CAJ | 학술논문

本文采用不同重复率的串声刺激,模拟大棕蝠回声定位不同阶段听到的调频声纳信号,利用电生理方法和微电泳技术研究不同重复率串刺激条件下GABA能抑制对下丘神经元强度敏感性的影响.结果发现,随串刺激重复率的增加,有的神经元强度敏感性增强,有的神经元强度敏感性则降低.在不同串刺激条件下,微电泳荷包牡丹碱,神经元放电率均增加,随重复率增加强度敏感性增强或减弱的趋势消失,提示GABA能抑制调制下丘神经元对不同重复率串刺激反应的强度敏感性.串刺激强度在最低阈值附近时,微电泳荷包牡丹碱导致放电率增加的百分率最大,随串刺激强度增加,放电率增加的百分率逐渐减小.提示刺激强度较低时,GABA能抑制对下丘神经元强度敏感性的影响更有效.
본문채용불동중복솔적천성자격,모의대종복회성정위불동계단은도적조빈성납신호,이용전생리방법화미전영기술연구불동중복솔천자격조건하GABA능억제대하구신경원강도민감성적영향.결과발현,수천자격중복솔적증가,유적신경원강도민감성증강,유적신경원강도민감성칙강저.재불동천자격조건하,미전영하포모단감,신경원방전솔균증가,수중복솔증가강도민감성증강혹감약적추세소실,제시GABA능억제조제하구신경원대불동중복솔천자격반응적강도민감성.천자격강도재최저역치부근시,미전영하포모단감도치방전솔증가적백분솔최대,수천자격강도증가,방전솔증가적백분솔축점감소.제시자격강도교저시,GABA능억제대하구신경원강도민감성적영향경유효.
The echolocating big brown bats(Eptesicus fuscus)emit trains of frequency-modulated(FM)biosonar signals with duration,amplitude,repetition rate,and sweep structure changing systematically during interception of their prey.In the present study,the sound stimuli of temporally patterned pulse trains at three different pulse repetition rates(PRRs) were used to mimic the sounds received during search,approach,and terminal stages of echolocation.Electrophysiological method was adopted in recordings from the inferior colliculus (IC) of midbrain.By means of iontophoretic application of bicuculline,the effect of GABAergic inhibition on the intensity sensitivity of IC neurons responding to three different PRRs of 10,30 and 90 pulses per second (pps) was examined.The rate-intensity functions(RIFs) were acquired.The dynamic range(DR) of RIFs was considered as a criterion of intensity sensitivity.Comparing the average DR of RIFs at different PRRs,we found that the intensity sensitivity of some neurons improved,but that of other neurons decayed when repetition rate of stimulus trains increased from 10 to 30 and 90 pps.During application of bicuculline,the number of impulses responding to the different pulse trains increased under all stimulating conditions,while the DR differences of RIFs at different PRRs were abolished.The results indicate that GABAergic inhibition was involved in modulating the intensity sensitivity of IC neurons responding to pulse trains at different PRRs.Before and during bicuculline application.the percentage of changes in responses was maximal in lower stimulus intensity near to the minimum threshold(MT),and decreased gradually with the increment of stimulus intensity.This observation suggests that GABAergic inhibition contributes more effectively to the intensity sensitivity of the IC neurons responding to pulse trains at lower sound level.