Open AccessGeometry of abstract learned knowledge in the hippocampus
Author(s) -
Edward H. Nieh,
Manuel Schottdorf,
Nicolas W. Freeman,
Ryan Low,
Sam Lewallen,
Sue Ann Koay,
Lucas Pinto,
Jeffrey Gauthier,
Carlos D. Brody,
David W. Tank
Publication year - 2021
Publication title -
nature
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 15.993
H-Index - 1226
eISSN - 1476-4687
pISSN - 0028-0836
DOI - 10.1038/s41586-021-03652-7
Subject(s) - encode , hippocampus , embodied cognition , functional magnetic resonance imaging , representation (politics) , computer science , encoding (memory) , hippocampal formation , spatial cognition , cognition , calcium imaging , curse of dimensionality , cognitive map , task (project management) , population , somatosensory system , manifold (fluid mechanics) , artificial intelligence , neuroscience , psychology , biology , chemistry , law , sociology , biochemistry , political science , calcium , demography , organic chemistry , politics , gene , engineering , management , mechanical engineering , economics
Hippocampal neurons encode physical variables 1-7 such as space 1 or auditory frequency 6 in cognitive maps 8 . In addition, functional magnetic resonance imaging studies in humans have shown that the hippocampus can also encode more abstract, learned variables 9-11 . However, their integration into existing neural representations of physical variables 12,13 is unknown. Here, using two-photon calcium imaging, we show that individual neurons in the dorsal hippocampus jointly encode accumulated evidence with spatial position in mice performing a decision-making task in virtual reality 14-16 . Nonlinear dimensionality reduction 13 showed that population activity was well-described by approximately four to six latent variables, which suggests that neural activity is constrained to a low-dimensional manifold. Within this low-dimensional space, both physical and abstract variables were jointly mapped in an orderly manner, creating a geometric representation that we show is similar across mice. The existence of conjoined cognitive maps suggests that the hippocampus performs a general computation-the creation of task-specific low-dimensional manifolds that contain a geometric representation of learned knowledge.