Interindividual variation in behavior and brain activity is universal and provides substrates for natural selection [1, 2, 3, 4, 5, 6, 7, 8, 9]. Selective pressures shift the expression of behavioral traits at the population level [10, 11], but the accompanying changes of the underlying neural circuitry have rarely been identified [12, 13]. Selection likely acts through the genetic and/or epigenetic underpinnings of neural activity controlling the selected behavior [14]. Endocrine and neuromodulatory systems participate in behavioral diversity and could provide the substrate for evolutionary modifications [15, 16, 17, 18, 19, 20, 21]. Here, we examined brain-wide patterns of activity in larval zebrafish selectively bred over two generations for extreme differences in habituation of the acoustic startle response (ASR) [22]. The ASR is an evolutionarily conserved defensive behavior induced by strong acoustic/vibrational stimuli. ASR habituation shows great individual variability that is stable over days and heritable [4, 22]. Selection for high ASR habituation leads to stronger sound-evoked activation of ASR-processing brain areas. In contrast, animals selected for low habituation displayed stronger spontaneous activity in ASR-processing centers. Ablation of dopaminergic tyrosine hydroxylase (TH) neurons decreased ASR sensitivity. Independently selected ASR habituation lineages link the effect of behavioral selection to dopaminergic caudal hypothalamus (HC) neurons [23]. High ASR habituation co-segregated with decreased spontaneous swimming phenotypes, but visual startle responses were unaffected. Furthermore, high- and low-habituation larvae differed in stress responses as adults. Thus, selective pressure over a couple of generations on ASR habituation behavior is able to induce substantial differences in brain activity, carrying along additional behaviors as piggyback traits that might further affect fitness in the wild.

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中文翻译：

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选择对全脑活动和行为的快速影响。

行为和大脑活动的个体差异是普遍存在的，并为自然选择提供了基础 [1, 2, 3, 4, 5, 6, 7, 8, 9]。选择压力改变了群体水平上行为特征的表达 [10, 11]，但很少发现潜在神经回路的伴随变化 [12, 13]。选择可能通过控制选择行为的神经活动的遗传和/或表观遗传基础起作用 [14]。内分泌和神经调节系统参与行为多样性，可以为进化修饰提供基础 [15, 16, 17, 18, 19, 20, 21]。在这里，我们检查了两代选择性繁殖的斑马鱼幼虫的全脑活动模式，以适应声惊吓反应 (ASR) 的极端差异 [22]。ASR 是一种由强烈的声学/振动刺激引起的进化上保守的防御行为。ASR 习惯显示出很大的个体变异性，这种变异性在几天内是稳定的并且是可遗传的 [4, 22]。选择高 ASR 习惯会导致 ASR 处理大脑区域更强的声音诱发激活。相比之下，选择适应度低的动物在 ASR 处理中心表现出更强的自发活动。多巴胺能酪氨酸羟化酶 (TH) 神经元的消融降低了 ASR 敏感性。独立选择的 ASR 习惯谱系将行为选择的影响与多巴胺能尾下丘脑 (HC) 神经元联系起来 [23]。高 ASR 习惯与自发游泳表型降低共同隔离，但视觉惊吓反应不受影响。此外，高习惯和低习惯幼虫成年后的应激反应不同。因此，几代人对 ASR 习惯行为的选择压力能够引起大脑活动的显着差异，携带额外的行为作为可能进一步影响野外健康的捎带性状。

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