Neuroplasticity in songbirds: how changing behaviour and experience affect learning and the brain

在一年的过程中，动物必须改变自己的行为，以适应不断变化的环境。例如，鸟类利用日长的变化或资源的可获得性作为提示，告诉它们何时繁殖或何时不繁殖。动物还必须每天根据不同的情况调整自己的行为：雌性可能会听到并评估潜在的配偶，并学习对该雄性的发声做出反应。为了改变行为，大脑也必须有改变的潜力和能力。因此，测量环境变化如何影响大脑是很重要的。我的研究项目旨在了解对环境的反应所产生的神经可塑性，从而产生适当的行为反应。为了做到这一点，我研究了繁殖条件(动物是否准备繁殖的生理状态)和学习如何影响两种鸣鸟的大脑：黑帽山雀和斑马雀。 黑帽山雀是季节性繁殖者，它们会对日长的变化做出反应，反过来，它们的行为和大脑也会随着季节的变化而变化。在春季，在繁育条件下，它们唱的歌更多，大脑中重要的歌唱区域比非繁育条件下的更大。在冬天，当它们处于非繁殖状态时，它们会花大量时间隐藏和取回种子(这是一项需要在哪里进行空间学习记忆的任务)，而海马体--一个对空间记忆至关重要的大脑区域--比一年中的其他时候有更多的新神经元(神经发生)。我将进行的一项研究将确定，与执行不适合季节的任务相比，执行适合季节的任务(在繁殖条件下区分歌曲，在非繁殖条件下记住种子藏在哪里)是否有助于更多的新神经元存活更长时间。这将告诉我们，是否繁殖条件、学习或两者都会影响神经可塑性。 斑马雀是机会主义的繁殖者，它们对资源可获得性的变化做出反应，但人们对它们的大脑如何根据繁殖条件变化知之甚少。我将通过让斑马雀接触到配偶和筑巢材料等资源，并将它们的大脑与没有资源的鸟类进行比较，来研究斑雀的神经活动和神经发生(细胞出生和存活)是如何受到繁殖条件的影响的。我还将研究与不执行认知丰富任务的鸟类相比，暴露在困难的学习任务中是否会促进神经发生，以确定主动学习是否有助于更多新神经元存活更长时间。 我将整合我的实验结果，以实现我的长期目标，即确定行为变化对内部(繁殖条件)和外部因素(经验)的反应如何影响神经可塑性。我的研究结果有可能影响人们对鸣禽和其他生物的行为和神经可塑性的理解。

Over the course of a year, animals must change their behaviour in response to their changing environment. For example, birds use changes in day length or availability of resources as a cue to tell them when to breed or when not to breed. Animals must also adapt their behaviour to different situations on a daily basis: females may hear and evaluate a potential mate and learn to respond to that male's vocalizations. In order to change behaviour, the brain must have the potential and capacity to change as well. It is therefore important to measure how environmental change affects the brain. My research program aims to understand the neuroplasticity that occurs in response to the environment resulting in appropriate behavioural response. To do this, I study how both breeding condition (the physiological state of animal as ready to breed or not) and learning affect the brain of two species of songbirds: black-capped chickadees and zebra finches. Black-capped chickadees are seasonal breeders they respond to changes in day length, and in turn their behaviour and brains change with the season. In spring when in breeding condition, they sing more songs and regions in their brain important for song are larger than when they are in non-breeding condition. In winter, when in non-breeding condition, they spend a lot of time hiding and retrieving seeds (a task requiring spatial learning memory for “where”) and the hippocampus, a brain region critical for spatial memory, has more new neurons (neurogenesis) than at other times of year. One study I will perform will be to determine whether performing a task appropriate to the season (discriminating among songs when in breeding condition, remembering where seeds are hidden when in non-breeding condition) helps more new neurons live longer than when performing a task not appropriate to the season. This will tell us whether breeding condition, learning, or both affect neuroplasticity. Zebra finches are opportunistic breeders they respond to changes in resource availability, however much less is known about how their brains change depending on breeding condition. I will study how neural activity and neurogenesis (cell birth and survival) are affected by breeding condition in zebra finches by exposing some birds to resources such as a mate and nesting materials and comparing their brains to those without resources. I will also study whether exposure to a difficult learning task promotes neurogenesis compared to birds that do not perform a cognitively enriching task, to determine whether active learning helps more new neurons live longer. I will integrate the results of my experiments to achieve my long-term goal of determining how behavioural change in response to internal (breeding condition) and external factors (experience) affect neuroplasticity. My results have the potential to impact understanding of behavioural and neuroplasticity in songbirds and other organisms.