Unique potential of immature adult-born neurons for the remodeling of CA3 spatial maps
Matías Mugnaini,
Mariela F. Trinchero,
Alejandro F. Schinder,
Verónica C. Piatti,
Emilio Kropff
Affiliations
Matías Mugnaini
Department of Physiology, Molecular and Cellular Biology Dr. Héctor Maldonado, Faculty of Exact and Natural Science, University of Buenos Aires, Buenos Aires C1428EGA, Argentina; Laboratory of Physiology and Algorithms of the Brain, Leloir Institute (IIBBA-CONICET), Buenos Aires C1405BWE, Argentina
Mariela F. Trinchero
Laboratory of Neuronal Plasticity, Leloir Institute (IIBBA-CONICET), Buenos Aires C1405BWE, Argentina
Alejandro F. Schinder
Laboratory of Neuronal Plasticity, Leloir Institute (IIBBA-CONICET), Buenos Aires C1405BWE, Argentina; Corresponding author
Verónica C. Piatti
Laboratory of Neuronal Plasticity, Leloir Institute (IIBBA-CONICET), Buenos Aires C1405BWE, Argentina; Corresponding author
Emilio Kropff
Laboratory of Physiology and Algorithms of the Brain, Leloir Institute (IIBBA-CONICET), Buenos Aires C1405BWE, Argentina; Corresponding author
Summary: Mammalian hippocampal circuits undergo extensive remodeling through adult neurogenesis. While this process has been widely studied, the specific contribution of adult-born granule cells (aGCs) to spatial operations in the hippocampus remains unknown. Here, we show that optogenetic activation of 4-week-old (young) aGCs in free-foraging mice produces a non-reversible reconfiguration of spatial maps in proximal CA3 while rarely evoking neural activity. Stimulation of the same neuronal cohort on subsequent days recruits CA3 neurons with increased efficacy but fails to induce further remapping. In contrast, stimulation of 8-week-old (mature) aGCs can reliably activate CA3 cells but produces no alterations in spatial maps. Our results reveal a unique role of young aGCs in remodeling CA3 representations, a potential that can be depleted and is lost with maturation. This ability could contribute to generate orthogonalized downstream codes supporting pattern separation.
