Structure and function of the hippocampal CA3 module¶
The Memory Decoding Challenge: Decode a non-trivial memory from a static map of synaptic connectivity.
A journal club by Aspirational Neuroscience & the Carboncopies Foundation.
Presented by Dr. Kenneth Hayworth
June 3, 2025
Paper: Structure and function of the hippocampal CA3 module
Rosanna P. Sammons, Mourat Vezir, Laura Moreno-Velasquez, Gaspar Cano, Marta Orlando, Meike Sievers, Eleonora Grasso, Verjinia D. Metodieva, Richard Kempter, Helene Schmidt, and Dietmar Schmitz
Proc. Natl. Acad. Sci. U.S.A. 121 (6) e2312281120, (2024). https://doi.org/10.1073/pnas.2312281120
Abstract¶
The hippocampal formation is crucial for learning and memory, with submodule CA3 thought to be the substrate of pattern completion. However, the underlying synaptic and computational mechanisms of this network are not well understood. Here, we perform circuit reconstruction of a CA3 module using three dimensional (3D) electron microscopy data and combine this with functional connectivity recordings and computational simulations to determine possible CA3 network mechanisms. Direct measurements of connectivity schemes with both physiological measurements and structural 3D EM revealed a high connectivity rate, multi-fold higher than previously assumed. Mathematical modelling indicated that such CA3 networks can robustly generate pattern completion and replay memory sequences. In conclusion, our data demonstrate that the connectivity scheme of the hippocampal submodule is well suited for efficient memory storage and retrieval.
Register for updates about the Memory Decoding journal club and Aspirational Neuroscience Prize.