Flood J F, Morley J E
GRECC, VA Medical Center, St. Louis.
J Gerontol. 1992 Mar;47(2):B52-9. doi: 10.1093/geronj/47.2.b52.
SAM-P/8 (P/8if) mice, trained on aversive and appetitive training tasks, showed age-related impairment of learning on more difficult tasks. Using aversive training tasks, acquisition of step-down passive avoidance did not differ between 4- and 12-month-old mice. T-maze footshock avoidance acquisition detected impairment from 9 to 12 months of age. On the appetitive tasks, 12-month-old mice required significantly more trails than 4-month-old mice to learn to press a lever for milk reinforcement or to learn a specific sequence of 10 black-white, left-right discriminations. However, learning a simple black-white discrimination in the same 10-unit maze did not discriminate between the performance of 4- and 12-month-old mice. A lack of age-related changes in food, water, and milk consumption suggests that changes in motivation do not account for the decline in learning in older P/8if mice. The results suggest an early onset of impaired learning relative to the 17.2-month median life span of the P/8if mice.
SAM-P/8（P/8if）小鼠在厌恶性和奖赏性训练任务中接受训练，在更具难度的任务上表现出与年龄相关的学习障碍。在厌恶性训练任务中，4个月和12个月大的小鼠在获得阶梯式被动回避反应方面没有差异。T迷宫电击回避反应的获得在9至12个月大时检测到障碍。在奖赏性任务中，12个月大的小鼠比4个月大的小鼠需要显著更多的试验次数来学会按压杠杆以获得牛奶奖励，或学会10次黑白、左右辨别任务的特定顺序。然而，在同一个10单元迷宫中学习简单的黑白辨别任务时，4个月和12个月大的小鼠的表现没有差异。食物、水和牛奶消耗量不存在与年龄相关的变化，这表明动机变化不能解释老年P/8if小鼠学习能力下降的原因。结果表明，相对于P/8if小鼠17.2个月的中位寿命，学习障碍在早期就已出现。
