Progressive transformation of hippocampal neuronal representations in "morphed" environments.
Hippocampal neural codes for different, familiar environments are thought to reflect distinct attractor states, possibly implemented in the recurrent CA3 network. A defining property of an attractor network is its ability to undergo sharp and coherent transitions between pre-established (learned) representations when the inputs to the network are changed. To determine whether hippocampal neuronal ensembles exhibit such discontinuities, we recorded in CA3 and CA1 when a familiar square recording enclosure was morphed in quantifiable steps into a familiar circular enclosure while leaving other inputs constant. We observed a gradual noncoherent progression from the initial to the final network state. In CA3, the transformation was accompanied by significant hysteresis, resulting in more similar end states than when only square and circle were presented. These observations suggest that hippocampal cell assemblies are capable of incremental plastic deformation, with incongruous information being incorporated into pre-existing representations.
Leutgeb
Jill K
JK
Center for the Biology of Memory, Norwegian University of Science and Technology, NO-7489 Trondheim, Norway.
Leutgeb
Stefan
S
Treves
Alessandro
A
Meyer
Retsina
R
Barnes
Carol A
CA
McNaughton
Bruce L
BL
Moser
May-Britt
MB
Moser
Edvard I
EI
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001522:Behavior, Animal; D001931:Brain Mapping; D003198:Computer Simulation; D004777:Environment; D006624:Hippocampus / Q000166:cytology*; D008297:Male; D009415:Nerve Net / Q000502:physiology; D016571:Neural Networks, Computer; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D051381:Rats; D020318:Rats, Long-Evans; D012044:Regression Analysis; D013028:Space Perception / Q000502:physiology*; D013223:Statistics as Topic