Hunter Damien S, Hazel Susan J, Kind Karen L, Liu Hong, Marini Danila, Owens Julie A, Pitcher Julia B, Gatford Kathryn L
Robinson Research Institute, University of Adelaide, South Australia 5005, Australia; School of Paediatrics and Reproductive Health, University of Adelaide, South Australia 5005, Australia; School of Animal and Veterinary Sciences, Roseworthy, University of Adelaide, South Australia 5371, Australia.
School of Animal and Veterinary Sciences, Roseworthy, University of Adelaide, South Australia 5371, Australia.
Physiol Behav. 2015 Feb;139:244-53. doi: 10.1016/j.physbeh.2014.11.037. Epub 2014 Nov 18.
Brain development and function are susceptible to perturbation by environmental factors. Sheep are increasingly being used as a neurodevelopmental model due to timing similarities with humans, but effects of age, experience and sex on cognition are not well characterised in this species. We therefore studied memory and reversal learning in sheep using a modified Y-maze at two ages: naive 18 weeks old (18N: 23 male, 17 female), experienced 40 week old sheep that had previously been tested at 18 weeks (40E: 22 male, 17 female), and naive 40 weeks old (40N: 4 male, 10 female). Younger naive animals (18N) required more trials and time to solve the first reversal task (task R1) than 40E (P=0.007 and P<0.001 respectively). Experience also improved outcomes, with 40N sheep requiring more time to solve tasks L (P=0.034) and R1 (P=0.002) than 40E. Increasing age (40N cf. 18N) decreased bleat frequency in tasks R1, M2 and R2 (each P<0.05). In 40N females, outcomes also differed by exit method in task R1, with those that exited via an indirect route taking less time to pass tasks R1 (P=0.009) and R2 (P=0.015) than those that used a direct route. Age plus experience improved learning outcomes, demonstrating knowledge retention for 22 weeks in this species, whilst age alone affected mostly behavioral responses. These results provide comparison data, and can be utilised to improve experimental design, for studies of neurodevelopment in the sheep.
大脑发育和功能易受环境因素的干扰。由于与人类在时间上的相似性，绵羊越来越多地被用作神经发育模型，但该物种中年龄、经验和性别对认知的影响尚未得到充分表征。因此，我们使用改良的Y迷宫研究了两个年龄段绵羊的记忆和逆向学习：18周龄的幼稚绵羊（18N：雄性23只，雌性17只）、40周龄且之前在18周时已接受测试的有经验绵羊（40E：雄性22只，雌性17只）以及40周龄的幼稚绵羊（40N：雄性4只，雌性10只）。较年轻的幼稚动物（18N）在解决第一个逆向任务（任务R1）时比40E需要更多的试验次数和时间（分别为P = 0.007和P < 0.001）。经验也改善了结果，40N绵羊在解决任务L（P = 0.034）和R1（P = 0.002）时比40E需要更多时间。年龄增长（40N与18N相比）在任务R1、M2和R2中降低了咩叫频率（每个P < 0.05）。在40N雌性绵羊中，任务R1的退出方式也导致结果不同，通过间接路线退出的绵羊在通过任务R1（P = 0.009）和R2（P = 0.015）时比使用直接路线的绵羊花费的时间更少。年龄加上经验改善了学习结果，表明该物种在22周内能够保持知识，而仅年龄因素主要影响行为反应。这些结果提供了比较数据，可用于改进绵羊神经发育研究的实验设计。
