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Parasubiculum (Presubiculum)

The Parasubiculum—also commonly referred to as the Presubiculum—is a key component of the parahippocampal region of the brain. Located medially in the parahippocampal gyrus, between the subiculum and entorhinal cortex, it plays an important role in spatial navigation, memory processing, and integration of cortical input. This thin cortical area is part of the hippocampal formation and is notable for its unique cellular architecture and connectivity with both hippocampal and neocortical regions.

Synonyms

  • Parasubiculum

  • Presubiculum

  • Pre-subiculum

  • Transitional area of subiculum

Arterial Supply

  • Supplied primarily by branches of the posterior cerebral artery (PCA), especially the hippocampal arteries.

  • Some contribution may come from the anterior choroidal artery.

Venous Drainage

  • Venous outflow is mainly via the inferior ventricular veins.

  • Drains into the basal vein of Rosenthal and eventually into the great cerebral vein (vein of Galen).

Function

  • Involved in spatial orientation and navigation.

  • Integrates cortical sensory input and relays information to the hippocampus.

  • Participates in memory encoding and retrieval, particularly for spatial and contextual information.

  • Functions as an intermediary between the entorhinal cortex and the hippocampus proper.

MRI Appearance

  • T1-weighted Images:

    • Parasubiculum appears as a thin, hypointense (dark) band situated between the subiculum and the entorhinal cortex.

    • Difficult to distinguish precisely without high-resolution imaging.

  • T2-weighted Images:

    • Appears hyperintense (bright) relative to surrounding white matter, but differentiation from adjacent structures may be subtle.

    • Laminar structure may be appreciated with advanced MRI techniques.

  • FLAIR Sequences:

    • Generally appears similar to T2, with subtle hyperintensity.

    • No abnormal signal unless affected by pathology.

CT Appearance

  • Typically not distinctly visualized on routine CT due to limited contrast resolution.

  • Parasubiculum may be inferred as part of the medial temporal lobe anatomy.

  • Only becomes apparent if affected by mass effect, atrophy, or pathology altering regional density.

MRI images

Parasubiculum (Presubiculum) mri 3t coronal image