New and distinct hippocampal place codes are generated in a new environment during septal inactivation.
The hippocampus generates distinct neural codes to disambiguate similar experiences, a process thought to underlie episodic memory function. Entorhinal grid cells provide a prominent spatial signal to hippocampus, and changes in their firing pattern could thus generate a distinct spatial code in each context. We examined whether we would preclude the emergence of new spatial representations in a novel environment during muscimol inactivation of the medial septal area, a manipulation known to disrupt theta oscillations and grid cell firing. We found that new, highly distinct configurations of place fields emerged immediately and remained stable during the septal inactivation. The new place code persisted when theta oscillations had recovered. Theta rhythmicity and feedforward input from grid cell networks were thus not required to generate new spatial representations in the hippocampus.
Neurobiology Section and Center for Neural Circuits and Behavior, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
Mark P
MP
Brandon
Neurobiology Section and Center for Neural Circuits and Behavior, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
Julie
J
Koenig
Neurobiology Section and Center for Neural Circuits and Behavior, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
Jill K
JK
Leutgeb
Neurobiology Section and Center for Neural Circuits and Behavior, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA; Kavli Institute for Brain and Mind, University of California, San Diego, La Jolla, CA 92093, USA. Electronic address: sleutgeb@ucsd.edu.
Stefan
S
Leutgeb
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001931:Brain Mapping; D003216:Conditioning, Operant / Q000502:physiology*; D004777:Environment; D005106:Exploratory Behavior / Q000502:physiology; D058785:GABA-A Receptor Agonists / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology*; D008297:Male; D009118:Muscimol / Q000494:pharmacology; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D051381:Rats; D020318:Rats, Long-Evans; D020665:Septum of Brain / Q000187:drug effects / Q000502:physiology*; D013028:Space Perception / Q000502:physiology*; D018709:Statistics, Nonparametric
D058785:GABA-A Receptor Agonists; D009118:Muscimol