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Topic

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Prosubiculum

The prosubiculum is a distinct subfield of the hippocampal formation, located between the subiculum and the CA1 region of the hippocampus. Though sometimes overlooked in routine neuroanatomical descriptions, the prosubiculum plays a key role in hippocampal circuitry, acting as a transitional zone both structurally and functionally. It features unique cytoarchitectonic characteristics and is implicated in the modulation of information flow from the hippocampus to other limbic structures. The prosubiculum can be identified on high-resolution imaging, particularly in dedicated research protocols.

Synonyms

  • Subicular transitional zone

  • Prosubicular area

  • Hippocampal prosubiculum

Arterial Supply

  • Primarily supplied by branches of the posterior cerebral artery (PCA)

  • Specifically, the hippocampal branches of the PCA provide arterial blood

  • Possible minor contribution from the anterior choroidal artery

Venous Drainage

  • Drained by the hippocampal veins

  • These veins empty into the basal vein of Rosenthal and internal cerebral vein

  • Ultimately drains into the great cerebral vein (vein of Galen)

Function

  • Acts as a relay and integration zone between the subiculum and CA1 region

  • Involved in spatial memory, learning, and cognitive processing

  • Contributes to modulation of signals from the hippocampus to the entorhinal cortex and other limbic areas

MRI Appearance

  • T2-weighted MRI:

    • Appears as a thin, hyperintense band between the subiculum and CA1

    • May be better visualized on high-resolution coronal sections

  • T1-weighted MRI:

    • Presents as a subtle hypointense or isointense layer relative to surrounding hippocampal subfields

    • Differentiation from adjacent structures may be challenging without dedicated protocols

  • FLAIR MRI:

    • Generally demonstrates similar characteristics as T2, though with greater suppression of CSF signal

    • Appears as a discrete area with signal intensity intermediate between the subiculum and CA1

CT Appearance

  • Not distinctly visualized on standard CT imaging due to limited soft tissue contrast

  • The prosubiculum, like other hippocampal subfields, blends with adjacent grey matter structures

  • Only gross pathological changes (e.g., atrophy, calcification, or hemorrhage) might suggest involvement

MRI images

Prosubiculum mri 3t coronal image