Smith P H, Joris P X, Carney L H, Yin T C
Department of Neurophysiology, University of Wisconsin, Madison 53705.
J Comp Neurol. 1991 Feb 15;304(3):387-407. doi: 10.1002/cne.903040305.
We made intraaxonal recordings from 30 individual globular bushy cell axons in the trapezoid body of the cat using HRP-filled glass microelectrodes. With subsequent HRP injection, we determined their axonal projection patterns. For cells with characteristic frequencies (CFs) above 3 kHz, short-tone peristimulus time histograms (PSTHs) at CF were typically primarylike at low tone intensities and primarylike with notch (PLN) or onset with low sustained activity (OL) at higher stimulus levels. Cells with CFs between 1 and 3 kHz showed the same response features with the spikes in the sustained region of the response phase-locked to the stimulus tone. Cells with CFs below 1 kHz showed phase-locked PSTHs with exceptionally high levels of synchrony compared to eighth nerve fibers with comparable CFs. This exceptional phase-locking was also noted when cells with CFs of 1-3 kHz were presented with tones below 1 kHz. Although the globular bushy cell axons were not completely filled from the soma of origin to terminal fields in the contralateral brainstem, a number of consistent anatomical features were distinguished in the population. All but one of the myelinated axons crossed the midline in the middle, large fiber component of the trapezoid body. Ipsilaterally, the axon always gave off from one to four collateral branches whose major targets were the posterior periolivary nucleus (PPO) and the lateral nucleus of the trapezoid body (LNTB). Minor termination sites for ipsilateral collateral branches were the dorsolateral periolivary nucleus (DLPO) and the lateral superior olive (LSO). Contralaterally the axon gave rise to one or two calyces of Held in the medial nucleus of the trapezoid body (MNTB). Three other major collateral branches arose from the contralateral axon and innervated a consistent set of areas. One headed caudally to innervate an area just ventromedial to the facial nucleus. Another followed the sixth nerve dorsally to innervate the dorsomedial periolivary nucleus (DMPO). A third collateral headed rostrally toward the ventral nucleus of the lateral lemniscus (VNLL), giving off occasional small sidebranches. Although each injected axon gave rise to a collateral that innervated the MNTB, it did not necessarily give rise to all three of the other collateral branches.
我们使用充满辣根过氧化物酶（HRP）的玻璃微电极，对猫的梯形体内30条单个球状浓密细胞轴突进行了轴突内记录。随后通过注射HRP，我们确定了它们的轴突投射模式。对于特征频率（CF）高于3kHz的细胞，在CF频率下的短音刺激后时间直方图（PSTH）在低声强时通常类似初级反应，在较高刺激水平时则类似带缺口的初级反应（PLN）或起始伴有低持续活动（OL）。CF在1至3kHz之间的细胞在反应的持续区域中，其动作电位与刺激音调锁相，表现出相同的反应特征。CF低于1kHz的细胞与具有可比CF的第八神经纤维相比，表现出锁相的PSTH，且同步性极高。当向CF为1至3kHz的细胞呈现低于1kHz的音调时，也观察到了这种异常的锁相现象。尽管球状浓密细胞轴突从起源的胞体到对侧脑干中的终末场并未完全充满，但在这群细胞中仍可区分出一些一致的解剖学特征。除了一条有髓轴突外，其余所有轴突都在梯形体中间的大纤维部分交叉中线。在同侧，轴突总是发出一到四条侧支，其主要靶标是后橄榄周核（PPO）和梯形体外侧核（LNTB）。同侧侧支的次要终末位点是背外侧橄榄周核（DLPO）和外侧上橄榄核（LSO）。在对侧，轴突在梯形体内侧核（MNTB）中形成一到两个 Held 壶腹。对侧轴突还发出另外三条主要侧支，支配一组一致的区域。一条向尾侧延伸，支配面神经核腹内侧的一个区域。另一条沿着第六神经向背侧延伸，支配背内侧橄榄周核（DMPO）。第三条侧支向头侧延伸至外侧丘系腹侧核（VNLL），偶尔发出小的侧支。尽管每条注射的轴突都发出一条支配MNTB的侧支，但不一定会发出其他三条侧支。
