Contributions of Dentate Gyrus Cell Types to Associative Learning


The dentate gyrus is the first region for information processing within the classic hippocampal trisynaptic circuit, and this position makes it an important structure for the formation of associative memories. The dentate gyrus contains two major types of excitatory neurons: granule cells and mossy cells. While previous work has shown that granule cells are necessary for memory formation, the functional contributions of mossy cells in associative learning has not been thoroughly explored. Dentate gyrus also contains several types of interneurons, which are inhibitory cells that help coordinate population activity. Finally, dentate gyrus is unique as it is one of the only places in the adult brain where new neurons are born. These neural progenitor cells are highly excitable and are believed to provide enhanced plasticity to the hippocampus. In this work, we demonstrate that ablation of neural progenitor cells prior to training impairs acquisition of trace eyeblink conditioning, and that levels of neurogenesis are correlated with measures of learning in male mice. Additionally, through in vivo recording, we show unique learning-related changes in granule cells, mossy cells, and interneurons. Ultimately, these data demonstrate the important contributions of various dentate gyrus cell types to associative learning, which then improves our ability to discern how aging and disease might disrupt this process.

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