Behavioural Ecology Group, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
Research Laboratory for Stereology and Neuroscience, Bispebjerg-Frederiksberg Hospital, Copenhagen, Denmark.
Brain Struct Funct. 2018 May;223(4):1989-1998. doi: 10.1007/s00429-018-1606-4. Epub 2018 Jan 9.
Conspecifics vary consistently in their behavioural responses towards environment stimuli such as exposure to novel objects; ethologists often refer to this variability as animal personality. The neurological mechanisms underlying animal personality traits remain largely unknown, but linking the individual variation in emotional expression to brain structural and neurochemical factors is attracting renewed interest. While considerable research has focused on hormonal and neurotransmitter effects on behavioural responses, less is known about how individual variation in the number of specific neuron populations contributes to individual variation in behaviour. The basolateral amygdala (BLA) and the central nuclei of the amygdala (CeA) mediate emotional processing by regulating behavioural responses of animals in a potentially threatening situation. As such, these structures are good candidates for evaluating the relationship between neuronal populations and behavioural traits. We now show that individual American mink (Neovison vison) reacting more boldly towards novelty have more neurons in the BLA than do their more timid conspecifics, suggesting that a developmental pattern of the number of amygdala neurons can influence behavioural traits of an adult animal. Furthermore, post hoc correlations revealed that individuals performing with higher arousal, as reflected by their frequency of startle behaviour, have more CeA neurons. Our results support a direct link between the number of neurons in amygdala regions and aspects of animal personality.
同种动物在面对环境刺激时的行为反应存在一致性变化，例如接触新奇物体；行为生物学家通常将这种可变性称为动物个性。动物个性特征的神经机制在很大程度上仍不清楚，但将情绪表达的个体差异与大脑结构和神经化学因素联系起来正引起新的关注。虽然大量研究集中在激素和神经递质对行为反应的影响上，但对于特定神经元群体数量的个体差异如何导致行为的个体差异知之甚少。基底外侧杏仁核（BLA）和杏仁核中央核（CeA）通过调节动物在潜在威胁情况下的行为反应来介导情绪处理。因此，这些结构是评估神经元群体与行为特征之间关系的良好候选者。我们现在表明，与更胆怯的同类相比，对新奇事物反应更勇敢的个体美洲水貂（Neovison vison）的 BLA 中有更多的神经元，这表明杏仁核神经元数量的发育模式可能会影响成年动物的行为特征。此外，事后相关性分析表明，表现出更高唤醒状态的个体（反映在其惊跳行为的频率上）的 CeA 神经元数量更多。我们的研究结果支持杏仁核区域神经元数量与动物个性特征之间的直接联系。
