Structure, function, and plasticity of hippocampal dentate gyrus microcircuits

The hippocampus mediates several higher brain functions, such as learning, memory, and spatial coding. The input region of the hippocampus, the dentate gyrus, plays a critical role in these processes. Dentate gyrus granule cells receive excitatory neuron input from the entorhinal cortex and send excitatory output to the hippocampal CA3 region via the mossy fibers. Furthermore, several types of GABAergic interneurons are present in this region, providing inhibitory control over granule cell activity via feedback and feedforward inhibition. Finally, hilar mossy cells mediate another excitatory loop in the circuit. Throughout the brain, the dentate gyrus is unique, because adult neurogenesis takes place in this region. Thus, new neurons are generated and functionally integrated throughout life.

Several higher order computational operations are believed to take place in the dentate gyrus. For example, the dentate gyrus is involved in pattern separation, converting relatively similar inputs into substantially different outputs. Thus, the dentate gyrus may act as a preprocessor of incoming information, preparing it for efficient storage in the hippocampal CA3 region. How these complex functions are generated at the cellular and synaptic level has remained largely unclear. In this series of papers, we plan to generate a database of structure, function, and plasticity of the cells and synapses in the dentate gyrus neuronal network. We will cover neuroscience at the molecular, cellular, systems, and computational level. Specifically, we plan to present original publications and focused reviews on the following topics:

- Connectivity in the dentate gyrus.
- Structure of synapses in the dentate gyrus.
- Function of glutamatergic synapses the circuit.
- Function of GABAergic synapses in the circuit (dentate gyrus interneurons).
- Mechanisms of synaptic plasticity in the dentate gyrus.
- Functional relevance of adult neurogenesis.
- Network activity in the dentate gyrus in vitro and in vivo.
- Network oscillations in the dentate gyrus.
- Network models of the dentate gyrus.

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