Rhode W S
Department of Physiology, University of Wisconsin, 1300 University Avenue, Madison, WI 53706, USA.
Neuroscience. 2008 Jun 12;154(1):87-98. doi: 10.1016/j.neuroscience.2008.03.013. Epub 2008 Mar 20.
The mammalian cochlear nucleus (CN) consists of a diverse set of neurons both physiologically and morphologically that are involved in processing different aspects of the sound signal. One class of CN neurons that is located near the entrance of the auditory nerve (AN) to the CN has an oval soma with an eccentric nucleus and a short-bushy dendritic tree and is called a globular/bushy cell (GBC). They contact the principal cells of the medial nucleus of the trapezoid body (MNTB) with the very large calyx of Held that is one of the most secure synapses in the brain. Because MNTB cells provide an inhibitory input to the lateral superior olive (LSO), a structure purported to play a role in lateralizing high frequency sounds, GBC physiology is of great interest. Results were obtained with intracellular recording and subsequent labeling with neurobiotin of 32 GBCs along with a number of cells characterized extracellularly as likely GBCs in the cochlear nucleus (CN) of cat. Their poststimulus discharge response pattern to repeated tones varies from a primarylike pattern, i.e. similar to the AN, to a primarylike pattern with a 0.5-2 ms notch after the initial spike, to an onset pattern with a low-sustained rate. They can represent low frequency tones and amplitude modulated signals exceptionally well with a temporal code.
哺乳动物的耳蜗核(CN)由生理和形态各异的神经元组成,这些神经元参与声音信号不同方面的处理。一类位于听神经(AN)进入CN入口附近的CN神经元,其胞体呈椭圆形,细胞核偏心,树突短而浓密,被称为球状/浓密细胞(GBC)。它们通过非常大的 Held 氏花萼与梯形体内侧核(MNTB)的主细胞接触,Held 氏花萼是大脑中最稳定的突触之一。由于MNTB细胞向外侧上橄榄核(LSO)提供抑制性输入,LSO被认为在高频声音的定位中起作用,因此GBC的生理学备受关注。通过细胞内记录以及随后用神经生物素对32个GBC进行标记,并对猫耳蜗核(CN)中一些细胞进行细胞外特征分析,确定其可能为GBC,从而获得了相关结果。它们对重复音调的刺激后放电反应模式各不相同,从类似初级的模式(即类似于听神经的模式),到初始尖峰后有0.5 - 2毫秒缺口的类似初级模式,再到低持续率的起始模式。它们能够通过时间编码非常出色地呈现低频音调和调幅信号。