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Rolls ET, Treves A. A theory of hippocampal function: New developments. Prog Neurobiol 2024; 238:102636. [PMID: 38834132 DOI: 10.1016/j.pneurobio.2024.102636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Revised: 04/15/2024] [Accepted: 05/30/2024] [Indexed: 06/06/2024]
Abstract
We develop further here the only quantitative theory of the storage of information in the hippocampal episodic memory system and its recall back to the neocortex. The theory is upgraded to account for a revolution in understanding of spatial representations in the primate, including human, hippocampus, that go beyond the place where the individual is located, to the location being viewed in a scene. This is fundamental to much primate episodic memory and navigation: functions supported in humans by pathways that build 'where' spatial view representations by feature combinations in a ventromedial visual cortical stream, separate from those for 'what' object and face information to the inferior temporal visual cortex, and for reward information from the orbitofrontal cortex. Key new computational developments include the capacity of the CA3 attractor network for storing whole charts of space; how the correlations inherent in self-organizing continuous spatial representations impact the storage capacity; how the CA3 network can combine continuous spatial and discrete object and reward representations; the roles of the rewards that reach the hippocampus in the later consolidation into long-term memory in part via cholinergic pathways from the orbitofrontal cortex; and new ways of analysing neocortical information storage using Potts networks.
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Affiliation(s)
- Edmund T Rolls
- Oxford Centre for Computational Neuroscience, Oxford, UK; Department of Computer Science, University of Warwick, Coventry CV4 7AL, UK.
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Sammons RP, Vezir M, Moreno-Velasquez L, Cano G, Orlando M, Sievers M, Grasso E, Metodieva VD, Kempter R, Schmidt H, Schmitz D. Structure and function of the hippocampal CA3 module. Proc Natl Acad Sci U S A 2024; 121:e2312281120. [PMID: 38289953 PMCID: PMC10861929 DOI: 10.1073/pnas.2312281120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 11/01/2023] [Indexed: 02/01/2024] Open
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.
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Affiliation(s)
- Rosanna P. Sammons
- Neuroscience Research Center, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Neuroscience Research Center, Berlin10117, Germany
| | - Mourat Vezir
- Ernst Strüngmann Institute for Neuroscience, Frankfurt am Main60528, Germany
| | - Laura Moreno-Velasquez
- Neuroscience Research Center, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Neuroscience Research Center, Berlin10117, Germany
| | - Gaspar Cano
- Institute for Theoretical Biology, Department of Biology, Humboldt-Universität zu Berlin, Berlin10115, Germany
| | - Marta Orlando
- Neuroscience Research Center, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Neuroscience Research Center, Berlin10117, Germany
| | - Meike Sievers
- Department of Connectomics, Max Planck Institute for Brain Research, Frankfurt am Main60438, Germany
| | - Eleonora Grasso
- Ernst Strüngmann Institute for Neuroscience, Frankfurt am Main60528, Germany
| | - Verjinia D. Metodieva
- Neuroscience Research Center, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Neuroscience Research Center, Berlin10117, Germany
| | - Richard Kempter
- Institute for Theoretical Biology, Department of Biology, Humboldt-Universität zu Berlin, Berlin10115, Germany
- Bernstein Center for Computational Neuroscience Berlin, Berlin10115, Germany
- Einstein Center for Neurosciences Berlin, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Einstein Center for Neurosciences Berlin, Berlin10117, Germany
| | - Helene Schmidt
- Ernst Strüngmann Institute for Neuroscience, Frankfurt am Main60528, Germany
| | - Dietmar Schmitz
- Neuroscience Research Center, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Neuroscience Research Center, Berlin10117, Germany
- Bernstein Center for Computational Neuroscience Berlin, Berlin10115, Germany
- Einstein Center for Neurosciences Berlin, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Einstein Center for Neurosciences Berlin, Berlin10117, Germany
- German Center for Neurodegenerative Diseases Berlin, Berlin10117, Germany
- Max-Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin13125, Germany
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