How does the monosynaptic circuit differ from the trisynaptic circuit in the hippocampus?

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Patient H.M. and short-term memory loss explained — hippocampus Learn about Henry Molaison (better known as “patient H.M.”), whose short-term memory loss following a lobotomy helped researchers to understand how brain structures are related to brain function.

The hippocampus processes information through two primary neural circuits that differ in their anatomical pathways and the subregions they engage.1

Trisynaptic Circuit: This pathway forwards information from the entorhinal cortex to the dentate gyrus via the perforant path. From there, information flows to the CA3 region through the mossy fibre pathway and finally to the CA1 region along bundles of axons known as Schaffer collaterals.1
Monosynaptic Circuit: This circuit provides a more direct route by bypassing the dentate gyrus and the CA3 region entirely. It transmits information directly from the entorhinal cortex to the CA1 region.1

These circuits represent distinct methods of information flow within the hippocampal formation, allowing for different levels of processing and integration of neural signals.1