Recently, I was wondering how long the rat hippocampus on the septal-temporal axis actually is. With my 3d model of the rat hippocampus and the Measure Panel Addon for Blender this is easy to measure. Simply select an edge loop within one of the planes and compute the path length.

I was pretty surprised when I saw that the dentate gyrus in my model is about 9.7mm long! First, I couldn’t believe that but when I looked into the original data by Kjonigsen et al. 2011, it became clear that this seems to be really the length of the rat hippocampus when it is unfolded in 2D.

Given the thin unmyelinated fibers in CA3 which have pretty long conduction times, signal processing within the hippocampal loop suddenly appears to be very slow. 😉