Evidence for a widespread brain stem escape network in larval zebrafish
Evidence for a widespread brain stem escape network in larval zebrafish
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DOI：
10.1152/jn.00596.2001
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发表时间：
2002-01-01
影响因子：
2.5
通讯作者：
O'Malley, DM
中科院分区：
文献类型：
--
作者：
Gahtan, E;Sankrithi, N;O'Malley, DM
斑马鱼的逃逸行为，通常包括一个C弯曲，一个反转身，和一轮快速游泳，启动的Mauthner细胞和两个节段同源物的发射。然而，在激光烧蚀Mauthner细胞及其同源物后，仍会发生类似逃逸的行为，尽管潜伏期要长得多。这可能表明，额外的神经元有助于这种行为。因此，我们记录了其他下行神经元的活动，在脑干使用共聚焦成像的细胞逆行标记荧光钙指标。一个大部分确定的下行神经元存在于幼虫斑马鱼，包括同侧和对侧投射的网状脊髓神经元，以及神经元的内侧纵束的核，表现出短潜伏期的钙反应后，轻轻水龙头的头幼虫的刺激，可靠地唤起一个逃避行为。先前的研究已经将这种体内钙反应与动作电位的激发相关联，并且因为所有反应细胞都具有投射到脊髓中的轴突，这表明这些细胞将与逃避相关的信息传递到脊髓。其他确定的神经元未能表现出一致的钙逃避引发刺激的反应。结合先前的损伤研究，这些结果表明，神经控制系统的转向和游泳行为广泛分布在斑马鱼幼虫脑干。该系统的鲁棒性或冗余度的程度有影响的脊椎动物运动的下降控制。
Zebrafish escape behaviors, which typically consist of a C bend, a counter-turn, and a bout of rapid swimming, are initiated by firing of the Mauthner cell and two segmental homologs. However, after laser-ablation of the Mauthner cell and its homologs, escape-like behaviors still occur, albeit at a much longer latency. This might suggest that additional neurons contribute to this behavior. We therefore recorded the activity of other descending neurons in the brain stem using confocal imaging of cells retrogradely labeled with fluorescent calcium indicators. A large majority of identified descending neurons present in the larval zebrafish, including both ipsilaterally and contralaterally projecting reticulospinal neurons, as well as neurons from the nucleus of the medial longitudinal fasciculus, showed short-latency calcium responses after gentle taps to the head of the larva-a stimulus that reliably evokes an escape behavior. Previous studies had associated such in vivo calcium responses with the firing of action potentials, and because all responding cells have axons projecting into to spinal cord, this suggests that these cells are relaying escape-related information to spinal cord. Other identified neurons failed to show consistent calcium responses to escape-eliciting stimuli. In conjunction with previous lesion studies, these results indicate that the neural control systems for turning and swimming behaviors are widely distributed in the larval zebrafish brain stem. The degree of robustness or redundancy of this system has implications for the descending control of vertebrate locomotion.