Carnegie Institution for Science, Department of Embryology, Baltimore, United States.
Jupiter Life Science Initiative, Florida Atlantic University, Jupiter, United States.
Elife. 2021 Dec 8;10:e72345. doi: 10.7554/eLife.72345.
Hemispheric specializations are well studied at the functional level but less is known about the underlying neural mechanisms. We identified a small cluster of cholinergic neurons in the dorsal habenula (dHb) of zebrafish, defined by their expression of the a () gene and their efferent connections with a subregion of the ventral interpeduncular nucleus (vIPN). The -expressing neurons in the right dHb are innervated by a subset of mitral cells from both the left and right olfactory bulb and are activated upon exposure to the odorant cadaverine that is repellent to adult zebrafish. Using an intersectional strategy to drive expression of the botulinum neurotoxin specifically in these neurons, we find that adults no longer show aversion to cadaverine. Mutants with left-isomerized dHb that lack these neurons are also less repelled by cadaverine and their behavioral response to alarm substance, a potent aversive cue, is diminished. However, mutants in which both dHb have right identity appear more reactive to alarm substance. The results implicate an asymmetric dHb-vIPN neural circuit in the processing of repulsive olfactory cues and in modulating the resultant behavioral response.
大脑半球的偏侧化在功能水平上研究得很好，但对于其潜在的神经机制知之甚少。我们在斑马鱼的背被盖核(dHb)中鉴定出一小群胆碱能神经元，它们的特征是表达基因和与腹侧脚间核(vIPN)的一个亚区的传出连接。右侧 dHb 中的表达神经元被来自左右嗅球的一小部分僧帽细胞支配，并在暴露于对成年斑马鱼有排斥作用的气味剂 cadaverine 时被激活。使用一种交叉策略，特异性地在这些神经元中驱动肉毒杆菌神经毒素的表达，我们发现成年斑马鱼不再对 cadaverine 表现出厌恶。缺乏这些神经元的左侧异构体 dHb 的突变体对 cadaverine 的排斥反应也较弱，它们对警报物质（一种有效的厌恶线索）的行为反应也减弱。然而，两侧 dHb 都具有右侧特征的突变体对警报物质的反应似乎更为强烈。这些结果表明，不对称的 dHb-vIPN 神经回路参与了排斥性嗅觉线索的处理，并调节了由此产生的行为反应。
