Department of Physiology, School of Medicine and Public Health, University of Wisconsin, 1300 University Avenue, Madison, WI 53706, USA.
Hear Res. 2011 Jun;276(1-2):61-9. doi: 10.1016/j.heares.2010.10.018. Epub 2010 Nov 4.
Acoustic information is brought to the brain by auditory nerve fibers, all of which terminate in the cochlear nuclei, and is passed up the auditory pathway through the principal cells of the cochlear nuclei. A population of neurons variously known as T stellate, type I multipolar, planar multipolar, or chopper cells forms one of the major ascending auditory pathways through the brainstem. T Stellate cells are sharply tuned; as a population they encode the spectrum of sounds. In these neurons, phasic excitation from the auditory nerve is made more tonic by feedforward excitation, coactivation of inhibitory with excitatory inputs, relatively large excitatory currents through NMDA receptors, and relatively little synaptic depression. The mechanisms that make firing tonic also obscure the fine structure of sounds that is represented in the excitatory inputs from the auditory nerve and account for the characteristic chopping response patterns with which T stellate cells respond to tones. In contrast with other principal cells of the ventral cochlear nucleus (VCN), T stellate cells lack a low-voltage-activated potassium conductance and are therefore sensitive to small, steady, neuromodulating currents. The presence of cholinergic, serotonergic and noradrenergic receptors allows the excitability of these cells to be modulated by medial olivocochlear efferent neurons and by neuronal circuits associated with arousal. T Stellate cells deliver acoustic information to the ipsilateral dorsal cochlear nucleus (DCN), ventral nucleus of the trapezoid body (VNTB), periolivary regions around the lateral superior olivary nucleus (LSO), and to the contralateral ventral lemniscal nuclei (VNLL) and inferior colliculus (IC). It is likely that T stellate cells participate in feedback loops through both medial and lateral olivocochlear efferent neurons and they may be a source of ipsilateral excitation of the LSO.
声信息由听神经纤维传递至耳蜗核,所有纤维均终止于耳蜗核,并通过耳蜗核的主要细胞向上传递至听觉通路上行。一群神经元,有多种名称,如 T 形星形细胞、I 型多极细胞、平面多极细胞或斩波器细胞,形成了脑干中主要的上行听觉通路上的一个分支。T 形星形细胞具有锐利的调谐特性;作为一个群体,它们对声音频谱进行编码。在这些神经元中,来自听神经的相位兴奋通过前馈兴奋、兴奋性输入与抑制性输入的共激活、通过 NMDA 受体的相对较大的兴奋性电流以及相对较少的突触抑制而变得更为紧张。使放电紧张的机制也掩盖了来自听神经的兴奋性输入中所代表的声音的精细结构,并解释了 T 形星形细胞对音调的响应特征性的斩波响应模式。与腹侧耳蜗核(VCN)的其他主要细胞不同,T 形星形细胞缺乏低电压激活的钾电导,因此对小而稳定的神经调制电流敏感。存在胆碱能、5-羟色胺能和去甲肾上腺素能受体使得这些细胞的兴奋性能够被内侧橄榄耳蜗传出神经元和与觉醒相关的神经元回路调制。T 形星形细胞将声信息传递至同侧耳蜗背核(DCN)、梯形体腹核(VNTB)、外侧上橄榄核周围的periollivary 区域以及对侧腹侧丘系核(VNLL)和下丘(IC)。T 形星形细胞可能通过内侧和外侧橄榄耳蜗传出神经元参与反馈回路,并且它们可能是 LSO 同侧兴奋的来源。