Final answer:
The hypothesis that older rats show more defensive behavior compared to younger rats would be supported if the older rats spent more time in the closed arms of the elevated plus maze, indicating increased anxiety-like behavior associated with altered amygdala function due to age.
Step-by-step explanation:
To determine if older rats show more defensive behavior compared to younger rats using the elevated plus maze, the results that would confirm your hypothesis would likely involve older rats spending more time in the closed arms of the maze, indicating a preference for protected areas, which reflects increased anxiety or defensive behavior. The elevated plus maze is a classic test in behavioral neuroscience that measures anxiety-like behavior in rodents, typically by the proportion of time spent in open versus closed arms.
Studies such as the one by Raineki, Cortés, Belnoue, and Sullivan (2012), have shown that negative early life experiences can alter the function of the amygdala, which is associated with these anxiety-like behaviors. Moreover, maze experiments by H.C. Blodgett have highlighted how reward can influence learning and behavior in rats. It would be important to conclude that increased time spent in the closed arms by older rats compared to younger ones supports the hypothesis that aging increases defensive behavior in rats.