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Free keywords:
Animals
Bromodeoxyuridine/metabolism
Cell Differentiation
Cytoskeletal Proteins/metabolism
Dendrites/*physiology
Dentate Gyrus/*cytology
Evoked Potentials/genetics
Functional Laterality
Green Fluorescent Proteins/genetics/metabolism
Imaging, Three-Dimensional
Male
Models, Neurological
Nerve Tissue Proteins/metabolism
Neurogenesis/*physiology
Neuroimaging
Neuronal Plasticity/physiology
Neurons/*classification
Rats
Rats, Sprague-Dawley
Synapsins/metabolism
Transduction, Genetic
*Arc
*Dentate gyrus
*hfs
*Morphological model
*Neurogenesis
Abstract:
Adult-born dentate granule cells (abGCs) exhibit a critical developmental phase during function integration. The time window of this phase is debated and whether abGCs become indistinguishable from developmentally born mature granule cells (mGCs) is uncertain. We analyzed complete dendritic reconstructions from abGCs and mGCs using viral labeling. AbGCs from 21-77 days post intrahippocampal injection (dpi) exhibited comparable dendritic arbors, suggesting that structural maturation precedes functional integration. In contrast, significant structural differences were found compared to mGCs: AbGCs had more curved dendrites, more short terminal segments, a different branching pattern, and more proximal terminal branches. Morphological modeling attributed these differences to developmental dendritic pruning and postnatal growth of the dentate gyrus. We further correlated GC morphologies with the responsiveness to unilateral medial perforant path stimulation using the immediate-early gene Arc as a marker of synaptic activation. Only abGCs at 28 and 35 dpi but neither old abGCs nor mGCs responded to stimulation with a remodeling of their dendritic arbor. Summarized, abGCs stay distinct from mGCs and their dendritic arbor can be shaped by afferent activity during a narrow critical time window.
