Functional Role of a Specialized Class of Spinal Commissural Inhibitory Neurons during Fast Escapes in Zebrafish
Functional Role of a Specialized Class of Spinal Commissural Inhibitory Neurons during Fast Escapes in Zebrafish
复制标题
DOI：
10.1523/jneurosci.0801-09.2009
复制
发表时间：
2009-05-27
影响因子：
5.3
通讯作者：
Higashijima, Shin-ichi
中科院分区：
文献类型：
--
作者：
Satou, Chie;Kimura, Yukiko;Higashijima, Shin-ichi
在硬骨鱼中，Mauthner（M）细胞，脑干中的一个大型网状脊髓神经元，触发逃避行为。脊髓连合抑制性中间神经元是由M-轴突电紧张兴奋已被确定，但这些神经元的行为作用尚未得到解决。在这里，我们研究了这些神经元，命名为科洛（连合局部），在幼斑马鱼使用增强子陷阱线，其中整个人口的CoLos可视化的绿色荧光蛋白。每个半节段有一个细胞存在CoLos。电生理记录表明，M-棘波引起的尖峰在CoLos通过电紧张性传输和CoLos对对侧初级运动神经元的单突触抑制连接，在成年金鱼的结果一致。我们进一步表明，CoLos只在逃跑时活跃。我们研究的行为作用的CoLos通过调查逃避行为的CoLo消融幼虫。结果表明，声/振动刺激引起的逃避行为往往随着身体初始弯曲的减少而受损，表明CoLos在启动逃避中起重要作用。我们获得了几条有力的证据表明，受损的逃逸发生在双边激活的M-细胞：在正常的幼虫，CoLo介导的抑制电路，使动物能够执行逃逸，即使在这些场合沉默的输出略有延迟发射的第二个M-细胞。这项研究说明了（1）一类特殊的中间神经元的行为作用的一个明确的例子，（2）脊髓回路过滤下行命令的能力，从而产生适当的行为。
In teleost fish, the Mauthner (M) cell, a large reticulospinal neuron in the brainstem, triggers escape behavior. Spinal commissural inhibitory interneurons that are electrotonically excited by the M-axon have been identified, but the behavioral roles of these neurons have not yet been addressed. Here, we studied these neurons, named CoLo (commissural local), in larval zebrafish using an enhancer-trap line in which the entire population of CoLos was visualized by green fluorescent protein. CoLos were present at one cell per hemi-segment. Electrophysiological recordings showed that an M-spike evoked a spike in CoLos via electrotonic transmission and that CoLos made monosynaptic inhibitory connections onto contralateral primary motoneurons, consistent with the results in adult goldfish. We further showed that CoLos were active only during escapes. We examined the behavioral roles of CoLos by investigating escape behaviors in CoLo-ablated larvae. The results showed that the escape behaviors evoked by sound/vibration stimuli were often impaired with a reduced initial bend of the body, indicating that CoLos play important roles in initiating escapes. We obtained several lines of evidence that strongly suggested that the impaired escapes occurred during bilateral activation of the M-cells: in normal larvae, CoLo-mediated inhibitory circuits enable animals to perform escapes even in these occasions by silencing the output of the slightly delayed firing of the second M-cell. This study illustrates (1) a clear example of the behavioral role of a specialized class of interneurons and (2) the capacity of the spinal circuits to filter descending commands and thereby produce the appropriate behavior.