Winter I M, Palmer A R
Department of Experimental Psychology, School of Biological Sciences, University of Sussex, Falmer, Brighton, U.K.
Hear Res. 1990 Mar;44(2-3):161-78. doi: 10.1016/0378-5955(90)90078-4.
Single unit responses have been recorded from the anteroventral cochlear nucleus of the anaesthetised guinea-pig. For each unit a response profile was obtained consisting of spike waveform shape, suprathreshold post-stimulus time histogram at characteristic frequency, frequency/intensity response area, a measure of phase-locking and where possible variation in post-stimulus time histogram shape as a function of position within the response area. Units were classified according to schemes based on both post-stimulus time histogram shape and response area. The majority of units with Type I response areas were primarylike and most with Type III response areas were choppers. One-to-one correspondence between the two classification schemes was found for units which were classified as onset by the post-stimulus time histogram scheme and Type I/III by the response area scheme. Primarylike units with a prepotential in their spike waveform most faithfully preserved the temporal information (as measured by phase-locking) present in the auditory nerve input. Primarylike units in which a prepotential was not detected showed varying abilities to phase-lock. Non-primarylike units do not phase-lock as well as auditory nerve fibres in the same species. Nonmonotonic rate-level functions for tones at characteristic frequency were observed across all unit types (with the exception of onset units) classified by the post-stimulus time histogram scheme. An unexpected finding was a small number of primarylike units characterised by reduced driven discharge rates within their response areas. We hypothesize that the mechanism for this reduction is centre-band inhibition.
已从麻醉豚鼠的前腹侧耳蜗核记录到单单位反应。对于每个单位，获得了一个反应图谱，包括尖峰波形形状、特征频率下的阈上刺激后时间直方图、频率/强度反应区域、锁相测量以及在可能的情况下刺激后时间直方图形状随反应区域内位置的变化。根据基于刺激后时间直方图形状和反应区域的方案对单位进行分类。大多数具有I型反应区域的单位是初级样的，大多数具有III型反应区域的单位是切碎器样的。对于那些根据刺激后时间直方图方案被分类为起始型且根据反应区域方案被分类为I/III型的单位，发现了两种分类方案之间的一一对应关系。尖峰波形中具有预电位的初级样单位最忠实地保留了听神经输入中存在的时间信息（通过锁相测量）。未检测到预电位的初级样单位表现出不同的锁相能力。非初级样单位的锁相能力不如同一物种中的听神经纤维。在根据刺激后时间直方图方案分类的所有单位类型（起始单位除外）中，均观察到特征频率音调的非单调率-级函数。一个意外发现是少数初级样单位，其特征是在其反应区域内驱动放电率降低。我们假设这种降低的机制是中心带抑制。
