Novartis Institutes for Biomedical Research, Chemical Biology & Therapeutics, 181 Massachusetts Avenue, Cambridge, MA 02139, USA.
Harvard University, Department of Stem Cell and Regenerative Biology, 7 Divinity Avenue, Cambridge, MA 02138, USA.
Curr Biol. 2019 Aug 5;29(15):2541-2546.e3. doi: 10.1016/j.cub.2019.06.047. Epub 2019 Jul 18.
Mating and flight from threats are innate behaviors that enhance species survival [1, 2]. Stimuli to these behaviors often are contemporaneous and conflicting [3, 4]. Both how such conflicts are resolved and where in the brain such decisions are made are poorly understood. For teleosts, olfactory stimuli are key elements of mating and threat responses [5-7]. For example, zebrafish manifest a stereotypical escape response when exposed to an alarm substance released from injured conspecific skin ("skin extract") [8, 9]. We find that when mating, fish ignore this threatening stimulus. Water conditioned by the mating fish ("mating water") suffices to suppress much of the alarm-response behavior. By 2-photon imaging of calcium transients [10], we mapped the regions of the brain responding to skin extract and to mating water. In the telencephalon, we found regions where the responses overlap, one region (medial Dp) to be predominantly activated by skin extract, and another, Vs, to be predominantly activated by mating water. When mating water and skin extract were applied simultaneously, the alarm-specific response was suppressed, while the mating-water-specific response was retained, corresponding to the dominance of mating over flight behavior. The choice made, for reproduction over escape, is opposite to that of mammals, presumably reflecting how the balance affects species survival.
交配和逃避威胁是增强物种生存能力的先天行为[1,2]。这些行为的刺激通常是同时发生且相互冲突的[3,4]。对于这些冲突如何解决以及大脑中何处做出这些决策，人们知之甚少。对于硬骨鱼来说，嗅觉刺激是交配和威胁反应的关键因素[5-7]。例如，斑马鱼在暴露于来自受伤同种鱼皮肤释放的警报物质（“皮肤提取物”）时会表现出刻板的逃避反应[8,9]。我们发现，在交配时，鱼类会忽略这种威胁性刺激。由交配鱼产生的水（“交配水”）足以抑制大部分警报反应行为。通过 2 光子钙瞬变成像[10]，我们绘制了对皮肤提取物和交配水做出反应的大脑区域图谱。在端脑，我们发现了一些区域，其中一些区域（内侧 Dp）主要受皮肤提取物激活，另一个区域 Vs 则主要受交配水激活。当同时施加交配水和皮肤提取物时，警报特异性反应被抑制，而交配水特异性反应被保留，这对应于交配行为对飞行行为的优势。相对于逃避，选择繁殖而不是逃避，与哺乳动物相反，这可能反映了这种平衡如何影响物种的生存。
