Common sensory inputs and differential excitability of segmentally homologous reticulospinal neurons in the hindbrain
Common sensory inputs and differential excitability of segmentally homologous reticulospinal neurons in the hindbrain
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DOI：
10.1523/jneurosci.4419-03.2004
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发表时间：
2004-03-31
影响因子：
5.3
通讯作者：
Oda, Y
中科院分区：
文献类型：
--
作者：
Nakayama, H;Oda, Y
在斑马鱼和金鱼的后脑中，网状脊髓（RS）神经元排列成七个节段，相邻节段中有节段同源物。已知第四节（r4）中的Mauthner细胞（M-细胞）触发快速逃逸行为。它的系列同系物，MiD 2cm在r5和MiD 3cm在r6，预计有助于这种行为，这可以引起头部敲击刺激。然而，人们对它们的输入-输出特性知之甚少.因此，我们研究了传入投射从听觉后第八神经（pVIIIn）和放电特性的MiD 2cm和MiD 3cm的比较与M-细胞在成年金鱼。RS神经元和pVIIIn传入与荧光示踪剂的标记表明，pVIIIn投射到r4 - r6。短纯音和电刺激pVII In诱发M细胞、MiD 2cm和MiD 3cm的EPSP。逐步去极化通常在M细胞中的起始处引起单个尖峰，但在MiD 2cm和MiD 3cm中引起重复尖峰。这种非典型性质的M-细胞介导的树突状毒素-I（DTX-I）敏感的电压门控钾通道与复发性抑制，因为DTX-I，士的宁，荷包牡丹碱的联合应用导致连续重复发射的M-细胞。M细胞表达DTX-I敏感性钾通道亚基Kv1.2，而MiD 2cm和MiD 3cm不表达。因此，M细胞和它的节段同源物可能感觉到共同的听觉信息，但向脊髓回路发送不同的输出以控制适应性逃避行为。
In the hindbrain of zebrafish and goldfish, reticulospinal (RS) neurons are arranged in seven segments, with segmental homologs in adjacent segments. The Mauthner cell (M-cell) in the fourth segment (r4) is known to trigger fast escape behavior. Its serial homologs, MiD2cm in r5 and MiD3cm in r6, are predicted to contribute to this behavior, which can be evoked by head-tap stimuli. However, little is known about their input - output properties. Therefore, we studied afferent projections from the auditory posterior eighth nerve (pVIIIn) and firing properties of MiD2cm and MiD3cm for comparison with the M-cell in adult goldfish. Labeling of RS neurons and the pVIIIn afferents with fluorescent tracers showed that the pVIIIn projected to r4 - r6. Tone burst and electrical stimulation of the pVIIIn evoked EPSPs in the M-cell, MiD2cm, and MiD3cm. Stepwise depolarization typically elicited a single spike at the onset in the M-cell but repetitive spiking in MiD2cm and MiD3cm. This atypical property of the M-cell was mediated by dendrotoxin-I (DTX-I)-sensitive voltage-gated potassium channels together with recurrent inhibition, because combined application of DTX-I, strychnine, and bicuculline led to continuous repetitive firing in M-cells. The M-cell but not MiD2cm or MiD3cm expressed Kv1.2, a DTX-I-sensitive potassium channel subunit. Thus, the M-cell and its segmental homologs may sense common auditory information but send different outputs to the spinal circuits to control adaptive escape behavior.