Trisynaptic loop

The trisynaptic loop is a relay of synaptic transmission in the hippocampus. The hippocampal relay involves 3 main regions within the hippocampus which are classified according to their cell type and projection fibers. The first projection of the hippocampus occurs between the entorhinal cortex and the dentate gyrus. The entorhinal cortex transmits its signals from the parahippocampal gyrus to the dentate gyrus via granuel cell fibers. The dentate gyrus then synapses on pyramidal cells in CA3 via mossy cell fibers. CA3 then fires to CA1 shaffer collaterals which synapse in the subiculum and are carried out through the fornix. Collectively the dentate gyrus, CA1 and CA3 of the hippocampus compose the trisynaptic loop.