It has been well-documented that peripheral glucose administration enhances memory in both young and old rodents and humans. It has also been shown that aged rats receive more benefit from epinephrine administration shortly after a learning episode than do non-aged adult rats. The general purpose of the proposed research is to determine if the effects of glucose on recently reactivated memories are related to age in a developmental sequence. A combination of different designs will be used to test the general hypotheses that: a) aged subjects receive significantly more benefit from a reminder cue (reactivation) than do younger adult subjects, and b) while greater memory enhancement may be produced by glucose in younger subjects than in older subjects, the actual benefit received from glucose administration increases as subjects age. The main experimentation will involve a combination of longitudinal and cross-sectional designs. In the longitudinal part of the design 3, 6, 9, 12, 15, 18, 21, and 24-month old rats will be injected with either glucose or saline after a reactivation treatment. In the cross-sectional part of the design, cohort groups of rats matched for age will be treated in a manner similar to those in the longitudinal part of the design. A passive avoidance-to-active avoidance negative transfer design will be used to measure the ways in which memory reactivation and glucose modulate the memories of rats during various stages of the lifespan. Because in the memory impaired (e.g., aged and Alzheimer's patients) glucose enhances memory, and because reactivation treatments affect both infant memory and adult emotional memory, the proposed studies may have both practical and clinical significance.
