Cognitive function of hippocampal dentate gyrus during goal-guided spatial behavior

SOLDI, N.; PIATTI, V. C.; SCHINDER, A. F.; FERELLA, L.

MODALIDAD VIRTUAL

Congreso; XXXV Reunión Anual SAN 2020 VIRTUAL; 2020

The hippocampus is essential for episodic memory and is thought to be involved in binding stimuli to their spatio-temporal context. However, how similar experiences are distinguished remains unknown. The dentate gyrus (DG) of the hippocampus is needed for the discrimination of similar spatial stimuli. Therefore, we think that DG could contribute to the distinction of similar events experienced temporally close in the same context. We set up an everyday spatial memory task in a crossword-like maze with easy or difficult paths to find a reward. Adult mice were co-infected with an AAV-floxed HA-hM4Di plus a CAG-Cre retrovirus in the dorsal DG, which resulted in the expression of the silencing synthetic receptor hM4Di in commissural DG fibers. This strategy allowed the DG perturbation upon application of the synthetic agonist clozapine-N-oxide (CNO) while the animals explored the maze. In a single day we evaluated the animals? learning of two new spatial routes of the same level of challenge with or without CNO. The mice learned easy or difficult journeys to the goal, but CNO-mediated DG perturbation slowed down the acquisition of the second daily route, independently of the complexity of the path. Performance on the difficult but not the easy path was impaired on the everyday memory test under CNO effect. These results suggest that the DG is necessary for learning similar spatial experiences and for daily complex memory retrieval.