was used to locate A1,followed by transferred to loose-patch and whole-cell patch in vivo to record the spike activity,synaptic onset latency and threshold responses respectively.Rats were divided into 4 groups according to ages,postnatal 12-15 days,16-18 days,19-24 days and adult （＞ 3 months）.Results 1.The onset latency of local field potential in A1 of adult rats [（10-20） ms] was shorter than young rats [（20-30） ms].2.During development,the onset latency of spikes of a single neuron in response to white noise pulses decreased.And the latency in young rats P12-15 [（40.15 ± 2.67） ms] and P16-18 [（33.86 ±4.61） ms] were longer than in adults [（22.93 ± 2.94） ms] （ANOVA-test,t =4.330 and 1.995,P =0.00 and 0.04）.However,the onset latencies of P19-24 [（24.80 ± 3.63） ms] and adult had no significant difference （P ＞ 0.05）.3.Synaptic onset latencies of both excitation and inhibition were significantly longer in P12-15 [（38.94±1.90）ms,（35.26±2.40）ms] and P16-18[（32.68 ±2.52）ms,（30.24±2.18）ms] than in adults [（19.4 ± 1.06） ms,（18.91 ± 0.77） ms] excitation （t =6.255 and 4.662,P ＜ 0.01） inhibition （t =8.918 and 4.820,P ＜ 0.01） showed significant difference.Whereas the onset latencies of P19-24 [（23.67 ± 2.46） ms,（21.43 ± 1.80） ms] and adults displayed no prominent difference （P ＞ 0.01）.Meanwhile,the difference between the onset latencies of excitation and inhibition became narrower during development[（3.15 ± 1.02）ms,（2.01 ±0.73）ms,（1.79 ±0.85） ms,（0.39 ±0.48） ms].P12-15 had notably difference in comparison to adults （t =1.739,P ＜ 0.01）.4.The thresholds of synaptic response were notably higher in P12-15（40.0 ± 1.6）dB and P16-18 （41.3 ± 11.6）dB when compared with adults （30.9 ± 0.6） dB （t =5.284 and 5.867,P ＜ 0.01?