Thread by @hipposubfields

Last week we talked about hippocampal variability in the hippocampal head.

The hippocampal tail is another area of the hippocampus that can vary anatomically across individuals

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But first, what do we mean by the hippocampal tail? Definitions vary, but one way to define the tail is the part of the hippocampus located posterior to the corpora quadrigemina (i.e. superior and inferior colliculi).

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The hippocampal dentations that can be visualized in the hippocampal body on the sagittal plane (pointed out earlier by @thomcat992). But they can also often be seen in the coronal plane in the hippocampal tail (as shown by @lemwisse and colleagues).

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That’s because of the curvature of the hippocampus—it often curves medially in the tail region. See these images from the Big Brain (@BigBrainProject) for 3D renderings that show off this curvature. (paper by @jordandekraker)

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.@RobindeFlores @david_berron @lemwisse and colleagues showed that sometimes the tail is more “curvey” and sometimes it is “straighter”.

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What about hippocampal subfields in the tail?

Yes, there are different subfields in the tail! Examples include the paper by De Flores (2019), Winterburn (2013) and Dalton below.

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As pointed out above, the anatomy is complicated and variable across individuals in the tail. Some protocols do not label the individual subfields in the tail (e.g. FreeSurfer v6 and v7) and instead give it a single label (periwinkle color in Fig below).

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That's it for this week! Do you have any more questions about anatomical variability in the medial temporal lobe? If so, send them along! ❓🧠❓

We are planning to host an "Ask me anything" session in the coming weeks! Stay tuned for more details! 😎

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