Caracterização comportamental da memória similar à episódica em roedores ao longo da ontogênese

Abstract

Episodic memory consists of the ability to remember, in an integrated way, contextual information about events. Studies with animal models have used behavioral criteria to assess this type of memory, using elements such as what (event) occurred, in a certain place (where), at a given moment in time (when), and its occurrence is treated in an associative way between the aspects mentioned above. Its ontogenetic trajectory is not yet well understood. The present study sought to describe the behavior of Wistar rats submitted to a memory task similar to episodic memory during neurodevelopment. To this end, 140 Wistar rats were used, 30 of which were breeders and 110 pups at 18, 24, 35, 60, 80 and 90 days of birth, kept under controlled conditions. This study standardized the apparatus and objects for different ages, so a set of 3D objects was evaluated. The episodic-like memory task consisted of 3 sessions, 2 samples and 1 test. Each session lasted five minutes, with an interval of one hour between them. They were also subjected to a novel object recognition task to serve as a control for evaluating the rats' discrimination and the existence of false positives. The results of the discrimination index showed that rats at different ages predominantly expressed non-integrative temporal memory in the WWWhen/ELM test, especially from P35 onwards, in addition to a tendency towards temporal memory at P60 [t(14) = 1.954, p=0.071]. For NOR, only rats on P33 were able to discriminate objects in the first and second minute. The results showed that one of them was differentially explored. Analyses relating to locomotion, anxiety-like behavior and neophobia indicate that rats at different ages show a similar pattern. This is the first episodic memory task that simultaneously evaluates the temporal and spatial aspects of episodic memory at various ages of ontogeny with a time interval of one hour, with objects and a standardized field for each age. It was concluded that no variables related to neophobia were identified, with the main result of the study being the emergence of temporal order memory in P35.