Photoperiodic Changes in Aggression

大多数动物在一年中的各个季节都会经历环境条件的巨大波动。因此，许多动物在生理和行为上表现出季节性的变化，使它们能够应对季节的变化。昼长是动物用来协调季节性行为和生理反应的主要环境线索。例如，生活在漫长的“类似夏天”白天的动物将保持高水平的睾丸激素，从而继续繁殖，而生活在短的“类似冬天”白天的动物将由于睾丸激素水平低而抑制繁殖。此外，最近有研究表明，尽管雄性激素水平较低，但在短白天生活的啮齿动物比在长白天生活的啮齿动物表现出更强的攻击性。考虑到睾酮调节攻击性的传统观点，这一发现尤其有趣。本项目旨在研究调节啮齿动物攻击性季节变化的激素机制。具体来说，动物将被安置在实验室或长或短的时间内，并通过实验控制特定激素的水平，包括睾酮和肾上腺激素皮质醇。然后，攻击行为将被录像，并使用基于计算机的视频分析系统进行量化。根据先前的研究，预测是肾上腺激素皮质醇，而不是睾丸激素，调节季节性攻击。这些实验挑战了一个简单的观念，即所有形式的攻击都依赖于睾丸激素，并对激素如何作用于大脑来调节社会行为以及这些行为如何被环境改变的研究具有重要意义。总的来说，这些研究将有助于确定激素控制攻击的重要和新的机制。重要的是，这些研究将为研究生和本科生（包括少数族裔）提供极好的机会，让他们获得实践经验，并通过进行、发表和发表科学研究，培养重要的科学技能。

Most animals experience large fluctuations in environmental conditions across the seasons of the year. Consequently, many animals display seasonal changes in physiology and behavior which allow them to cope with seasonal changes. Day length is the main environmental cue used by animals to coordinate seasonal behavioral and physiological responses. For example, animals living in long "summer-like" day lengths will maintain high levels of the hormone testosterone and thus will continue to breed, whereas animals housed on short "winter-like" days will inhibit their breeding due to low testosterone. In addition, it has recently been demonstrated that rodents housed in short days display increased aggression compared with animals housed on long days, despite lower levels of testosterone. This finding is particularly interesting given the traditional belief that testosterone regulates aggression. This project is designed to investigate the hormonal mechanisms regulating seasonal changes in aggression in rodents. Specifically, animals will be housed in long or short days in the lab and levels of specific hormones, including testosterone and the adrenal hormone cortisol, will be experimentally manipulated. Aggression will then be videotaped and quantified using a computer-based video analysis system. Based on previous research, it is predicted that the adrenal hormone cortisol, rather than testosterone, regulates seasonal aggression. These experiments challenge the simple notion that all forms of aggression are testosterone-dependent and have important implications for the study of how hormones act on the brain to regulate social behaviors and how these behaviors may be altered by the environment. Collectively, these studies will help identify important and novel mechanisms of hormonal control of aggression. Importantly, these studies will provide excellent opportunities for both graduate and undergraduate students, including under-represented minorities, to gain hands-on experience and to allow them to develop important scientific skills by conducting, presenting and publishing scientific research.