摘要
目的研究下丘神经元对纯音刺激的相位锁定反应特性。方法采用单极玻璃镀膜钨丝电极记录14只豚鼠单神经元单位的动作电位。双耳给予200ms持续时间的纯音,频率范围为50～3000Hz,用TDTSystem3(Tucker-DaviesTechnologies)记录神经元单位的特征性频率、频率反应面积(Frequencyresponsearea)及围刺激时间柱形图(Peristimulustimehistogram,PSTH)。用计算机软件重建周期柱形图(Periodhistogram),并计算向量强度(Vectorstrength)。结果共记录188个下丘神经元单位,其中70%(131/188)的神经元为相位锁定反应阳性。绝大多数(87%)相位锁定反应神经元单位的特征性频率在100～1000Hz范围内。能记录到的具有相位锁定反应的最高刺激频率为1500Hz。绝大多数神经元的相位锁定反应的上限频率均低于1000Hz。有些神经元单位仅显示微弱的相位锁定反应,其向量强度不超过0.3;而另外一些则显示较强的相位锁定反应,其向量强度>0.9。在下丘中共记录到带通相位锁定反应神经元单位12个(9.5%),其余均为低通反应。根据特征性频率及其附近频率的PSTH特点,可以将神经元单位分为6类,不同PSTH类型的相位锁定反应有差异;在四类较常见的神经元单位之间,相位锁定反应的强度有显著的交叉和重叠。相位锁定反应强度也随刺激强度的改变而变化,不同的神经元单位,其变化特点有差异。结论相位锁定反应特性在下丘神经元中有不同程度的保存。不同神经元的相位锁定反应的频率范围和强度差异较大。来自下级神经核团的不同细胞群的锁相传入信息可汇聚到同一神经元。
Objective To investigate the property of the phase-locked response to pure tones in the inferior colliculus. Methods Recordings from single units of the inferior colliculus at a time were made with glass insulated tungsten electrodes in 14 pigmented guinea pigs. The main stimuli were pure tones （duration 200 ms） gated on and off with cosine squared ramps lasting 2 ms and with a repetition period of 600 ms. Extracellular action potentials were discriminated using a level-crossing detector （SD1, Tucker-Davies Technologies）. The characteristic frequency （CF） and frequency response area were determined by making automated frequency-intensity plots. Peristimulus time histograms were made of responses to 100 presentations of tones, of at least 8 frequencies, that were determined by the boundaries of the frequency response area. Period histograms were plotted for each of these so that the degree of synchronisation （vector strength） could be calculated. Results Recordings were made from 188 units/clusters in total. Of these 131 units （70%） showed phase- locking to pure tones at one or more frequencies. The CFs of most （87%, 114/131） phase-locked units were within the range of 100-1 000 Hz. The highest frequency at which phase-locking was detected was 1 500 Hz but for most units the upper limit of phase-locking was lower than 1 000 Hz. Some units showed weak phase-locking where the vector strength never increased above 0.3 whereas other units showed strong phase-locking and had vector strengths of above 0.9. There were 12 band-pass units in the IC （9.5 %） while the rest of the IC units were low-pass and had the best vector strengths at the lowest frequencies to which they gave a sustained response. We identified 6 types of unit by following the definitions of Le Beau et al. There was a considerable variation in phase-locked response frequency range and strength among different PSTH types. And there was considerable overlap in the strength of phase-locking between the four larger groups. The str
出处
《中华耳科学杂志》
CSCD
2006年第2期90-97,共8页
Chinese Journal of Otology
关键词
相位锁定反应
下丘
纯音
Phase-locked response
Inferior colliculus
Pure tone
