The brain beta-endorphin system and behavior: the modulation of consecutively and simultaneously processed memories.

This article shows how new memories may be acquired, or old ones retrieved, in animals who have recently released brain beta-endorphin and why some memories may be insensitive to beta-endorphin modulation even if they are processed in parallel to others that are sensitive to that system. In addition, one example is given of an interaction between tasks that is possibly independent from the brain beta-endorphin system. The data examined here represent a new approach to memory modulation in that they apply findings previously obtained in isolated tasks to the analysis of interactions between training and test sessions of the same or different tasks. This may be viewed as a step toward understanding the organization of memory mechanisms in everyday behavior, which consists of consecutive and simultaneous, rather than isolated, behavioral training and test paradigms. The present approach, however, still relies on the individual analysis of separate behaviors, and is therefore no substitute for studies on complex behaviors per se. Indeed, both approaches may be complementary for a full understanding of the organization of memory processes, along with further investigations studying isolated tasks.