Newborn and mature neurons contribution to memory engrams

RODRÍGUES, LUCÍA; MARIN-BURGIN, ANTONIA; OGANDO, MORA; FEDERMAN, NOEL; RAMOS, MARÍA SOL; ROMANO, SEBASTIÁN A.

Villa Carlos Paz, Córdoba

Congreso; XXXIV Congreso Anual de la Sociedad Argentina de Investigación en Neurociencias; 2019

A fundamental goal of neuroscience is to understand how memories are encoded and stored in the brain. Groups of neurons are thought to serve as the physical representation of memory, the memory trace or ?engram?. The hippocampus is a brain region highly implicated in memory formation and one of the few regions of the brain with adult neurogenesis in the dentate gyrus (DG). The contribution of immature cells to information encoding and storage is under current investigation. Here we labeled newborn and activated neurons using cfostTA; Ascl1CreERT2; CAGFloxStopTom mice to evaluate their participation in engram formation. During on-Dox diet, these mice were administered with tamoxifen (to express Tomato in newborn neurons) and injected with AAV9-TRE-GFP in the DG. After 4 weeks, mice were moved to off-Dox diet for 2 days to express GFP in activated cells when exposed to an enriched environment (EE). Our preliminary results showed that the proportion of activated newborn neurons after EE was higher than the mature neurons activation suggesting that young granule cells would be more likely to be recruited into engrams. To further evaluate the contribution of newborn neurons to other hippocampal dependent behaviors, we are conducting experiments training the transgenic mice in a head-fixed apparatus to perform a GO/NO GO discrimination task in a virtual reality environment. These experiments will shed light on the contribution of newborn neurons to contextual memory engrams.